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1

AEROMYCOBIOTA OF WESTERN DESERT OF EGYPT  

Microsoft Academic Search

The prevalence of airborne mycobiota at six different regions of Western desert (5 regions) and Eastern desert (1) of Egypt was determined using the exposed-plate method. A total of 44 genera, 102 species and one variety in addition to some unidentified yeasts and dark sterile mycelia were collected. Of the above, only 5 species were isolated from the 15 exposures

M. A. Ismail; S. I. I. Abdel-Hafez; A. M. Moharram

2

Groundwater sapping processes, Western Desert, Egypt  

Microsoft Academic Search

Depressions of the Western Desert of Egypt (specifically, Kharga, Farafra, and Kurkur regions) are mainly occupied by shales that are impermeable, but easily erodible by rainfall and runoff, whereas the surrounding plateaus are composed of limestones that are permeable and more resistant to fluvial erosion under semiarid to arid conditions. Scallop-shaped escarpment edges and stubby-looking channels that cut into the

W. Luo; R. E. Arvidson; M. Sultan; R. Becker; M. K. Crombie; N. Sturchio; Z. El Alfy

1997-01-01

3

Groundwater sapping processes, Western Desert, Egypt.  

SciTech Connect

Depressions of the Western Desert of Egypt (specifically, Kharga, Farafra, and Kurkur regions) are mainly occupied by shales that are impermeable, but easily erodible by rainfall and runoff, whereas the surrounding plateaus are composed of limestones that are permeable and more resistant to fluvial erosion under semiarid to arid conditions. Scallop-shaped escarpment edges and stubby-looking channels that cut into the plateau units are suggestive of slumping of limestones by ground-water sapping at the limestone-shale interfaces, removal of slump blocks by weathering and fluvial erosion, and consequent scarp retreat. Spring-derived tufa deposits found near the limestone escarpments provide additional evidence for possible ground-water sapping during previous wet periods. A computer simulation model was developed to quantify the ground-water sapping processes, using a cellular automata algorithm with coupled surface runoff and ground-water flow for a permeable, resistant layer over an impermeable, friable unit. Erosion, deposition, slumping, and generation of spring-derived tufas were parametrically modeled. Simulations using geologically reasonable parameters demonstrate that relatively rapid erosion of the shales by surface runoff, ground-water sapping, and slumping of the limestones, and detailed control by hydraulic conductivity inhomogeneities associated with structures explain the depressions, escarpments, and associated landforms and deposits. Using episodic wet pulses, keyed by {delta}{sup 18}O deep-sea core record, the model produced tufa ages that are statistically consistent with the observed U/Th tufa ages. This result supports the hypothesis that northeastern African wet periods occurred during interglacial maxima. The {delta}{sup 18}O-forced model also replicates the decrease in fluvial and sapping activity over the past million years, as northeastern Africa became hyperarid. The model thus provides a promising predictive tool for studying long-term landform evolution that involves surface and subsurface processes and climatic change.

Luo, W.; Arvidson, R.E.; Sultan, M.; Becker, R.; Crombie, M.K.; Sturchio, N.; El Alfy, Z.; Environmental Research; Washington Univ.; Egyptian Geological Survey and Mining Authority

1997-01-01

4

The corrosive well waters of Egypt's western desert  

USGS Publications Warehouse

The discovery that ground waters of Egypt's Western Desert are highly corrosive is lost in antiquity. Inhabitants of the oases have been aware of the troublesome property for many decades and early investigators mention it in their reports concerning the area. Introduction of modern well-drilling techniques and replacements of native wood casing with steel during the 20th century increased corrosion problems and, in what is called the New Valley Project, led to an intense search for causes and corrective treatments. This revealed that extreme corrosiveness results from combined effects of relatively acidic waters with significant concentrations of destructive sulfide ion; unfavorable ratios of sulfate and chloride to less aggressive ions; mineral equilibria and electrode potential which hinder formation of protective films; relative high chemical reaction rates because of abnormal temperatures, and high surface velocities related to well design. There is general agreement among investigators that conventional corrosion control methods such as coating metal surfaces, chemical treatment of the water, and electrolytic protection with impressed current and sacrificial electrodes are ineffective or impracticable for wells in the Western Desert's New Valley. Thus, control must be sought through the use of materials more resistant to corrosion than plain carbon steel wherever well screens and casings are necessary. Of the alternatives considered, stainless steel appears to. be the most promising where high strength and long-term services are required and the alloy's relatively high cost is acceptable. Epoxy resin-bonded fiberglass and wood appear to be practicable, relatively inexpensive alternatives for installations which do. not exceed their strength limitations. Other materials such as high strength aluminum and Monel Metal have shown sufficient promise to. merit their consideration in particular locations and uses. The limited experience with pumping in these desert wells leaves uncertainties concerning the durability of conventional pump designs. Egypt's New Valley Project provides an excellent opportunity for continuing study of the corrosion problems that concern ground-water developers in many parts of the world.

Clarke, Frank Eldridge

1979-01-01

5

Normal faulting mechanisms in the Western Desert of Egypt  

NASA Astrophysics Data System (ADS)

Egypt is recognized as a moderate seismicity region where earthquakes are distributed within several active regions. Owing to sparse distribution of both seismicity and seismic stations, mostly moderate-size Egyptian earthquakes were recorded by regional stations. One of such cases is the moderate-size earthquakes of moment magnitudes greater than 4.0 which struck the Western Desert of Egypt in 1998 and 1999. These events are the first instrumentally recorded earthquakes occurring in the area. In the present study, the source mechanism for these earthquakes was estimated using the waveform data recorded from one of the very broadband MedNet seismograph stations and polarities from the national short-period seismographs. An iterative technique was applied to find the best-fit double-couple mechanism by a grid search over strike, dip and rake. Regional synthetic seismograms were calculated by using f- k integration in the frequency range of 0.03-0.1 Hz. A crustal structure fitted to surface wave dispersion curves was used to compute Green’s function. Focal depths were determined through the grid search method for a range of source depths. Our results show a normal faulting mechanism with minor strike-slip component. The NNW trend has been chosen as a preferred rupture plane in consistence with surface and subsurface faults and microearthquake seismicity in the epicenteral area as well.

Abdel-Fattah, Ali K.; Badawy, Ahmed; Kim, K. Y.

2007-01-01

6

Radiological assessment of Abu-Tartur phosphate, Western Desert Egypt.  

PubMed

The contents of natural radionuclides ((226)Ra, (232)Th and (40)K) were measured in sedimentary phosphate rock samples (Abu-Tartur phosphate, Western Desert Egypt) by using gamma spectrometry (NaI (Tl) 3"x 3"). Phosphate and environmental samples were collected from Abu-Tartur phosphate mine and the surrounding region. The results are discussed and compared with the levels in phosphate rocks from different countries. The activities of (226)Ra, (232)Th series and (40)K are between (14.9 +/- 0.8 and 302.4 +/- 15.2), (2.6 +/- 1.0 and 154.9 +/- 7.8) and (10.0 +/- 0.5 and 368.4 +/- 18.4) Bq kg(-1), respectively. The Abu-Tartur phosphate deposit was found to have lower activity than many others exploited phosphate sedimentary deposits, with its average total annual dose being only 114.6 microSv y(-1). This value is about 11.46% of the 1.0 mSv y(-1) recommended by the International Commission on Radiological Protection (ICRP-60, 1990) as the maximum annual dose to members of the public. PMID:18252854

Uosif, M A M; El-Taher, A

2008-01-01

7

Ground-water sapping processes, Western Desert, Egypt  

SciTech Connect

Depressions of the Western Desert of Egypt (specifically, Kharga, Farafra, and Kurkur regions) are mainly occupied by shales that are impermeable, but easily erodible by rainfall and runoff, whereas the surrounding plateaus are composed of limestones that are permeable and more resistant to fluvial erosion under semiarid to arid conditions. A computer simulation model was developed to quantify the ground-water sapping processes, using a cellular automata algorithm with coupled surface runoff and ground-water flow for a permeable, resistant layer over an impermeable, friable unit. Erosion, deposition, slumping, and generation of spring-derived tufas were parametrically modeled. Simulations using geologically reasonable parameters demonstrate that relatively rapid erosion of the shales by surface runoff, ground-water sapping, and slumping of the limestones, and detailed control by hydraulic conductivity inhomogeneities associated with structures explain the depressions, escarpments, and associated landforms and deposits. Using episodic wet pulses, keyed by {delta}{sup 18}O deep-sea core record, the model produced tufa ages that are statistically consistent with the observed U/Th tufa ages. This result supports the hypothesis that northeastern African wet periods occurred during interglacial maxima. This {delta}{sup 18}O-forced model also replicates the decrease in fluvial and sapping activity over the past million years. 65 refs., 21 figs., 2 tabs.

Luo, W.; Arvidson, R.E.; Sultan, M.; Becker, R.; Crombie, M.K. [Washington Univ., St. Louis, MO (United States)] [Washington Univ., St. Louis, MO (United States); Sturchio, N. [Argonne National Lab., IL (United States)] [Argonne National Lab., IL (United States); Alfy, Z.E. [Egyptian Geological Survey and Mining Authority, Cairo (Egypt)] [Egyptian Geological Survey and Mining Authority, Cairo (Egypt)

1997-01-01

8

Geochemistry and microprobe investigations of Abu Tartur REE-bearing phosphorite, Western Desert, Egypt  

Microsoft Academic Search

Phosphorites in Egypt occur in the Eastern Desert, the Nile Valley and the Western Desert at Abu Tartur area and present in Duwi Formation as a part of the Middle Eastern to North African phosphogenic province of Late Cretaceous to Paleogene age (Campanian–Maastrichtian). The Maghrabi-Liffiya phosphorite sector is considered as the most important phosphorite deposits in the Abu Tartur area

Gamal S. Awadalla

2010-01-01

9

SEDIMENTOLOGICAL AND TECHNICAL STUDIES ON THE MONTMORILLONITIC CLAYS OF ABU TARTUR PLATEAU, WESTERN DESERT, EGYPT  

Microsoft Academic Search

One of the most known sedimentary formation among Egyptian Upper Cretacous rock units is named Duwi Formation (Lower Maastrichtian), an outcrop at the Abu Tartur plateau, Kharga Oasis, Western Desert, Egypt. This formation displays three montmorillonitic clayey layers. The investigations of these sediments provide information on the texture, constituents and type of clay minerals, which helps define and describe their

Kadry N. SEDIEK; Ashraf M. AMER

10

Distribution of REE in shales overlying the Abu Tartur phosphorite deposit, Western Desert, Egypt  

Microsoft Academic Search

The phosphorite deposit of Abu-Tartur plateau, Western Desert, Egypt is one of the largest phosphorite deposits of the world. Previous investigations had revealed that these deposits contain appreciable amounts of rare earth elements (REE) reaching up to 2000 ppm. The distribution pattern of REE indicate terrestrial origin, whereas the phosphorites are of marine origin. This situation suggests that the REE

A. A Fakhry; K. A Eid; A. A Mahdy

1998-01-01

11

SEDIMENTOLOGICAL AND TECHNOLOGICAL STUDIES OF ABU TARTUR BLACK SHALES, WESTERN DESERT, EGYPT  

Microsoft Academic Search

Newly conventional combination of sedimentological and technological studies aid in estimation of the resource potential of the Upper Cretaceous clays of Duwi Formation Abu Tartur plateau Western Desert, Egypt. This formation consists of interbedded black to Grey shale, phosphatic and glauconitic sandstones. The granulometric, mineralogical, and geochemical analyses were carried out on the black clays, which provided detailed information about

Kadry N. SEDIEK; Ashraf M. AMER

2001-01-01

12

Habitat of oil in Abu Gharadig and Faiyum basins, Western Desert, Egypt  

Microsoft Academic Search

The Abu Gharadig and Faiyum basins are areas which have some of the greatest hydrocarbon potential in the Western Desert of Egypt. Several extensive cycles of marine transgression and regression occurred in these territories through geologic time. The depositional cycles combined with at least 3 tectonic cycles - (1) the Hercynian orogeny at the end of the Paleozoic, (2) from

Awad

1984-01-01

13

Habitat of oil in Abu Gharadig and Faiyum basins, Western Desert, Egypt  

Microsoft Academic Search

The Abu Gharadig and Faiyum basins are areas which have some of the greatest hydrocarbon potential in the Western Desert of Egypt. Several extensive cycles of marine transgression and regression occurred in these territories through geologic time. The depositional cycles combined with at least 3 tectonic cycles--the Hercynian orogeny at the end of the Paleozoic, from Late Jurassic to early

Awad

1984-01-01

14

New age constraints on the Middle Stone Age occupations of Kharga Oasis, Western Desert, Egypt  

E-print Network

New age constraints on the Middle Stone Age occupations of Kharga Oasis, Western Desert, Egypt, can provide a directly datable stratigraphic context for Middle Stone Age/Middle Paleolithic (MSA-series analysis. At Mata'na Site G (KH/MT-02), Middle Stone Age (``Upper Levalloisian'') material is underlain

Asmerom, Yemane

15

Volatiles in the Desert: Subtle Remote-sensing Signatures of the Dakhleh Oasis Catastrophic Event, Western Desert, Egypt  

NASA Technical Reports Server (NTRS)

Over the past decade members of the Dakhleh Oasis Project have studied enigmatic signatures in the Pleistocene geologic record of portions of the Dakhleh oasis and palaeo-oasis in Egypt's Western Desert [1,2]. In particular, Si-Ca-Al rich glass melt (Dakhleh Glass, Fig. 1) points to a catastrophic event between c.100,000-200,000 years ago [3] in this well-studied African savannah and freshwater lake Middle Stone Age environment [4,5].

Haldemann, A. F. C.; Kleindienst, M. R.; Churcher, C. S.; Smith, J. R.; Schwarcz, H. P.; Osinski, G.

2005-01-01

16

Mesozoic rift basins in western desert of Egypt, their southern extension and impact on future exploration  

SciTech Connect

Rift basins are a primary target of exploration in east, central, and west Africa. These intracratonic rift basins range in age from the Triassic to the Neogene and are filled with lagoonal-lacustrine sand-shale sequences. Several rift basins may be present in the Western Desert of Egypt. In the northeastern African platform, the Mesozoic Tethyan strand lines were previously interpreted to have limited southern extension onto the continent. This concept, based upon a relatively limited amount of subsurface data, has directed and focused the exploration for oil and gas to the northernmost 120 km of the Western Desert of Egypt. Recent well and geophysical data indicate a southerly extension of mesozoic rift basins several hundred kilometers inland from the Mediterranean Sea. Shushan/Faghur and Abu Gharadig/Bahrein basins may represent subparallel Mesozoic basins, trending northeast-southwest. Marine Oxfordian-Kimmeridgian sediments were recently reported from wells drilled approximately 500 km south of the present-day Mediterranean shoreline. The link of these basins with the Sirte basin to the southwest in Libya is not well understood. Exploration is needed to evaluate the hydrocarbon potential of such basins.

Taha, M.A. (Conoco, Cairo (Egypt))

1988-08-01

17

Plant Lipids and Fossil Hydrocarbons in Embalming Material of Roman Period Mummies from the Dakhleh Oasis, Western Desert, Egypt  

Microsoft Academic Search

Embalming material contained in four mummies from the Roman Period (4th century ad ) excavated in the Dakhleh Oasis, Western Desert of Egypt, were analysed for the soluble lipid components. According to the distribution patterns of n -alkanes, steroid hydrocarbons, polycyclic terpane hydrocarbons, n -fatty acids, diterpenoid acids and wax esters, the embalming material mainly consists of plant material including

Joachim Maurer; Thomas Möhring; Jürgen Rullkötter; Arie Nissenbaum

2002-01-01

18

Indications for a humid climate in the Western Desert of Egypt 11–10 Myr ago: evidence from Galagidae (Primates, Mammalia)  

Microsoft Academic Search

The timing of desertification of the Sahara Desert is poorly understood, with recent estimates indicating an onset of hyper-aridity during the Latest Miocene. Field work in Egypt in 2005 has led to the discovery of evidence that indicates that 11–10 Ma the Western Desert was covered in woodland. Fossiliferous cave breccia at Sheikh Abdallah, Western Desert, Egypt, has yielded a Late

Martin Pickford; Hamdallah Wanas; Hosny Soliman

2006-01-01

19

Optimal well locations using genetic algorithm for Tushki Project, Western Desert, Egypt  

NASA Astrophysics Data System (ADS)

Groundwater depletion is one of the most important problems threaten the national projects in Egypt. The optimal distribution of well locations and pumping rates mitigate this problem. In this paper, a trial to mitigate this problem in Tushki National Project, south western desert, Egypt was carried out via delineating the optimal well locations and optimal pumping rates. The methodology of combination between simulation and optimization techniques was applied. A linked simulation-optimization model for obtaining the optimum management of groundwater flow is used in this research. MODFLOW packages are used to simulate the groundwater flow system. This model is integrated with an optimization model OLGA (Optimal well Location using Genetic Algorithm technique) which is based on the genetic algorithm (GA). Two management cases were considered by running the model in Abu Simbel-Tushki area with adopted steady and transit calibrated parameters. The first case (fixed well location) is found that the optimum value of the objective function (maximum pumping rate). In the second case (flexible well location with the moving well option) locations of wells are to be decided by the OLGA model itself within a user defined region of the model grid until the optimal location is reached. Also, the prediction of the future changes in both head and flow were made in steady and transient states.

Khalaf, S.; Gad, M. I.

2014-10-01

20

Uranium isotopic study of artesian and pluvial contributions to the Nubian Aquifer, Western Desert, Egypt  

NASA Astrophysics Data System (ADS)

The groundwater systems of the Nubian Aquifer beneath six major oases (Baris, Kharga, Dakhla, Farafra, Bahariya, and Siwa) in the Western Desert of Egypt have been studied to establish their sources and mixing volumes using uranium isotopes. One hundred six groundwater samples from different depths of the Nubian Aquifer have been analyzed for uranium content and 234U/ 238U activity ratio (AR). The aquifer under the Western Desert is known to have more than one source of water. At Bahariya and Farafra Oases, the Nubian artesian water migrating from the south has been augmented by local recharge during pluvial times. At Siwa Oasis in the northwestern desert, a shallower aquifer component migrating from the north or west is also present. At Dakhla, Kharga and Baris Oases in the southwestern desert, the main source is the Nubian artesian water migrating from southeast Uweinat Upland and northwest Sudan. These water masses have distinctive uranium isotopic signatures. The Nubian Aquifer water is characterized by very low U concentrations (<0.05 ppb) and a relatively high 234U/ 238U AR (>1.5). The shallow northwest aquifer water also has a high AR but a much higher U concentration. The locally recharged pluvial waters have high U concentrations (>0.1 ppb) but low ARs, near unity. A diagnostic derivative parameter is excess 234U content. The deep Nubian Aquifer water is characterized by a relatively low excess 234U (<0.02 ppb equivalent), while the shallow Siwa water has a very high excess 234U [(AR-1)(U conc.)]. The Bahariya and Farafara waters are also high in this component, probably because of pluvial water percolation through phosphate rich strata. At all oases, U isotopic mixing diagrams show that the deep aquifer sources predominate; however, the pluvial contributions are significant, ranging from about 5% at remote Baris Oasis to about 26% at the more northerly Farafra Oasis. The observed lowering of potentiometric surfaces in the Western Desert is caused not only by pumping at a rate greater than inflow from the aquifer systems, but also by the withdrawal of pluvial water which in modern times is not being replaced at all.

Dabous, A. A.; Osmond, J. K.

2001-03-01

21

Precipitation Source Inferred from Stable Isotopic Composition of Pleistocene Groundwater and Carbonate Deposits in the Western Desert of Egypt  

Microsoft Academic Search

An Atlantic source of precipitation can be inferred from stable isotopic data (H and O) for fossil groundwaters and uranium-series-dated carbonate spring deposits from oases in the Western Desert of Egypt. In the context of available stable isotopic data for fossil groundwaters throughout North Africa, the observed isotopic depletions (?D ?72 to ?81‰; ?18O ?10.6 to ?11.5‰) of fossil (?32,000

Mohamed Sultan; Neil Sturchio; Fekri A. Hassan; Mohamed Abdel Rahman Hamdan; Abdel Moneim Mahmood; Zeinhom El Alfy; Tom Stein

1997-01-01

22

Habitat of oil in Abu Gharadig and Faiyum basins, Western Desert, Egypt  

SciTech Connect

The Abu Gharadig and Faiyum basins are areas which have some of the greatest hydrocarbon potential in the Western Desert of Egypt. Several extensive cycles of marine transgression and regression occurred in these territories through geologic time. The depositional cycles combined with at least 3 tectonic cycles--the Hercynian orogeny at the end of the Paleozoic, from Late Jurassic to early Tertiary, and from Late Cretaceous to middle Tertiary--resulted in a highly deformed, thick sedimentary sequence. This organic-rich Jurassic-Upper Cretaceous-lower Tertiary sequence in large areas of these basins was subjected to enough heat and depth to generate hydrocarbons. It is evident from recent discoveries that these source rocks generated large amounts of highquality oil and gas. Exploration efforts should be concentrated on deep structures close to the main depocenters and inside or very close to the 150/sup 0/F geothermal contour. Contemporaneous structures on the northern rims of the basins should have high potential, resulting from migration of hydrocarbons from the south across major faults. The Jurassic in the northeastern part of the Abu Gharadig basin may provide good hydrocarbon potential. The lower Tertiary sequence present in the troughs also may have large amounts of oil entrapped in situ or resulting in shortdistance migration to the northern structures or to the Late Cretaceous-early Tertiary Syrian arc traps.

Awad, G.M.

1984-05-01

23

Habitat of oil in Abu Gharadig and Faiyum basins, Western Desert, Egypt  

SciTech Connect

The Abu Gharadig and Faiyum basins are areas which have some of the greatest hydrocarbon potential in the Western Desert of Egypt. Several extensive cycles of marine transgression and regression occurred in these territories through geologic time. The depositional cycles combined with at least 3 tectonic cycles - (1) the Hercynian orogeny at the end of the Paleozoic, (2) from Late Jurassic to early Tertiary, and (3) from Late Cretaceous to middle Tertiary - resulted in a highly deformed, thick sedimentary sequence. This organic-rich Jurassic-Upper Cretaceous-lower Tertiary sequence in large areas of these basins was subjected to enough heat and depth to generate hydrocarbons. The Abu Gharadig and Faiyum basins are separated structurally by a major ridge. Both basins are bounded on the north by another major ridge associated with Cretaceous and Tertiary faulting. A major platform with tin sedimentary cover forms the southern boundary. The hydrocarbon potential exists in cyclic sequences of sandstone, shale, and carbonate, having moderate porosities and permeabilities. An important hydrologic phenomenon prevails in major parts of the basins; fresh water has flushed the early Cenomanian and older reservoirs. Exploration efforts should be concentrated on deep structures close to the main depocenters and inside or very close to the main depocenter and inside or very close to the 150/sup 0/F (65/sup 0/C) geothermal contour.

Awad, G.M.

1984-05-01

24

Authigenic dolomite cementation in the Upper Cretaceous Phosphate Formation, Western Desert, Egypt  

NASA Astrophysics Data System (ADS)

The Upper Cretaceous Phosphate Formation in the Western Desert of Egypt displays a characteristic facies association that includes marine phosphorites interbedded with black shales and glauconitic sandstones. The upper part of the formation is characterized by the presence of thin phosphatic beds, which are filled-extensively-with disordered and non stoichiometric (mean MgCO 3 = 41.4 ± 0.34 mol%) authigenic dolomite cement. SEM and the back scattered images of these coarse crystalline dolomite cements reveal that they display planar euhedral crystal boundaries, polymodal crystal size distribution and variable inclusion pattern. The relatively low and wide ranged ?18O (- 0.87 to - 4.15‰ VPDB) values of the dolomite cements coupled with their depleted Sr (mean = 187 ± 26 ppm) and high iron and manganese values (mean = 6851 ± 554 ppm and 11599 ± 229 ppm respectively) invoke that they were formed from mixed hypo-saline fluids within a mixing marine-meteoric zone probably during a low stand period at the vicinity of the Maastrichtian/Early Tertiary unconformity. Meanwhile, their negative ?13C (- 1.31 to - 3.56‰ VPDB) values argue for a possible involvement of isotopically light carbon, derived from degradation of organic matter, during their precipitation.

Rifai, Rifai I.; Shaaban, Mohamad N.

2007-12-01

25

Remote sensing and geophysical investigations of Moghra Lake in the Qattara Depression, Western Desert, Egypt  

NASA Astrophysics Data System (ADS)

The Western Desert covers two-thirds of the land area of Egypt and occupies one of the driest regions of the Sahara. Seven depressions within the desert - Siwa, Qattara, Fayum, Bahariya, Farafra, Dakhla, and Kharga - may represent parts of old drainage systems with deflation, extensive erosion, and possibly, some tectonic activity. Oases with freshwater exist in these depressions. Geological and geophysical investigations in the Qattara Depression indicate the presence of buried fluvial channels with southeast to northwest flow directions from the highland areas. The origin of these fluvial systems, as well as the origin of the depressions themselves, is still unresolved, and many ideas have been suggested. Moghra Lake at the northeastern tip of the Qattara basin may be a remnant of a larger paleolake, including the mouth of a paleo-river. We present here the results of our recent work in this area using ALOS PALSAR radar remote sensing data, which indicated the presence of buried channels that may have fed the larger Moghra paleolake. Ground penetrating radar (GPR) data along 2D profiles were acquired; the migrated GPR sections identified a major paleochannel with numerous minor channels at its margins. GPR interpretations are verified by field observations, trenching, and stratigraphic information from outcrop data. Potential field analyses identify possible aquifers that are controlled by regional structures. Density contrasts within the sedimentary units, physical boundaries of uplifted basement blocks and depths to causative sources were also identified. This work contributes to the reconstruction of paleodrainage of this region and helps in understanding processes involved in the formation of the Qattara Depression.

Khan, Shuhab D.; Fathy, Mohamed S.; Abdelazeem, Maha

2014-02-01

26

Reconstructing Quaternary pluvial episodes and paleohydrology using travertines from Egypt's Western Desert  

NASA Astrophysics Data System (ADS)

Quaternary climate in North Africa was marked by multiple wet periods overprinting extreme aridity, but pluvial drivers, as well as their timing and geographic extent, are poorly constrained. We address these factors in the first comprehensive analysis of travertine from Egypt's Western Desert, which represents a unique and under-utilized record of paleoclimate and paleohydrology. We infer large-volume travertine mound deposition along faults near the area's central limestone plateau to reflect times of high discharge (high groundwater head) from springs of the Nubian aquifer, likely associated with so-called Green Sahara pluvial episodes. Similarly, we assume that travertine platforms in depressions (oases) represent related marsh and lake deposition, including a widespread late Cenozoic dolostone of probable lacustrine origin in Farafra Oasis, which needs additional mapping. We present the results of uranium-series analysis of travertines from oasis areas spanning a north-south gradient through the Western Desert; we dated the tops and bottoms of inset deposits at different wadi (wash) elevations to resolve the inception and termination of high spring heads/pluvials as well as regional aggradation or incision patterns. Our dates, combined with published literature ages, suggest wet intervals around 100-115, 125-140, 180-200, 350-360, 450, and 600 ka. Heights of inset terrace travertines in wadis are potentially correlative between sites and are seen as approximately 5, 10, and 25 m above the modern wadi levels. Assuming that paleohydrological changes reflect paleoclimate changes, we examine correlations between times of travertine deposition, relative to glacial cycles or to more specific orbital forcings, acting on the North African summer monsoon. Initial comparison of travertine occurrence to glacial cycles shows no obvious correlation, although there are major travertine deposition episodes at important paleoclimate transitions such as MIS 6 to 5, 7 to 6, and 11 to 10. Perhaps the best preliminary association is to orbital forcing, particularly precession, consistent with the hypothesis that orbital forcing is a driver of the North African monsoon and thus pluvials.

Jimenez, G.; Crossey, L. J.; Karlstrom, K. E.; Ricketts, J. W.; Tafoya, A. J.; Anan, T.; Mohammed, A.; Asmerom, Y.; Polyak, V.; Farouk, S.

2012-12-01

27

Remote Sensing and Shallow Geophysical Investigations on Moghra Lake in Northeastern Qattarra Depression, Western Desert, Egypt  

NASA Astrophysics Data System (ADS)

The Western Desert of Egypt encompasses two thirds of the land area of Egypt and constitutes one of the driest regions of the Sahara. This desert has seven depressions; Siwa, Qattara, Fayium, Bahariya, Farafra, Dakhla and Kharga. These depressions may be the manifestation of old drainage basins with extensive erosion and possibly some tectonic activity. Several oases with freshwater can be found in these depressions. Geological and geophysical investigations in Qattara Depression indicate several buried fluvial channels with flow direction from highlands in southeast to northwest. Moghra Lake at the northeastern tip of Qatarra basin may be a small remnant of a larger paleo-lake including the mouth of a paleo-river. This study probed this area for presence of buried channels that may have fed the larger Moghra paleo-lake. We have used ALOS - PALSAR radar remote sensing data to identify the surface features in this region, such as channels, channel fills, and fractures. In addition, dual polarization PALSAR data (HV, HH) allowed analysis of the near surface geology and assisted in delineating areas of interest for GPR surveys. GPR data along 2D profiles were acquired using the GSSI SIR-3000 system with a 400 MHz antenna that provided images to approximately three meters in depth. All the GPS data were processed using RADAN 6.6 software. A conventional processing flow was used for data processing: The positional correction tool removed the air wave. A range-gain balanced the amplitudes and a final band-pass (50 kHz to 500 kHz) filter was applied to the data. Deconvolution was also applied for highlighting the finer details. In addition, spatial filters were used to attenuate continuous vertical noise. The migrated sections of GPR identified a major paleochannel distributary with two minor channels at the margins. The bedrock of the studied area consists of the Lower Miocene Moghra Formation (sandstone and shale intercalations). The area around the present lake is covered by about 2 m of lacustrine sediments of post-Miocene age in the east side and by recent eolian dunes in the west. These sediments are characterized by shallowing upward, horizontal to cross-bedded with an unconformity in between. The eastern end of the paleochannel surveyed by GPR is covered by recent sand dunes followed by an ephemeral stream that feeds the current lake. Field observations suggest that the movement of sand dunes in the northeast direction may have blocked the paleo-channel. A two meters deep trench was dug to confirm the GPR findings. Regional gravity mapping of this area also shows major gravity anomalies. More work is planned to carry out additional high resolution potential field surveys in conjunction with remote sensing and GPR studies to understand the paleo-drainage of this area. Identifying the exact track of the paleo-channels will help reconstructing of paleo drainage of this region and may help in mapping groundwater, this will be very important for the development of this rapidly expanding desert area.

Khan, S. D.; Fathy, M. S.; Azeem, M. A.

2012-12-01

28

Diagenetic origin of ironstone crusts in the Lower Cenomanian Bahariya Formation, Bahariya Depression, Western Desert, Egypt  

NASA Astrophysics Data System (ADS)

In this paper, a new interpretation of the ironstone crusts of the Bahariya Formation as late diagenetic products is provided. The siliciclastic Lower Cenomanian Bahariya Formation outcropping in the northern part of the Bahariya Depression (Western Desert, Egypt) is subdivided into three informal units that are mainly composed of thinly laminated siltstone, cross-bedded and massive sandstone, fossiliferous sandstone/sandy limestone and variegated shale. Abundant ironstone crusts occur preferentially within its lower and upper units but are absent in the middle unit. The ironstone crusts show selective replacement of carbonate components, including calcretes, by iron oxyhydroxides. More permeable parts of the terrigenous beds such as burrow traces, subaerial exposure surfaces, concretionary features and soft-sediment deformation structures led to heterogeneous distribution of the iron oxyhydroxides. A variety of diagenetic minerals, where goethite and hematite are the main end-products, were characterized by mineralogical analysis (XRD), petrography and SEM observation, and geochemical determinations (EMPA). Other diagenetic minerals include Fe-dolomite/ankerite, siderite, manganese minerals, barite, silica, illite/smectite mixed-layer, and bitumen. These minerals are interpreted to be formed in different diagenetic stages. Some minerals, especially those formed during eodiagenesis, show features indicative of biogenic activity. During burial, dolomite and ankerite replaced preferentially the depositional carbonates and infilled secondary porosity as well. Also during mesodiagenesis, the decomposition of organic matter resulted in the formation of bitumen and created reducing conditions favorable for the mobilization of iron-rich fluids in divalent stage. Telodiagenesis of the Cenomanian Bahariya deposits took place during the Turonian-Santonian uplift of the region. This resulted in partial or total dissolution of Fe-dolomite and ankerite which was concomitant to iron oxyhydroxide precipitation upon mixing with shallow oxygenated water. Circulation of reducing iron-rich fluids through fractures and inter and intrastratal discontinuities is proposed as an alternative model to explain the controversial source of iron for the ironstone crusts of the Bahariya Formation. The origin of iron-rich fluids is probably related to the basement rocks. The provided model relates the fluid movements through fractures and discontinuities with the preferential replacement of carbonates. This combination of processes is consistent with the heterogeneous geometries and the wide distribution of the ironstones.

Afify, A. M.; Sanz-Montero, M. E.; Calvo, J. P.; Wanas, H. A.

2015-01-01

29

PALEOMAGNETISM OF THE UPPER CRETAEOUS BAHARIYA FORMATION, BAHARIYA OASIS, WESTERN DESERT, EGYPT  

Microsoft Academic Search

A total of 70 samples were collected at 14 sites from the Upper Cretaceous Nubia Sandstones of Gebel El Dist, Bahariya Formation, Bahariya Oasis, Western Desert for paleomagnetic and rock magnetic studies. Rock magnetic measurements indicated that the main magnetic carrier is hematite. Magnetite and goethite are also present as subordinate constituents. Careful thermal demagnetization was applied to the samples

Hatem Odah

2004-01-01

30

Sedimentary cover in the South Western Desert of Egypt as deduced from Bouguer gravity and drill-hole data  

NASA Astrophysics Data System (ADS)

The Western Desert, Egypt includes the major groundwater aquifer in the country. It is apart from the Major Sahara Nubian Aquifer which is present in Sudan, Chad, Egypt and Libya. Thickness of this aquifer is changed laterally from south to north and also from west to east. The changes may structurally or litheologicalley control. The present study is focused on using of Bouguer gravity anomaly mapped at a scale of 1:500,000 and the lithological logs of about 120 deep wells used to determine the thickness of the sedimentary sequence containing the main Nubian sandstone water aquifer in important area of Egypt. The area is located in the southern part of the Western Desert bounded by the latitudes 22°00'-26°30'N, and longitudes 28°30'-33°00'E. The predominant structures affecting the basement rocks and the sedimentary cover were traced and analyzed. The gravity stripping approach was applied to eliminate the gravity effects caused by sedimentary sequence and to separate density anomalies within the sedimentary fill from the influence of rocks at deeper levels in the crystalline crust. The study indicated that the surface of the basement rocks is highly rugged and mostly controlled by structures which have a direct effect on thickness variation of the sedimentary cover all over the area. Regionally the area is characterized by two major intracratonic basins (the Dahkla Basin and the Nile valley Basin) separated by a NE-SW trending swell of the Kharga uplift and bounded at the south by the Oweinat-Bir Safsaf-Aswan uplift. These major tectonic units are controlled by fault structures trending in N-S, E-W, NE-SW, NW-SE, which cut the basement rocks and extend upward in the sedimentary cover. The maximum thickness of sandstone formations is recorded at west Oweinat, west Kurkur, southwest of Aswan, Gramashin, Dakhla oasis and some localities west of Sohag and Qena towns. At these localities the thickness ranges between 600 and 900 m. As this formation is the main water aquifer in the study area, therefore these localities are characterized by the presence of big amount of ground water. Accordingly, these areas must take the priority in the sustainable development programs of southern Egypt.

Senosy, M. M.; Youssef, M. M.; Abdel Zaher, M.

2013-06-01

31

Eolian features in the Western Desert of Egypt and some applications to Mars.  

USGS Publications Warehouse

Relations of landform types to wind regimes, bedrock composition, sediment supply, and topography are shown by field studies and satellite photographs of the Western Desert. This desert provides analogs of Martian wind-formed features and sand dunes, alternating light and dark streaks, knob 'shadows' and yardangs. Surface particles have been segregated by wind into dunes, sand sheets, and light streaks, that can be differentiated by their grain size distributions, surface shapes, and colors. Throughgoing sand of mostly fine to medium grain size is migrating S in longitudinal dune belts and barchan chains whose long axes lie parallel to the prevailing W winds, but topographic variations such as scarps and depressions strongly influence the zones of deposition and dune morphology. -from Authors

El-Baz, F.; Breed, C.S.; Grolier, M.J.; McCauley, J.F.

1979-01-01

32

Thermochronometric Investigation of Multiple Unconformities and Post-depositional Thermal History of a Fault Block in the Northern Western Desert, Egypt  

E-print Network

. Geological Setting 7 3.1 Proterozoic Formation of Gondwana and Proterozoic Effects of 7 Gondwanan Suture Zones 3.2 Paleozoic Evolution and Neotethys Formation 8 3.3 Mesozoic Evolution and Supercontinental Breakup 9 4. Northern Western... CHAPTER 1: Thermochronometric investigation of multiple unconformities and post- depositional thermal history of a fault block in the northern Western Desert, Egypt Abstract 1 1. Introduction 2 2. Detrital Geochronology and Thermochronology 4 3...

Glauser, Travis Robert

2010-12-13

33

Magnetization of three Nubia Sandstone formations from Central Western Desert of Egypt  

NASA Astrophysics Data System (ADS)

A total of 198 oriented cores (from 16 sites) have been sampled from three Cretaceous Nubia sandstone formations distributed around the Kharga-Dakhla and Dakhla-Uwainat roads in the Western Desert for paleomagnetic studies. Two of these formations are of the Early Cretaceous (the Six Hills, Abu Ballas formations) and the third one is of the Late Cretaceous (Maghrabi formation). The studied rocks are subjected to rock magnetic measurements as well as demagnetization treatment. Rock magnetic experiments reveal that the presence of hematite is the main magnetic mineral in the three formations. Therefore, present study relies mostly on thermal demagnetization. Two magnetic components have been isolated from the studied rocks. The first component has been isolated from the Six Hills and Abu Ballas formations and is carried by hematite with D = 347.1°, I = 41.6° with ?95 = 7.8° and the corresponding pole lies at lat. = 78.2° N and long. = 294.1° E. The second component has been isolated from the Maghrabi formation and is carried also by hematite with D = 22.7°, I = 28.4° with ?95 = 9.9° and pole position lies at lat. = 66.3° N and long. = 140.6° E. The first magnetic component obtained from the two older formations is considered primary, as the corresponding pole reflects the age when compared with the previously obtained Cretaceous poles for North Africa. On other hand, the second pole obtained from the Maghrabi formation (the younger) is inconsistent with the Cretaceous pole positions for North Africa, but falls closer to the Eocene pole indicating that the rocks of this formation could have suffered remagnetization during the late Eocene time.

El-Shayeb, H.; El-Hemaly, I. A.; Abdel Aal, E.; Saleh, A.; Khashaba, A.; Odah, H.; Mostafa, R.

2013-06-01

34

3D slicing of radiogenic heat production in Bahariya Formation, Tut oil field, North-Western Desert, Egypt.  

PubMed

A 3D block of radiogenic heat production was constructed from the subsurface total gamma ray logs of Bahariya Formation, Western Desert, Egypt. The studied rocks possess a range of radiogenic heat production varying from 0.21 ?Wm(-3) to 2.2 ?Wm(-3). Sandstone rocks of Bahariya Formation have higher radiogenic heat production than the average for crustal sedimentary rocks. The high values of density log of Bahariya Formation indicate the presence of iron oxides which contribute the uranium radioactive ores that increase the radiogenic heat production of these rocks. The average radiogenic heat production produced from the study area is calculated as 6.3 kW. The histogram and cumulative frequency analyses illustrate that the range from 0.8 to 1.2 ?Wm(-3) is about 45.3% of radiogenic heat production values. The 3D slicing of the reservoir shows that the southeastern and northeastern parts of the study area have higher radiogenic heat production than other parts. PMID:23291561

Al-Alfy, I M; Nabih, M A

2013-03-01

35

Precipitation Source Inferred from Stable Isotopic Composition of Pleistocene Groundwater and Carbonate Deposits in the Western Desert of Egypt  

NASA Astrophysics Data System (ADS)

An Atlantic source of precipitation can be inferred from stable isotopic data (H and O) for fossil groundwaters and uranium-series-dated carbonate spring deposits from oases in the Western Desert of Egypt. In the context of available stable isotopic data for fossil groundwaters throughout North Africa, the observed isotopic depletions (?D -72 to -81‰; ? 18O -10.6 to -11.5‰) of fossil (?32,000 yr B.P.) groundwaters from the Nubian aquifer are best explained by progressive condensation of water vapor from paleowesterly wet oceanic air masses that traveled across North Africa and operated at least as far back as 450,000 yr before the present. The values of ? 18O (17.1 to 25.9‰) for 45,000- to >450,000-yr-old tufas and vein-filling calcite deposits from the Kharga and Farafra Oases are consistent with deposition from groundwaters having oxygen isotopic compositions similar to those of fossil groundwaters sampled recently at these locations.

Sultan, Mohamed; Sturchio, Neil; Hassan, Fekri A.; Hamdan, Mohamed Abdel Rahman; Mahmood, Abdel Moneim; Alfy, Zeinhom El; Stein, Tom

1997-07-01

36

Age of the Dakhleh impact event and implications for Middle Stone Age archeology in the Western Desert of Egypt  

Microsoft Academic Search

Dakhleh Glass comprises a suite of chemically distinctive and heterogeneous glassy rocks that occur over an area of ca. 400km2 in and around the Dakhleh Oasis in central western Egypt. Previous studies establish a meteorite impact origin for the Dakhleh Glass. No impact crater has yet been found, suggesting an airburst origin. The Dakhleh Glass-forming impact event occurred during the

Paul R. Renne; Henry P. Schwarcz; Maxine R. Kleindienst; Gordon R. Osinski; John J. Donovan

2010-01-01

37

Assessment of waterlogging in agricultural megaprojects in the closed drainage basins of the Western Desert of Egypt  

NASA Astrophysics Data System (ADS)

This paper investigates the development of waterlogging in the cultivated and arable areas within typical dryland closed drainage basins (e.g. the Farafra and Baharia Oases), which are located in the Western Desert of Egypt. Multi-temporal remote sensing data of the Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM+) were collected and processed to detect the land cover changes; cultivations, and the extent of water ponds and seepage channels. The Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) has been processed to delineate the catchment morphometrical parameters (i.e. drainage networks, catchment divides and surface areas of different basins) and to examine the spatial distribution of cultivated fields and their relation to the extracted drainage networks. The soil of these closed drainage basins is mainly shallow and lithic with high calcium carbonate content; therefore, the downward percolation of excess irrigation water is limited by the development of subsurface hardpan, which also saturates the upper layer of soil with water. The subsurface seepage from the newly cultivated areas in the Farafra Oasis has revealed the pattern of buried alluvial channels, which are waterlogged and outlined by the growth of diagnostic saline shrubs. Furthermore, the courses of these waterlogged channels are coinciding with their counterparts of the SRTM DEM, and the recent satellite images show that the surface playas in the downstream of these channels are partially occupied by water ponds. On the other hand, a large water pond has occupied the main playa and submerged the surrounding fields, as a large area has been cultivated within a relatively small closed drainage basin in the Baharia Oasis. The geomorphology of closed drainage basins has to be considered when planning for a new cultivation in dryland catchments to better control waterlogging hazards. The "dry-drainage" concept can be implemented as the drainage and seepage water can be conveyed through the inactive alluvial channels into certain abandoned playas for evaporation.

El Bastawesy, M.; Ramadan Ali, R.; Faid, A.; El Osta, M.

2013-04-01

38

Sedimentology, sequential analysis and clay mineralogy of the lower Eocene sequence at Farafra Oasis area, Western Desert of Egypt  

NASA Astrophysics Data System (ADS)

Integrated sedimentological studies, sequential analysis and clay mineralogy on the lower Eocene rocks in the Western Desert provided important information on the reconstruction of the depositional basin, cyclicity, and paleoclimatic conditions. Two formations are recognized; the Esna and Farafra formations, with a gradational contact in-between. The studied sequence exhibits lateral facies changes as revealed from field and microfacies investigations. Eight facies were recognized and summarized in a carbonate ramp model. It represents also a general regressive trend, which records a transition from an outer ramp into a peritidal zone. The facies stacking patterns constitute several kinds of meter-scale, shallowing-upward cycles. Two different types of depositional cycles are here defined. The stratigraphic sections show a hierarchical organization of many cycles defined by five depositional sequences. It is suggested that composite eustatic sea level oscillations caused by cyclic perturbations of the Earth's orbit played a fundamental role in determining the formation of the observed hierarchical cyclic organization. Summing up, it is believed that the paleotopography had resulted from the impact of the Syrian Arc Folding System. A confusing additional complication is introduced by syndepositional sedimentary structures, especially during the late Cretaceous/Eocene times, coupled by several tensional forces. Clay mineralogy has revealed the presence of smectite, kaolinite and illite. Their origin may be attributed to the gradual increase in the amount of erosion of the newly elevated crystalline source rocks to the south of Egypt, in areas of moderate rainfall and rapid weathering and/or to reworking processes of soils which presumably developed on basement rocks. Changes in source rocks or climatic influence during the early Eocene may account for the observed differences in clay mineral abundances.

El Ayyat, Abdalla M.

2013-02-01

39

Palaeoenvironment and Holocene land use of Djara, Western Desert of Egypt  

NASA Astrophysics Data System (ADS)

The results of the interdisciplinary project ACACIA support the assumption of a more humid climate at Djara, on the Egyptian Limestone Plateau, which is a hyper-arid desert today, during the early and mid-Holocene. The ancient plant and animal inventories give new impetus for the suggestion of an interfingering of two climatic regimes, the winter rains from the north and west and the summer monsoonal rains from the south, on the latitude of Djara. A playa sediment sequence, the composition of plant and animal taxa as well as the reconstructed settlement patterns indicate a semi-arid climate with alternating more humid and drier conditions. The concentration of prehistoric sites in the Djara depression points to locally favourable conditions in contrast to the surrounding plateau surface. The widespread catchment and a distinct system of palaeochannels offered fresh water over a period of time due to the run-off from the plateau surface after rain events. Although the ecological conditions were better during the Holocene humid phase than they are today, a sedentary way of life was improbable. The hydrological constraints require altogether highly mobile subsistence strategies. Shells of the Nile bivalve Aspatharia sp. ( Spathopsis sp.) give evidence for contacts between Djara and the Nile Valley, which remains beside the Egyptian oases an important retreat area with perennially available water. The decrease of radiocarbon dates and related archaeological sites around 6300 BP (c. 5300 cal BC) indicate the depopulation of the Djara region as a consequence of the drying trend. While the drop off of the 14C-dates can also be observed in other desert research areas of the ACACIA-project, we date the end of the Holocene humid phase about 300 years earlier than previously suggested.

Kindermann, Karin; Bubenzer, Olaf; Nussbaum, Stefanie; Riemer, Heiko; Darius, Frank; Pöllath, Nadja; Smettan, Ursula

2006-07-01

40

A Study of Hydrogeological Conditions of the Nubian Sandstone Aguifer in the Area between Abu Simbel and Toschka, Western Desert, Egypt.  

NASA Astrophysics Data System (ADS)

A Study of Hydrogeological Conditions of the Nubian Sandstone Aquifer in the Area between Abu Simbel and Toschka, Western Desert, Egypt. By K. A. Dahab*, A. M. Ebraheem**, and E. El Sayed*** *Geology Department, Faculty of Science, Menofia University, Shibin El Kom, Egypt. ** Geology Department, Faculty of Science, Assiut University, Assiut, Egypt. *** Geology Department, Faculty of Science, Minia University, Minia, Egypt. The Nubian Sandstone Aquifer in the area between Toschka and Abu Simbil is small portion of the very well known Nubian Sandstone Aquifer System in the Eastern Sahara, which covers the entire area of southwest Egypt, southeast Libya, northeast Chad, and northern Sudan. Toscha area is currently the site of intensive drilling and development for a huge land reclamation project. The drilling information was used to study the hydrogeological setting of the Nubian Sandstone aquifer in the area. The obtained results indicate that the lithological characteristics and tectonic setting is strongly affecting the groundwater flow pattern as well as the aquifer potentiality of the nubian sandstone aquifer in the area. The aquifer potentiality in this area is low if compared to that of east Oweinat or Dakhla areas. The aquifer is mainly composed of hard ferruginous sandstone with great shale and clay intercalation with a thickness ranging from 140 to 230 meters. Groundwater in this aquifer belongs to fresh to slightly brackish type (salinity is ranging from 240 to 1300 ppm). Ion dominance ordering reveals that sodium cation is mostly predominating over calcium and magnesium whereas chloride is predominant over sulfate and bicarbonate. The groundwater is related to meteoric origin. The high concentration of sodium, chloride, and sulfates reflect leaching and dissolution processes of gypsiferous shales and clay as well as long residence time of water.

Dahab, K. A.; Ebraheem, A. M.; El Sayed, E. A.

2001-05-01

41

Age of the Dakhleh impact event and implications for Middle Stone Age archeology in the Western Desert of Egypt  

NASA Astrophysics Data System (ADS)

Dakhleh Glass comprises a suite of chemically distinctive and heterogeneous glassy rocks that occur over an area of ca. 400 km 2 in and around the Dakhleh Oasis in central western Egypt. Previous studies establish a meteorite impact origin for the Dakhleh Glass. No impact crater has yet been found, suggesting an airburst origin. The Dakhleh Glass-forming impact event occurred during the Middle Stone Age time of occupation, but the timing of this event has not been well established. 40Ar/ 39Ar incremental heating of three aliquots from a sample of Dakhleh Glass yield data that can be ascribed to quenched glass which efficiently purged radiogenic 40Ar inherited from the target rocks. One of the aliquots yielded data suggestive of an undegassed clast of target material, but these are easily resolved. The age of the impact event is determined from a compositionally filtered subset of the data that yield an isochron age of 145 ± 19 ka.

Renne, Paul R.; Schwarcz, Henry P.; Kleindienst, Maxine R.; Osinski, Gordon R.; Donovan, John J.

2010-03-01

42

Thickness variation of the sedimentary cover in the South Western Desert of Egypt as deduced from Bouguer gravity and drill-hole data using neural network method  

NASA Astrophysics Data System (ADS)

The Bouguer anomaly map of scale 1:500,000 and the lithological logs of more than 120 deep wells distributed in the Southern part of Western Desert of Egypt were used to determine the thickness of the sedimentary cover containing the main sandstone water formation. The predominant structures affecting both the basement rock and the sedimentary cover were also studied. Gravity stripping approach was applied to separate density anomalies within the sedimentary fill from the influence of deeper levels in the crystalline crust. The study indicated that the surface of the basement rock is highly rugged and mostly controlled by structures causing variation of the sedimentary cover thickness from location to other all over the area. Isopach maps were constructed based on the Artificial Neural Network (ANN) model which is considered a best method for that operation. The maximum thickness of sandstone formations is recorded at west Oweinat, southwest of Aswan, Dakhla oasis and west of Qena town. As this formation is the main water aquifer in the study area, therefore these locations are characterized by the presence of huge amount of ground water. Accordingly, these areas must be taking the priority in the programs of sustainable development in southern Egypt.

Abdel Zaher, M.; Senosy, M. M.; Youssef, M. M.; Ehara, S.

2009-06-01

43

RETRACTED: Thickness variation of the sedimentary cover in the south Western Desert of Egypt as deduced from Bouguer gravity and drill-hole data  

NASA Astrophysics Data System (ADS)

Bouguer gravity anomaly mapped at a scale of 1:500,000 and the lithological logs of about 120 deep wells were used to determine the thickness of the sedimentary sequence containing the main sandstone water formation in important area of Egypt. The area is located in the southern part of the Western Desert bounded by the latitudes 22°00'-26°30' N, and longitudes 28°30'-33°00' E. The predominant structures affecting the basement rocks and the sedimentary cover were also studied. The gravity stripping approach was applied to eliminate the gravity effects caused by sedimentary sequence and to separate density anomalies within the sedimentary fill from the influence of rocks at deeper levels in the crystalline crust. The present study indicated that the surface of the basement rocks is highly rugged and mostly controlled by structures which have a direct effect on thickness variation of the sedimentary cover all over the area. Regionally the area is characterized by two major intracratonic basins (the Dahkla Basin and the Nile valley Basin) separated by a NE-SW trending swell of the Kharga uplift and bounded at the south by the Oweinat-Bir Safsaf-Aswan uplift. These major tectonic units are controlled by fault structures trending in N-S, E-W, NE-SW, NW-SE, which cut the basement rocks and extend upward in the sedimentary cover. The maximum thickness of sandstone formations is recorded at west Oweinat, west Kurkur, southwest of Aswan, Gramashin, Dakhla oasis and some localities west of Sohag and Qena towns. At these localities the thickness ranges between 600 and 900 m. As this formation is the main water aquifer in the study area, therefore these localities are characterized by the presence of big amount of groundwater. Accordingly, these areas must take the priority in the sustainable development programs of southern Egypt.

Senosy, M. M.; Youssef, M. M.; Abdel Zaher, M.

2013-01-01

44

ORIGINAL PAPER Neoproterozoic diamictite in the Eastern Desert of Egypt  

E-print Network

ORIGINAL PAPER Neoproterozoic diamictite in the Eastern Desert of Egypt and Northern Saudi Arabia in Wadi Kareim and Wadi Mobarak in the Eastern Desert of Egypt and the Nuwaybah formation in NW Saudi and extends from Egypt, Israel, and Jordan to Ethiopia and Yemen. The ANS (Fig. 1a) developed during

Stern, Robert J.

45

The contribution of geographic information systems and remote sensing in determining priority areas for hydrogeological development, Darb el-Arbain area, Western Desert, Egypt  

NASA Astrophysics Data System (ADS)

The Darb el-Arbain study area is in the southern Western Desert of Egypt and has been attracting increasing developmental interest in the last few decades, especially since agricultural development of the southern Baris area, where the groundwater resources of the Nubian Sandstone Aquifer System (NSAS) have been utilized for the cultivation of valuable lands. Due to the proven high potential of both groundwater and land resources, determining the priority areas for sustainable hydrogeological development becomes a necessity. A geographic information system, as a platform for geospatial modeling techniques, has been built, which depends on the recently collected data about the NSAS, in addition to the published databases. Certain criteria of practical value, like depth to groundwater, hydraulic conductivity, groundwater salinity, sodium adsorption ratio, and the safe yield of wells, were selected as decisive parameters for hydrogeological prioritization. The model pinpoints areas characterized by favorable hydrogeological conditions, which could be used for future development and implementation of an artificial storage and recovery (ASR) program. The designated priority areas for hydrogeological development occur at the southern, middle southern and some localized northern parts of the Darb el-Arbain area. The newly formed Tushka Lakes represent a suitable and excellent natural source of freshwater for implementing an ASR program.

Elewa, Hossam H.; Fathy, Rafik G.; Qaddah, Atef A.

2010-08-01

46

Characterization of magnetic spherical fractions in sand deposits for interpretation of environmental change around the El- Zayyan temple, Kharga Oasis, Western Desert, Egypt  

NASA Astrophysics Data System (ADS)

Desertification in North Africa has rapidly advanced over the last 6,000 years. Such environmental changes began in the Early Dynastic Period of Egypt (4200 - 3150 BC), and the occupation of Achaemenid Persian and Roman cultures in Egypt occurred under even drier climates. Kharga is the largest oasis of the five oases, located in the western desert of Egypt that contains a treasure trove of archaeological resources. This oasis has been highlighted to promote resource exploration and development of archaeological tourism since the 1980's. The El-Zayyan temple is located 27 km south of the central Kharga oasis. Zayyan was once called 'Tchonemyris', which has connection with the means of 'huge well' in Greek. Although major portions of the temple were rebuilt in 140 AD during the rule of the Roman Emperor Antoninus Pius, this temple is considered to be originally built in the Ptolemaic period (4c-1c BC). It is likely that the area had a sufficient water supply in the past as the El-Zayyan temple stands at the lowest point (-18 m a.s.l.) in the Kharga oasis. Furthermore, the El-Ghueita temple that stands on a hill top at 68.5 m a.s.l., 4 km northward from the El-Zayyan temple, has given name that means 'beautiful garden' in Greek. From these facts, we can imagine that the past landscape of this area contained green surroundings. The El-Ghueita temple was well known as a production centre of high quality wine since the mid-Dynastic age (2050 -1786 BC). As this area is currently arid, it is expected that there were irrigation facilities to maintain the vast farm land during the ancient period. To deepen our knowledge of how people developed their technologies and conducted their life within the natural environment of a drastic drying period, understanding the process of environmental change on a region scale is necessary. The aim of this study was to extract proxies from sand deposits in the western desert area to estimate the change in the environment. We examined the sand layers with a focus on the spherical magnetic fractions having relations with accumulation of free iron oxides, condition of water and microbial activities. The study sites were located west of the El-Zayyan temple, and six and seven samples were collected every 10 cm from the two sand profiles, Zy-R and Zy-6, respectively. AMS 14C dating was conducted using fine fractions of an organo-mineral complex; date ranges 5,000-8,400 yBP and 5,500-7,800 yBP were assigned to Zy-R and Zy-6, respectively. Spherical fractions, separated into six colored-types, were extracted using a neodymium magnet, and then characterized by SEM observation, EDX elemental analysis (FE-SEM S4700, Hitachi, Genesis, EDAX), and X-ray micro-crystal structural analysis (D8-Discover, Bruker axs) to discuss their origins. The vertical change in the density of each fraction by weight and counts in sand revealed the environmental change.

Watanabe, Makiko; Koizumi, Natsuko; Kato, Sayuri; Kikuchi, Ryohei; Kamei, Hiroyuki

2014-05-01

47

Hydrogeological aspects and environmental concerns of the New Valley Project, Western Desert, Egypt, with special emphasis on the southern area  

NASA Astrophysics Data System (ADS)

The New Valley Project has been given much attention in the past 20 years especially from the hydrogeological point of view concerning groundwater utilization for the reclamation of a large area of the Western Desert. Lithological, petrophysical, and petrographical studies were conducted on four wells south of Beris Oasis, namely Beris 20, Beris 15, Beris 14, and Beris 13, and are defined by latitudes 24°25'E and 24°35'E and longitudes 30°30'N and 30°46'N. The Nubian sedimentation is of Posttectonic deposition that took place over the uplifted Precambrian granitic basement and is Lower Cretaceous, whereas the upper most variegated shales of the cap rock are Upper Cretaceous. The Nubian sandstones in the area south of Beris Oasis contain hematitic stains and/or fine granular authigenic hematite, thin laminae of brown ferruginous quartzite is also recorded denoting oxidizing conditions in the basin of deposition. Thin streaks of carbonaceous shales are met with in different depths to the south of Beris area, may be taken to denote oscillations in the sea level and accordingly its depths, and are responsible for the change in the oxidation-reduction potential during the deposition of the corresponding beds. Lithologic logs were interpreted together with the electric and micro-logs for adjustment of the shale breaks and showed that there are five water-bearing zones, named from bottom to top: A, B, C, D, and E, and are mainly unfossiliferous orthoquartzites, separated from each other by impervious beds of siltstones, shales, and clays of varying thicknesses. This zoning had been found valid in other parts of the Kharga Oases and could be applied locally in the Kharga Oases area. Mechanical analysis was performed mainly on 39 samples, of which 18 were core samples and 21 were cuttings, that were raised from four wells dug in the area south of Beris Oasis, Kharga Oases. Porosity and permeability tests were carried out on the 18 core samples only. The implication of these data on the environment of deposition of the Nubia Sandstone is discussed. Petrographic examination of a thin section of the subsurface Nubia sandstones in the South of Beris Oasis showed that the lithified rocks fall into three types depending on the nature of cement being, silicious or ferruginous, and on the amount of primary matrix, which at present is reorganized into iron oxides, microquartz, and muscovite flakes, thus reaching the phyllomorphic stage of diagensis. Rounding of the quartz grains shows that transportation had a minor effect on the grain morphology and favor a fluviatile transporting agent.

Assaad, Fakhry A.

1988-12-01

48

Evidence for Early and Mid-Cryogenian glaciation in the Northern ArabianNubian Shield (Egypt, Sudan, and western Arabia)  

E-print Network

(Egypt, Sudan, and western Arabia) ROBERT J. STERN1*, PETER R. JOHNSON2, KAMAL A. ALI1,3 & SUMIT K over broad regions of the Central Eastern Desert of Egypt, NW Arabia and possible correlative units diamictite and BIFs of the Central Eastern Desert of Egypt and the correlative Nuwaybah diamictite and BIF

Stern, Robert J.

49

Paleozoic and Mesozoic stratigraphy and oil potential of Western Desert  

Microsoft Academic Search

The depocenter of the Paleozoic basin in western Egypt lies in the northwestern part of the Western Desert. The depositional axis of the basin, where thicknesses in excess of 2800 m (9200 ft) have been recorded, has a northwesterly trend to the vicinity of the Siwa Oasis. A less well-defined shallower basin with a northerly trend lies to the southwest.

N. A. Khalil; D. Young; A. E. M. Nairn

1983-01-01

50

The Dakhleh Glass: Product of an impact airburst or cratering event in the Western Desert of Egypt?  

NASA Astrophysics Data System (ADS)

Impact cratering is a ubiquitous geological process on the terrestrial planets. Meteorite impact craters are the most visible product of impact events, but there is a growing recognition that large aerial bursts or airbursts should occur relatively frequently throughout geological time. In this contribution, we report on an unusual impact glass—the Dakhleh Glass (DG)—which is distributed over an area of ~400 km2 of the Dakhleh Oasis, Egypt. This region preserves a rich history of habitation stretching back to over 400,000 years before the emergence of Homo sapiens. We report on observations made during recent fieldwork and subsequent analytical analyses that strengthen previous suggestions that the DG formed during an impact event. The wide distribution and large size of DG specimens (up to ~50 cm across), the chemistry (e.g., CaO and Al2O3 contents up to ~25 and ~18 wt%, respectively), the presence of lechatelierite and burnt sediments, and the inclusion of clasts and spherules in the DG is inconsistent with known terrestrial processes of glass formation. The age and other textural characteristics rule out a human origin. Instead, we draw upon recent numerical modeling of airbursts to suggest that the properties of DG, coupled with the absence of a confirmed crater, can best be explained by melting of surficial sediments as a result of a large airburst event. We suggest that glass produced by such events should, therefore, be more common in the rock record than impact craters, assuming that the glass formed in a suitable preserving environment.

Osinski, G. R.; Kieniewicz, J.; Smith, J. R.; Boslough, M. B. E.; Eccleston, M.; Schwarcz, H. P.; Kleindienst, M. R.; Haldemann, A. F. C.; Churcher, C. S.

2008-12-01

51

Pseudospherulitic fibrous calcite from the Quaternary shallow lacustrine carbonates of the Farafra Oasis, Western Desert, Egypt: A primary precipitate with possible bacterial influence  

NASA Astrophysics Data System (ADS)

Pseudospherulitic fibrous calcite (PFC) has been found as a major constituent (85-90%) within thin massive limestone beds of the Quaternary mudflat-shallow lacustrine facies association (1.5-2 m thick) that forms part of combined facies associations of the Quaternary clastic-carbonate unit (25-30 m thick) at Bir-Karawein area in the Farafra Oasis, Western Desert, Egypt. The thin massive limestone beds (2-5 cm thick) are devoid of pedogenic features and marine fossils. They form a rhythmic cyclic succession with thin massive mudrocks (5-10 cm thick). The mudflat-shallow lacustrine facies association herein occurs within a depositional sequence of distal alluvial-floodplain (6-12 m thick) and palustrine (1.5-4.5 m thick) facies associations. The PFC is a composed of loosely packed rounded to sub-rounded single low-Mg-calcite crystals (150-250 ?m-sized) with intracrystalline fibrous microfabric marked by fibers (150-250 ?m long and 10-20 ?m wide) radiating from the center of the individual crystals and displaying irregular internal growth with lobate pattern. The PFC crystals show non-planar to highly irregular intercrystalline boundaries. Under SEM, the individual crystal fibers group of PFC form ellipsoid to sub-globular bodies. Each PFC crystal exhibits successive zones of thick non-luminescence and thin brightly orange to dull luminescence. The matrix (10-15%) between the PFC crystals is mainly a honeycomb-like smectite. The PFC is postulated to be a primary precipitate. This concept is reached because the PFC: (i) does not display the criteria of typical Microcodium structures, root-calcification, speleothem structures, calcite spherulites of laminar calcretes, and calcitization of precursor dolomite or aragonite, (ii) possesses homogenous compositional and textural characteristics, and (iii) occurs within limestone beds that lie in between impermeable massive mudrock beds that dampen diagenesis. A role for possible bacterial contribution in crystallization of the PFC is assumed in the view of its internal microfabric characteristics (pseudospherulitic and lobate internal growth patterns), and morphological features (ellipsoidal to subglobular appearance), in addition to its slightly negative values of ?13C (-0.51‰ to -2.19‰). The low concentration of Na (0.11-0.20%), Sr (70-110 ppm) and Mn (0.04-0.31%), in addition to the negative values of ?18O (-4.65‰ to -5.96‰) in the PFC reflect its deposition from oxygenated freshwater. In addition, the absence of covariance between ?13C and ?18O values (r = -0.202) of the PFC indicates precipitation in a hydrologically-open, short-lived lake setting. In summary, the PFC is of low-Mg type and formed in a hydrologically-open, short-lived, freshwater lake as a primary precipitate with possible bacterial contribution.

Wanas, H. A.

2012-04-01

52

Neoproterozoic tectonothermal evolution of the Central Eastern Desert, Egypt: a slow velocity tectonic process  

E-print Network

Neoproterozoic tectonothermal evolution of the Central Eastern Desert, Egypt: a slow velocity, University of Assiut, Egypt Received 10 January 2001; received in revised form 24 October 2001; accepted 25 in the Central Eastern Desert of Egypt is constraint by 40 Ar/39 Ar ages of hornblende and muscovite from Meatiq

Fritz, Harald

53

Sites with Holocene dung deposits in the Eastern Desert of Egypt: Visited by herders?  

E-print Network

Sites with Holocene dung deposits in the Eastern Desert of Egypt: Visited by herders? V. Linseele a by the Belgian Middle Egypt Prehistoric Project of Leuven University under the direction of P.M. Vermeersch

Marinova, Elena

54

Precambrian Research 136 (2005) 2750 The Wadi Mubarak belt, Eastern Desert of Egypt  

E-print Network

Precambrian Research 136 (2005) 27­50 The Wadi Mubarak belt, Eastern Desert of Egypt, Graz, Austria b Mansoura University, Faculty of Science, Geology Department, El Mansoura, Egypt c February 2003; accepted 3 September 2004 Abstract The Wadi Mubarak belt in Egypt strikes west­east (and

Fritz, Harald

2005-01-01

55

Paleozoic and Mesozoic stratigraphy and oil potential of Western Desert  

SciTech Connect

The depocenter of the Paleozoic basin in western Egypt lies in the northwestern part of the Western Desert. The depositional axis of the basin, where thicknesses in excess of 2800 m (9200 ft) have been recorded, has a northwesterly trend to the vicinity of the Siwa Oasis. A less well-defined shallower basin with a northerly trend lies to the southwest. Farther east, a possible Paleozoic basin lies in the Abu Gharadig area where 1300 m (4265 ft) of sediments were drilled. Following the deposition of the Paleozoic section, there was a marked hiatus; the time of Hercynian movements for Permian and Triassic beds is absent. Uplift and the presence of volcanics dated in Permian-Carboniferous time are indicative of Hercynian tectonic activity. Further tectonic uplift accompanied by faulting and marine regression is dated from late Kimmeridgian time to the beginning of the Cretaceous, when transgression began once again. The dominant feature, new in the Western Desert, was the development of an east-west extensional basin, the Abu Gharadig basin, in Cretaceous time. The trough became less distinctive in Cenozoic times when a further trough, the Tiba basin, developed north of the ridge. Production from the northern Western Desert until recently has been disappointing. Exploration results from the Paleozoic Section have yielded little, but the existence of a marine section suggests that the area northeast of Siwa still has potential. The thick deeply buried Jurassic marine sequence in the Western Desert may be the source for at least part of the production from Cretaceous horizons in the Abu Ghradig, Alamein, and Razzak oil and gas fields.

Khalil, N.A.; Young, D.; Nairn, A.E.M.

1983-03-01

56

Phanerozoic tectonothermal history of the ArabianNubian shield in the Eastern Desert of Egypt: evidence from fission track  

E-print Network

Phanerozoic tectonothermal history of the Arabian­Nubian shield in the Eastern Desert of Egypt were performed in the Eastern Desert of Egypt. The results provide insights into the processes driving reserved. Keywords: Phanerozoic; Fission track thermochronology; Palaeostress; Arabian­Nubien shield; Egypt

Fritz, Harald

57

Holocene freshwater carbonate structures in the hyper-arid Gebel Uweinat region of the Sahara Desert (Southwestern Egypt) q  

E-print Network

Desert (Southwestern Egypt) q Margarita M. Marinova a,b , A. Nele Meckler c , Christopher P. McKay b region of the Sahara Desert, near the triple border of Egypt, Sudan, and Libya (N22°, E25°), re- ceives- ibrated years BP; Wendorf and expedition, 1977). While some parts of southwest Egypt have been extensively

Gilli, Adrian

58

Formation of Neoproterozoic metamorphic core complexes during oblique convergence (Eastern Desert, Egypt)  

Microsoft Academic Search

Major portions of the Pan-African Orogen in the Eastern Desert of Egypt were formed by island-arc accretion in the Neoproterozoic. These areas are characterized by their lack of major crustal thickening. Metamorphic core complexes occur parallel to the strike of the Eastern Desert Orogen. These domes exhibit polyphase metamorphism and deformation in contrast to the structurally overlying nappes which include

H. FRITZ; E. WALLBRECHER; A. A. KHUDEIR; F. ABU EL ELA; D. R. DALLMEYER

1996-01-01

59

Aeolian erosional lineations in the Libyan Desert, Dakhla Region, Egypt  

NASA Astrophysics Data System (ADS)

This paper presents results of a study of aeolian erosion at the landscape scale. There have been few such studies in desert geomorphology compared to those focused on individual landforms and on rock surface sculpture. The present study area lies in the southern part of the Libyan Desert in south-central Egypt, between 25° and 27°N, 29° and 30°E. Bedrock comprises Paleogene limestone of various lithologies. Climate is hyperarid. The following topics are treated. (i) Correspondences between rock outcrop belts and belts of terrain lineated by aeolian erosion and unlineated terrain. (ii) The effect of lithology on aeolian lineation, which works through the presence or absence of chert in the limestones. Lineation is produced by aeolian erosion in chert-free/poor rocks, whereas erosion of chert-rich rocks produces a desert pavement that armors the surface, suppressing erosion. (iii) The effect of large valleys eroded upwind of lineated terrain, which deflect winds and trap sand, ending erosion, so that downwind lineations are reduced and finally erased by weathering. (iv) Sample lineated landscapes in the area show stages of evolution, arranged in the time domain into a proposed cycle of aeolian erosion; the cycle progresses from initial smooth plain to grooves separating long, blade-shaped ridges, to segmentation of ridges into shorter blades along diagonal joints, to streamlining of shorter blades and size reduction, to final planation. In any one wind-parallel swath of lineated terrain, stages in the cycle progress downwind in the space domain, so that upwind landscapes are more advanced in the cycle. (v) The structure of air flow responsible for lineation is still uncertain, but initial grooving may respond to stable longitudinal horseshoe vortices, or self-organized regularity of erosion by random vortices; subsequently, the erosion pattern is fixed by evolving relief. (vi) Large, smooth basins within the lineated terrain were carved by aeolian erosion before Oxygen Isotope Stage (OIS) 5 (70-130 ka), as were similar basins along the Dakhla piedmont below the scarp; little geomorphic change has occurred since, so in this field of aeolian erosional lineations (AELs) the aeolian erosion cycle may have occupied 10 times as long. Since continental scale aridity set in at ca. 2.4 Ma, there have been only two cycles in this area. A completed cycle earlier than the current incomplete one is indicated by rare small yardangs riding 'piggyback' on larger ones.

Brookes, Ian A.

2001-08-01

60

Desert pavement development and landscape stability on the Eastern Libyan Plateau, Egypt  

Microsoft Academic Search

Desert pavement surfaces of the eastern Libyan Plateau in central Egypt represent a stable landscape preserving Middle and Upper Paleolithic artifacts. Detailed measurements of pavement clasts indicate significant variability in clast size, density, lithology and orientation between pavements, but no spatial relationship among any of these pavement variables over the study area. Pavement characteristics are unrelated to local geomorphic features

Katherine A. Adelsberger; Jennifer R. Smith

2009-01-01

61

Petrogenesis and tectonic setting of late Precambrian ensimatic volcanic rocks, central eastern desert of Egypt  

Microsoft Academic Search

Early stages in the geologic evolution of the central eastern desert of Egypt (CED) reflect an ilatense episode of ensimatic volcanic activity similar to modern magmatism of the ocean floors and island arcs. This paper reports results from studies of the petrology and petrogenesis, and interprets the significance of these Late Precambrian volcanic rocks. A three-fold stratigraphy is preserved in

ROBERT JAMES STERN

1981-01-01

62

The El Mayah molasse basin in the Eastern Desert of Egypt A. Shalaby a,b,*, K. Stuwe a,*, H. Fritz a  

E-print Network

The El Mayah molasse basin in the Eastern Desert of Egypt A. Shalaby a,b,*, K. Stu¨we a,*, H. Fritz, Austria b Department of Geology, Mansoura University, Mansoura, Egypt Received 8 September 2004; received of kilometres of the East- ern Desert of Egypt. Its sedimentary record shows that deposition occurred in two

Fritz, Harald

63

Banded Iron Formations from the Eastern Desert of Egypt: A new type of Ore? KHALIL, Khalil Isaac1 and EL-SHAZLY, Aley K.2  

E-print Network

Banded Iron Formations from the Eastern Desert of Egypt: A new type of Ore? KHALIL, Khalil Isaac1 and EL-SHAZLY, Aley K.2 1 Department of Geology, University of Alexandria, Egypt 2 Geology Department localities in an area approximately 30,000 km2 within the eastern desert of Egypt. With the exception

El-Shazly, Aley

64

The photosynthetic pathway types of some desert plants from India, Saudi Arabia, Egypt, and Iraq  

Microsoft Academic Search

Plants collected from different habitats in the deserts of India, Saudi Arabia, Egypt, and Iraq were screened for their photosynthetic CO2-fixation pathways using d13C and dD values. The analyses comprised 128 species belonging to 108 genera and 46 families. Neither the C4 nor the CAM pathway was prevalent in the plant families analyzed except in Poaceae, where C4 metabolism absolutely

H. Ziegler; K. H. Batanouny; N. Sankhla; O. P. Vyas; W. Stichler

1981-01-01

65

Upper Cenomanian – Lower Turonian (Cretaceous) calcareous algae from the Eastern Desert of Egypt: taxonomy and significance  

Microsoft Academic Search

An assemblage of calcareous algae (dasycladaleans and halimedaceans) is described from the Upper Cenomanian to Lower Turonian of the Galala and Maghra el Hadida formations (Wadi Araba, northern Eastern Desert, Egypt). The following taxa have been identified: Dissocladella sp., Neomeris mokragorensis RADOI?I? & SCHLAGINTWEIT 2007, Salpingoporella milovanovici RADOI?I? 1978, Trinocladus divnae RADOI?I? 2006, Trinocladus cf. radoicicae ELLIOTT 1968, and Halimeda

Ioan I. Bucur; Emad Nagm; Markus Wilmsen

2010-01-01

66

Remote sensing observations of sand movement in the Bahariya Depression, Western Egypt  

NASA Technical Reports Server (NTRS)

Aerial photographs taken in the 1940's have been used in combination with recent Landsat MSS and TM data to study dune movement in the Western Desert of Egypt. The El-Ghorabi dunes track northwest to southeast along the eastern edge of the Bahariya Depression. These dunes are of complex longitudinal form with well-defined, lag-covered interdune corridors. Studies using both aerial coverage and multitemporal MSS and TM image data reveal little or no net southward extension or movement of the seifs, although field measurements and remote sensing data indicate small-scale lateral migration of dune crests and interdune corridors through time. The primary process of sand transport for these dunes seems to be in response to seasonal shifts in dominant wind direction, as reflected in the development and rapid response of sand shadows leeward of the main dune masses.

Maxwell, Ted A.; Jacobberger, Patricia A.

1987-01-01

67

Age constraints on the formation and emplacement of Neoproterozoic ophiolites along the AllaqiHeiani Suture, South Eastern Desert of Egypt  

E-print Network

­Heiani Suture, South Eastern Desert of Egypt K.A. Ali a,d, , M.K. Azer b , H.A. Gahlan c , S.A. Wilde d , M., Richardson, TX 75080, USA b Geology Department, National Research Centre, Dokki-Cairo, Egypt c Geology Department, Faculty of Science, Assiut University, Assiut 71516, Egypt d Department of Applied Geology

Stern, Robert J.

68

Soil seed bank in different habitats of the Eastern Desert of Egypt  

PubMed Central

The floristic composition and species diversity of the germinable soil seed bank were studied in three different habitats (desert salinized land, desert wadi, and reclaimed land) in the Eastern Desert of Egypt. Moreover, the degree of similarity between the seed bank and the above-ground vegetation was determined. The seed bank was studied in 40 stands representing the three habitats. Ten soil samples (each 25 × 20 cm and 5 cm depth) were randomly taken per stand. The seed bank was investigated by the seedling emergence method. Some 61 species belonging to 21 families and 54 genera were identified in the germinable seed bank. The recorded species include 43 annuals and 18 perennials. Ordination of stands by Detrended Correspondence Analysis (DCA) indicates that the stands of the three habitats are markedly distinguishable and show a clear pattern of segregation on the ordination planes. This indicates variations in the species composition among habitats. The results also demonstrate significant associations between the floristic composition of the seed bank and edaphic factors such as CaCO3, electrical conductivity, organic carbon and soil texture. The reclaimed land has the highest values of species richness, Shannon-index of diversity and the density of the germinable seed bank followed by the habitats of desert wadi and desert salinized land. Motyka’s similarity index between the seed bank and the above-ground vegetation is significantly higher in reclaimed land (75.1%) compared to desert wadi (38.4%) and desert salinized land (36.5%). PMID:23961181

Gomaa, Nasr H.

2012-01-01

69

Desert pavement development and landscape stability on the Eastern Libyan Plateau, Egypt  

NASA Astrophysics Data System (ADS)

Desert pavement surfaces of the eastern Libyan Plateau in central Egypt represent a stable landscape preserving Middle and Upper Paleolithic artifacts. Detailed measurements of pavement clasts indicate significant variability in clast size, density, lithology and orientation between pavements, but no spatial relationship among any of these pavement variables over the study area. Pavement characteristics are unrelated to local geomorphic features including slope gradient and aspect, suggesting a desert pavement surface that has developed without significant influence from transporting mechanisms such as overland flow and slope failure. Meridional vertical cracks in surface clasts implicate thermal stresses due to diurnal solar variation as a mechanical weathering process, whereas the presence of a clast-free silty layer within all soil profiles indicates that these are accretionary pavement surfaces that have grown upward over time. The desert pavement in this region has likely developed in situ through mechanical breakdown of surface clasts and desert pedogenesis, indicating long-term stability for this region and minimal taphonomic effects on artifacts > 2 cm in diameter deposited on this surface over the last ca. 100 ka.

Adelsberger, Katherine A.; Smith, Jennifer R.

2009-06-01

70

Neoproterozoic post-collisional granitoids in the Central Eastern Desert of Egypt: Petrological and geochemical constraints  

NASA Astrophysics Data System (ADS)

The Um Had and Um Effein (UHUE), Central Eastern Desert of Egypt, are elliptical and circular bodies of monzogranite to syenogranite with subordinate alkali feldspar granite. The UHUE granites are quite evolved (SiO2 = 67-74 wt.%), and have characteristics of high-K calc-alkaline peraluminous rocks. They are relatively enriched in K, Ba, La, Rb, Zr and total REEs, while are depleted in Sr, Y, Ti, HREE. The rocks have LREE-enriched patterns with significant negative Eu anamolies suggesting post-collision granites. The gradual increase of Rb/Sr and Rb/Ba ratios from the monzogranite to the alkali feldspar granites indicates that these granites are genetically related. The various geochemical discrimination diagrams strongly suggest that the studied granitoids were generated from crustal sources through fractional crystallization with some crustal contamination which have played a major role during the magmatic evolution of the plutons. These granites display transitional character from orogenic calc-alkaline arc-type up to subsequent anorogenic within-plate environments, suggesting continuous crystallization of magma in a transitional “post-collision” tectonic setting. This transition from compression to extension was controlled mainly by lithospheric delamination following continental collision in the Eastern Desert of Egypt.

Osman, Ali F.; El Kalioubi, Baher A.

2014-11-01

71

Genetic Aspects of Gold Mineralization at Some Occurrences in the Eastern Desert of Egypt  

NASA Astrophysics Data System (ADS)

The Eastern Desert of Egypt is well known as a gold-mining area since ancient times, there're more than 95 gold deposits and occurrences spread the whole area covered by the basement rocks of Precambrian age. The basement rocks of the Eastern Desert of Egypt constitute the Nubian Shield that has formed a continuous part of the Arabian-Nubian Shield before the opening of Red Sea (Oligocene-Early Miocene). Commonly, the system of gold-bearing quartz veins in the Eastern Desert is clearly structural controlled related to brittle-ductile shear zones that mostly developed during late deformational stages of the evolution history for basement rocks in the Eastern Desert. This running study principally aims to contribute the mineral resource potential of the gold deposits in Egypt, so particularly Fatira, Gidami and Atalla occurrences have been involved into a comprehensive study based on field, structural, mineralogical, geochemical and genetic investigations. It is intended to better understanding for the characteristics, distribution controls, conditions and age of mineralization in relation to the age of the hosting rocks intrusion to find if there're genetic links between the gold mineralization and the evolution of the host intrusive complex. Several authors suggested that the gold mineralization was related to the intrusion of the (postorogenic) Younger granites. Other authors interpret these deposits as products of hydrothermal activity induced either by metamorphism or cooling effects of early Paleozoic magmatism or as combined metamorphic/magmatic episodes. The prime focus will be directed to the ore itself and the associated hydrothermal alteration zones based on detailed maps and well-distributed samples network and geochemical anomalies distribution. The laboratory studies included microscopic examination (reflecting and transmitting microscopy) to allow for determination of the hosting rocks types and mineralogical changes related to the gold mineralization in each area and revealing the ore mineralogy and the ore textures, geochemical analyses (including rare earth elements) are to be used in order to determine the tectonic setting and magmatic evolution of the host intrusions, scanning electron microscope, microprobe analysis, stable isotopes and fluid inclusions will serve as a new part of this study in detection of the origin and the physico-chemical conditions (P-T condition) for the gold precipitation, Age dating of the host intrusion and mineralization will be based on K-Ar for dating potassium-bearing minerals in fresh host rocks and hydrothermal mineral phases.

Abd El Monsef, M.; Slobodník, M.; Salem, I. A.

2012-04-01

72

Microfacies analysis of foraminifera rich sedimentary rocks from the Desert Plateau, central Egypt.  

NASA Astrophysics Data System (ADS)

Microfacies analysis on some samples from the Thebes Group have been carried on by means of thin sections. The study area is included in the Libyan Desert Plateau (central Egypt) at following coordinates N27° 36'30.58" E29° 44'58.34", near the biggest dune of Egypt, the Ghard Abu Muharik. Because of the round shape of the rocks and the desert patina on the surface they could easily be classified as the so called "Melonstones", which are located more southwards and mainly composed by stromatolites. On the contrary, the investigated samples show a completely different fauna and therefore have been separated from the "Melonstones". Even if shape and size are very similar and the desert patina covers all surfaces the same way the differences are impressive. To investigate the samples, two thin-sections have been prepared and analyzed at the microscope. The observed fauna is composed by: agglutinated benthic foraminifera (e.g., Dictyoconus egypticus), complex larger miliolids (e.g., Pseudolacazina cf. danatae, Fabularia sp.), alveolinids (Alveolina vredenburgi), green algae (Dasycladaceae), echinoids and corals. Because of the presence of symbionts bearing larger benthic foraminifera, which need light to feed photosymbionts, the rock was formed in a shallow water environment. With the abundant rock-building benthic foraminifera and calcareous algae the limestone shows a tendency to the packstone/wackestone facies. Based on the presence of Alveolina vredenburgi, the age of the samples can be estimate as lowermost Eocene belonging to the shallow benthic zone 5 (sensu Serra-Kiel et al., 1998). According the obtained data on stratigraphy and palaeoecology, a partial palaeoenvironmental reconstruction is possible for the Libyan Desert Plateau where outcrops are largely missing. Because of the round shape of the samples and the patina which covers them all around it can be assumed that they have been transported from longer distance. According to the geological map of the area and to the fauna observed in the sections, the source of the samples can be related to the Farafra Formation, which is characterized by white to grey alveolinid shallow water limestone. The closest outcrop belonging to this formation can be found around 50 kilometers westwards from the location where the samples were taken. Serra-Kiel J., Hottinger L., Caus E., Drobne K., Ferrà Ndez C., Jauhria.K., Less G., Pavlovec R., Pignatti J., Samsó J.M., Schaub H., Sirel E., Strougo A., Tambareau Y., Tosquella J., ZAKREVSKAYA E., 1998 - Larger Foraminiferal Biostratigraphy Of The Tethyan Paleocene And Eocene. Bull. Soc. géol. France, 169 (2): 281-299.

Karnitschar, C.; Briguglio, A.; Hohenegger, J.

2012-04-01

73

PLEISTOCENE BIRD FAUNA FROM BIR TARFAWI (EGYPTIAN WESTERN DESERT)  

Microsoft Academic Search

Boche?ski, Z. 1991. Pleistocene bird fauna from Bir Tarfawi (Egyptian Western Desert). Ostrich 62: 29–34.At Bir Tarfawi, an archaeological site in the Egyptian Sahara dated to about 135000 years (before present), 202 bone fragments were identified as belonging to 24 bird species or genera. Most of the material is apparently from owl pellets. The birds represent aquatic and terrestrial forms

Zygmunt Boche?ski

1991-01-01

74

Geochemistry of the Banded Iron Formations and their Host Rocks in the Eastern Desert of Egypt BACKUS, Ethan L.1, GAGNON, Kelli E.1, EL-SHAZLY, Aley K.1, and KHALIL, Khalil Isaac2  

E-print Network

Geochemistry of the Banded Iron Formations and their Host Rocks in the Eastern Desert of Egypt University, Egypt Sponsored by NSF-OISE-1004021 Session 92:T3. Sigma Gamma Epsilon Undergraduate Research over 30,000 km2 in the central Eastern Desert of Egypt. The deposits most resemble Algoma-type iron

El-Shazly, Aley

75

Silver and silver-bearing minerals at the Um Samiuki volcanogenic massive sulphide deposit, Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

The Um Samiuki Zn Cu Pb Ag mineralisation, south Eastern Desert, Egypt is hosted by felsic volcanic rocks which form part of the 712-Ma-old, east-west-trending Shadli Volcanic Belt. Two major occurrences of massive sulphides are present at the top of rhyolitic breccia in the Western and Eastern mine areas. In each occurrence, a bornite-bearing zone is overlain by a pyrite-chalcopyrite-bearing zone and underlain by a disseminated, Cu-depleted zone. In the massive sulphide ore, sphalerite, chalcopyrite, pyrite, galena, bornite and tetrahedrite tennantite are major minerals, whereas arsenopyrite, pyrrhotite, molybdenite and magnetite are accessory phases. Covellite and digenite are common secondary minerals. Bornite, tetrahedrite tennantite and covellite contain high amounts of silver (averages of 1.97, 1.39 and 1.82 wt% respectively). Based on mineralogical balance calculations, bornite and covellite accommodate 80% of silver in the Um Samiuki deposit. Ag was incorporated in the crystal structure of the early-crystallised copper sulphides and sulphosalts and silver minerals. The temperature, sequential precipitation of the fluids and the structure of the crystallising phases control the distribution of silver. Post-depositional deformation and metamorphic processes caused liberation, remobilisation and redeposition of silver within the massive sulphides.

Shalaby, Ibrahim M.; Stumpfl, Eugen; Helmy, Hassan M.; El Mahallawi, Mahmoud M.; Kamel, Omar A.

2004-10-01

76

Natural radioactivity and rare earth elements in feldspar samples, Central Eastern desert, Egypt.  

PubMed

The pegmatite bodies of the Eastern Desert of Egypt are widely distributed especially along the Marsa-Alam-Idfu road. The Abu Dob area covers about 150km(2) of the Arabian Nubian shield at the central part of the Eastern Desert of Egypt. Most of the pegmatite is zoned; the zonation starts with milky quartz at the core followed by alkali feldspar at the margins. The feldspars vary in color from rose to milky and in composition from K-feldspar to Na-feldspar, sometimes interactions of both types are encountered. Thirteen feldspar samples were collected from different locations in the Abu Dob area for measuring the natural radioactivity of (238)U, (232)Th and (40)K using an HPGe detector. The variation in concentration of radionuclides for the area under investigation can be classified into regions of high, medium and low natural radioactivity. The average concentration in BqKg(-1) has been observed to be from 9.5 to 183675.7BqKg(-1) for (238)U, between 6.1 and 94,314.2BqKg(-1) for (232)Th and from 0 to 7894.6BqKg(-1) for (40)K. Radium equivalent activities (Ra(eq)), dose rate (D(R)) and external hazard (H(ex)) have also been determined. In the present work, the concentration of rare earth elements are measured for two feldspar samples using two techniques, Environmental Scanning Electron microscope XIL 30 ESEM, Philips, and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). The existence of rare earth elements in this area are very high and can be used in different important industries. PMID:21324705

Walley El-Dine, Nadia; El-Shershaby, Amal; Afifi, Sofia; Sroor, Amany; Samir, Eman

2011-05-01

77

Springs in Egypt  

NASA Astrophysics Data System (ADS)

Examples of springs in Egypt deal only with examples of natural springs producing potable water. None of the natural springs producing highly mineralized thermal water for therapeutical are considered. No water from natural springs in Egypt is bottled. Egyptian standards state that the total dissolved solids in potable water should not exceed 1000 ppm, except in Siwa, where the only available source for water for human consumption is from springs that have water containing more than 2000 ppm TDS. Six natural springs in Egypt provide typical examples for the Sinai and the Western Desert: Ain Furtaga in the southern pre-Cambrian province of Sinai Peninsula; Ain El Gudeirat in the sedimentary plateau of North Sinai; and Ain El Bishmo, Ain El Bousa, and Ain El Gabal in the Western Desert Oases of Bahariya, Kharga, and Dakhla. They discharge from the Nubian Sandstone aquifer system. The sixth spring, Ain El Arayes, is a spring in Siwa Oasis.

Idris, H.

1996-03-01

78

Classification and origin of the Neoproterozoic ophiolitic mélanges in the Central Eastern Desert of Egypt  

NASA Astrophysics Data System (ADS)

The Eastern Desert of Egypt is part of the Neoproterozoic Arabian-Nubian Shield and displays different occurrences of Neoproterozoic ophiolitic mélanges. The mélanges contain exotic and native blocks and fragments of variable sizes and types set in a sheared and schistose volcaniclastic matrix. The main exotic blocks are ophiolitic and include metamorphosed ultramafic rocks, metagabbros, massive and pillowed metabasalts and pelagic sedimentary rocks. Based on the mode of occurrences of the ophiolitic components and the processes of mélange formation, the ophiolitic mélanges of the Central Eastern Desert are classified and mapped into tectonic mélange, olistostrome and olistostromal mélange. The whole rock associations of these mélanges were subjected to two different events of deformation (D1 and D2) and contemporaneous metamorphism (M1 and M2). The metagreywackes of the mélange matrix are similar to oceanic island arc sandstone and appear to have been deposited in a back-arc or inter-arc basin. The blocks of ophiolitic metabasalts within the mélange show tholeiitic affinity and have back-arc basin (BAB) tectonic origins. Metamorphosed ultramafic blocks in the mélange display both mid-ocean ridge (MOR) and suprasubduction zone (SSZ) affinities. The ophiolitic components represent fragments of oceanic lithosphere that formed in a back-arc/arc environment, and were incorporated into the mélange through tectonic and/or sedimentary processes. Both tectonic and sedimentary processes played a major role during mélange formation in a back-arc or inter-arc setting.

El Bahariya, Gaafar A.

2012-09-01

79

Extensional collapse along the Sevier Desert reflection, northern Sevier Desert basin, western United States  

NASA Astrophysics Data System (ADS)

Newly released and previously published seismic reflection data from the northern Sevier Desert basin provide a complete seismic transect between the tilted western margin of the basin and the eastern breakaway zone. When tied to well and surface age data, the transect delineates a continuum of extensional fault and basin fill geometries that developed between late Oligocene and Pleistocene time across the basin. A minimum of 18 km of top-to-the-west normal displacement is estimated across the Sevier Desert from only the most conspicuous growth geometries and offsets across listric normal faults that sole downward into the Sevier Desert reflection (SDR). The SDR clearly marks a normal fault zone beneath the entire basin, where stratal truncations are imaged for 50% of the 39 km length of the reflection east of the Cricket Mountains block. Restoration of extensional displacement along this entire 39 km fault length is necessary to reconstruct the pre-Oligocene configuration and erosion level of Sevier thrust sheets across the Sevier Desert area. The SDR normal fault zone underlies the former topographic crest of the Sevier orogenic belt, where it accommodated extensional collapse after cessation of regional contractile tectonism.

Coogan, James C.; Decelles, Peter G.

1996-10-01

80

Aerospectrometric and aeromagnetic characteristics associated Nb–Ta–Sn mineralization, G. Nuweibi albite granite Central Eastern Desert, Egypt  

Microsoft Academic Search

A geophysical signature associated with Nb–Ta–Sn mineralization of G. (G. : abbreviation to word Gebel which means mountain\\u000a in Arabic) Nuweibi area, located the Central Eastern Desert of Egypt is presented. This signature was established by an integration\\u000a of airborne gamma ray spectrometric and magnetic data. Variations seen in the gamma ray spectrometric data are used as a base\\u000a to

Sami Hamed Abd El Nabi; El Nabi

81

Sequence stratigraphy of the Cenomanian Galala Formation, north Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

The sequence stratigraphic framework of the Cenomanian Galala Formation (north Eastern Desert, Egypt) is estimated on the basis of the Sedimentological and obtainable biostratigraphic data, in addition to the regional correlation of the studied sections. Five sequence boundaries are identified. The first sequence boundary separates between the Galala and Malha formations. The second, third and fourth sequence boundary exhibit a differentiated nature. It is noticed that such sequence boundaries in Gebel El-Zeit are mainly represented by paleosols and caliche, while those of the Northern Galala, Gebel Ataqa and Gebel Shabraweet are mostly typified by emergence horizons of dolomites and dedolomites. The fifth (last) sequence boundary separates the Galala Formation from the overlying El-Khashm Formation at Gebel El-Zeit, the Northern Galala and Gebel Ataqa and from Maghra El-Hadida Formation at Gebel Shabraweet. The Galala Formation in the study area is subdivided into four depositional sequences, which are built up of three systems tracts; the lowstand (LST), transgressive (TST) and highstand (HST) systems tracts. The LSTs are realized only from Gebel El-Zeit, where they are made up of clastic facies organized in coarsening- and fining-upward parasequences. The TSTs form a series of aggradational-retrogradational, shallowing-upward parasequences, which transgress across the ramp till the point of maximum flooding is reached. The HSTs are built up of aggradational-progradational, shallowing-upward parasequences of shallow subtidal to peritidal facies.

Khalifa, M. A.; Abu El-Ghar, Mohamed S.; Helal, S. A.; Hussein, A. W.

2014-01-01

82

Kinematic analysis of the Migif area in the Eastern Desert of Egypt  

NASA Astrophysics Data System (ADS)

The use of porphyroclasts rotating in a flowing matrix to estimate mean kinematic vorticity number (Wm) is important for quantifying the relative contributions of pure and simple shear in penetratively deformed rocks. The kinematic vorticity number determined for high temperature mylonitic gneisses in the Migif area in the Eastern Desert of Egypt range from ?0.6 to 0.9. The results from vorticity and strain analyses indicate that deformation in the area deviated from simple shear. It is concluded that nappe stacking occurred early during the thrusting event, probably by brittle imbrications, and that ductile strain was superimposed on the nappe structure at high-pressure as shown by a penetrative subhorizontal foliation is developed subparallel to the tectonic contacts with the under- and overlying nappes. The accumulation of ductile strain during underplating was not by simple shear but involved a component of vertical shortening, which caused the subhorizontal foliation in the Migif area. In most cases, this foliation was formed during thrusting of the nappes onto each other, suggesting that nappe stacking was associated with vertical shortening.

Kassem, Osama M. K.

2014-11-01

83

Technologies Applied in the Toshka Project of Egypt  

ERIC Educational Resources Information Center

The Toshka Project, located in Egypt, involves excavating a canal to carry about 380 billion ft[supercript 3] of water every year from Lake Nasser to the Toshka Depression, southwest of Aswan. This will eventually create a new valley to the River Nile in the western desert of Egypt in addition to the currently existing prehistoric river course.…

Wahby, Wafeek S.

2004-01-01

84

Greenstone-hosted lode-gold mineralization at Dungash mine, Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

The auriferous quartz ± carbonate veins at Dungash mine, central Eastern Desert of Egypt, are confined to ?E-trending dilation zones within variably foliated/sheared metavolcanic/volcaniclastic rocks. The vein morphology and internal structures demonstrate formation concurrent with a dextral shear system. The latter is attributed to flexural displacement of folded, heterogeneous rock blocks through transpression increment, late in the Neoproterozoic deformation history of the area. Geochemistry of the host metavolcanic/metavolcaniclastic rocks from the mine area suggests derivation from a low-K, calc-alkaline magma in a subduction-related, volcanic arc setting. In addition, chemistry of disseminated Cr-spinels further constrain on the back-arc basin setting and low-grade metamorphism, typical of gold-hosting greenstone belts elsewhere. Mineralogy of the mineralized veins includes an early assemblage of arsenopyrite-As-pyrite-gersdorffite ± pyrrhotite, a transitional pyrite-Sb-arsenopyrite ± gersdorffite assemblage, and a late tetrahedrite-chalcopyrite-sphalerite-galena-gold assemblage. Based on arsenopyrite and chlorite geothermometers, formation of gold-sulfide mineralization occurred between ?365 and 280 °C. LA-ICP-MS measurements indicate the presence of refractory Au in arsenian pyrite (up to 53 ppm) and Sb-bearing arsenopyrite (up to 974 ppm). Abundant free-milling gold associated with the late sulfide assemblage may have been mobilized and re-distributed by circulating, lower temperature ore fluids in the waning stages of the hydrothermal system. Based on the isotopic values of vein quartz and carbonate, the calculated average ?18OH2O values of the ore fluids are 5.0 ± 1.4‰ SMOW for quartz, and 3.3 ± 1.4‰ for vein carbonate. The measured carbonate ?13C values correspond to ore fluids with ?13CCO2 = -6.7 ± 0.7‰ PDB. These results suggest a mainly metamorphic source for ore fluids, in good agreement with the vein morphology, textures and hydrothermal alteration. The calculated ?34SH2S values for early, transitional, and late sulfide assemblages define three distinct ranges (?1.5-3.6‰), (?0.4-1.0‰), and (-3.7‰ to -1.9‰), respectively. The systematic evolution towards lighter ?34S values may be attributed to recrystallization, or to ore fluid buffering under variable physicochemical conditions. The shear zone-related setting, mineralogy and isotopic characteristics of gold mineralization in Dungash mine are comparable with other orogenic gold deposits in the region (e.g., Barramiya deposit), which may suggest a regional setting controlling gold metallogeny of the region. This setting should guide future exploration programs in the central Eastern Desert province.

Zoheir, Basem; Weihed, Pär

2014-11-01

85

Oppositely dipping thrusts and transpressional imbricate zone in the Central Eastern Desert of Egypt  

NASA Astrophysics Data System (ADS)

This paper documents the 40-60 km wide ENE-WSW trending Mubarak-Barramiya shear belt (MBSB) in the Central Eastern Desert of Egypt by examining its structural styles, kinematics and geometry. Our study revealed the existence of prevalent dextral and minor sinistral conjugate shear zones. The MBSB is metamorphic belt (greenschist-amphibolite) characterized by at least three post-collisional (740-540 Ma) ductile Neoproterozoic deformation events (D1, D2 and D3) followed by a brittle neotectonic deformation (D4). D1 event produced early top-to-the-northwest thrust displacements due to NW-SE shortening. D2 produced discrete zones of NNW-trending upright folds and culminated in initiation of major NW-trending sinistral shear zones of the Najd Fault System (NFS, at c. 640-540 Ma ago) as well as steeply dipping S2 foliation, and shallowly plunging L2 lineation. NW-to NNW-trending F2 folds are open to steep and vary in plunge from horizontal to vertical. D2 deformational fabrics are strongly overprinted by D3 penetrative structures. D3 is characterized by a penetrative S3 foliation, steeply SE- to NW-plunging and shallowly NE-plunging stretching lineations (L3), asymmetric and sheath folds (F3) consistent with dextral sense of movement exhibited by delta- and sigma-type porphyroclast systems and asymmetric boudinage fabrics. D2-D3 represent a non-coaxial progressive event formed in a dextral NE- over NW-sinistral shear zone during a partitioned transpression in response to E-W-directed compression during oblique convergence between East and West Gondwana developed due to closure of the Mozambique Ocean and amalgamation of the Arabian-Nubian Shield in Cryogenian-early Ediacaran time.

Abd El-Wahed, Mohamed A.

2014-12-01

86

Holocene Paleoecology of the Western Tenere Desert, Niger, Africa  

NASA Astrophysics Data System (ADS)

Multiple paleontological, sedimentological, and isotopic/ionic geochemical indicators permit reconstruction of the Holocene ecology of the western Tenere Desert (southern Sahara hyper-desert). Modern precipitation is highly erratic, averaging 25 mm yearly, and vegetative cover is negligible. From the early to middle Holocene, however, grassland-shrublands and seasonal to permanent lakes and wetlands predominated, supporting diverse limnic, riparian, and upland communities. Annual precipitation probably was comparable to that of the modern southern Sahel, exceeding 350 mm. Coarse-grained sediment washed into the large lacustrine basin from exposures of metamorphic, plutonic, and volcanic rocks in the nearby Air Massif highland. Lake margins fluctuated in response to runoff and limited ground-water discharge. The water was non-saline and there is no evidence of evaporite deposition. Aquatic and riparian macrophytes thrived, as did an extensive lacustrine-palustrine macrofauna. A Sahelian flora of mixed grasses, thorn shrubs, and perhaps some larger woodland species occupied the contiguous uplands, supporting resident and migratory mammalian and avian faunas. Lake levels were high until 6300 to 5200 BP, possibly as late as 4800 BP locally. Deflation of lacustrine deposits during a subsequent dry period provided finer-grained eolian sediment accreting as proximal dunes. The composition of mineral sediment within the middle to late Holocene dunes is different from, but clearly a subset of the lacustrine deposits. Organic matter reworked from the lake sediment was deposited in the dunes and oxidized in situ, generating CO2 that dissolved in soil moisture, producing bicarbonate. The bicarbonate reacted with calcium from weathered minerals, producing calcic cementation about 5100 BP. The resulting petrocalcic horizon was later exposed, weathered, and colonized by sparse terrestrial vegetation for one or more brief periods. A late phase of pedogenesis concurrent with or closely post-dating plant colonization produced secondary porosity and metallic oxide cementation. The metallic oxide cement preserved minute quantities of organic matter from the terrestrial flora and invertebrate microfauna. Regional ecology was controlled by global post-Pleistocene deglaciation, sea-level changes, and establishment of zonal weather systems. The modern Okavango Delta of Botswana is, in part, a suitable analog for the late Pleistocene to early/middle Holocene environment of the western Tenere Desert, as are smaller, lesser-known, extant wetlands in Niger.

Sereno, P. C.; Caran, S. C.; Housh, T. B.

2007-12-01

87

Genesis of the Abu Marawat gold deposit, central Eastern Desert of Egypt  

NASA Astrophysics Data System (ADS)

Gold mineralisation at the Abu Marawat mine, central Eastern Desert of Egypt, is related to a system of massive and sheared, milky quartz veins cutting a sequence of Neoproterozoic island arc metavolcanic/volcaniclastic rocks and related banded iron formation (BIF). Sulphide-bearing quartz veins and related hydrothermal breccia bodies display a range of textures including sheared, boudinaged and recrystallised quartz, open space filling and microbreccia. These variable textures imply a complex history of crack-seal mechanism characterising the relation between mineral deposition and a major N-S-trending shear zone, during a late brittle-ductile deformation event which affected the area at about 550 Ma. Gold-base metal mineralisation is associated with brecciation and fracturing of the iron ore bands, close to silicified shears and related quartz veins. The auriferous quartz lodes are characterised by the occurrence of visible pyrite-chalcopyrite ± pyrrhotite ± sphalerite ± galena mineralisation. Gold is refractory in pyrite and chalcopyrite, but rare visible gold/electrum and telluride specks were observed in a few samples. Hydrothermal alteration includes pervasive silicification, pyritisation, sericitisation, carbonatisation confined to a delicate set of veins and altered shears, and a more widespread propylitic alteration assemblage (quartz + chlorite + pyrite + calcite ± epidote). Fluid inclusion petrography and microthermometric studies suggest heterogeneous trapping of a low-salinity (1.4-6.7 wt.% eq. NaCl) aqueous solution and a carbonic fluid. Evidence for fluid immiscibility during ore formation includes variable liquid/vapour ratios in inclusions along individual trails and bulk inclusion homogenisation into liquid and occasionally to vapour at comparable temperatures. The trapping conditions of intragranular aqueous-carbonic inclusions approximate 264-378 °C at 700-1300 bar. Similar temperature estimates have been obtained from Al-in-chlorite geothermometry of chlorite associated with sulphides in the mineralised quartz veins. Fracturing enhanced fluid circulation through the wallrock and related BIF, allowing reaction of the S-bearing ore fluid with iron oxides. This caused pyrite formation and concomitant Au precipitation, enhanced by fluid immiscibility as H 2S partitioned preferentially into the carbonic phase. The ore fluids may have originated from granitoid intrusions (likely the post-Hammamat felsites, whereas gold and base metals might have been leached from the Abu Marawat basic metavolcanics.

Zoheir, Basem A.; Akawy, Ahmed

2010-06-01

88

Recharge to the interdune lakes and Holocene climatic changes in the Badain Jaran Desert, western China  

Microsoft Academic Search

We present new estimates on evaporation and groundwater recharge in the Badain Jaran Desert, western Inner Mongolia of northwestern China, based on a modified Penman Equation suitable for lakes in China. Geochemical data and water balance calculations suggest that local rainfall makes a significant contribution to groundwater recharge and that past lake-level variations in this desert environment should reflect palaeoclimatic

Xiaoping Yang; Nina Ma; Jufeng Dong; Bingqi Zhu; Bing Xu; Zhibang Ma; Jiaqi Liu

2010-01-01

89

The paleomagnetism of certain Late Precambrian and Early Paleozoic rocks from the Red Sea Hills, Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

A stable remanence was isolated from three groups of rocks collected in the Eastern Desert of Egypt. Two groups of dikes, one collected north of the Qena-Safaga road and the other about 200 km to the south near the Um Rus gold mine, gave paleomagnetic pole positions of 87°N, 304°E and 86°N, 185°E, respectively. Both have K/Ar ages in the range 480-530 m.y. The results are compatible with data reported from other Gondwana cratonic areas for this time period. The third group of rocks were samples of the Dokhan Volcanic Series collected at seven sites along the Qena-Safaga road. The paleomagnetic pole position of the higher-coercivity component, 36°S, 17°E, acquired about 600 m.y. ago is not easily reconciled with established polar wander paths. The younger component, however, with a paleomagnetic pole lying at 54°N, 327°E, suggests a Cambro-Ordovician age.

Davies, J.; Nairn, A. E. M.; Ressetar, R.

1980-07-01

90

Deserts  

NSDL National Science Digital Library

Deserts, one of the four major terrestial biomes, cover about one-fifth of Earth's land area. This interactive slide presentation shows some aspects of deserts, including dunes, desert-adapted plants, oases, and sculpted rock formations. There is also a map showing the distribution of the world's deserts. A background essay and discussion questions are included.

91

Potential Impacts of Climate Change on Modern Recharge in the Eastern Desert and Sinai Peninsula of Egypt  

NASA Astrophysics Data System (ADS)

Aquifers in Egypt (e.g., Nubian Sandstone, shallow alluvial) were primarily recharged in previous wet climatic periods in the Quaternary. Previous studies have shown that both aquifers are receiving modern recharge under the current drier climatic conditions. The validity of these advocated models was tested using geophysical (conventional Electrical Resistivity, [ER]) and isotopic (O, H) data, and estimates for modern recharge were obtained using continuous rainfall-runoff modeling over the period 1998-2007. First-order estimates of the average annual modern recharge for the NSS aquifer (~13.0 x 10^6m^3/yr) and the shallow Alluvial aquifers in the Sinai Peninsula for the investigated watersheds (456 x 10^6m^3/yr) and the shallow Alluvial aquifers in the Eastern Desert (147 x 10^6m^3/yr) were computed using the SWAT (Soil Water Assessment Tool) model and readily available global remote sensing data sets (e.g., TRMM). Projections of climate change over North Africa from three of the leading general circulation models (GCMs) (GISS, GFDL, and UKMO) indicate a potentially high degree of vulnerability in the future precipitation amounts in Egypt. For each of the major watersheds and the Nubian Sandstone outcrops, we ran the calibrated model over the investigation period (1998-2007) using the obtained average annual precipitation and additional values of 10, 50, 100, and 150 mm. The SWAT model outputs were then used to extract relationships describing variations in runoff, recharge, and evaporation in relation to average annual precipitation amounts. Using developed tools on a web-based GIS interface we described these relationships under various climatic trends. Using a 10% decrease in rainfall in Egypt results in decreasing the average annual recharge to the shallow Alluvial aquifers in the Sinai Peninsula (384 x 10^6m^3/yr) and in the Eastern Desert (111 x 10^6m^3/yr). The observed differences between the watersheds in the partitioning of precipitation and in their response to increasing precipitation, is largely related to the variations in their lithologic characteristics. Findings bear on the sustainable exploitation of the Nubian Sandstone and shallow Alluvial aquifers, where the aquifer is being locally recharged, and on the exploitation of similar extensive aquifers largely recharged in previous wet climatic periods yet are still receiving modest modern meteoric contributions.

Milewski, A.; Sultan, M.; Becker, D.; Soliman, F.; Yan, E.; Becker, R.; Chouinard, K.

2011-12-01

92

Petrology and petrogenesis of the older and younger granitoids of Wadi Beizah area, Central Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

The studied granitoids of Wadi Beizah area, Central Eastern Desert, Egypt, are represented by older arc-granitoids intruded by a post-collisional stock of younger pink granite. The arc-granitoids (I-type) cover a wide compositional spectrum from meladiorites, diorites, quartzdiorites/monzodiorites and tonalites, to leucogranodiorites. Their distribution pattern is unimodal dominated by diorites. They are of low-K calc-alkaline character and represent the plutonic rocks of the mature, ensimatic island arc stage. Three models for the geotectonic environment of the younger granites of the Eastern Desert of Egypt have been suggested: (1) Within-plate, rifting, tensional environment similar to the Oslo Rift of Norway (Greenberg, 1981) Stern et al., 1984, 1986), (2) Extensive crustal anatexis during collisional tectonics, compression, thickening of the crust and thrust imbrication (Hussein et al., 1982; Ragab, 1987b), (3) Active continental margin geotectonic environment (Abdel-Rahman and Martin, 1987). These three models are discussed in detail. The present workers believe that the Younger Granites in general are the products of extensive crustal anatexis at the culmination of the Pan-African orogenic cycle when arc-arc suturing is complete. Recent studies revealed a low-angle thrust event in the Central Eastern Desert followed the initial arc-arc collision and continued after the deposition of the molasse-type sediments (Ries et al., 1983; El-Ramly et al., 1984; Greiling et al., 1984; Habib et al., 1985; Greiling and El-Ramly, 1985) which indicate thickening of the crust and compression regime at the time of emplacement of the Younger Granites. The dominance of ?granite minimum? composition of these late orogenic granites suggests extensive crustal anatexis. Their low Nb-content (< 40 ppm) precludes within-plate hot-spot related magma, in comparison with: (1) The post-Pan-African (400-100 M.a.) granitic rocks from the NE Sudan which on a geochemical evidence are the products of within-continental plate ?hot-spot? magmatism with Nb-content of about 50-300 ppm (Gass, 1979); (2) The Oslo Rift within-plate granites with Nb-content of 226 ppm (Pearce et al., 1984). A post-collision model showing the formation of the ?petrotectonic assemblage? of this stage (molasse-type sediments deposited in fault-bounded troughs, and calc-alkaline bimodal intermediate and felsic magmas) as well as the heat sources in the geotectonic environment of thrust imbrication and the mode of formation of the Younger Granites by crustal anatexis is suggested. K/Ar dating of a younger granite sample gave an age of 584 ± 5 M.a. which is compatible with several similar ages of younger pink granites in the Eastern Desert of Egypt. An older granite sample gave an age of 591 ± 7 M.a. (K/Ar method) indicating resetting of its isotopic clocks probably as a result of the extensive crustal anatexis event.

Ragab, A. I.; Menesy, M. Y.; Diab, M. M.

93

Deserts.  

ERIC Educational Resources Information Center

The abundance of life, the highly varied geologic formations, and climatic variations found in a wide range of deserts is presented. Misconceptions held about the desert are discussed. A list of resources and activities are included. (KR)

Mogil, H. Michael; And Others

1991-01-01

94

Heat flow measurements in Egypt  

Microsoft Academic Search

Temperature measurements in recent mineral exploration boreholes allow the first heat flow estimates to be made for Egypt. Gradients ranging from 15.6 to 32.0 mK m⁻¹ have been determined from 22 boreholes at 4 locations in the Eastern Desert, and a range of 18.0 to 18.5 mK m⁻¹ was measured in 3 boreholes at a single locality in the Western

P. Morgan; D. D. Blackwell; F. K. Boulos

1976-01-01

95

Paleosols of the Upper Cretaceous Lower Tertiary Maghra El-Bahari Formation in the northeastern portion of the Eastern Desert, Egypt: Their recognition and geological significance  

Microsoft Academic Search

The Upper Cretaceous\\/Lower Tertiary Maghra El-Bahari Formation at Gabal Ataqa and Gabal Shabrawet in the northeastern portion of the Eastern Desert of Egypt is subdivided into two informal lithostratigraphic parts: lower and upper. The lower part has common features of alluvial floodplain-dominated deposits with occasional occurrences of crevasse splay deposits. The upper part has sediments typical of marginal lacustrine environments.

H. A. Wanas; M. M. Abu El-Hassan

2006-01-01

96

Paleosols of the Upper Cretaceous–Lower Tertiary Maghra El-Bahari Formation in the northeastern portion of the Eastern Desert, Egypt: Their recognition and geological significance  

Microsoft Academic Search

The Upper Cretaceous\\/Lower Tertiary Maghra El-Bahari Formation at Gabal Ataqa and Gabal Shabrawet in the northeastern portion of the Eastern Desert of Egypt is subdivided into two informal lithostratigraphic parts: lower and upper. The lower part has common features of alluvial floodplain-dominated deposits with occasional occurrences of crevasse splay deposits. The upper part has sediments typical of marginal lacustrine environments.Both

H. A. Wanas; M. M. Abu El-Hassan

2006-01-01

97

Biological nitrogen fixation to maximize productivity of intercropped legumes and non?legumes: Ten years of field experimentations in semi?arid deserts of egypt  

Microsoft Academic Search

A number of field trials was executed in semi?arid deserts of Ismailia, Egypt, to experiment growth and productivity of sole or mixed canopies of legumes (soybean, leucaena, sesbania, berseem and grasspea) and non?legumes (corn, Rhodes grass, elephant grass, ryegrass and barley) when inoculated with N2?fixing bacteria (diazotrophs) in presence or absence of N fertilizers. An average estimate of > 20

N. A. Hegazi; M. Fayez

2001-01-01

98

Mineralogy and geochemistry of Nb, Ta, Sn, U-, Th-, and Zr-bearing granitic rocks from Abu Rusheid shear zones, South Eastern Desert, Egypt  

Microsoft Academic Search

Granite-hosted, Nb-, Ta-, Sn-, U-, Th-, and Zr (Hf)-bearing mineralization from the Abu Rusheid shear zones occurs about 97\\u000a km southwest of the town of Marsa Alam, South Eastern Desert, Egypt. The SSE-trending brittle-ductile Abu Rusheid shear zones\\u000a crosscut the peralkalic granitic gneisses and cataclastic to mylonitic rocks (mylonite, protomlyonite, and ultramylonite).\\u000a The northern shear zone varies in width from

M. A. Ali; D. R. Lentz; D. C. Hall

2011-01-01

99

Desert landforms of southwest Egypt: A basis for comparison with Mars  

NASA Technical Reports Server (NTRS)

Geologic interpretations of The Gilf Kebir-Uweinat of Apollo-Soyuz photographs were verified. The photographs and LANDSAT images showed features reminiscent of those depicted by Mariner and Viking missions to Mars. These features were to better understand their morphologic analogs on Mars. It is indicated that climate change played a significant role in the formation of the eastern Sahara. It is also revealed that correlations between the eolian features in southwestern Egypt and the wind blown patterns on the surface of Mars result in a better understanding of eolian activity on both planets.

El-Baz, F. (editor); Maxwell, T. A. (editor)

1982-01-01

100

Integrating Indigenous Knowledge of Wildland Fire and Western Technology to Conserve Biodiversity in an Australian Desert  

Microsoft Academic Search

The relatively recent exodus of Aboriginal people from parts of the Western Desert region of Australia has coincided with an alarming decline in native mammals and a contraction of some fire sensitive plant communities. Proposed causes of these changes, in what is an otherwise pristine environment, include an altered fire regime resulting from the departure of traditional Aboriginal burning, predation

N. D. Burrows; A. A. Burbidge; P. J. Fuller

101

Late Pleistocene and Holocene dune activity and wind regimes in the western Sahara Desert of Mauritania  

Microsoft Academic Search

The western Sahara Desert in Mauritania is dominated by extensive sand seas consisting largely of linear dunes. Analyses of Landsat images, geomorphic and stratigraphic studies, and optically stimulated luminescence dating of dunes in the Azefal, Agneitir, and Akchar sand seas provide evidence that three main generations of dunes were formed during the periods 25 15 ka (centered around the Last

Nicholas Lancaster; Gary Kocurek; Ashok Singhvi; V. Pandey; Max Deynoux; Jean-Francois Ghienne; Khalidou Lô

2002-01-01

102

Magmatic and solid state structures of the Abu Ziran pluton: Deciphering transition from thrusting to extension in the Eastern Desert of Egypt  

NASA Astrophysics Data System (ADS)

The 606 Ma old Abu Ziran granite of the Eastern Desert of Egypt intruded the southern margin of the Meatiq dome in a sinistral shear extensional setting. Its emplacement was enabled by a system of NW-trending sinistral shears, related Riedel shears and N-S extensional shear zones and faults. Magmatic flow was east-directed and controlled by Riedel shears that progressively rotated to an orientation favourable for extension. Strain markers that document magmatic flow show eastward decreasing strain together with strain increase from pluton centre to margins. This is explained by Newtonian flow between non-parallel plates and differences in flow velocities across the pluton. Solid state fabrics including shear fabrics, orientation of late magmatic dykes and quartz tension gashes, together with quartz C-axes distributions, document southward extensional shear within the solidified pluton and adjacent host rocks. Extensional shear is correlated with exhumation of the Meatiq dome coeval and soon after pluton solidification (585 Ma). Pressure temperature evolutionary paths, derived from fluid inclusions, show a clockwise path with exhumation by isothermal decompression in the Meatiq dome. By contrast, the overlying volcanosedimentary nappes experienced an anti-clockwise path released by temperature rise due to pluton emplacement followed by isobaric cooling. Quartz fabrics indicate high-temperature coaxial N-S flow in the northern Meatiq dome and lower-temperature, non-coaxial southward flow within the overlaying superficial nappe. This is explained by the exhumation process itself that progressively localised into simple shear domains when rocks approached higher crustal levels. Late extension at ca. 580 Ma was pure shear dominated and resulted in reversal of shear, now dextral, in the western Meatiq shear zone.

Fritz, Harald; Loizenbauer, Jürgen; Wallbrecher, Eckart

2014-11-01

103

Groundwater quality and management in arid and semi-arid regions: Case study, Central Eastern Desert of Egypt  

NASA Astrophysics Data System (ADS)

This study presents a model budget for groundwater in the Central Eastern Desert of Egypt. The stable isotopic composition and hydrochemistry of groundwater samples collected from different aquifers were determined to identify recharge sources and water quality. Stable isotopic values suggest that shallow alluvial and fracture zone aquifers are recharged from seasonal precipitation, while groundwater in deeper sedimentary sub-basins is paleowater that was recharged during periods of less arid regional climate. Hydrochemical analysis indicates elevated salinity in each aquifer type, which is attributed to leaching and dissolution of terrestrial salts and to mixing with marine water. Groundwater from sedimentary sub-basin aquifers can be treated and used for drinking and domestic purposes. Groundwater from shallow alluvial and fracture zone wells is suitable for animal husbandry and mineral ore dressing. A model water budget shows that approximately 4.8 × 109 m3 of recoverable groundwater is stored in sedimentary sub-basin aquifers, or approximately 550 years of water at present utilization rates.

Amer, Reda; Ripperdan, Robert; Wang, Tao; Encarnación, John

2012-07-01

104

Geothermal potential of Egypt  

NASA Astrophysics Data System (ADS)

One hundred and sixty samples of groundwater from nearly all parts of Egypt have been collected and chemically analyzed in order to assess the country's geothermal potential. The samples considered to be thermal include 20 wells ( T > 35° C), 4 springs ( T > 30° C) and 1 spring not included in the present inventory. The remaining samples, together with data from the literature, establish background chemistry. The hottest springs are located along the east shore of the Gulf of Suez: Uyun Musa (48°C) and 'Ain Hammam Faraoun (70°C). Additional warm springs are located along both shores of the Gulf of Suez and this region is the most promising for geothermal development. The Eastern Desert of Egypt, particularly the coastal area adjacent to the Red Sea has above normal heat flow ( ~ 72.0 < mWm-2) and therefore some geothermal potential although only one thermal well (Umm Kharga: 35.8°C) could be located, In the major oases of the Western Desert (Kharga, Dakhla, Farafra and Bahariya), the regional temperature gradient is low (< 20° C/ km), but many of the wells tap deep artesian aquifers and produce large volumes of water in the 35-43°C range. Such wells constitute a low temperature geothermal resource. None of our samples in northern Egypt can be considered thermal including several reported "hot springs." Application of the silica, NaKCa. and NaKCaMg geothermometers does not indicate the presence of a high temperature geothermal resource at any area we visited.

Swanberg, Chandler A.; Morgan, Paul; Boulos, F. K.

1983-04-01

105

The Cretaceous glauconitic sandstones of Abu Tartur, Egypt  

Microsoft Academic Search

The Abu Tartur mine is located in the Western Desert of Egypt, 50 km west of El Kharga City. Geologically, the Abu Tartur plateau is built by a sequence of Upper Cretaceous (Campanian - Maastrichtian) phosphorites, black shales and glauconitic sandstones. The phosphate deposits are of great economic importance and have been mined since their discovery in 1967. Outcrop sections

Brigitte Pestitschek; Susanne Gier; Mahmoud Essa; Johannes Kurzweil

2010-01-01

106

El-Dab'a ground water aquifer assessment, Egypt  

NSDL National Science Digital Library

El-Dabaa area is an area located in the norther part of the western desert, Egypt and planed to be nuclear power point. Some vertical electrical sounding have been done there to evaluate the ground water aquifer there to monitor the effect of sea water intrusion and its effect on the fresh water aquifer

elhamy Tarabees

107

Heat production rate from radioactive elements in igneous and metamorphic rocks in Eastern Desert, Egypt.  

PubMed

Radioactive heat-production data of Igneous and Metamorphic outcrops in the Eastern Desert are presented. Samples were analysed using a low level gamma-ray spectrometer (HPGe) in the laboratory. A total of 205 rock samples were investigated, covering all major rock types of the area. The heat-production rate of igneous rocks ranges from 0.11 (basalt) to 9.53 microWm(-3) (granite). In metamorphic rocks it varies from 0.28 (serpentinite ) to 0.91 microWm(-3) (metagabbro). The contribution due to U is about 51%, as that from Th is 31% and 18% from K. The corresponding values in igneous rocks are 76%, 19% and 5%, respectively. The calculated values showed good agreement with global values except in some areas containing granites. PMID:16120480

Abbady, Adel G E; El-Arabi, A M; Abbady, A

2006-01-01

108

Diversity of bacteria nesting the plant cover of north Sinai deserts, Egypt  

PubMed Central

North Sinai deserts were surveyed for the predominant plant cover and for the culturable bacteria nesting their roots and shoots. Among 43 plant species reported, 13 are perennial (e.g. Fagonia spp., Pancratium spp.) and 30 annuals (e.g. Bromus spp., Erodium spp.). Eleven species possessed rhizo-sheath, e.g. Cyperus capitatus, Panicum turgidum and Trisetaria koelerioides. Microbiological analyses demonstrated: the great diversity and richness of associated culturable bacteria, in particular nitrogen-fixing bacteria (diazotrophs); the majority of bacterial residents were of true and/or putative diazotrophic nature; the bacterial populations followed an increasing density gradient towards the root surfaces; sizeable populations were able to reside inside the root (endorhizosphere) and shoot (endophyllosphere) tissues. Three hundred bacterial isolates were secured from studied spheres. The majority of nitrogen-fixing bacilli isolates belonged to Bacillus megaterium,Bacillus pumilus, Bacillus polymexa,Bacillus macerans,Bacillus circulans and Bacillus licheniformis. The family Enterobacteriaceae represented by Enterobacter agglomerans,Enterobacter sackazakii, Enterobacter cloacae, Serratia adorifera,Serratia liquefaciens and Klebsiella oxytoca. The non-Enterobacteriaceae population was rich in Pantoae spp., Agrobacterium rdiobacter, Pseudomonas vesicularis, Pseudomonas putida, Stenotrophomonas maltophilia, Ochrobactrum anthropi, Sphingomonas paucimobilis and Chrysemonas luteola.Gluconacetobacter diazotrophicus were reported inside root and shoot tissues of a number of tested plants. The dense bacterial populations reported speak well to the very possible significant role played by the endophytic bacterial populations in the survival, in respect of nutrition and health, of existing plants. Such groups of diazotrophs are good candidates, as bio-preparates, to support the growth of future field crops grown in deserts of north Sinai and irrigated by the water of El-Salam canal. PMID:25685397

Hanna, Amira L.; Youssef, Hanan H.; Amer, Wafaa M.; Monib, Mohammed; Fayez, Mohammed; Hegazi, Nabil A.

2012-01-01

109

Diversity of bacteria nesting the plant cover of north Sinai deserts, Egypt.  

PubMed

North Sinai deserts were surveyed for the predominant plant cover and for the culturable bacteria nesting their roots and shoots. Among 43 plant species reported, 13 are perennial (e.g. Fagonia spp., Pancratium spp.) and 30 annuals (e.g. Bromus spp., Erodium spp.). Eleven species possessed rhizo-sheath, e.g. Cyperus capitatus, Panicum turgidum and Trisetaria koelerioides. Microbiological analyses demonstrated: the great diversity and richness of associated culturable bacteria, in particular nitrogen-fixing bacteria (diazotrophs); the majority of bacterial residents were of true and/or putative diazotrophic nature; the bacterial populations followed an increasing density gradient towards the root surfaces; sizeable populations were able to reside inside the root (endorhizosphere) and shoot (endophyllosphere) tissues. Three hundred bacterial isolates were secured from studied spheres. The majority of nitrogen-fixing bacilli isolates belonged to Bacillus megaterium, Bacillus pumilus, Bacillus polymexa, Bacillus macerans, Bacillus circulans and Bacillus licheniformis. The family Enterobacteriaceae represented by Enterobacter agglomerans, Enterobacter sackazakii, Enterobacter cloacae, Serratia adorifera, Serratia liquefaciens and Klebsiella oxytoca. The non-Enterobacteriaceae population was rich in Pantoae spp., Agrobacterium rdiobacter, Pseudomonas vesicularis, Pseudomonas putida, Stenotrophomonas maltophilia, Ochrobactrum anthropi, Sphingomonas paucimobilis and Chrysemonas luteola. Gluconacetobacter diazotrophicus were reported inside root and shoot tissues of a number of tested plants. The dense bacterial populations reported speak well to the very possible significant role played by the endophytic bacterial populations in the survival, in respect of nutrition and health, of existing plants. Such groups of diazotrophs are good candidates, as bio-preparates, to support the growth of future field crops grown in deserts of north Sinai and irrigated by the water of El-Salam canal. PMID:25685397

Hanna, Amira L; Youssef, Hanan H; Amer, Wafaa M; Monib, Mohammed; Fayez, Mohammed; Hegazi, Nabil A

2013-01-01

110

Geochemical and K Ar age constraints on the Late Neoproterozoic (?) gneisses at Um Tenassib area, north Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

Wadi Um Tenassib metamorphic rocks consist mainly of biotite gneiss and biotite-hornblende gneiss with subordinate intercalations of amphibolite, migmatitic gneiss, and aplitic granite. Biotite-hornblende gneiss, biotite gneiss, and aplitic granite are geochemically characterized and their cooling ages are determined by using the K-Ar method on biotite. The Um Tenassib gneisses (UTG) range in composition from quartz diorite/monzodiorite to granodiorite. They were derived from igneous rocks that pertain to calc alkaline and metaluminous to weakly peraluminous affinities and were generated in continental volcanic arc setting. REE patterns of the UTG are moderately fractionated (La N/Lu N = 5.9-7.5) relative to those of the aplitic granite (La N/Lu N = 33). The similarity in the geochemical characteristics and REE patterns of both gneiss types indicate their magmatic consanguinity. Amphiboles of the UTG biotite-hornblende gneisses are mainly hornblende, together with few paragasitic hornblende and edenite. Plagioclase composition is oligoclase to andesine (An 21-46) in the biotite-hornblende gneiss, and oligoclase (An 11-26) in the biotite gneiss. Mineral chemistry of amphibole and plagioclase indicate that the gneisses were metamorphosed under low- to medium-pressure of 2.6-6.4 kbar and at medium to high temperatures of 660-755 °C. The K-Ar biotite cooling ages (seven samples) range from 585 ± 12 Ma to 598 ± 12 Ma for the UTG, except one biotite-hornblende gneiss sample gives age of 577 ± 11 Ma. These ages suggest a latest metamorphic cooling event at ca. 585-600 Ma time span, which is consistent with the proposed cooling ages of ˜600 Ma for the Elat metamorphic rocks [Cosca, M.A., Shimron, A., Caby, R., 1999. Late Precambrian metamorphism and cooling in the Arabian-Nubian Shield: petrology and 40Ar/ 39Ar geochronology of metamorphic rocks of the Elat area (southern Israel). Precamb. Res. 98, 107-127]. It may indicate that the metamorphism of the UTG might have been contemporaneous with the suggested regional metamorphism at 620 ± 10 Ma for Sinai metamorphic rocks (Cosca et al., 1999) and/or the emplacement age at 614 Ma for the granodiorite in the study area [Stern, R.J., Hedge, C.E., 1985. Geochronological and isotopic constraints on the Late Precambrian crustal evolution in the Eastern Desert of Egypt. Am. J. Sci. 285, 97-127]. These ages also lie within the range of magmatic activity of the Younger Granites in the North Eastern Desert (575-600 Ma).

Eliwa, Hassan A.

2007-05-01

111

Late Neoproterozoic Nuqara Dokhan Volcanics, Central Eastern Desert, Egypt: Geochemistery and petrogenesis  

NASA Astrophysics Data System (ADS)

The Nuqara volcanic is one of the northernmost outcrops of the Arabian-Nubian Shield Dokhan volcanics. The origin and tectonic setting of the late Neoproterozoic Dokhan volcanics (ca. 610-560 Ma) in the Egyptian Eastern Desert is highly debated. The debate concerns the tectonic setting where they formed during transition between convergent to extensional regime or after the East- and the West-Gondwana collision (~600Ma). In order to solve this problem, lavas from Nuqara area were studied geologically and geochemically. Nuqara Dokhan volcanics comprises two main rock suites: (a) an intermediate volcanic suite, consisting of basaltic andesite, andesite and their associated pyroclastics rocks; and (b) a felsic volcanic suite composed of dacite, rhyolite and ignimbrites. The two suites display well-defined major and trace element trends and continuum in composition with wide ranges in SiO2 (52-75.73%), CaO (9.19-0.22%), MgO (5.29-0.05%), Sr (1367-7.4 ppm), Zr (688.5-172.7 ppm), Cr (207-0.4 ppm), and Ni (94.3-0.2 ppm). The Nuqara Dokhan volcanics are characterized by strong enrichment in LILE relative to HFSE and affiliated to the calc-alkaline subducted - related magmatism. Geochemical Modeling displays that the evolution of these rocks was governed by fractional crystallization of plagioclase, amphiboles, pyroxene, magnetite and apatite in the intermediate varieties and plagioclase, amphibole, magnetite, apatite and zircon in the felsic varieties. The obtained mineral chemistry of these volcanics reveals: (a) Plagioclase range in composition from An55 to An40 in basaltic andesite and from An39 to An24 in andesite. (b) Alkali feldspars have sanidine composition. (c) Clinopyroxenes have augite composition. The low Al2O3 contents (1.94-5.588 wt %) indicate that clinopyroxene crystallized at low - pressure conditions. (d) Amphiboles have magnesio- hornblende composition.

Hassan, Tharwat; Asran, Asran; Amron, Taha; Natflos, Theo

2014-05-01

112

Magmatic unmixing in spinel from late Precambrian concentrically-zoned mafic-ultramafic intrusions, Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

Spinel is widespread in the ultramafic core rocks of zoned late Precambrian mafic-ultramafic complexes from the Eastern Desert of Egypt. These complexes; Gabbro Akarem, Genina Gharbia and Abu Hamamid are Precambrian analogues of Alaskan-type complexes, they are not metamorphosed although weakly altered. Each intrusion is composed of a predotite core enveloped by pyroxenites and gabbros at the margin. Silicate mineralogy and chemistry suggest formation by crystal fractionation from a hydrous magma. Relatively high Cr 2O 3 contents are recorded in pyroxenes (up to 1.1 wt.%) and amphiboles (up to 1.4 wt.%) from the three plutons. The chrome spinel crystallized at different stages of melt evolution; as early cumulus inclusions in olivine, inclusions in pyroxenes and amphiboles and late-magmatic intercumulus phase. The intercumulus chrome spinel is homogenous with narrow-range of chemical composition, mainly Fe 3+-rich spinel. Spinel inclusions in clinopyroxene and amphibole reveal a wide range of Al (27-44 wt.% Al 2O 3) and Mg (6-13 wt.% MgO) contents and are commonly zoned. The different chemistries of those spinels reflect various stages of melt evolution and re-equilibration with the host minerals. The early cumulus chrome spinel reveals a complex unmixing structures and compositions. Three types of unmixed spinels are recognized; crystallographically oriented, irregular and complete separation. Unmixing products are Al-rich (Type I) and Fe 3+-rich (Type II) spinels with an extensive solid solution between the two end members. The compositions of the unmixed spinels define a miscibility gap with respect to Cr-Al-Fe 3+, extending from the Fe 3+-Al join towards the Cr corner. Spinel unmixing occurs in response to cooling and the increase in oxidation state. The chemistry and grain size of the initial spinel and the cooling rate control the type of unmixing and the chemistry of the final products. Causes of spinel unmixing during late-magmatic stage are analogous to those in metamorphosed complexes. The chemistry of the unmixed spinels is completely different from the initial spinel composition and is not useful in petrogenetic interpretations. Spinels from oxidized magmas are likely to re-equilibrate during cooling and are not good tools for genetic considerations.

Ahmed, Ahmed Hassan; Helmy, Hassan Mohamed; Arai, Shoji; Yoshikawa, Masako

2008-08-01

113

Stratigraphy, sedimentology and tectonic evolution of the Upper Cretaceous/Paleogene succession in north Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

The stratigraphy, sedimentology and syn-depositional tectonic events (SdTEs) of the Upper Cretaceous/Paleogene (K-P) succession at four localities in north Eastern Desert (NED) of Egypt have been studied. These localities are distributed from south-southwest to north-northeast at Gebel Millaha, at North Wadi Qena, at Wadi El Dakhal, and at Saint Paul Monastery. Lithostratigraphically, four rock units have been recorded: Sudr Formation (Campanian-Maastrichtian); Dakhla Formation (Danian-Selandian); Tarawan Formation (Selandian-Thanetian) and Esna Formation (Thanetian-Ypresian). These rock units are not completely represented all over the study area because some of them are absent at certain sites and others have variable thicknesses. Biostratigrapgically, 18 planktonic foraminiferal zones have been recorded. These are in stratigraphic order: Globotruncana ventricosa Zone (Campanian); Gansserina gansseri, Contusotruncana contusa, Recimguembelina fructicosa, Pseudohastigerina hariaensis, Pseudohastigerina palpebra and Plummerita hantkenenoides zones (Maastrichtian); Praemurica incostans, Praemurica uncinata, Morozovella angulata and Praemurica carinata/Igorina albeari zones (Danian); Igorina albeari, Globanomanlina pseudomenradii/Parasubbotina variospira, Acarinina subsphaerica, Acarinina soldadoensis/Globanomanlina pseudomenardii and Morozovella velascoensis zones (Selandian/Thantian); and Acarinina sibaiyaensis, Pseudohastigerina wilcoxensis/Morozovella velascoensis zones (earliest Ypresian). Sedimentologically, four sedimentary facies belts forming southwest gently-dipping slope to basin transect have been detected. They include tidal flats, outer shelf, slumped continental slope and open marine hemipelagic facies. This transect can be subdivided into a stable basin plain plus outer shelf in the extreme southwestern parts; and an unstable slope shelf platform in the northeastern parts. The unstable slope shelf platform is characterized by open marine hemipelagic, fine-grained limestones and fine siliciclastic shales (Sudr, Dakhla, Tarawan and Esna formations). The northeastern parts are marked by little contents of planktonic foraminifera and dolomitized, slumped carbonates, intercalated with basinal facies. Tectonically, four remarkable syn-depositional tectonic events (SdTEs) controlled the evolution of the studied succession. These events took place strongly within the Campanian-Ypresian time interval and were still active till Late Eocene. These events took place at: the Santonian/Campanian (S/C) boundary; the Campanian/Maastrichtian (C/M) boundary; the Cretaceous/Paleogene (K/P) boundary; and the Middle Paleocene-Early Eocene interval. These tectonic events are four pronounced phases in the tectonic history of the Syrian Arc System (SAS), the collision of the Afro-Arabian and Eurasian plates as well as the closure of the Tethys Sea.

El Ayyat, Abdalla M.; Obaidalla, Nageh A.

2013-05-01

114

Structural and remote sensing studies of gold mineralization and associated alteration in Abu-Marawat area, northern Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

Gold has been mined in the Eastern Desert of Egypt since the time of the Pharaohs, yet the geologic setting of the gold mineralization, the structural controls, and its association with hydrothermal alteration zones is still not fully understood. A common application of remote sensing is to identify variations in surface mineralogy, structural elements, and geologic contacts. In this study, surface reflectance data derived from the Advanced Spaceborne Thermal Emission and reflection Radiometer (ASTER) imagery is used to map areas of high potential gold mineralization within hydrothermal alteration zones through refining previously used satellite image processing techniques. Spectral unmixing in n-dimentional spectral feature space has proven very accurate in distinguishing different alteration minerals, as well as highlighting the extent and main trend of alteration zones around Abu-Marawat area. Band ratio image (bands 4/8, 4/2, 8/9 in RGB) has proved to be efficient in highlighting areas for high-potential gold mineralization. Studying the areas of potential gold mineralization by looking at the associated structural elements has helped us understand the formation and evolution of mineralized zones. Detailed field mapping and structural analysis has helped to identify the main phases of deformation affecting the study area of Abu-Marawat. Mineralized quartz veins, mainly hosted in normal fault shear zones, developed during a period of island arc formation and represent the oldest phase of hydrothermal events in the area. These mineralized veins have been deformed by folding and were subsequently cut by relatively undeformed barren quartz veins. This proposed early phase of arc-related gold mineralization is consistent with the presence of gold-rich banded iron formations of Abu-Marawat that also formed during the arc formation stage. The tectonic evolution model of the area is illustrated by relating the main structural elements to the major tectonic events that are known to have affected the study area. This model is compared to other tectonic model(s) proposed for the area for further validation.

Gabr, Safwat Salah

115

Morphodynamic implications for shoreline management of the western-Mediterranean sector of Egypt  

NASA Astrophysics Data System (ADS)

Although the western-Mediterranean coast of Egypt between Sallum and Alexandria, ~550 km long, has maintained a considerable equilibrium throughout history, developers have built traditional protective structures in an effort to form sheltered recreational beaches without taking into consideration its geomorphologic characteristics, coastal processes and their harmful impact on the coastal environment and human safety. The improper practices in this environmentally valuable region have induced us to undertake an initiative to carry out a morphodynamic analysis to provide a framework for understanding the relationship between coastal morphology and the prevailing dynamic forces. Based on the degree of natural protection or wave sheltering, the study shoreline can be categorized into four distinct morphotypical stretches: (1) high-energy wave-exposed shores and the outer margins of the rocky headlands, (2) moderate to high wave-energy beaches along semi-exposed embayments and bays mostly downdrift of the rocky headlands, (3) low-wave energy at semi-exposed headland lee-sided and pocket beaches, and (4) calm wave-sheltered enclosing water basins for safe anchorages, moorings and recreation beaches. The results deducted will have practical applications for shoreline management initiatives regarding sustained sites suitable for future beachfront development such as safe swimming conditions, sport facilities, water intakes and sheltered areas for vessels. In addition, benefits realized by the understanding of the morphodynamic processes would enhance our awareness of the significance of the role of western coast morphodynamics in supporting sustainable development via shoreline management. As far as sustainability is concerned, the selection of appropriate sites would help avoiding or minimizing the formation of the hard structures needed for creating safe recreation beaches. On a national scale, results reached could provide reliable database for information that can be used in establishing a sustainable shoreline management plan, which is, in turn, an essential part when implementing an Integrated Coastal Zone Management Plan for this region of attraction.

Frihy, Omran E.

2009-09-01

116

Integrating geologic and satellite imagery data for high-resolution mapping and gold exploration targets in the South Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

The granitoid-greenstone belts of the Arabian-Nubian Shield are well-endowed with lode gold and massive sulfide ores. Although generally characterized by excellent outcrops and arid desert realm, poor accessibility and lack of finance have been always retardant to detailed geologic mapping of vast areas of the shield. Lack of comprehensive geological information and maps at appropriate scales would definitely hinder serious exploration programs. In this study, band ratioing, principal component analysis (PCA), false-color composition (FCC), and frequency filtering (FFT-RWT) of ASTER and ETM+ data have substantially improved visual interpretation for detailed mapping of the Gebel Egat area in South Eastern Desert of Egypt. By compiling field, petrographic and spectral data, controls on gold mineralization have been assessed in terms of association of gold lodes with particular lithological units and structures. Contacts between foliated island arc metavolcanics and ophiolites or diorite are likely to be favorable loci for auriferous quartz veins, especially where the NW-SE foliation is deflected into steeply dipping NNW-trending shear planes. High-resolution mapping of the greenstone belt, structures and alteration zones associated with gold lodes in the study area suggests that dilatation by foliation deflection was related to emplacement of the Egat granitic intrusion, attendant with a sinistral transpression regime (i.e., ˜640-550 Ma?). Gold mineralization associated with granitoid intrusions in transpression-induced pull-apart structures elsewhere in the Eastern Desert (e.g., Fawakhir, Sukari and Hangaliya mines) emphasize the reliability of this setting as a model for gold exploration targets in greenstone terrains of Egypt, and may be elsewhere in the Arabian-Nubian Shield.

Zoheir, Basem; Emam, Ashraf

2012-05-01

117

Pan-African adakitic rocks of the north Arabian-Nubian Shield: petrological and geochemical constraints on the evolution of the Dokhan volcanics in the north Eastern Desert of Egypt  

NASA Astrophysics Data System (ADS)

The Precambrian basement of Egypt is part of the Red Sea Mountains and represents the north-western part of the Arabian-Nubian Shield (ANS). Five volcanic sections are exposed in the Egyptian basement complex, namely El Kharaza, Monqul, Abu Had, Mellaha and Abu Marwa. They are located in the north Eastern Desert (ED) of Egypt and were selected for petrological and geochemical studies as they represent the Dokhan volcanics. The volcanics divide into two main pulses, and each pulse was frequently accompanied by deposition of immature molasse type sediments, which represent a thick sequence of the Hammamat group in the north ED. Compositionally, the rocks form a continuum from basaltic andesite, andesite, dacite (lower succession) to rhyodacite and rhyolite (upper succession), with no apparent compositional gaps. These high-K calc-alkaline rocks have strong affinities to subduction-related rocks with enriched LILEs (Rb, Ba, K, Th, Ce) relative to high field strength elements (Nb, Zr, P, Ti) and negative Nb anomalies relative to NMORB. The lower succession displays geochemical characteristics of adakitic rocks with SiO2 >53 wt%, Al2O3 >15 wt%, MgO >2.5 wt%, Mg# >49, Sr >650 ppm, Y <17 ppm, Yb <2 ppm, Ni >25 ppm, Cr >50 ppm and Sr/Y >42.4. They also have low Nb, Rb and Zr compared to the coexisting calc-alkaline rhyodacites and rhyolites. The highly fractionated rhyolitic rocks have strong negative Eu anomalies and possess the geochemical characteristics of A-type suites. Trace element geochemical signatures indicate a magma source consistent with post-collisional suites that retain destructive plate signatures associated with subduction zones. The adakitic rocks in the northern ANS are generated through partial melting of delaminated mafic lower crust interacting with overlying mantle-derived magma. The Dokhan volcanics were likely generated by a combination of processes, including partial melting, crystal fractionation and assimilation.

Obeid, Mohamed A.; Azer, Mokhles K.

2014-11-01

118

The Predynastic of Egypt  

Microsoft Academic Search

The Predynastic of Egypt, spanning an interval from ca. 4000 to 3050 B.C., was an eventful period. After the inception of food production in the Nile Valley at least a millennium before, it was the time when the identity of Egyptian society was forged. Egypt was settled by refugees from the deserts of the eastern Sahara and the southern Levant,

Fekri A. Hassan

1988-01-01

119

Northeast Egypt as seen from STS-58  

NASA Technical Reports Server (NTRS)

This oblique view, looking northeast from central Egypt, shows great expanses of the sand covered and rocky Western Desert in the foreground (bottom). The dark patches bottom right are the Dakhla Oases on the south side of an escarpment. The northern half of Egypt's Nile appears here, from about the latitude of Luxor to the delta. Green colors indicate the small area of crops which feed Egypt's population of 55 million. The Nile Delta is partly obscured by a band of clouds, but can be discerned at the coast as a flattened triangle of green. The smaller triangle close by is the Falyum Basin, a depression irrigated by water from the Nile. The coast of the Mediterranean Sea appears left.

1993-01-01

120

100 Kyr Old Desert of Western India: Morhodynamics and Environmental Significance  

NASA Astrophysics Data System (ADS)

The Late Quaternary oscillations in sea levels and resultant changes in the coastal environment have remained a popular aspect of study amongst the earthscientists and archaeologists. The Saurashtra peninsula of the western India that lies on the southwestern side of the Thar Desert, has archived a fascinating record of such environmental changes since last interglacial (~120kyr) in the form of a fossil desert exhibiting various aeolian land forms constituted by the sand largely derived from the coastal areas due to an oscillatory sea level change. A variety of dunes viz., coastal transverse, parabolic, longitudinal, barchans, climbing and falling dunes along with valley fills and sand sheets have been mapped. Being biogenic calcium carbonate rich, the sands have been lithified under the influence of an increase in moisture and thus the dune and bed forms are preserved in its best shape. The intense aeolian activities are also evident in the form of desert varnish on rocky outcrops. The sequence comprises smaller climate perturbations in the form of stabilization, erosion and karstification of older dunes and deposition of fluvial sediments in between. The paper deals with the mode of occurrence, response of sediments to wind dynamics and palaeo topography, internal structures, later modifications of sediments and significance of the geochronologically constrained aeolianites in understanding of environmental changes since 100kyr in the region.

Bhatt, N.

2012-04-01

121

Luminescence dating of Holocene playa sediments of the Egyptian Plateau Western Desert, Egypt  

NASA Astrophysics Data System (ADS)

This study is part of a multidisciplinary project dealing with the investigation of geoarchaeological sites on the Egyptian Plateau. With the aim of reconstructing the palaeoecological background, providing age assessment which put the various results in an age frame that is of special interest. Here, results of one particular section have been selected because of a discrepancy in age determination based on different approaches. Radiocarbon ages were inconsistent with the age range provided by the archaeological context in this area. The underestimation observed is inferred to be caused by poor 14C-sample quality. An attempt to overcome this problem was the determination of the depositional ages of the non-organic sediments by using optically stimulated luminescence (OSL). Equivalent doses of four sediment samples were estimated from OSL measurements carried out on sand-sized quartz grains using the single-aliquot regenerative-dose (SAR) protocol. Dose rates were calculated from neutron activation analysis results. From the OSL ages obtained, we conclude that the sediment sequence exposing an alternation of lacustrine and eolian layers was deposited in a short period of time during the mid-Holocene (mean of OSL ages ˜7.8 ka). Compared to the 14C ages, the luminescence ages fit better into the archaeological context confirmed by surface dating.

Bubenzer, O.; Hilgers, A.

2003-05-01

122

Human Impact On Landscape And The Revenue In Wadi El Rayan Western Desert Egypt  

NASA Astrophysics Data System (ADS)

Wadi El-Rayan depression occupy about 1800 Km2, it lies in 170 km southwest Cairo. Two lakes in El-Rayan depression initiated since 1973 in a big project when people inundate with excess agricultural sewage water. This article aim to estimate the landscape's response and it's revenue to human's intervention. Two new geomorphological maps, before and after the lakes prepared in the field to understand the landscape changes and its characteristics. Water fluctuation in El Rayan Lakes required multitemporal Landsat image. Geomorphological landforms disappeared and others initiated and neo-ecosystem had been generated. Active elongated sand dune fields covered by water and the dune pattern changed from straight-linear pattern to braided pattern and sand sheets delineating that linear dunes lost activity. Hence avoid and avert dune‘s hazards on the agriculture west of Nile Valley. Landforms and geologic heritage demonstrated that there is an old lake under El Rayan depression. The artificial lakes lead to rise the water table which may abut attempts to utilize from the underground water my stored and water from artificial lakes may infiltrate and contaminate this water. The water volume changed in the southern lake from 501,2 km³ at 1984 to 1097,4 km³ at 1999.

Asayed El Gammal, El

2010-05-01

123

Magnetic fabrics and Pan-African structural evolution in the Najd Fault corridor in the Eastern Desert of Egypt  

NASA Astrophysics Data System (ADS)

In order to assess the Pan-African structural evolution from early orogenic fabrics through Najd wrenching to the latest orogenic collapse/extension, the authors used field work, aided by aerial photographs and satellite images. This work is complemented by the study of the anisotropy of the magnetic susceptibility (AMS, or magnetic fabric). The Pan-African rock associations of the Um Gheig-Kadabora area can be divided into a lower tier composed mainly of amphibolite-migmatite and granitoid gneisses, and an upper tier of ophiolitic rocks, metavolcanics and their related volcaniclastics, and molasse-type Hammamat sediments. Both these units are intruded by late orogenic granitoid plutons and dykes. The lower tier is exposed in a domal structure in the El Sibai area, the upper tier forms a series of weakly to highly deformed thrust units, called Pan-African Nappes here, which are dissected by high strain shear zones. According to their age, these rock units are divided here into early and late-orogenic. The early orogenic rock association is characterized by medium-high metamorphic grades. The late orogenic rock association is characterized by low metamorphic grade. The rocks in the upper tier form a series of low angle thrust sheets, which are bounded by NW-striking high angle shear zones related to the Najd Fault System. The early orogenic rocks show a polyphase structural evolution with early folds, thrusts, and strike-slip shear zones. The late orogenic rocks show a relatively weaker deformation. The latest intrusives studied here are the dykes dissecting the late orogenic Kadabora granite. In the present work magnetic fabric data document the deformational features in detail and assess the role of the Najd Fault System in the deformational evolution. A strong variation in volume susceptibility of various rocks, due to their variations in mineral composition, is observed. Lower values are in the range of 10-6 SI units for late-orogenic alkaline granite and the dykes dissecting it, the highest susceptibilities exceed 7 × 10-2 SI units in magnetite-bearing serpentinite. Early orogenic rocks are characterized by relatively high anisotropies (P? up to 1.7) and are deformed in numerous shear zones. Most of these shear zones can be related to the Najd Fault System. In contrast, late orogenic sediments and intrusives show mostly low anisotropies. However, magnetic lineations are still distinctly oriented parallel with the Najd Fault trend. The very latest Pan-African intrusives, the broadly N-S trending dykes crosscutting the Kadabora pluton, imply c. E-W directed extension. Such an extension is consistent with the magnetic fabric in some of the dykes. Therefore, the Kadabora dykes mark the end of Najd wrenching and a late stage of extension in this part of the Eastern Desert of Egypt. The other dykes display mostly primary fabrics, related to magma flow during their intrusion and are thus post-deformational with regard to the Pan-African orogeny.

Abdeen, Mamdouh M.; Greiling, Reinhard O.; Sadek, Mohamed F.; Hamad, Sayed S.

2014-11-01

124

Benefits of protective fencing to plant and rodent communities of the western Mojave Desert, California  

NASA Astrophysics Data System (ADS)

Human disturbance in the western Mojave Desert takes many forms. The most pervasive are livestock grazing and off-highway vehicle use. Over the past few decades several areas within this region have been fenced to preclude human disturbance. These areas provide opportunities to study the impact of human activities in a desert ecosystem. This paper documents the response of plant and small mammal populations to fencing constructed between 1978 and 1979 at the Desert Tortoise Research Natural Area, Kern County, California. Aboveground live annual plant biomass was generally greater inside than outside the fenced plots during April 1990, 1991, and 1992. The alien grass Schismus barbatus was a notable exception, producing more biomass in the unprotected area. Forb biomass was greater than that of alien annual grasses inside the fence during all three years of the study. Outside the fence, forb biomass was significantly higher than that of alien grasses only during spring 1992. Percent cover of perennial shrubs was higher inside the fence than outside, while no significant trend was detected in density. There was als more seed biomass inside the fence; this may have contributed to the greater diversity and density of Merriam's kangaroo rats ( Dipodomys merriami), long-tailed pocket mice ( Chaetodipus formosus), and southern grasshopper mice ( Onychomys torridus) in the protected area. These results show that protection from human disturbance has many benefits, including greater overall community biomass and diversity. The significance and generality of these results can be further tested by studying other exclosures of varying age and configurations in different desert regions of the southwestern United States.

Brooks, Matthew L.

1995-01-01

125

Ecological status of the Mediterranean Juniperus phoenicea L. Relicts in the desert mountains of North Sinai, Egypt  

Microsoft Academic Search

Juniperus phoenicea L. is listed as threatened tree by IUCN Red List. In Egypt, J. phoenicea L. is the only conifer tree that is restricted to the three mountains of northern Sinai: Gabal El-Halal, Gabal El-Maghara and Gabal Yelleq. As a Mediterranean relict it has been included in a national list as target for conservation and management. To provide baseline

Magdy El-Bana; Kamal Shaltout; Ahmed Khalafallah; Hosni Mosallam

2010-01-01

126

Habitat invasibility and dominance by alien annual plants in the western Mojave Desert  

USGS Publications Warehouse

Patterns of habitat invasibility and alien dominance, respectively measured as species richness and biomass of alien annual plants, were evaluated in association with four habitat factors at the Desert Tortoise Research Natural Area (DTNA) in the western Mojave Desert, USA. Habitat factors varied in levels of disturbance outside (high) and inside (low) the DTNA, and in levels of soil nutrients in washlet (high) and hummock (low) topographic positions, in Larrea-north (high), Larrea-south (medium), and interspace (low) microhabitats near creosote bushes (Larrea tridentata), and during 1995 when rainfall was 207% (high) and 1994 when rainfall was 52% (low) of the long-term average. Dominant alien plants included the annual grasses Bromus rubens, Bromus trinii, and Schismus spp., and the forb Erodium cicutarium. Species richness and dominance of alien annual plants were slightly higher where disturbance was high, and much higher where soil nutrients were high. B. rubens and B. trinii were most dominant in washlets and in the Larrea-north microhabitats during both years. These two species evolved in mesic ecosystems, and appeared to be particularly limited by soil nutrients at this site. Schismus spp. and E. cicutarium were also most dominant in washlets, but their dominance varied between interspaces in 1994 and the Larrea-south microhabitat in 1995. Monitoring to detect the invasion of new annual plants should focus on regions of high rainfall and nitrogen deposition and on washes and beneath-canopy microhabitats. The ecological range of each alien species should be evaluated separately, because their evolutionary origins may greatly affect their patterns of invasion and dominance in the Mojave Desert.

Brooks, M.L.

1999-01-01

127

Nest site characteristics and nesting success of the Western Burrowing Owl in the eastern Mojave Desert  

USGS Publications Warehouse

We evaluated nest site selection at two spatial scales (microsite, territory) and reproductive success of Western Burrowing Owls (Athene cunicularia hypugaea) at three spatial scales (microsite, territory, landscape) in the eastern Mojave Desert. We used binary logistic regression within an information-theoretic approach to assess factors influencing nest site choice and nesting success. Microsite-scale variables favored by owls included burrows excavated by desert tortoise (Gopherus agassizii), burrows with a large mound of excavated soil at the entrance, and a greater number of satellite burrows within 5 m of the nest burrow. At the territory scale, owls preferred patches with greater cover of creosote bush (Larrea tridentata) within 50 m of the nest burrow. An interaction between the presence or absence of a calcic soil horizon layer over the top of the burrow (microsite) and the number of burrows within 50 m (territory) influenced nest site choice. Nesting success was influenced by a greater number of burrows within 5 m of the nest burrow. Total cool season precipitation was a predictor of nesting success at the landscape scale. Conservation strategies can rely on management of habitat for favored and productive nesting sites for this declining species.

Longshore, Kathleen M.; Crowe, Dorothy E.

2013-01-01

128

Resilience to disturbance and resistance to alien grass invasions in the cold desert of western North America  

Technology Transfer Automated Retrieval System (TEKTRAN)

Alien grass invasions are resulting in ecosystem-level transformations of entire landscapes in arid and semi-arid ecosystems. The cold desert of western US is undergoing such a transformation, and is considered one of the most imperiled large ecosystems in the US. To address the rapid and complex ch...

129

Bi-Static Deep Electromagnetic Soundings for Martian Subsurface Characterization: Experimental Validation in the Egyptian Western Desert  

NASA Astrophysics Data System (ADS)

A bi-static version of the HF GPR TAPIR developed for martian deep soundings has been operated in the Egyptian Western Desert. The study presented focuses on the retrieval of the direction of arrival of the observed echoes on both simulated and measured d

Ciarletti, V.; Le Gall, A.; Berthelier, J. J.; Corbel, Ch.; Dolon, F.; Ney, R.; Reineix, A.; Guiffaud, Ch.; Clifford, S.; Heggy, E.

2007-03-01

130

Application and calibration of the subsurface mapping capability of SIR-B in desert regions  

NASA Technical Reports Server (NTRS)

The penetration capability of the shuttle imaging radar (SIR-B) sensor in desert regions is investigated. Refined models to explain this penetration capability in terms of radar physics and regional geologic conditions are devised. The sand-buried radar-rivers discovered in the Western Desert in Egypt and Sudan are defined. Results and procedures developed during previous SIR-A investigation of the same area are extrapolated.

Schaber, G. G.; Mccauley, J. F.; Breed, C. S.; Grolier, M. J.; Issawi, B.; Haynes, C. V.; Mchugh, W.; Walker, A. S.; Blom, R.

1984-01-01

131

Stable-isotope stratigraphy of the Cenomanian-Turonian (Upper Cretaceous) boundary event (CTBE) in Wadi Qena, Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

A high-resolution ?13C isotope record from Cenomanian-Turonian boundary interval of shallow marine successions in Egypt is presented. The ?13C curves show the typical features of the globally documented Cenomanian-Turonian positive excursion, including three of the main positive isotope peaks defining the Cenomanian-Turonian Boundary Event (CTBE). Based on high-resolution ammonite biostratigraphy, the CTBE started in the study area above the Late Cenomanian Neolobites vibrayeanus Zone within the Galala Formation, directly above the global sequence boundary Cenomanian 5 (SB Ce 5). A stratigraphic gap at that level cuts out the lower a-peak of the CTBE. The Cenomanian-Turonian boundary is located within the upper part of the positive excursion between carbon excursion peaks c and d, coinciding with the boundary between the Late Cenomanian Vascoceras cauvini and the Early Turonian Vascoceratid zones. The CTBE ended up-section of peak d, at the base of the Choffaticeras spp. Zone. The amplitude of the positive ?13C excursion in Egypt is very high (reaching 6.5‰ vs. V-PDB) and largely matches curves of European standard sections and others localities from different basins. Furthermore, the Lower Turonian Holywell Isotope Event, an important marker within the lowermost Turonian, has tentatively been recognized. The positive carbon stable isotope curves presented herein represent the outreach of the oceanic anoxic event (OAE) 2 in shallow-water nearshore sequences.

Nagm, Emad; El-Qot, Gamal; Wilmsen, Markus

2014-12-01

132

The Release of Chromium in Aquifers Underlying the Western Mojave Desert  

NASA Astrophysics Data System (ADS)

Recent studies suggest that chromium (Cr) in aquifers underlying the western part of the Mojave Desert may be naturally occurring, resulting from the release of this element from aquifer materials in oxic ground water with pH > 8.0. In order to test this hypothesis, we studied the kinetic release of Cr from aquifer material collected from the Sheep Creek fan near Victorville, CA. Pulverized and untreated aquifer material were incubated in 15mL Falcon tubes with water at three different pH values (2, 7, and 9) for 227 days. Duplicate samples were incubated in a heating bath at temperatures 20oC above ambient, in order to accelerate the kinetics of Cr release. Samples from each tube were collected, filtered through a 0.22 ? m filter, and analyzed using a graphite furnace atomic absorption photospectrometer using EPA Method 7199. Due to the heterogeneity of the aquifer material an accurate measure of Cr release kinetics was not possible; results presented here represent equilibrium values at the end of the incubation period. For untreated aquifer material incubated at ambient temperatures, Cr was found at concentrations of 26.0 ± 8.0 ppb at pH = 2, 5.2 ± 0.6 ppb at pH=7, and 9.1 ± 0.9 ppb at pH=9. As expected, the highest value of Cr was found for the samples incubated at pH=2. Pulverization of the samples resulted in an increase in Cr release by a factor of 1.5, 2.4, and 1.6 at pH values of 2, 7, and 9, respectively. Heating the pulverized samples at pH 7 and 9 resulted in an increase in the concentration of Cr released (by 25% and 9% respectively). However, heating the pulverized sample at pH=2 resulted in an almost 95% decrease in the concentration of released Cr (from 37.8 ppb to 2.2 ppb). The reason for this decrease is not known at this point. Our results indicate that significant concentrations of Cr are released naturally in Western Mojave Desert aquifers under various geochemical conditions. Additional studies are underway to study the kinetic release of Cr in packed columns.

Khachikian, C. S.; Plotkin, C.; Monterrosa, A.; Ramirez, P.

2004-12-01

133

Zr-Y-Nb-REE mineralization associated with microgranite and basic dykes at EL Sela shear zone, South Eastern Desert, Egypt.  

PubMed

El Sela shear zone occurs in the younger granite rock of Gabal El Sela area, south Eastern Desert, Egypt near the Sudan Frontier. It comprises lines-arranged intrusions trending ENE-WSW and extend for about 1.5 km in length and reach up to 40 meters in width. These lines-arranged intrusions include multi-phase quartz veins, altered microgranite and altered basic dykes. These dykes hosting or acting as a source for uranium, rare metals (Zr, Y, Nb and Ga) and light rare earths (La, Ce, Sm and Nd) mineralizations. They show highly alteration, uranium enrichment and a strong enrichment in some rare metals and light rare earths contents (Zr?=?644, Y?=?133, Nb?=?136, Ga =184, La?=?50.19, Ce?=?105.47, Sm?=?24.81, Nd?=?78.91 ppm and and ? LREEs?=?259.38.). The chondrite normalised rare earth elements trends indicate strongly fractionated rare earth elements pattern with significant enriched of LREE according to HREE in both altered microgranite and altered basic dykes. Field radiometric measurements of the studied altered microgranite dyke revealed that eU reach up to 359 ppm with an average 78 ppm, while in the altered basic dyke reach up to 1625 ppm with an average 144 ppm. PMID:25332873

Shahin, Hassan Abd El-Razek Aly

2014-01-01

134

Paleosols of the Upper Cretaceous Lower Tertiary Maghra El-Bahari Formation in the northeastern portion of the Eastern Desert, Egypt: Their recognition and geological significance  

NASA Astrophysics Data System (ADS)

The Upper Cretaceous/Lower Tertiary Maghra El-Bahari Formation at Gabal Ataqa and Gabal Shabrawet in the northeastern portion of the Eastern Desert of Egypt is subdivided into two informal lithostratigraphic parts: lower and upper. The lower part has common features of alluvial floodplain-dominated deposits with occasional occurrences of crevasse splay deposits. The upper part has sediments typical of marginal lacustrine environments. Both the floodplain and marginal lacustrine deposits exhibit pedogenic features comprising various types of paleosols. Among other soil-forming processes, diversity in the paleosols studied is mainly attributed to paleoclimatic and paleohydrologic changes. The paleosol criteria suggest two climatic regimes, a subhumid-semiarid one succeeded by a semiarid-arid one. The continental depositional environments recognized (floodplain and lacustrine) with their associated paleosols helped in the recognition of a marine regression in the area studied. In a regional perspective, comparison of the data presented in this study with paleosol data spanning the same time period in other localities suggests that the proposed paleoclimatic changes may have been of regional extent.

Wanas, H. A.; Abu El-Hassan, M. M.

2006-01-01

135

Neoproterozoic diamictite in the Eastern Desert of Egypt and Northern Saudi Arabia: evidence of ~750 Ma glaciation in the Arabian-Nubian Shield?  

NASA Astrophysics Data System (ADS)

The Neoproterozoic Atud diamictite in Wadi Kareim and Wadi Mobarak in the Eastern Desert of Egypt and the Nuwaybah formation in NW Saudi Arabia consist of poorly sorted, polymictic breccia, with clasts up to 1 m of granitoid, quartz porphyry, quartzite, basalt, greywacke, marble, arkose, and microconglomerate in fine-grained matrix. Stratigraphic relations indicate that the diamictite was deposited in a marine environment. Integrated field investigation, petrographic study and U-Pb SHRIMP zircon ages demonstrate that the Atud and Nuwaybah are correlative. The distribution of zircon ages indicate that ~750 Ma ages are dominant with a significant component of older materials, characterized by minor Mesoproterozoic and more abundant Paleoproterozoic and Neoarchean ages. Some matrix and metasedimentary clast zircons yield ages that are a few 10s of Ma younger than the age of the youngest clast (754 ± 15 Ma), suggesting Atud/Nuwaybah diamictite deposition ~750 Ma or slightly later, broadly consistent with being deposited during the Sturtian glaciation (740-660 Ma). The Paleoproterozoic and Neoarchean clasts have no source within the ensimatic Arabian-Nubian Shield. The distribution of the pre-Neoproterozoic ages are similar to the distribution of the pre-Neoproterozoic ages in Yemen and Saharan Metacraton, suggesting that these clasts have been transported hundreds of kilometers, maybe by ice-rafting. The Atud diamictite may represent important evidence for Cryogenian “Snowball Earth” in the Arabian-Nubian Shield.

Ali, Kamal A.; Stern, Robert J.; Manton, William I.; Johnson, Peter R.; Mukherjee, Sumit K.

2010-06-01

136

An assessment of the external radiological impact in granites and pegmatite in central Eastern Desert in Egypt with elevated natural radioactivity.  

PubMed

The contents of natural radionuclides ((226)Ra, (232)Th and (40)K) were measured in investigated samples (granite Gabal Ras Barud, Eastern Desert in Egypt) by using gamma spectrometry (NaI (Tl) 3?×3?). The activities of (226)Ra, (232)Th series and (40)K are between (3.8±0.5 and 172.8±1135.1±56.8 8.6), (2.3±0.3 and 103.8±5.2) and (53.1±2.7 and 1135.1±56.8) Bq kg(-1), respectively. With average total annual dose being only 67.2 ?Sv y(-1), this value is about 6.72 % of the 1.0 mSv y(-1) recommended by the International Commission on Radiological Protection (ICRP-60, 1990) as the maximum annual dose to members of the public. Geochemical studies revealed that Gabal Ras Barud is formed from a highly fractionated biotite granite, with SiO(2) >75 % and generally enriched in alkali with K/Na >8 %. PMID:21131664

Uosif, M A M; Abdel-Salam, L M

2011-11-01

137

Finite strain analysis of metavolcanics and metapyroclastics in gold-bearing shear zone of the Dungash area, Central Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

The Dungash gold mine area is situated in an EW-trending quartz vein along a shear zone in metavolcanic and metasedimentary host rocks in the Eastern Desert of Egypt. These rocks are associated with the major geologic structures, which are attributed to various deformational stages of the Neoproterozoic basement rocks. Field geology, finite strain and microstructural analyses were carried out and the relation-ships between the lithological contacts and major/minor structures have been studied. The R f/? and Fry methods were applied on the metavolcano-sedimentary and metapyroclastic samples from 5 quartz veins samples, 7 metavolcanics samples, 3 metasedimentary samples and 4 metapyroclastic samples in Dungash area. Finite-strain data show that a low to moderate range of deformation of the metavolcano-sedimentary samples and axial ratios in the XZ section range from 1.70 to 4.80 for the R f/? method and from 1.65 to 4.50 for the Fry method. We conclude that finite strain in the deformed rocks is of the same order of magnitude for all units of metavolcano-sedimentary rocks. Furthermore, the contact between principal rock units is sheared in the Dungash area under brittle to semi-ductile deformation conditions. In this case, the accumulated finite strain is associated with the deformation during thrusting to assemble nappe structure. It indicates that the sheared contacts have been formed during the accumulation of finite strain.

Kassem, Osama M. K.; Abd El Rahim, Said H.

2014-11-01

138

Bistatic GPR Measurements in the Egyptian Western Desert - Measured and Simulated data  

NASA Astrophysics Data System (ADS)

The TAPIR (Terrestrial And Planetary Investigation Radar) instrument has been designed at CETP (Centre d'etude des Environnements Terrestre et Planetaires) to explore the deep Martian subsurface (down to a few kilometers) and to detect liquid water reservoirs. TAPIR is an impulse ground penetrating radar operating at central frequencies ranging from 2 to 4 MHz operating from the surface. In November 2005, an updated version of the instrument working either in monostatic or in bi-static mode was tested in the Egyptian Western Desert. The work presented here focuses on the bi-static measurements performed on the Abou Saied plateau which shows a horizontally layered sub-surface. The electromagnetic signal was transmitted using one of the two orthogonal 70 m loaded electrical dipole antennas of the transmitting GPR. A second GPR, 50 or 100 meters apart, was dedicated to the signal reception. The received waves were characterized by a set of 5 measurements performed on the receiving GPR : the two horizontal components of the electric field and the three composants of the magnetic field. They were used to compute the direction of arrival of the incoming waves and to retrieve more accurately their propagation path and especially to discriminate between waves due to some sub-surface reflecting structure and those due to interaction with the surface clutter. A very efficient synchronization between the two radars enabled us to perform coherent additions up to 2^{31} which improves dramatically the obtained signal to noise ratio. Complementary electromagnetic measurements were conducted on the same site by the LPI (Lunar and Planetary Institute) and the SwRI (Southwest Research Institute). They provided independent information which helped the interpretation of the TAPIR data. Accurate simulations obtained by FDTD taking into account the information available are presented and used for both the interpretation of the measured data and the validation of the instrument.

Ciarletti, V.; Le Gall, A.; Berthelier, J.; Ney, R.; Corbel, C.; Dolon, F.

2006-12-01

139

Unique chemistry of a diamond-bearing pebble from the Libyan Desert Glass strewnfield, SW Egypt: Evidence for a shocked comet fragment  

NASA Astrophysics Data System (ADS)

We have studied a small, very unusual stone, here named “Hypatia”, found in the area of southwest Egypt where an extreme surface heating event produced the Libyan Desert Glass 28.5 million years ago. It is angular, black, shiny, extremely hard and intensely fractured. We report on exploratory work including X-ray diffraction, Raman spectroscopy, transmission electron microscopy, scanning electron microscopy with EDS analysis, deuteron nuclear reaction analysis, C-isotope and noble gas analyses. Carbon is the dominant element in Hypatia, with heterogeneous O/C and N/C ratios ranging from 0.3 to 0.5 and from 0.007 to 0.02, respectively. The major cations of silicates add up to less than 5%. The stone consists chiefly of apparently amorphous, but very hard carbonaceous matter, in which patches of sub-?m diamonds occur. ?13C values (ca. 0‰) exclude an origin from shocked terrestrial coal or any variety of terrestrial diamond. They are also higher than the values for carbonaceous chondrites but fall within the wide range for interplanetary dust particles and comet 81P/Wild2 dust. In step heating, 40Ar/36Ar ratios vary from 40 to the air value (298), interpreted as a variable mixture of extraterrestrial and atmospheric Ar. Isotope data of Ne, Kr and Xe reveal the exotic noble gas components G and P3 that are normally hosted in presolar SiC and nanodiamonds, while the most common trapped noble gas component of chondritic meteorites, Q, appears to be absent. An origin remote from the asteroid belt can account for these features. We propose that the Hypatia stone is a remnant of a cometary nucleus fragment that impacted after incorporating gases from the atmosphere. Its co-occurrence with Libyan Desert Glass suggests that this fragment could have been part of a bolide that broke up and exploded in the airburst that formed the Glass. Its extraordinary preservation would be due to its shock-transformation into a weathering-resistant assemblage.

Kramers, Jan D.; Andreoli, Marco A. G.; Atanasova, Maria; Belyanin, Georgy A.; Block, David L.; Franklyn, Chris; Harris, Chris; Lekgoathi, Mpho; Montross, Charles S.; Ntsoane, Tshepo; Pischedda, Vittoria; Segonyane, Patience; Viljoen, K. S. (Fanus); Westraadt, Johan E.

2013-11-01

140

Late Pan-African granite emplacement during regional deformation, evidence from magnetic fabric and structural studies in the Hammamat-Atalla area, Central Eastern Desert of Egypt  

NASA Astrophysics Data System (ADS)

Field investigations, microstructural observations, and magnetic fabric analyses revealed a polyphase, late Pan-African deformational evolution in the Um Sheqila-Um Had (595 Ma) composite pluton and in the Hammamat and Atalla areas of the Central Eastern Desert of Egypt in Ediacaran times. Major stages are early shortening (NNW-SSE), subsequent strike-slip (NW-SE shear zones), and late shortening (NW-SE). Strain studies on pebbles and xenoliths together with AMS data show a predominance of shallow, NW-SE trending X axes or magnetic lineations, associated with steep, NW-SE striking magnetic foliations. Magnetic fabrics and microstructures indicate a tectonic fabric in the Um Sheqila-Um Had granitoid plutons, which is dominated by steep NW-SE striking foliations and shallow NW-SE trending lineations, similar to those in the high-angle Atalla Shear Zone. There is a change of lineation directions from ESE-WNW at Um Sheqila (oldest) to NW-SE to Um Had II (youngest). This pattern may indicate an influence of strike-slip and is also consistent with NE-SW compression. This holds also true for the asymmetry of the contact aureole, which is extended towards NW, parallel with the trend of the magnetic lineation. The character and orientation of the deformation pattern in the Um Sheqila-Um Had plutons and the Atalla Shear Zone is thus similar to the pattern of the late shortening phase. The intrusion of the Um Sheqila-Um Had granitoid rocks, therefore, took place before the late shortening stage, but postdates early deformation, which, according to published data, was associated with lithospheric thinning in the Central Eastern Desert. Therefore, these Pan-African plutons do not represent the earliest post-deformational intrusions but a late stage of syn-deformational magmatic activity. At a regional scale, this deformation with steep foliations and shallow lineations may also be related with lateral escape tectonics. The pluton emplacement, the importance of transcurrent shear zones, and the low lithospheric thickness in the area are not consistent with tectonic elements at the Pan-African orogenic margin but imply a more internal position for the Wadi Hammamat area.

Greiling, R. O.; de Wall, H.; Sadek, M. F.; Dietl, C.

2014-11-01

141

Effects of protective fencing on birds, lizards, and black-tailed hares in the Western Mojave Desert  

USGS Publications Warehouse

Effects of protective fencing on birds, lizards, black-tailed hares (Lepus californicus), perennial plant cover, and structural diversity of perennial plants were evaluated from spring 1994 through winter 1995 at the Desert Tortoise Research Natural Area (DTNA), in the Mojave Desert, California. Abundance and species richness of birds were higher inside than outside the DTNA, and effects were larger during breeding than wintering seasons and during a high than a low rainfall year. Ash-throated flycatchers (Myiarchus cinerascens), cactus wrens (Campylorhynchus brunneicapillus), LeConte's thrashers (Toxostoma lecontei), loggerhead shrikes (Lanius ludovicianus), sage sparrows (Amphispiza belli), and verdins (Auriparus flaviceps) were more abundant inside than outside the DTNA. Nesting activity was also more frequent inside. Total abundance and species richness of lizards and individual abundances of western whiptail lizards (Cnemidophorous tigris) and desert spiny lizards (Sceloporus magister) were higher inside than outside. In contrast, abundance of black-tailed hares was lower inside. Structural diversity of the perennial plant community did not differ due to protection, but cover was 50% higher in protected areas. Black-tailed hares generally prefer areas of low perennial plant cover, which may explain why they were more abundant outside than inside the DTNA. Habitat structure may not affect bird and lizard communities as much as availability of food at this desert site, and the greater abundance and species richness of vertebrates inside than outside the DTNA may correlate with abundances of seeds and invertebrate prey.

Brooks, M.

1999-01-01

142

Multi-stage emerald formation during Pan-African regional metamorphism: The Zabara, Sikait, Umm Kabo deposits, South Eastern desert of Egypt  

NASA Astrophysics Data System (ADS)

The genesis of gem-quality deep green emeralds of Zabara, Sikait and Umm Kabo (South Eastern Desert, Egypt) is to date a controversial topic. The emerald-bearing biotite schists and quartz lenses are interpreted alternatively as a product of (i) thrust-fault-shear zone - controlled large scale alkali-metasomatism driven by post-magmatic fluid flow or of (ii) a large scale interaction between syntectonic pegmatitic magma or hydrothermal fluids with pre-existing basic to ultrabasic rocks, or of (iii) a syn- to post-tectonic regional metamorphism and small scale blackwall metasomatism. Detailed microstructural and chemical analyses of the Egyptian emeralds and their host rocks show that three generations of beryl can be distinguished: a colourless pegmatitic beryl; a pale green Cr-poor beryl crystallized from pegmatite-related hydrothermal fluids; and a deep green Cr- and Mg-rich emerald. The crystallization of the Cr- and Mg-rich emerald was controlled by the very local availability of Cr, Mg and Be-rich metamorphic fluids during the Pan-African tectono-thermal event. Emerald-rich quartz lenses demonstrate that those fluids locally did mobilize quartz, too. The pale green emeralds found within the pegmatites in association with colourless beryl are the product of a mobilization of colourless pegmatitic beryl and/or phenakite by late pegmatitic fluids slightly enriched in Cr by an interaction with the Cr-rich country rocks. The late pegmatitic fluids are typically Na-rich as is demonstrated by the pervasive albitization of the pegmatites. The complex interplay of magmatic and regional metamorphic events during the genesis of the Egyptian emeralds/beryls makes it impossible through stable oxygen isotope data to relate their genesis to the one or the other event.

Grundmann, G.; Morteani, G.

2008-02-01

143

Origin of wehrlite cumulates in the Moho transition zone of the Neoproterozoic Ras Salatit ophiolite, Central Eastern Desert, Egypt: crustal wehrlites with typical mantle characteristics  

NASA Astrophysics Data System (ADS)

Ultramafic cumulates, mainly crustal true wehrlites, were discovered and described in the mantle-crust transition zone (MTZ) and the extremely lower layered gabbro sequence of the Ras Salatit ophiolite, Central Eastern Desert, Egypt. They form either boudinaged lensoidal tabular bodies or interdigitated layers often concordant with the planolinear fabrics of the Ras Salatit ophiolite rocks. The contact between wehrlites and the host MTZ dunite or layered gabbro is razor sharp, lobate and/or sinuous, without chilled margins or any visible deformations. The Ras Salatit wehrlites are orthopyroxene-free and composed mainly of olivine and clinopyroxene. They are texturally equilibrated and show a characteristic poikilitic texture. Crystallization order of the Ras Salatit wehrlites is olivine/spinel followed by clinopyroxene with the absence of plagioclase. Olivine and clinopyroxene of the Ras Salatit wehrlites are compositionally uniform and conspicuously high in Mg#, mostly around 0.93 and 0.92, respectively. Moreover, the clinopyroxene shows low Ti and Al contents coupled with marked depletion in LILE. The calculated melt in equilibrium with clinopyroxene from the Ras Salatit wehrlites is largely similar to lavas from the Izu-Bonin forearc. Given the above characteristics, the Ras Salatit wehrlites were produced by crystal accumulation from a hydrous depleted basaltic/tholeiitic melt corresponding to temperatures between 1,000 and 1,100°C at the oceanic crustal pressure (~2 kbar). The involved hydrous tholeiitic melt has been probably formed by fluid-assisted partial melting of a refractory mantle source (similar to the underlying harzburgites) in a somewhat shallow sub-arc environment.

Gahlan, Hisham A.; Arai, Shoji; Abu El-Ela, Fawzy F.; Tamura, Akihiro

2012-02-01

144

Slip distribution model of two small-sized inland earthquakes and its tectonic implication in north-eastern desert of Egypt  

NASA Astrophysics Data System (ADS)

Two slip distribution models of the 1999 and 2006 Beni-Suef earthquakes ( Mw 4.5 and Mw 4.2, respectively) were revealed using waveform inversion with an empirical Green's function method. Waveform data used were recorded by the Egyptian Seismic Network's short-period stations. To identify the active fault plane associated with each event and to estimate the best fitting rupture velocity, a set of slip distribution models was recovered on both nodal planes of the focal mechanism with a range of fixed rupture velocities. The result for the 1999 event shows that the northwest trending plane consistently provided better fitting solutions than the southwest trending plane. This implies that the slip was left-lateral on a northwest trending plane dipping toward the southwest. The 2006 event caused a slip movement on a dip-slip fault dipping towards the north. The rupture velocities were founded to be 3.5 km/s and 3.0 km/s which gave a comparatively small residual for the 1999 and 2006 earthquakes, respectively. The corresponding slip distribution models for the 1999 and 2006 events provide their seismic moments of 7.6E + 15 N m and 2.5E + 15 N m and moment magnitudes of 4.5 and 4.2, respectively. From the viewpoint of tectonics in the region, the present results imply an extensional tectonic process along the pre-existing WNW-ESE/NW-SE faults that may be transferred from the Gulf of Suez-Red Sea rift towards the northeastern desert in Egypt. This finding implies the diving of the northeastern of African plate beneath the Eurasian plate.

Abdel-Fattah, A. K.; Kim, K. Y.; Fnais, M. S.

2011-11-01

145

Variations in eruptive style and depositional processes of Neoproterozoic terrestrial volcano-sedimentary successions in the Hamid area, North Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

Two contrasting Neoproterozoic volcano-sedimentary successions of ca. 600 m thickness were recognized in the Hamid area, Northeastern Desert, Egypt. A lower Hamid succession consists of alluvial sediments, coherent lava flows, pyroclastic fall and flow deposits. An upper Hamid succession includes deposits from pyroclastic density currents, sills, and dykes. Sedimentological studies at different scales in the Hamid area show a very complex interaction of fluvial, eruptive, and gravitational processes in time and space and thus provided meaningful insights into the evolution of the rift sedimentary environments and the identification of different stages of effusive activity, explosive activity, and relative quiescence, determining syn-eruptive and inter-eruptive rock units. The volcano-sedimentary deposits of the study area can be ascribed to 14 facies and 7 facies associations: (1) basin-border alluvial fan, (2) mixed sandy fluvial braid plain, (3) bed-load-dominated ephemeral lake, (4) lava flows and volcaniclastics, (5) pyroclastic fall deposits, (6) phreatomagmatic volcanic deposits, and (7) pyroclastic density current deposits. These systems are in part coeval and in part succeed each other, forming five phases of basin evolution: (i) an opening phase including alluvial fan and valley flooding together with a lacustrine period, (ii) a phase of effusive and explosive volcanism (pulsatory phase), (iii) a phase of predominant explosive and deposition from base surges (collapsing phase), and (iv) a phase of caldera eruption and ignimbrite-forming processes (climactic phase). The facies architectures record a change in volcanic activity from mainly phreatomagmatic eruptions, producing large volumes of lava flows and pyroclastics (pulsatory and collapsing phase), to highly explosive, pumice-rich plinian-type pyroclastic density current deposits (climactic phase). Hamid area is a small-volume volcano, however, its magma compositions, eruption styles, and inter-eruptive breaks suggest, that it closely resembles a volcanic architecture commonly associated with large, composite volcanoes.

Khalaf, Ezz El Din Abdel Hakim

2013-07-01

146

Biostratigraphy and paleoenvironment of the Danian/Selandian (D/S) transition in the Southern Tethys: A case study from north Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

In the present study, the sedimentary succession of the Danian/Selandian (D/S) transition exposed at Wadi El Maheer, north Eastern Desert, Egypt, has been subjected to quantitative high-resolution planktic and benthic foraminiferal analysis. The succession is here subdivided into six planktic foraminiferal biozones, documenting a case of continuous sedimentation during the D/S transition. The planktic foraminiferal biozones are: the Danian Praemurica inconstans (P1c), Praemurica uncinata (P2), Morozovella angulata (P3a) and Igorina albeari/Praemurica carinata (lower most part of P3b) biozones and the Selandian I. albeari (main part of P3b) and Globanomalina pseudomenardii (P4a) biozones. The D/S boundary is marked by a distinctive organic-rich phosphatic shale layer (˜25 cm thick) within the upper part of the Dakhla Formation, corresponding to the last appearance datum of P. carinata (El Naggar). The concerned organic-rich phosphatic shale layer reflects a deficiency in the marine oxygen content with bottom water rich in organic matter during its deposition. It is characterized by changes in both planktic and benthic foraminiferal fauna. Across the D/S boundary, the planktic foraminiferal taxa of the nonspinose praemuricids were gradually replaced by nonspinose morozovellids and acarininids, whereas the Danian outer neritic-upper bathyal benthic foraminiferal taxa were substituted by inner-middle neritic ones indicating shallowing at the D/S boundary. The Selandian deposits are marked by planktic and benthic foraminiferal genera of outer neritic-upper bathyal conditions. Oscillation in the mean sea level during the D/S transition was probably due to a true eustatic change rather than to a tectonic origin.

Obaidalla, Nageh A.; El-Dawy, Moustafa H.; Kassab, Ahmed S.

2009-01-01

147

Effects of Protective Fencing on Birds, Lizards, and Black-Tailed Hares in the Western Mojave Desert.  

PubMed

/ Effects of protective fencing on birds, lizards, black-tailed hares (Lepus californicus), perennial plant cover, and structural diversity of perennial plants were evaluated from spring 1994 through winter 1995 at the Desert Tortoise Research Natural Area (DTNA), in the Mojave Desert, California. Abundance and species richness of birds were higher inside than outside the DTNA, and effects were larger during breeding than wintering seasons and during a high than a low rainfall year. Ash-throated flycatchers (Myiarchus cinerascens), cactus wrens (Campylorhynchus brunneicapillus), LeConte's thrashers (Toxostoma lecontei), loggerhead shrikes (Lanius ludovicianus), sage sparrows (Amphispiza belli), and verdins (Auriparus flaviceps) were more abundant inside than outside the DTNA. Nesting activity was also more frequent inside. Total abundance and species richness of lizards and individual abundances of western whiptail lizards (Cnemidophorous tigris) and desert spiny lizards (Sceloporus magister) were higher inside than outside. In contrast, abundance of black-tailed hares was lower inside. Structural diversity of the perennial plant community did not differ due to protection, but cover was 50% higher in protected areas. Black-tailed hares generally prefer areas of low perennial plant cover, which may explain why they were more abundant outside than inside the DTNA. Habitat structure may not affect bird and lizard communities as much as availability of food at this desert site, and the greater abundance and species richness of vertebrates inside than outside the DTNA may correlate with abundances of seeds and invertebrate prey. KEY WORDS: Birds; Fenced protection; Lepus californicus, Lizards; Mojave Desert; Off-highway vehicles; Protected area management; Sheep grazing PMID:9950700

BROOKS

1999-04-01

148

The hydrochemical evolution of brackish groundwater in central and northern Sinai (Egypt) and in the western Negev (Israel)  

NASA Astrophysics Data System (ADS)

SummaryCretaceous trans-boundary aquifers in the central and northern parts of Sinai (Egypt) and the Negev (Israel), are geographically and geologically both contiguous and continuous. Hydrogeological and hydrochemical studies of these aquifers, with disregard to political boundaries, are scarce. The Lower Cretaceous Kurnub Group aquifer in Sinai and the Negev hosts paleowater mostly replenished during the Pleistocene. The objectives of this study are to elucidate the relationship between regional structural elements and the salinization of groundwater in the Kurnub Group in Sinai and further downstream in the Negev. The stable plateaus in southern Sinai and the fold structures in the north continuing into the Negev are separated by the W-E striking Minshara-Ramon shear zone. With the exception of higher salinities in the north, the chemical composition of Kurnub Group groundwater north and south of the shear zone is similar. Similarly, groundwater in the overlying Upper Cretaceous aquifer differs from Kurnub groundwater only within and north of the shear zone and is characterized by higher Cl concentrations, lower Mg/rCa ratios (due to high Ca in the calcareous aquifer) and by a "heavier" isotopic signature. Inverse hydrogeochemical modeling using PHREEQC indicates that the increase in salinity of Kurnub groundwater within the shear zone and in adjacent areas could be due to two different sources: First, the salinization process could be the result of mixing with sulfate-rich brackish groundwater occurring in Jurassic formations, which are in fault-controlled lateral contact with the Kurnub Group aquifer. Second, the salinity differences could be from unflushed seawater in the subsurface of the northern Sinai and western Negev, i.e. possible remnants of the post-Messinian (Lower Pliocene) transgression, which penetrated into northern Sinai, the western Negev and the Coastal Plain of Israel both through erosional channels, which were incised during the Neogene, and by flooding over outcrops of permeable formations.

Rosenthal, E.; Zilberbrand, M.; Livshitz, Y.

2007-04-01

149

Occurrence of hexavalent chromium in ground water in the western Mojave Desert, California  

USGS Publications Warehouse

About 200 samples from selected public supply, domestic, and observation wells completed in alluvial aquifers underlying the western Mojave Desert were analyzed for total dissolved Cr and Cr(VI). Because Cr(VI) is difficult to preserve, samples were analyzed by 3 methods. Chromium(VI) was determined in the field using both a direct colorimetric method and EPA method 218.6, and samples were speciated in the field for later analysis in the laboratory using a cation-exchange method developed for the study described in this paper. Comparison of the direct colorimetric method and EPA method 218.6 with the new cation-exchange method yielded r2 values of 0.9991 and 0.9992, respectively. Total dissolved Cr concentrations ranged from less than the 0.1 ??g/l detection limit to 60 ??g/l, and almost all the Cr present was Cr(VI). Near recharge areas along the mountain front pH values were near neutral, dissolved O2 concentrations were near saturation, and Cr(VI) concentrations were less than the 0.1 ??g/l detection limit. Chromium(VI) concentrations and pH values increased downgradient as long as dissolved O 2 was present. However, low Cr(VI) concentrations were associated with low dissolved O2 concentrations near ground-water discharge areas along dry lakes. Chromium(VI) concentrations as high as 60 ??g/l occurred in ground water from the Sheep Creek fan alluvial deposits weathered from mafic rock derived from the San Gabriel Mountains, and Cr(VI) concentrations as high as about 36 ??g/l were present in ground water from alluvial deposits weathered from less mafic granitic, metamorphic, and volcanic rocks. Chromium(III) was the predominant form of Cr only in areas where dissolved O2 concentrations were less than 1 mg/l and was detected at a median concentration of 0.1 ??g/l, owing to its low solubility in water of near-neutral pH. Depending on local hydrogeologic conditions and the distribution of dissolved O2, Cr(VI) concentrations may vary considerably with depth. Samples collected under pumping conditions from different depths within wells show that Cr(VI) concentrations can range from less than the 0.1 ??g/l detection limit to 36 ??g/l in a single well and that dissolved O2 concentrations likely control the concentration and redox speciation of Cr in ground water.

Ball, J.W.; Izbicki, J.A.

2004-01-01

150

Chromium, chromium isotopes and selected trace elements, western Mojave Desert, USA  

USGS Publications Warehouse

Chromium(VI) concentrations in excess of the California Maximum Contaminant Level (MCL) of 50 ??g/L occur naturally in alkaline, oxic ground-water in alluvial aquifers in the western Mojave Desert, southern California. The highest concentrations were measured in aquifers eroded from mafic rock, but Cr(VI) as high as 27 ??g/L was measured in aquifers eroded from granitic rock. Chromium(VI) concentrations did not exceed 5 ??g/L at pH < 7.5 regardless of geology. ??53Cr values in native ground-water ranged from 0.7 to 5.1??? and values were fractionated relative to the average ??53Cr composition of 0??? in the earth's crust. Positive ??53Cr values of 1.2 and 2.3??? were measured in ground-water recharge areas having low Cr concentrations, consistent with the addition of Cr(VI) that was fractionated on mineral surfaces prior to entering solution. ??53Cr values, although variable, did not consistently increase or decrease with increasing Cr concentrations as ground-water flowed down gradient through more oxic portions of the aquifer. However, increasing ??53Cr values were observed as dissolved O2 concentrations decreased, and Cr(VI) was reduced to Cr(III), and subsequently removed from solution. As a result, the highest ??53Cr values were measured in water from deep wells, and wells in discharge areas near dry lakes at the downgradient end of long flow paths through alluvial aquifers. ??53Cr values at an industrial site overlying mafic alluvium having high natural background Cr(VI) concentrations ranged from -0.1 to 3.2???. Near zero ??53Cr values at the site were the result of anthropogenic Cr. However, mixing with native ground-water and fractionation of Cr within the plume increased ??53Cr values at the site. Although ??53Cr was not necessarily diagnostic of anthropogenic Cr, it was possible to identify the extent of anthropogenic Cr at the site on the basis of the ??53Cr values in conjunction with major-ion data, and the ??18O and ??D composition of water from wells.

Izbicki, J.A.; Ball, J.W.; Bullen, T.D.; Sutley, S.J.

2008-01-01

151

Petrogenesis of carbonated meta-ultramafic lenses from the Neoproterozoic Heiani ophiolite, South Eastern Desert, Egypt: A natural analogue to CO2 sequestration  

NASA Astrophysics Data System (ADS)

Among a set of peculiar meta-ultramafics, carbonate-orthopyroxenites are observed for the first time in the Heiani ophiolite belt, South Eastern Desert, Egypt. They form massive lensoidal masses up to 50 m long and 20 m wide. The lenses show a marked structural concordance with their neighboring country rocks. The typical country rocks are represented by the following high-grade metamorphic rocks: kyanite-muscovite schists, amphibolites, kyanite-bearing biotite gneisses, migmatites, granite gneisses and mobilizates. The studied carbonate-orthopyroxenites consist mainly of metamorphic orthopyroxene + magnesite, among other metamorphic, relict primary and retrograde secondary minerals. According to primary chromian spinel (Cr#, 0.7-0.84) chemistry and morphology, absence of clinopyroxene and presence of primary mantle olivine (Fo89-91) as relicts in the metamorphic orthopyroxene, the Heiani carbonate-orthopyroxenites seem to have formed from a highly depleted mantle peridotite precursor. At a late collisional stage during the Pan-Africa terrane accretion and the E-W crustal shortening (ca. 650-620 Ma), high-grade (upper amphibolite facies) low-P/high-T regional metamorphism (ca. 660 Ma) accompanied by CO2-metasomatism resulted in formation of the Heiani carbonate-orthopyroxenites. Mostly the carbonate-bearing shelf sediments beneath and/or in juxtaposition with the Heiani ophiolite are considered to be the proven source of the CO2-rich fluids. Although, a mixed sedimentary-mantle C source is not unlikely. A mineral paragenetic correlation with experimental data for the system MgO-SiO2-H2O-CO2 suggests metamorphic conditions consistent with those of the high-grade country rocks; i.e. 630-650 °C, 6-7 kbar (20-23 km depth) and high-XCO2 (0.6-0.7). The CO2-bearing fluids discharging along faults gave rise to regionally widespread carbonate-bearing assemblages. Accordingly, the Heiani carbonate-orthopyroxenites are considered the by-products of natural carbon sequestration by an ultramafic rock.

Gahlan, Hisham A.; Arai, Shoji; Almadani, Sattam A.

2015-02-01

152

Utilization of airborne gamma ray spectrometric data for geological mapping, radioactive mineral exploration and environmental monitoring of southeastern Aswan city, South Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

The present work utilizes airborne gamma ray spectrometric data in a trial to refine surface geology of igneous, metamorphic and sedimentary rocks, detect any radioactive mineralization and monitor environment at southeastern Aswan city, South Eastern Desert, Egypt. This area is mainly covered with igneous rocks (younger granites, older granites, metasediments, metavolcanics, metagabbro, Tertiary basalt and ring complex), metamorphic rocks as well as sedimentary rocks (Um Barmil Formation, Timsah Formation, Abu Aggag Formation and wadi sediments). Airborne gamma ray spectrometry can be very helpful in mapping surface geology. This provides estimates of the apparent surface concentrations of the most common naturally occurring radioactive elements, such as potassium (K), equivalent uranium (eU) and equivalent thorium (eTh). This is based on the assumption that, the absolute and relative concentrations of these radioelements vary measurably and significantly with lithology. The composite image technique is used to display simultaneously three parameters of the three radioelement concentrations and their three binary ratios on one image. The technique offers much in terms of lithological discrimination, based on colour differences and showed efficiency in defining areas, where different lithofacies occur within areas mapped as one continuous lithology. The integration between surface geological information and geophysical data led to detailing the surface geology and the contacts between different rock units. Significant locations or favourable areas for uranium exploration are defined, where the measurements exceed (X + 2S), taking X as the arithmetic mean of eU, eU/eTh and eU/K measurements and S as the standard deviation corresponding to each variables. The study area shows the presence of four relatively high uraniferous zones. These zones cannot be ignored and need further ground follow-up. In addition, the trend analysis based on the three radioelement maps and the published geological map shows that, most of the well-developed structural lineaments have NW, NE and ENE trends. Moreover, the average radiation dose rates in the study area, which range from 0.57 to 1.3 mSv yr-1 average, are calculated from the exposure rate for each rock unit. The dose rate levels still remain in the safe side to individuals and less than the maximum permissible from the natural gamma radiation sources, except younger granites and ring complex.

Youssef, Mohamed A. S.; Elkhodary, Shadia T.

2013-12-01

153

Calcareous nannofossil and planktonic foraminifera biostratigraphy through the Middle to Late Eocene transition of Fayum area, Western Desert, Egypt  

NASA Astrophysics Data System (ADS)

The Eocene sequence exposed at Gebel Naalun (Fayum-Nile divide), Guta section-I (West of Birket Qarun near Guta Village) and Guta section-II (Northwest of Birket Qarun near Guta Village) is differentiated, from base to top, into two formations; Gehannam Formation (Middle-Late Eocene) and Birket Qarun Formation (Late Eocene), respectively. Two calcareous nannofossil zones were recognized from the Eocene succession at Gebel Naalun; Discoaster saipanensis (NP17) and Chiasmolithus oamaruensis (NP18) zones as well as one planktonic foraminiferal zone; Truncorotaloides (Acaranina) rohri (P14) zone. However, at Guta section-I, two nannofossil zones were defined; Discoaster saipanensis (NP17) and Chiasmolithus oamaruensis (NP18) zones; the preservation of planktonic foraminiferal assemblage is too poor to enable us to recognize marker species as a result of many diagenetic processes. At Guta section-II, two nannofossil zones; Chiasmolitus oamaruensis (NP18) and Isthmolithus recurvus (NP19) and two planktonic foraminiferal zones; T. pseudoampliapertura zone and G. semiinvoluta zone are recorded. Several authors found that the lowest occurrence of Chiasmolithus oamaruensis is a poor criterion for defining the base of NP18 Zone, which is confirmed here. The same criticism has been applied to the lowest occurrence of Isthmolithus recurvus which defines the NP18/NP19 zonal boundary. It is generally agreed that NP19 Zone falls in the Priabonian (Late Eocene). As a result of the occurrence of the nannofossil marker species; Isthmolithus recurvus only in side views below and above the first appearance of Chiasmolithus oamaruensis at both Naalun and Guta section-I, this species is not reliable to define the NP18/NP19 zonal boundary. At Guta section-II, the Middle/Upper Eocene boundary can be delineated by the first appearance of Globigerinatheka semiinvoluta above the first occurrence of Isthmolithus recurvus in both plane and side views.

Marzouk, Akmal Mohamed; El Shishtawy, Ahmed Moustafa; Kasem, Atef Masoud

2014-12-01

154

Microseismic monitoring of the hydraulic-fracture growth and geometry in the Upper Bahariya member, Khalda concession, Western Desert, Egypt  

NASA Astrophysics Data System (ADS)

Three-component, downhole geophones are installed in production wells at the Khalda and Kahraman sites to monitor hydraulic fracturing treatment in a nearby well. Locatable microseismic events were distributed in space around the treatment well using the hypocenter-velocity inversion method. The E-W oriented microseismic pattern aligns with the proposed specifications of fracture model design at both the Khalda and Kahraman sites. Due to the small magnitude and long separation distance between the treatment well and the recording string, microseismicity was dominantly observed during the main fracturing operation at both the Khalda and Kahraman sites, with calculated magnitudes less than -0.3?Mw. In addition, the calculated confidence for locatable events was generally average or low. The seismic zone through the mainfrac treatment was estimated to spread over 58?m height and 320?m length at the Khalda site, while the zone of the Kahraman site was enclosed within 25?m height and 250?m length. The stimulated reservoir volume (SRV) at the Khalda site was estimated to be 433?200?m3, with asymmetrical wings around the stimulation well, but at the Kahraman site the stimulation imaging was marginally successful and the stimulated SRV was only 247?000?m3. In general, the two microseismic experiments at Khalda and Kahraman were relatively successful in locating the microseismic events and calculating the SRV within the producing horizon, elucidating the importance of the microseismic technique in monitoring reservoir stimulation.

Abdulaziz, Abdulaziz M.

2014-08-01

155

Depositional cycles: an approach to the sequence stratigraphy of the Dakhla Formation, west Dakhla-Farafra stretch, Western Desert, Egypt  

NASA Astrophysics Data System (ADS)

The latest Campanian-Middle Palæocene Dakhla Formation has been the subject of few sedimentological studies, despite its great areal distribution. This shale/mudstone unit exhibits marked facies variations in a northwest-southeast direction. The facies distribution patterns, stratal geometries and type, as well as frequency of the associated microfauna, allow a possible subdivision of the Dakhla Formation into ten depositional cycles. These cycles are delineated from each other by a bounding surface, which is defined by an abrupt facies change and/or intensively bioturbated hardground. The sediments of these cycles have been accumulated in a shallow subtidal-upper intertidal-flat environment during Late Cretaceous and in a middle/outer shelf-lower intertidal suite during Palæocene times. Deposition took place in a topographically irregular basin under a constantly high clastic input derived largely from the south and southwest. The cyclic pattern of deposition that characterises the Dakhla Formation, points to repeated relative sea level fluctuations. The submarine palæorelief also plays a significant role on the facies pattern. It is found that the succession was deposited along the marginal part of a palæostructural low. Its deeper area is located around present-day Edmonstone. The study of sedimentary facies characteristics and cyclicity of the Dakhla Formation leads to the recognition of four depositional sequences bounded by five type 2 sequence boundaries. The first and second type 2 depositional sequences correspond to the Late Maastrichtian Mawhoob Shale and lower-middle part of the Beris Mudstone Members, respectively. The third sequence comprises the Beris Mudstone Member 'upper part' and the Latest Maastrichtian partition of the Kharga Shale Member. The well-documented Cretaceous-Tertiary boundary marks the type 2 sequence boundary at the top of this sequence. The last depositional sequence coincides with the late Early-Middle Palæocene subdivision of the Kharga Shale Member. These sequences comprise nine systems tracts, mainly of transgressive and highstand systems tract deposits.

El-Azabi, M. H.; El-Araby, A.

2000-05-01

156

Late Quaternary environmental changes in the Taklamakan Desert, western China, inferred from OSL-dated lacustrine and aeolian deposits  

NASA Astrophysics Data System (ADS)

Sediment records from the Tarim Basin of western China are of great importance for understanding Late Quaternary climatic variability in Central Asia. A chronology of aeolian and lacustrine deposits from the centre and southern margin of the Taklamakan Desert, central Tarim Basin, has been established using optical dating methods. Distinct variations in humidity during the last 40,000 a in this extremely arid inland basin have been identified. Lacustrine sediments were deposited in the centre of the Taklamakan during two periods of wetter than present day conditions at around 2000 and 30,000 a ago. Another humid period is recorded between 40,000 and 30,000 a ago. Aeolian processes, the development of large migrating dune fields dominated during periods of more arid conditions. Sand wedges at the southern margin of the Taklamakan are dated at ca 40,000 a and ca 18,000 a, and imply a significant temperature decrease in that area. Sedimentological evidence for a late Holocene humid period are consistent with records in ancient Chinese literature. Wetter environmental conditions in the past within the Taklamakan, as indicated by the presence of lacustrine deposits, are also supported by data from adjacent regions. It is assumed that changes of global westerlies and of the mobile polar high triggered the fluctuations of precipitation in the study area. However, variations in temperature in the Taklamakan Desert are presumed to be mainly controlled by the intensity of the winter monsoon.

Yang, Xiaoping; Preusser, Frank; Radtke, Ulrich

2006-05-01

157

Zonation of primary haloes of Atud auriferous quartz vein deposit, Central Eastern Desert of Egypt: A potential exploration model targeting for hidden mesothermal gold deposits  

NASA Astrophysics Data System (ADS)

The Atud gold mine located in the Neoproterozoic diorite and metagabbro of the Central Eastern Desert of Egypt has been initially excavated during Pharaonic times. Between 1953 and 1969, the Egyptian Geological Survey and Mining Authority performed underground prospection in the auriferous quartz vein and metasomatic alteration zones in the main Atud area, estimating a principal gold lode of 19,000 tones (16.28 g/ton), and 1600 tons of damp (1.24 g/ton). Yet the potentiality of the deposit has not been exhausted. However, for exploration of hidden ore, quantitative characterization using trace elements zoning of mineralization haloes with 280 samples from surface and three underground mining levels is applied. This was through multivariate statistical analysis (Factor analysis) of 11 selected trace elements. Axial (vertical) extents of primary haloes above and beneath gently dipping orebody are also visualized to interpret the level of erosion, determine the direction of mineralizing solutions as well as to examine whether the hidden orebody is promising at the Atud mine. Axial zones of primary dispersion aureoles of trace elements are: Ag, As, S and U around the auriferous quartz veins; Cu, and Pb in the surface horizons; and Zn, Ni, Co, and U along the lower margin of mineralization zone. Gold contents in bedrock and quartz vein samples from level-42M are the highest (5.7 and 40.3 ppm, respectively). In the transverse (lateral) direction, the maximum relative accumulation of Au and Zn occurs at the Northern Shaft; Pb, Cu, As, and U at the Main Shaft; and Ag, S, Co, and Ni at the Southern Shaft. The estimated axial zonation sequence of indicator elements using the variability index is Pb ? Cu ? Ag ? Au ? As ? S ? Ni ? Co ? U ? Zn. According to this zonation, an index such as (Pb × Cu)D/(U × Zn)D can be a significant for predicting the Au potentiality at a particular depth. In addition, the Pb/U zonality index is an appropriate indicator for the degree of erosion at the Atud gold mine. The degree of surficial zonality of the mineralization as deduced from geochemical maps and the level of erosion of the geochemical anomalies as well as the decreasing of gold content with depth recorded throughout the different underground mine workings make it necessary for the prospection model to evaluate the drainage patterns dissecting the mineralized zone. The application of R-mode factor analysis estimated seven statistical factors, and factor score maps are portrayed. Factors 1 (Ag, Au, As, Co, S, U and Zn) and 2 (Zn, U, Co and S) significantly reflect the Au-mineralization (ore-controlled), and their score maps enable a more precise delineation of auriferous quartz veins and the area which may contain primary gold mineralization. The other factors reveal the distribution of Cu- and Pb-bearing minerals (supergene alteration factors), and Ba and Ni in the host diorite (lithologically-controlled). These are consistent with the calculated maximum relative accumulation of trace elements, proposing a potential model of exploration based on integrating underground geochemical data from old gold mine workings with spatial information from R-mode factor score maps.

Harraz, Hassan Z.; Hamdy, Mohamed M.

2015-01-01

158

Fairy, tadpole, and clam shrimps (Branchiopoda) in seasonally inundated clay pans in the western Mojave Desert and effect on primary producers  

Microsoft Academic Search

BACKGROUND: Fairy shrimps (Anostraca), tadpole shrimps (Notostraca), clam shrimps (Spinicaudata), algae (primarily filamentous blue-green algae [cyanobacteria]), and suspended organic particulates are dominant food web components of the seasonally inundated pans and playas of the western Mojave Desert in California. We examined the extent to which these branchiopods controlled algal abundance and species composition in clay pans between Rosamond and Rogers

WN Brostoff; JG Holmquist; J Schmidt-Gengenbach; PV Zimba

2010-01-01

159

Multiprocess evolution of landforms in the Kharga Region, Egypt: Applications to Mars  

NASA Technical Reports Server (NTRS)

In order to understand better the polygenetic evolution of landforms on the martian surface, field studies were conducted in and around the Kharga Depression, Egypt. The Kharga region, on the eastern edge of Egypt's Western Desert, was subject to erosion under mostly hyperarid climatic conditions, punctuated by brief pluvial episodes of lesser aridity, since early Pleistocene time. The region contains numerous landforms analogous to features on the martian surface: yardangs carved in layered surficial deposits and in bedrock, invasive dune trains, wind-modified channels and interfluves, and depressions bounded by steep scarps. Like many of the topographic depresions on Mars, the Kharga Depression was invaded by crescentic dunes. In Egypt, stratigraphic relations between dunes, yardangs, mass-wasting debris, and wind-eroded flash-flood deposits record shifts in the relative effectiveness of wind, water, and mass-wasting processes as a function of climate change.

Breed, C. S.; Mccauley, J. F.; Grolier, M. J.

1984-01-01

160

The use of multifrequency and polarimetric SIR-C\\/X-SAR data in geologic studies of Bir Safsaf, Egypt  

Microsoft Academic Search

Bir Safsaf, within the hyperarid “core” of the Sahara in the Western Desert of Egypt, was recognized following the SIR-A and SIR-B missions in the 1980s as one of the key localities in northeast Africa, where penetration of dry sand by radar signals delineates previously unknown, sand-buried paleodrainage valleys (“radar-rivers”) of middle Tertiary to Quaternary age. The Bir Safsaf area

Gerald G. Schaber; John F. McCauley; Carol S. Breed

1997-01-01

161

Aerosol transport over the western Mediterranean basin: Evidence of the contribution of fine particles to desert dust plumes over Alborán Island  

NASA Astrophysics Data System (ADS)

Eight months (June 2011 to January 2012) of aerosol property data were obtained at the remote site of Alborán Island (35.95°N, 3.03°W) in the western Mediterranean basin. The aim of this work is to assess the aerosol properties according to air mass origin and transport over this remote station with a special focus on air mass transport from North Africa. For air masses coming from North Africa, different aerosol properties showed strong contributions from mineral dust lifted from desert areas. Nevertheless, during these desert dust intrusions, some atmospheric aerosol properties are clearly different from pure mineral dust particles. Thus, Angström exponent ?(440-870) presents larger values than those reported for pure desert dust measured close to dust source regions. These results combine with ?(440, 670) - ?(670, 870) ? 0.1 and low single scattering albedo (?(?)) values, especially at the largest wavelengths. Most of the desert dust intrusions over Alborán can be described as a mixture of dust and anthropogenic particles. The analyses support that our results apply to North Africa desert dust air masses transported from different source areas. Therefore, our results indicate a significant contribution of fine absorbing particles during desert dust intrusions over Alborán arriving from different source regions. The aerosol optical depth data retrieved from Sun photometer measurements have been used to check Moderate Resolution Imaging Spectroradiometer retrievals, and they show reasonable agreement, especially for North African air masses.

Valenzuela, A.; Olmo, F. J.; Lyamani, H.; Granados-Muñoz, M. J.; Antón, M.; Guerrero-Rascado, J. L.; Quirantes, A.; Toledano, C.; Perez-Ramírez, D.; Alados-Arboledas, L.

2014-12-01

162

Optical characteristics of biomass burning and desert dust over the Western Mediterranean during summer: a case study  

NASA Astrophysics Data System (ADS)

The present contribution reports on the aerosol vertical distributions in Barcelona (Spain) which were obtained when very high aerosol concentrations were observed on summer 2012. An EARLINET lidar system and AERONET sunphotometer located in Barcelona performed intensive measurements in the framework of the ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure Network) project. The data that were collected allow the characterization of the optical properties of the aerosols in this region, benefiting from the synergy of various remote sensing instruments. Due to its location in the Mediterranean basin, Barcelona metropolitan area is influenced by two major aerosol source regions: Europe and the Western Mediterranean Basin, as a major source of anthropogenic pollutants, and North Africa, as a principal source of natural dust. As a result, the composition of atmospheric aerosols in Barcelona station is a mixing of aerosols. During the period between 1 - 2 July, AOD reached high values (~ 0.5). In addition to anthropogenic local contributions, other aerosols long-range transported were also detected. Between 1 - 3 July, strong forest fires occurred in Alicante where advected to Barcelona area. On the other hand, between 28th June and 1st July, the northeastern Iberian Peninsula was affected by the intrusion of Saharan dust. The presence of Saharan dust was successfully forecasted by the BSC-DREAM8b dust regional model. MODIS and AERONET data, as well as air-mass backward trajectories confirmed the existence of biomass burning and desert dust in the case examined. Desert dust was detected between 2 and 4 km (above sea level, a.s.l) with maximum dust concentrations at ~ 4 km a.s.l on 1st June. On the other hand, favourable meteorological conditions made possible that biomass burning from Alicante was southern advected to Barcelona during the study period.

Basart, Sara; Sicart, Michaël; María Baldasano, José; Lane, Diego; Comerón, Adolfo

2013-04-01

163

Magnetostratigraphy of the Western Borrego Badlands, Anza-Borrego Desert, California - Implications for Tectonics and Litho- and Biostratigraphic Control  

NASA Astrophysics Data System (ADS)

Over 200 meters of non-marine fluvial-floodplain sediments and volcanic ashes are exposed in the Borrego Badlands as part of the northwest margin of the Borrego-San Filipe Basin in the Anza-Borrego Desert, Califorinia. Our stratigraphic and paleomagnetic investigations provide data regarding the age and character of the sediments and tectonics of the region. The intrabasin sediments in Mammoth Cove and Rainbow Wash are especially favorable for paleomagnetic and biostratigraphic analysis due to their fine-grained lithology, abundant vertebrate fossils (Borrego Local Fauna) of Irvingtonian Land Mammal Age, and a continuous syndepositional record of alluvial fan, lacustrine, and playa-margin deposition in response to wrench tectonics associated with the seismogenic San Jacinto Fault Zone. The mean paleomagnetic directions following thermal demagnetization to 600°C are Incl. = 44.9°, Decl. = 11.6°, alpha-95 = 10.4°, k = 13.5, n = 16 for samples from the Brunhes Normal Chron, and Incl. = -46.5°, Decl. = 201.3°, alpha-95 = 8.6°, k = 18.1, n = 17 for samples from the Matuyama Reverse Chron. Those directions are reasonable when compared to the directions reported for older deposits in the Vallecito-Fish Creek Basin in the eastern part of the Anza-Borrego Desert (Johnson et al., 1983); those directions are Incl. = 41.6°, Decl. = 30.6°, alpha-95 = 7.4°, k = 13.1 for samples that record normal polarity, and Incl. = -35.1°, Decl. = 219.4°, alpha-95 = 7.4°, k = 9.6 for samples that record reverse polarity. By contrast, sediments deposited during the lower Matuyama Reverse Chron and upper Gauss Normal Chron where we sampled in Rainbow Wash are rotated clockwise by a greater amount - almost 90°. That rotation patterns the nearly 90° of clockwise rotation of volcanic rocks in the Western Transverse Ranges (Luyendyk, 1991) and non-marine Sespe Fm. (Liddicoat, 1990; 2001) north of the Los Angeles Basin that began about 15 million years ago (Luyendyk, 1991).

Remeika, P.; Liddicoat, J. C.; Beske-Diehl, S.

2008-12-01

164

Effects of Protective Fencing on Birds, Lizards, and Black-Tailed Hares in the Western Mojave Desert  

Microsoft Academic Search

Effects of protective fencing on birds, lizards, black-tailed hares (Lepus californicus), perennial plant cover, and structural diversity of perennial plants were evalu- ated from spring 1994 through winter 1995 at the Desert Tor- toise Research Natural Area (DTNA), in the Mojave Desert, California. Abundance and species richness of birds were higher inside than outside the DTNA, and effects were larger

MATTHEW BROOKS

1999-01-01

165

Water movement through a thick unsaturated zone underlying an intermittent stream in the western Mojave Desert, southern California, USA  

USGS Publications Warehouse

Previous studies indicated that small amounts of recharge occur as infiltration of intermittent streamflow in washes in the upper Mojave River basin, in the western Mojave Desert, near Victorville, California. These washes flow only a few days each year after large storms. To reach the water table, water must pass through an unsaturated zone that is more than 130 m thick. Results of this study, done in 1994-1998, showy that infiltration to depths below the root zone did not occur at control sites away from the wash. At these sites, volumetric water contents were as low as 0.01 and water potentials (measured as the combination of solute and matric potentials using a water activity meter) were as negative as -14,000 kPa. Water-vapor movement was controlled by highly negative solute potentials associated with the accumulation of soluble salts in the unsaturated zone. Highly negative matric potentials above and below the zone of maximum solute accumulation result from movement of water vapor toward the highly negative solute potentials at that depth. The ??18O and ??D (delta oxygen-18 and delta deuterium) isotopic composition of water in coarse-grained deposits plots along a Rayleigh distillation line consistent with removal of water in coarse-grained layers by vapor transport. Beneath Oro Grande Wash, water moved to depths below the root zone and, presumably, to the water table about 130 m below land surface. Underneath Oro Grande Wash, volumetric water contents were as high as 0.27 and water potentials (measured as matric potential using tensiometers) were between -1.8 and -50 kPa. On the basis of tritium data, water requires at least 180-260 years to infiltrate to the water table. Clay layers impede the downward movement of water. Seasonal changes in water vapor composition underneath the wash are consistent with the rapid infiltration of a small quantity of water to great depths and subsequent equilibration of vapor with water in the surrounding material. It may be possible to supplement natural recharge from the wash with imported water. Recharge to the wash may be advantageous because the unsaturated zone is not as dry as most areas in the desert and concentrations of soluble salts are generally lower underneath the wash.Previous studies indicated that small amounts of recharge occur as infiltration of intermittent streamflow in washes in the upper Mojave River basin, in the western Mojave Desert, near Victorville, California. These washes flow only a few days each year after large storms. To reach the water table, water must pass through an unsaturated zone that is more than 130 m thick. Results of this study, done in 1994-1998, show that infiltration to depths below the root zone did not occur at control sites away from the wash. At these sites, volumetric water contents were as low as 0.01 and water potentials (measured as the combination of solute and matric potentials using a water activity meter) were as negative as -14,000 kPa. Water-vapor movement was controlled by highly negative solute potentials associated with the accumulation of soluble salts in the unsaturated zone. Highly negative matric potentials above and below the zone of maximum solute accumulation result from movement of water vapor toward the highly negative solute potentials at that depth. The ??18O and ??D (delta oxygen-18 and delta deuterium) isotopic composition of water in coarse-grained deposits plots along a Rayleigh distillation line consistent with removal of water in coarse-grained layers by vapor transport. Beneath Oro Grande Wash, water moved to depths below the root zone and, presumably, to the water table about 130 m below land surface. Underneath Oro Grande Wash, volumetric water contents were as high as 0.27 and water potentials (measured as matric potential using tensiometers) were between -1.8 and -50 kPa. On the basis of tritium data, water requires at least 180-260 years to infiltrate to the water table. Clay layers impede the downwa

Izbicki, J.A.; Radyk, J.; Michel, R.L.

2000-01-01

166

Methanogens at the top of the world: occurrence and potential activity of methanogens in newly deglaciated soils in high-altitude cold deserts in the Western Himalayas  

PubMed Central

Methanogens typically occur in reduced anoxic environments. However, in recent studies it has been shown that many aerated upland soils, including desert soils also host active methanogens. Here we show that soil samples from high-altitude cold deserts in the western Himalayas (Ladakh, India) produce CH4 after incubation as slurry under anoxic conditions at rates comparable to those of hot desert soils. Samples of matured soil from three different vegetation belts (arid, steppe, and subnival) were compared with younger soils originating from frontal and lateral moraines of receding glaciers. While methanogenic rates were higher in the samples from matured soils, CH4 was also produced in the samples from the recently deglaciated moraines. In both young and matured soils, those covered by a biological soil crust (biocrust) were more active than their bare counterparts. Isotopic analysis showed that in both cases CH4 was initially produced from H2/CO2 but later mostly from acetate. Analysis of the archaeal community in the in situ soil samples revealed a clear dominance of sequences related to Thaumarchaeota, while the methanogenic community comprised only a minor fraction of the archaeal community. Similar to other aerated soils, the methanogenic community was comprised almost solely of the genera Methanosarcina and Methanocella, and possibly also Methanobacterium in some cases. Nevertheless, ~103 gdw?1 soil methanogens were already present in the young moraine soil together with cyanobacteria. Our results demonstrate that Methanosarcina and Methanocella not only tolerate atmospheric oxygen but are also able to survive in these harsh cold environments. Their occurrence in newly deglaciated soils shows that they are early colonizers of desert soils, similar to cyanobacteria, and may play a role in the development of desert biocrusts. PMID:24348469

Aschenbach, Katrin; Conrad, Ralf; ?eháková, Klára; Doležal, Ji?í; Janatková, Kate?ina; Angel, Roey

2013-01-01

167

Methanogens at the top of the world: occurrence and potential activity of methanogens in newly deglaciated soils in high-altitude cold deserts in the Western Himalayas.  

PubMed

Methanogens typically occur in reduced anoxic environments. However, in recent studies it has been shown that many aerated upland soils, including desert soils also host active methanogens. Here we show that soil samples from high-altitude cold deserts in the western Himalayas (Ladakh, India) produce CH4 after incubation as slurry under anoxic conditions at rates comparable to those of hot desert soils. Samples of matured soil from three different vegetation belts (arid, steppe, and subnival) were compared with younger soils originating from frontal and lateral moraines of receding glaciers. While methanogenic rates were higher in the samples from matured soils, CH4 was also produced in the samples from the recently deglaciated moraines. In both young and matured soils, those covered by a biological soil crust (biocrust) were more active than their bare counterparts. Isotopic analysis showed that in both cases CH4 was initially produced from H2/CO2 but later mostly from acetate. Analysis of the archaeal community in the in situ soil samples revealed a clear dominance of sequences related to Thaumarchaeota, while the methanogenic community comprised only a minor fraction of the archaeal community. Similar to other aerated soils, the methanogenic community was comprised almost solely of the genera Methanosarcina and Methanocella, and possibly also Methanobacterium in some cases. Nevertheless, ~10(3) gdw(-1) soil methanogens were already present in the young moraine soil together with cyanobacteria. Our results demonstrate that Methanosarcina and Methanocella not only tolerate atmospheric oxygen but are also able to survive in these harsh cold environments. Their occurrence in newly deglaciated soils shows that they are early colonizers of desert soils, similar to cyanobacteria, and may play a role in the development of desert biocrusts. PMID:24348469

Aschenbach, Katrin; Conrad, Ralf; Reháková, Klára; Doležal, Ji?í; Janatková, Kate?ina; Angel, Roey

2013-01-01

168

U.S. in the World: Arizona/Egypt  

NSDL National Science Digital Library

Residents of Arizona and Egypt face a daily challenge: living in increasing numbers and concentrations in desert ecosystems. Read about how both face surprisingly similar conflicts and issues over water, land and industry.

Population Reference Bureau

169

Remote sensing and geochemical investigations of selected surface processes in Egypt and Missouri  

NASA Astrophysics Data System (ADS)

This thesis consists of three studies of surface processes on Earth: 1. Age and isotopic constraints of pluvial episodes in the Western Desert of Egypt. North Africa has undergone drastic climatic change over the past several hundred thousand years. Timing of humid intervals called pluvials was investigated by uranium- series disequilibrium dating of travertines from the Kurkur Oasis, Western Desert, Egypt. Stable oxygen isotopes of the travertines were used in equilibrium oxygen isotope fractionation calculations indicating the Kurkur travertines have ?18O values similar to ancient Western Desert groundwaters (~[- ]11/perthous). The ages of the of the travertines correspond to times of monsoonal maxima, eustatic sea level high stands and interglacial maxima. Increased precipitation, recharge of Western Desert groundwaters, and resultant travertine deposition are interpreted to be consequences of Milankovitch cycle forcing, through enhanced Atlantic and Indian Ocean monsoons during periods of enhanced northern summer insolation. 2. Identification of soil moisture as an environmental risk factor for filariasis in Egypt. Bancroftian filariasis is a deforming illness transmitted by mosquitoes (Culex. pipiens) and caused by the parasite Wuchereria bancrofti (WHO technical report 821; Neva and Brown, 1994). Environmental variables, such as humidity, play an important role in the transmission cycle of filariasis. Landsat Thematic Mapper data were used to model the surface soil moisture conditions of the southern Nile Delta region of Egypt as a proxy for environmental humidity. Filariasis infection rates were found to be negligible for areas with low surface soil moisture availability (>20%). Variable infection rates were observed for regions with higher surface soil moisture content, possibly due to anthropogenic influences such as insect control and the use of anti- filarial drugs. 3. Monitoring of Pb aerosol fallout in the vicinity of the Glover smelter, Southeastern Missouri. Pb ore smelting in Southeastern Missouri is a point source for heavy metal particulates that are dispersed over a wide region. Pb ratios of the ores are distinct from local bedrock and background atmospheric Pb. A feasibility study to determine the usefulness of Sector Field ICP-MS analysis of Pb isotopes and heavy metal concentrations of leaves sampled at increasing distance from the smelter was initiated. The goal was to develop an inexpensive and relatively simple means of mapping the impact of heavy metals on the ecosystem surrounding the smelter.

Crombie, Mary Katherine

170

Effects of Protective Fencing on Birds, Lizards, and Black-Tailed Hares in the Western Mojave Desert  

Microsoft Academic Search

Lepus californicus  ), perennial plant cover, and structural diversity of perennial plants were evaluated from spring 1994 through winter 1995\\u000a at the Desert Tortoise Research Natural Area (DTNA), in the Mojave Desert, California. Abundance and species richness of birds\\u000a were higher inside than outside the DTNA, and effects were larger during breeding than wintering seasons and during a high\\u000a than a

MATTHEW BROOKS

1999-01-01

171

Thermodynamic modelling of Sol Hamed serpentinite, South Eastern Desert of Egypt: Implication for fluid interaction in the Arabian-Nubian Shield ophiolites  

NASA Astrophysics Data System (ADS)

The Arabian-Nubian Shield is the largest tract of juvenile continental crust of the Neoproterozoic. This juvenile crust is composed of intra-oceanic island arc/back arc basin complexes and micro-continents welded together along sutures as the Mozambique Ocean was closed. Some of these sutures are marked by ophiolite decorated linear belts. The Sol Hamed ophiolite (808 ± 14 Ma) in southeastern Egypt at the Allaqi-Heiani-Onib-Sol Hamed-Yanbu arc-arc suture represents an uncommon example of rocks that might be less deformed than other ophiolites in the Arabian-Nubian Shield. In order to understand fluid-rock interactions before and during arc-arc collision, petrological, mineral chemistry, whole-rock chemistry and thermodynamic studies were applied to the Sol Hamed serpentinized ophiolitic mantle fragment. These studies reveal that the protolith had a harzburgite composition that probably originated as forearc mantle in the subducted oceanic slab. We propose that these rocks interacted with Ti-rich melts (boninite) in suprasubduction zone, which latter formed the Sol Hamed cumulates. Spinel's Cr# associated with the whole rock V-MgO composition suggest that the harzburgites are highly refractory residues after partial melting up to 29%. The melt extraction mostly occurred under reducing conditions, similar to peridotites recovered from the subducted lithosphere. Protolith alteration resulted from two stages of fluid-rock interaction. The first stage occurred as a result of infiltration of concentrated CO2-rich fluid released from carbonate-bearing sediments and altered basalt at the subduction zone. The alteration occurred during isobaric cooling at a pressure of 1 kbar. The fluid composition during the isobaric cooling was buffered by the metamorphic reactions. The second stage of fluid-rock interactions took place through prograde metamorphism. The increase in pressure during this stage occurred as a result of thrusting within the oceanic crust. In this process the forearc crust was loaded by roughly 20-30 km of overthrust rocks.

Abu-Alam, Tamer S.; Hamdy, Mohamed M.

2014-11-01

172

Desert Ecosystems  

NSDL National Science Digital Library

The Desert Ecosystems site describes the geology and climate, plants and animals, and cultural history of the main U.S. desert regions including: the Mojave Desert, the Great Basin, and the Colorado/Sonoran desert. There are also descriptions and photos of water in the desert, coyotes, the desert tortoise, and the creosote bush.

173

Composition, age, and origin of the ~620 Ma Humr Akarim and Humrat Mukbid A-type granites: no evidence for pre-Neoproterozoic basement in the Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

The Humr Akarim and Humrat Mukbid plutons, in the central Eastern Desert of Egypt, are late Neoproterozoic post-collisional alkaline A-type granites. Humr Akarim and Humrat Mukbid plutonic rocks consist of subsolvus alkali granites and a subordinate roof facies of albite granite, which hosts greisen and Sn-Mo-mineralized quartz veins; textural and field evidence strongly suggest the presence of late magmatic F-rich fluids. The granites are Si-alkali rich, Mg-Ca-Ti poor with high Rb/Sr (20-123), and low K/Rb (27-65). They are enriched in high field strength elements (e.g., Nb, Ta, Zr, Y, U, Th) and heavy rare earth elements (La n /Yb n = 0.27-0.95) and exhibit significant tetrad effects in REE patterns. These geochemical attributes indicate that granite trace element distribution was controlled by crystal fractionation as well as interaction with fluorine-rich magmatic fluids. U-Pb SHRIMP zircon dating indicates an age of ~630-620 Ma but with abundant evidence that zircons were affected by late corrosive fluids (e.g., discordance, high common Pb). ?Nd at 620 Ma ranges from +3.4 to +6.8 (mean = +5.0) for Humr Akarim granitic rocks and from +4.8 to +7.5 (mean = +5.8) for Humrat Mukbid granitic rocks. Some slightly older zircons (~740 Ma, 703 Ma) may have been inherited from older granites in the region. Our U-Pb zircon data and Nd isotope results indicate a juvenile magma source of Neoproterozoic age like that responsible for forming most other ANS crust and refute previous conclusions that pre-Neoproterozoic continental crust was involved in the generation of the studied granites.

Ali, Kamal A.; Moghazi, Abdel-Kader M.; Maurice, Ayman E.; Omar, Sayed A.; Wang, Qiang; Wilde, Simon A.; Moussa, Ewais M.; Manton, William I.; Stern, Robert J.

2012-10-01

174

Nile River, Lake Nasser, Aswan Dam, Egypt  

NASA Technical Reports Server (NTRS)

Egypt's High Aswan Dam on the Nile River at the first cataracts, Nile River, (24.0N, 33.0E) was completed in 1971 to provide cheap hydroelectric power and to regulate the historically uneven flow of the Nile River. The contrast between the largely base rock desert east of the Nile versus the sand covered desert west of the river and the ancient irrigated floodplain downstream from the damsite is clearly shown.

1991-01-01

175

Geology and organic geochemistry of Dakla Shale, Egypt  

SciTech Connect

The Dakla Formation is late Campanian to Paleocene in age and, in eastern Egypt, is overlain by the Nubian Sandstone and underlain by the phosphate-bearing Duwi Formation. Lithologically, samples of the Dakla shale member collected in the Red Sea area consist of marls to marly clays, range from brown to black in color, and are bounded at the top and bottom by phosphate-bearing strata. Organic carbon and extractable C/sub 15+/ hydrocarbon concentrations for samples from Quseir, Hamrawein, and Safaga ranged from 3.8 to 5.9% C/sub org/ and 550 to 2400 ppM HC, and may be petroleum source rocks in areas where burial and thermal conditions are adequate. Shale samples from the Quseir region yielded Fischer assay results of 40 gal/ton, and thus have considerable potential as oil shales. Samples from the Sibaiya region in the Nile Valley are light to dark gray shale and average 0.2% C/sub org/. In this area, the phosphate deposits associated with the Dakla Formation are presently being exploited. The Dakla shale samples from the Abu Tartur region, in the Western Desert, contain organic carbon concentrations in excess of 4.0%. Such values are considered suitable for potential petroleum source rocks where other conditions are satisfied. Recent exploration activity in the Western Desert region may make petroleum source rock studies of the Dakla shales increasingly important.

Robison, V.D.; Troeeger, U.

1983-03-01

176

Nubian Complex strategies in the Egyptian high desert  

Microsoft Academic Search

Systematic survey by the Abydos Survey for Paleolithic Sites project has recorded Nubian Complex artifact density, distribution, typology, and technology across the high desert landscape west of the Nile Valley in Middle Egypt. Our work contrasts with previous investigations of Nubian Complex settlement systems in Egypt, which focused on a small number of sites in the terraces of the Nile

Deborah I. Olszewski; Harold L. Dibble; Shannon P. McPherron; Utsav A. Schurmans; Laurent Chiotti; Jennifer R. Smith

2010-01-01

177

Effect of the temperature variation between Mediterranean Sea and Syrian deserts on the dust storm occurrence in the western half of Iran  

NASA Astrophysics Data System (ADS)

Recent dust storms have caused crises in western Iran, which necessitate the prediction of these storms a few days before their occurrence. This is the first study of its type that analyzes the effect of temperature differences between the Mediterranean Sea surface and Syrian deserts (creation zone of the dusts storms) on the formation of dust storms in the west of Iran. The study also seeks to identify any changes in the atmospheric temperature created by the extreme dust storm of July 5, 2009 in west of Iran (Sanandaj City). In this study, the MODIS images from 2000 to 2008, and particulate matter data of the Sanandaj station from 2008 to 2012 were utilized to identify the dust storm days. The Mediterranean Sea surface temperature data were extracted from NOAA satellites for dust storm days up to four days preceding them. The web site of world weather was used to obtain the temperature of Damascus, Syria station as the selected land station. According to the results, significant differences were acquired between surface temperatures of Damascus station and the Mediterranean Sea in the dust storm days and up to three days before them. As the dust storm days approached, a rising trend was observed in changes of the temperature difference between land and sea. Thermal map analysis of the atmosphere of the Syrian deserts on July 5, 2009 showed significant decrease in the levels of 1000 hPa and 500 hPa but for the days preceding it no significant changes were observed. It can be concluded that the temperature difference between the Mediterranean Sea surface and the Syrian deserts four days before the dust storm occurrences is the important factor in predicting this event.

Amanollahi, Jamil; Kaboodvandpour, Shahram; Qhavami, Samira; Mohammadi, Bakhtiyar

2015-03-01

178

Solar Energy for Rural Egypt  

NASA Astrophysics Data System (ADS)

Egypt is currently experiencing the symptoms of an energy crisis, such as electricity outage and high deficit, due to increasing rates of fossil fuels consumption. Conversely, Egypt has a high solar availability of more than 18.5 MJ daily. Additionally, Egypt has large uninhabited deserts on both sides of the Nile valley and Sinai Peninsula, which both represent more than 96.5 % of the nation's total land area. Therefore, solar energy is one of the promising solutions for the energy shortage in Egypt. Furthermore, these vast lands are advantageous for commissioning large-scaled solar power projects, not only in terms of space availability, but also of availability of high quality silicon (sand) required for manufacturing silicon wafers used in photovoltaic (PV) modules. Also, rural Egypt is considered market a gap for investors, due to low local competition, and numerous remote areas that are not connected to the national electricity grid. Nevertheless, there are some obstacles that hinder the progress of solar energy in Egypt; for instance, the lack of local manufacturing capabilities, security, and turbulent market in addition to other challenges. This paper exhibits an experience of the authors designing and installing decentralized PV solar systems, with a total rated power of about 11 kW, installed at two rural villages in at the suburbs of Fayoum city, in addition to a conceptual design of a utility scale, 2 MW, PV power plant to be installed in Kuraymat. The outcomes of this experience asserted that solar PV systems can be a more technically and economically feasible solution for the energy problem in rural villages.

Abdelsalam, Tarek I.; Darwish, Ziad; Hatem, Tarek M.

179

Fission-track analysis of basement apatites at the western margin of the Gulf of Suez rift, Egypt: evidence for synchroneity of uplift and subsidence  

NASA Astrophysics Data System (ADS)

Fifty-six apatite fission-track ages and 52 horizontal confined track-length measurements are reported from Precambrian crystalline rocks along the western margin of the Gulf of Suez, Egypt. Ages fall in the range of ca. 11-385 m.y. and older ages often occur within very close geographic proximity to younger ones, indicating non-uniform uplift. The wide range in ages is accompanied by a systematic variation in the distribution of horizontal confined fission track lengths. On the basis of apatite fission track ages and their length distributions, data fall into three distinct groups. Group I: ages ranging from 43 to 385 m.y. Length distributions are all positively skewed and with decreasing age become progressively broader with shorter mean track length. Group II: ages ranging from 23 to 31 m.y. Length distributions are negatively skewed with either a distinct tail or a small peak of short tracks. Group III: ages ranging from 11 to 20.5 m.y. Length distributions are al unimodal, narrow, negatively skewed and have the longest mean lengths among samples studied. Apatite ages from groups I and II are interpreted as "mixed ages" as a result of cooling during uplift from different levels within the apatite partial track annealing zone. Ages from Group III are interpreted as "cooling ages" due to uplift from the apatite total track annealing zone with minor partial annealing. Correcting the ages of the two oldest samples in this group for track-length reduction yields ages of 21 ± 2.2and23 ± 1.5m.y. It is proposed that the onset of rift-flank uplift in the Gulf of Suez—northern Red Sea area occurred between 21 and 23 m.y. ago. Fission-track analysis in combination with subsidence data from the Gulf of Suez basin, indicate that commencement of basement uplift postdate the start of rifting and is interpreted as evidence for passive rifting at the Gulf of Suez. Furthermore, this uplift is contemporaneous with, and is directly related to, the process of extension and subsidence at the Gulf of Suez.

Omar, Gomaa I.; Steckler, Michael S.; Buck, W. Roger; Kohn, Barry P.

1989-09-01

180

Atom Trap, Krypton-81, and Egypt  

NASA Astrophysics Data System (ADS)

We are developing the Atom Trap Trace Analysis (ATTA) method for the analysis of two long-lived rare krypton isotopes, ^81Kr (t_1/2=2.3 × 10^5 years, I.A. ˜ 10-13) and ^85Kr (t_1/2=10.8 years, I.A. ˜ 10-11). ^81Kr analyses can be used to determine the ages of old ice and groundwater in a range (5 × 10^4 - 2 × 10^6 years) beyond the reach of radio-carbon dating; Analyses of ^85Kr , a fission product of uranium and plutonium, can serve as a means to help verify compliance with the Nuclear Non-Proliferation Treaty. In ATTA, individual atoms of the desired isotope are selectively captured into a laser trap and detected by observing the fluorescence of trapped atoms. The first application of ATTA is dating the ancient groundwater of the Nubian Aquifer underneath the Western Desert of Egypt. This is one of the largest aquifers in the world. The residence time of its water are of great interest in fundamental geology as well as for utilitarian reasons. This work marks the beginning of a useful tool in Earth sciences. * This work is supported by the U.S. Department of Energy, Division of Nuclear Physics, under contract W-31-109-ENG-38.

Lu, Zheng-Tian

2003-10-01

181

76 FR 59682 - Desert Southwest Customer Service Region-Western Area Lower Colorado Balancing Authority-Rate...  

Federal Register 2010, 2011, 2012, 2013, 2014

...through September 30, 2013, under Rate Order...through September 30, 2013. 76 FR 28767, May...Western Area Lower Colorado Ancillary Services...section 5 of the Flood Control Act of 1944...power plant on the Colorado River. Network Integration...through September 30, 2013. The formula...

2011-09-27

182

Eternal Egypt  

NSDL National Science Digital Library

Available in English, French, and Arabic, Eternal Egypt is a website with a wealth of information on "the artifacts, characters, and places that together comprise the wonder that is Eternal Egypt." The website is organized so visitors can choose between a guided tour, begin with one of the cultural highlights (such as The Temple of Luxor or Part of a Wall of a Tomb), or simply explore and discover. A key feature of the website is the context provided in relation to various topics, so that a visitor can learn about the artifacts, but also how they connect to other people, places and artifacts, and where they fit in terms of an overall timeline and on a multimedia map of Egypt. Topics include: Arts and Crafts (Libraries, Architecture, Paintings and Relief, Sculpture, Humanities, Crafts), Science (Archaeology, Mathematics, Astronomy, Medicine, Social Science, Engineering), Agriculture (Irrigation, Herding, Farming, Crops), Commerce and Trade (Transportation), Government (Leaders, Seats of Power, Theocracy, Military), and Society and Culture (Family, Food and Drinks, Clothing, Sports and Entertainment, Religion and Spirituality).

183

The Formation of the Patterns of Desert Shrub Communities on the Western Ordos Plateau, China: The Roles of Seed Dispersal and Sand Burial  

PubMed Central

The western Ordos Plateau is a key area of shrub diversity and a National Nature Reserve of endangered shrub species in north-west China. Desert expansion is becoming the most important threat to these endangered species. However, little is known about the effects of sand burial on the dynamics of the shrub community. This study aims to investigate how the shrubs as a community and as different individual shrubs respond to the disturbances caused by the desert expansion. The approach used by this study is to separate the seed-dispersal strategy from the sand-burial forces that are involved in structuring the shrub communities at different disturbance stages. Four communities for different disturbance stages were surveyed by using 50×50 m plots. The individual shrubs were classified into coloniser and successor groups at the seed-dispersal stage and strong and weak sand-burial tolerance groups at the sand-expansion stage. We employed spatial point pattern analysis with null models for each community to examine the seed-dispersal strategy and sand-burial forces affecting community distribution patterns. At the seed-dispersal stage, the interactions between the colonisers and the successors showed significant positive correlation at a scale of 0–1 m and significant negative correlation at a scale of 2 m; significant negative correlations between the groups with strong and weak sand-burial tolerance in the early stage of sand expansion at scales of 3–6 m, and significant positive correlation in the later stage of sand expansion at a scale of 13 m, were found. Seed-dispersal strategy is a reasonable mechanism to explain the shrub community pattern formation in the earlier stages, whereas sand burial is the primary reason for the disappearance of shrubs with weak sand-burial tolerance, this irreversible disturbance causes homogenisation of the community structure and produces aging populations of shrub species. This has an important influence on the succession direction of desert shrub communities. PMID:23922877

Wang, Yange; Yang, Xiaohui; Shi, Zhongjie

2013-01-01

184

The formation of the patterns of desert shrub communities on the Western Ordos Plateau, China: the roles of seed dispersal and sand burial.  

PubMed

The western Ordos Plateau is a key area of shrub diversity and a National Nature Reserve of endangered shrub species in north-west China. Desert expansion is becoming the most important threat to these endangered species. However, little is known about the effects of sand burial on the dynamics of the shrub community. This study aims to investigate how the shrubs as a community and as different individual shrubs respond to the disturbances caused by the desert expansion. The approach used by this study is to separate the seed-dispersal strategy from the sand-burial forces that are involved in structuring the shrub communities at different disturbance stages. Four communities for different disturbance stages were surveyed by using 50×50 m plots. The individual shrubs were classified into coloniser and successor groups at the seed-dispersal stage and strong and weak sand-burial tolerance groups at the sand-expansion stage. We employed spatial point pattern analysis with null models for each community to examine the seed-dispersal strategy and sand-burial forces affecting community distribution patterns. At the seed-dispersal stage, the interactions between the colonisers and the successors showed significant positive correlation at a scale of 0-1 m and significant negative correlation at a scale of 2 m; significant negative correlations between the groups with strong and weak sand-burial tolerance in the early stage of sand expansion at scales of 3-6 m, and significant positive correlation in the later stage of sand expansion at a scale of 13 m, were found. Seed-dispersal strategy is a reasonable mechanism to explain the shrub community pattern formation in the earlier stages, whereas sand burial is the primary reason for the disappearance of shrubs with weak sand-burial tolerance, this irreversible disturbance causes homogenisation of the community structure and produces aging populations of shrub species. This has an important influence on the succession direction of desert shrub communities. PMID:23922877

Wang, Yange; Yang, Xiaohui; Shi, Zhongjie

2013-01-01

185

Evolution of rattlesnakes (Viperidae; Crotalus) in the warm deserts of western North America shaped by Neogene vicariance and Quaternary climate change.  

PubMed

During Pleistocene, the Laurentide ice sheet rearranged and diversified biotic distributions in eastern North America, yet had minimal physical impact in western North America where lineage diversification is instead hypothesized to result from climatic changes. If Pleistocene climatic fluctuations impacted desert species, the latter would reflect patterns of restricted gene flow concomitant with indications of demographic bottlenecks. Accordingly, molecular evidence for refugia should be present within these distributions and for subsequent range expansions as conditions improved. We sought answers to these questions by evaluating mitochondrial DNA (mtDNA) sequences from four species of rattlesnakes [Crotalus mitchellii (speckled rattlesnake), Crotalus cerastes (sidewinder), Crotalus tigris (tiger rattlesnake), Crotalus ruber (red diamond rattlesnake)] with distributions restricted to desert regions of southwestern North America. We inferred relationships using parsimony and maximum likelihood, tested intraspecific clades for population expansions, applied an isolation-with-migration model to determine bi-directional migration rates (m) among regions, and inferred divergence times for species and clades by applying a semiparametric penalized likelihood approach to our molecular data. Evidence for significant range expansion was present in two of eight regions in two species (Crotalus mitchellii pyrrhus, C. tigris region north). Two species (C. cerastes, C. mitchellii) showed a distribution concomitant with northward displacement of Baja California from mainland México, followed by vicariant separation into subclades. Effects of Pleistocene climate fluctuations were found in the distributions of all four species. Three regional diversification patterns were identified: (i) shallow genetic diversity that resulted from Pleistocene climatic events (C. tigris, C. ruber); (ii) deep Pleistocene divisions indicating allopatric segregation of subclades within refugia (C. mitchellii, C. cerastes); and (iii) lineage diversifications that extended to Pliocene or Late Miocene (C. mitchellii, C. cerastes). Clade-diversifying and clade-constraining effects impacted the four species of rattlesnakes unequally. We found relatively high levels of molecular diversification in the two most broadly distributed species (C. mitchellii, C. cerastes), and lower levels of genetic diversification in the two species (C. tigris, C. ruber) whose ranges are relatively more restricted. Furthermore, in several cases, the distributions of subspecies were not congruent with our molecular information. We suggest regional conservation perspectives for southwestern deserts cannot rely upon subspecies as biodiversity surrogates, but must instead employ a molecular and deep historical perspective as a primary mechanism to frame biodiversity reserves within this region. PMID:16968275

Douglas, Michael E; Douglas, Marlis R; Schuett, Gordon W; Porras, Louis W

2006-10-01

186

Resilience to stress and disturbance, and resistance to Bromus tectorum l. invasion in cold desert shrublands of western North America  

USGS Publications Warehouse

Alien grass invasions in arid and semi-arid ecosystems are resulting in grass–fire cycles and ecosystem-level transformations that severely diminish ecosystem services. Our capacity to address the rapid and complex changes occurring in these ecosystems can be enhanced by developing an understanding of the environmental factors and ecosystem attributes that determine resilience of native ecosystems to stress and disturbance, and resistance to invasion. Cold desert shrublands occur over strong environmental gradients and exhibit significant differences in resilience and resistance. They provide an excellent opportunity to increase our understanding of these concepts. Herein, we examine a series of linked questions about (a) ecosystem attributes that determine resilience and resistance along environmental gradients, (b) effects of disturbances like livestock grazing and altered fire regimes and of stressors like rapid climate change, rising CO2, and N deposition on resilience and resistance, and (c) interacting effects of resilience and resistance on ecosystems with different environmental conditions. We conclude by providing strategies for the use of resilience and resistance concepts in a management context. At ecological site scales, state and transition models are used to illustrate how differences in resilience and resistance influence potential alternative vegetation states, transitions among states, and thresholds. At landscape scales management strategies based on resilience and resistance—protection, prevention, restoration, and monitoring and adaptive management—are used to determine priority management areas and appropriate actions.

Chambers, Jeanne C.; Bradley, Bethany A.; Brown, Cynthia S.; D'Antonio, Carla; Germino, Matthew J.; Grace, James B.; Hardegree, Stuart P.; Miller, Richard F.; Pyke, David A.

2013-01-01

187

AIRSAR Data for Geological and Geomorphological Mapping in the Great Sandy Desert and Pilbara Regions of Western Australia  

NASA Technical Reports Server (NTRS)

Enhancements of AIRSAR data have demonstrated the benefits of synthetic aperture radar (SAR) for revealing an additional and mich higher level of information about the composition of the terrain than enhancements f either SPOT-PAN or Landsat TM data. With appropriate image processing techniques, surface and near surface geological structures, hydrological systems (both current and ancient) and landform features, have been evidenced in a diverse range of landscapes. In the Great Sandy Desert region where spectral variability is minimal, radar's sensitivity to the micromorphology of sparse exposures of subcrop and lag gravels has provided a new insight into the region's geological framework, its landforms, and their evolution. In the Pilbara region, advanced processing of AIRSAR data to unmix the backscatter between and within the three frequencies of data has highlighted subsurface extensions of greenstone lithologies below sand cover and morphological evidence of past flow conditions under former climate regimes. On the basis of these observations, it is recommend that radar remote sensing technology involving the use of high resolution, polarimetric data be seriously considered as a viable tool for exploration in erosional and depositional environments located within Australia's mineral and oil-prospective provinces.

Tapley, Ian J.

1996-01-01

188

Ancient Egypt  

NSDL National Science Digital Library

Drawing on its superb collection of materials from archaeological excavations, the British Museum presents this extensive learning resource on Ancient Egypt. The site features texts, images, and interactive elements detailing Egyptian daily life, mythology, timekeeping, geography, architecture, governance, business, writing, and rituals of death. The material is clearly and simply written so that the site would be useful for primary school students, but it is informative and substantial enough to be of interest to college students and curious adults as well. Thoroughly hyperlinked and replete with images that can be enlarged for detailed perusal, the site goes beyond the typical teaser Websites so often posted by lesser museums.

189

Desert Features  

NSDL National Science Digital Library

Sand covers only about 20 percent of the Earth's deserts. Nearly 50 percent of desert surfaces are gravel plains where removal of fine-grained material by the wind has exposed loose gravel and occasional cobbles. This web page, produced by the U.S. Geological Survey, features text and photographs that describe desert landforms, soils, plants, and the role of water in the formation of desert landscapes.

190

Data from a thick unsaturated zone underlying Oro Grande and Sheep Creek washes in the western part of the Mojave Desert, near Victorville, San Bernardino County, California  

USGS Publications Warehouse

This report presents data on the physical properties of unsaturated alluvial deposits and on the chemical and isotopic composition of soil water and soil gas collected at 12 monitoring sites in the western part of the Mojave Desert, near Victorville, California. Sites were installed using the ODEX air-hammer method. Seven sites were located in the active channels of Oro Grande and Sheep Creek Washes. The remaining five sites were located away from the active washes. Most sites were drilled to a depth of about 100 feet below land surface; two sites were drilled to the water table almost 650 feet below land surface. Drilling procedures, lithologic and geophysical data, and site construction and instrumentation are described. Core material was analyzed for water content, bulk density, water potential, particle size, and water retention. The chemical composition of leachate from almost 1,000 subsamples of cores and cuttings was determined. Water extracted from selected subsamples of cores was analyzed for tritium and the stable isotopes of oxygen and hydrogen. Water from suction-cup lysimeters and soil-gas samples also were analyzed for chemical and isotopic composition. In addition, data on the chemical and isotopic composition of bulk precipitation from five sites and on ground water from two water-table wells are reported.

Izbicki, John A.; Clark, Dennis A.; Pimental, Maria I.; Land, Michael T.; Radyk, John C.; Michel, Robert L.

2000-01-01

191

Movement of water through the thick unsaturated zone underlying Oro Grande and Sheep Creek Washes in the western Mojave Desert, USA  

USGS Publications Warehouse

Previous studies indicate that a small quantity of recharge occurs from infiltration of streamflow in intermittent streams in the upper Mojave River basin, in the western Mojave Desert, near Victorville, California. Chloride, tritium, and stable isotope data collected in the unsaturated zone between 1994 and 1998 from boreholes drilled in Oro Grande and Sheep Creek Washes indicate that infiltration of streamflow occurs to depths below the root zone, and presumably to the water table, along much of Oro Grande Wash and near the mountain front along Sheep Creek Wash. Differences in infiltration at sites along each wash are the result of hydrologic variables such as proximity to the mountain front, quantity of streamflow, and texture of the subsurface deposits. Differences in infiltration between the washes are the result of large-scale geomorphic processes. For example, Oro Grande wash is incised into the Victorville fan and infiltration has occurred at approximately the same location over recent geologic time. In contrast, Sheep Creek Wash overlies an active alluvial fan and the stream channel can move across the fan surface through time. Infiltration does not occur to depths below the root zone at control sites outside of the washes.

Izbicki, J.A.; Radyk, J.; Michel, R.L.

2002-01-01

192

Sensitivity of growth and biomass allocation patterns to increasing nitrogen: a comparison between ephemerals and annuals in the Gurbantunggut Desert, north-western China  

PubMed Central

Background and Aims Biomass accumulation and allocation patterns are critical to quantifying ecosystem dynamics. However, these patterns differ among species, and they can change in response to nutrient availability even among genetically related individuals. In order to understand this complexity further, this study examined three ephemeral species (with very short vegetative growth periods) and three annual species (with significantly longer vegetative growth periods) in the Gurbantunggut Desert, north-western China, to determine their responses to different nitrogen (N) supplements under natural conditions. Methods Nitrogen was added to the soil at rates of 0, 0·5, 1·0, 3·0, 6·0 and 24·0 g N m?2 year?1. Plants were sampled at various intervals to measure relative growth rate and shoot and root dry mass. Key Results Compared with annuals, ephemerals grew more rapidly, increased shoot and root biomass with increasing N application rates and significantly decreased root/shoot ratios. Nevertheless, changes in the biomass allocation of some species (i.e. Erodium oxyrrhynchum) in response to the N treatment were largely a consequence of changes in overall plant size, which was inconsistent with an optimal partitioning model. An isometric log shoot vs. log root scaling relationship for the final biomass harvest was observed for each species and all annuals, while pooled data of three ephemerals showed an allometric scaling relationship. Conclusions These results indicate that ephemerals and annuals differ observably in their biomass allocation patterns in response to soil N supplements, although an isometric log shoot vs. log root scaling relationship was maintained across all species. These findings highlight that different life history strategies behave differently in response to N application even when interspecific scaling relationships remain nearly isometric. PMID:24287812

Zhou, Xiaobing; Zhang, Yuanming; Niklas, Karl J.

2014-01-01

193

Fairy, tadpole, and clam shrimps (Branchiopoda) in seasonally inundated clay pans in the western Mojave Desert and effect on primary producers  

PubMed Central

Background Fairy shrimps (Anostraca), tadpole shrimps (Notostraca), clam shrimps (Spinicaudata), algae (primarily filamentous blue-green algae [cyanobacteria]), and suspended organic particulates are dominant food web components of the seasonally inundated pans and playas of the western Mojave Desert in California. We examined the extent to which these branchiopods controlled algal abundance and species composition in clay pans between Rosamond and Rogers Dry Lakes. We surveyed branchiopods during the wet season to estimate abundances and then conducted a laboratory microcosm experiment, in which dried sediment containing cysts and the overlying algal crust were inundated and cultured. Microcosm trials were run with and without shrimps; each type of trial was run for two lengths of time: 30 and 60 days. We estimated the effect of shrimps on algae by measuring chlorophyll content and the relative abundance of algal species. Results We found two species of fairy shrimps (Branchinecta mackini and B. gigas), one tadpole shrimp (Lepidurus lemmoni), and a clam shrimp (Cyzicus setosa) in our wet-season field survey. We collected Branchinecta lindahli in a pilot study, but not subsequently. The dominant taxa were C. setosa and B. mackini, but abundances and species composition varied greatly among playas. The same species found in field surveys also occurred in the microcosm experiment. There were no significant differences as a function of experimental treatments for either chlorophyll content or algal species composition (Microcoleus vaginatus dominated all treatments). Conclusions The results suggest that there was no direct effect of shrimps on algae. Although the pans harbored an apparently high abundance of branchiopods, these animals had little role in regulating primary producers in this environment. PMID:21143855

2010-01-01

194

Desert dust in rural western US; the influence of dust storms, large particles, and land-use change on aerosol loads  

NASA Astrophysics Data System (ADS)

Atmospheric aerosols are common in urban settings as well as dryland rural environments and are important to both climate and biogeochemical cycling. Most urban and far traveled aerosols are less than 10 micrometers in diameter with many particles in the less than 2.5 or 1 micrometer-size classes. Small aerosols, including many generated by industrial activity, are the focus of federal environmental law and have a major impact on human health. In rural areas of the western US, however, these small industrially derived particles appear to make up a small part of the overall aerosol load. Rather, dust in the rural West is dominated by mineral aerosols including a large amount of particles that range in size from 10 to 40 microns. These particles can travel for hundreds of kilometers, particularly during periods when dust storms are common. In the dusty spring and summer periods in and around Canyonlands and Mesa Verde National Parks, large particles (particles greater than 10 micrometers in diameter) appear to contribute between 50 and 90% to the overall particle load several meters above the ground. During large dust storms, concentrations of total suspended particulates increase by a factor of 8 to 10 while particles less than 10 micrometers in diameter are minimally affected. The presence of large particles in the atmosphere of the rural West is notable for several reasons. First, the majority of the existing aerosol monitoring networks focus on the small particle-size classes of less than 2.5 and 10 microns. Because many aerosol-collection instruments are designed with specific particle-size cutoff criteria, these instruments and the networks that depend on them are effectively blind to the larger particles that can dominate aerosol loads in the West. Second, for large portions of the year including the spring and summer months when dust storms are common, large particles likely play a major role in visibility restrictions across the protected airsheds of the western US. Finally, the sources of large mineral aerosols are different from those of industrial aerosols that dominate urban areas, and thus the concentrations of large particles do not correspond with variations in urban concentrations of small industrial aerosols. Mineral aerosols are produced by both natural erosion of desert soils and the variety of human activities such as grazing, resource extraction, and recreation that lead to surface disturbance. In large areas of the rural West, resource extraction and recreational activities have been increasing leading to the potential for increases in mineral aerosol concentrations. Without improved monitoring capabilities that focus on these large particles, any potential long-term changes in large-particle aerosol loads in the rural west will continue to go undetected.

Parks, D.; MacDonald, A. E.; Rosen, R. D.; Edmonds, H. N.; Key, E.; Swanberg, N.; Wiseman, W. J.; Sandgathe, S. A.; Neff, J. C.; Fernandez, D.; Munson, S.; Reynolds, R. L.

2011-12-01

195

Egypt's fundamentalists say condoms immoral.  

PubMed

The first AIDS case in Egypt was reported almost 10 years ago, yet Egypt still does not have reliable statistics on the HIV/AIDS epidemic (officially, 513 HIV infections and 88 AIDS cases; more likely, 3000 and 10,000, respectively). HIV/AIDS bears a stigma. The government claims that every HIV-infected Egyptian acquired the infection through a blood transfusion while in the Gulf or through sexual intercourse in Europe. Cultural, social, and religious norms that discourage promiscuity may explain the low HIV/AIDS rate but these same taboos put women at risk by making it difficult for them to protect themselves. Islamic fundamentalist women reinforce the Islamic principle of forbidding sex education. They consider AIDS a plague of immoral Western society. They refuse to accept the fact that many men do not practice safer sex. These women consider condoms immoral. They think God will curse women who refuse to have sexual intercourse at their husbands' bidding. Many nongovernmental organizations consider an intensive education program as the only means to avert disaster. Egypt has yet to implement its model AIDS program. All hospitals in Cairo and some hospitals in rural areas have equipment to test for HIV. Surveillance systems have been limited to high risk groups. In Egypt, it is mandatory to test foreigners for HIV. Prisoners, prostitutes, homosexuals, and blood donors are tested randomly without their consent. Positive results are often reported to authorities before the persons learn their HIV status. A campaign for widespread sex education is the only action recommended so far. It includes a mass media component and community meetings and conferences. An Egyptian physician has found an anti-viral drug that stimulates the immune system, but his work does not receive much coverage outside Egypt. Egyptians need to tackle their cultural taboos about discussion of sex to curb the HIV/AIDS epidemic. PMID:12289036

Soliman, S

1995-06-01

196

Ancient Egypt  

NASA Astrophysics Data System (ADS)

This thesis involves development of an interactive GIS (Geographic Information System) based application, which gives information about the ancient history of Egypt. The astonishing architecture, the strange burial rituals and their civilization were some of the intriguing questions that motivated me towards developing this application. The application is a historical timeline starting from 3100 BC, leading up to 664 BC, focusing on the evolution of the Egyptian dynasties. The tool holds information regarding some of the famous monuments which were constructed during that era and also about the civilizations that co-existed. It also provides details about the religions followed by their kings. It also includes the languages spoken during those periods. The tool is developed using JAVA, a programing language and MOJO (Map Objects Java Objects) a product of ESRI (Environmental Science Research Institute) to create map objects, to provide geographic information. JAVA Swing is used for designing the user interface. HTML (Hyper Text Markup Language) pages are created to provide the user with more information related to the historic period. CSS (Cascade Style Sheets) and JAVA Scripts are used with HTML5 to achieve creative display of content. The tool is kept simple and easy for the user to interact with. The tool also includes pictures and videos for the user to get a feel of the historic period. The application is built to motivate people to know more about one of the prominent and ancient civilization of the Mediterranean world.

Swamy, Ashwin Balegar

197

WESTERN BIRDS  

Microsoft Academic Search

Common Barn-Owls (Tyro alba), Great Horned Owls (Bubo virginianus), Long-eared Owls (Asio otus), Western Screech-Owls (Otus kennicottii), and Burrowing Owls (Athene cunnicularia) all occur as year-round or seasonal residents of southern California deserts. This species richness provided me an opportunity to compare the diets of these owls both within and between desert regions. Within-region comparisons allowed analyses in situations where

CAMERON W. BARROWS

1989-01-01

198

Whole-Genome Optical Mapping and Finished Genome Sequence of Sphingobacterium deserti sp. nov., a New Species Isolated from the Western Desert of China  

PubMed Central

A novel Gram-negative bacterium, designated ZWT, was isolated from a soil sample of the Western Desert of China, and its phenotypic properties and phylogenetic position were investigated using a polyphasic approach. Growth occurred on TGY medium at 5–42°C with an optimum of 30°C, and at pH 7.0–11.0 with an optimum of pH 9.0. The predominant cellular fatty acids were summed feature 3 (C16:1?7c/C16:1?6c or C16:1?6c/C16:1?7c) (39.22%), iso-C15:0 (27.91%), iso-C17:0 3OH (15.21%), C16:0 (4.98%), iso-C15:0 3OH (3.03%), C16:0 3OH (5.39%) and C14:0 (1.74%). The major polar lipid of strain ZWT is phosphatidylethanolamine. The only menaquinone observed was MK-7. The GC content of the DNA of strain ZWT is 44.9 mol%. rDNA phylogeny, genome relatedness and chemotaxonomic characteristics all indicate that strain ZWT represents a novel species of the genus Sphingobacterium. We propose the name S. deserti sp. nov., with ZWT (= KCTC 32092T = ACCC 05744T) as the type strain. Whole genome optical mapping and next-generation sequencing was used to derive a finished genome sequence for strain ZWT, consisting of a circular chromosome of 4,615,818 bp in size. The genome of strain ZWT features 3,391 protein-encoding and 48 tRNA-encoding genes. Comparison of the predicted proteome of ZWT with those of other sphingobacteria identified 925 species-unique proteins that may contribute to the adaptation of ZWT to its native, extremely arid and inhospitable environment. As the first finished genome sequence for any Sphingobacterium, our work will serve as a useful reference for subsequent sequencing and mapping efforts for additional strains and species within this genus. PMID:25830331

Molnár, István; Li, Xinna; Tang, Ran; Chen, Ming; Wang, Lin; Su, Shiyou; Zhang, Wei; Lin, Min

2015-01-01

199

Whole-Genome Optical Mapping and Finished Genome Sequence of Sphingobacterium deserti sp. nov., a New Species Isolated from the Western Desert of China.  

PubMed

A novel Gram-negative bacterium, designated ZWT, was isolated from a soil sample of the Western Desert of China, and its phenotypic properties and phylogenetic position were investigated using a polyphasic approach. Growth occurred on TGY medium at 5-42°C with an optimum of 30°C, and at pH 7.0-11.0 with an optimum of pH 9.0. The predominant cellular fatty acids were summed feature 3 (C16:1?7c/C16:1?6c or C16:1?6c/C16:1?7c) (39.22%), iso-C15:0 (27.91%), iso-C17:0 3OH (15.21%), C16:0 (4.98%), iso-C15:0 3OH (3.03%), C16:0 3OH (5.39%) and C14:0 (1.74%). The major polar lipid of strain ZWT is phosphatidylethanolamine. The only menaquinone observed was MK-7. The GC content of the DNA of strain ZWT is 44.9 mol%. rDNA phylogeny, genome relatedness and chemotaxonomic characteristics all indicate that strain ZWT represents a novel species of the genus Sphingobacterium. We propose the name S. deserti sp. nov., with ZWT (= KCTC 32092T = ACCC 05744T) as the type strain. Whole genome optical mapping and next-generation sequencing was used to derive a finished genome sequence for strain ZWT, consisting of a circular chromosome of 4,615,818 bp in size. The genome of strain ZWT features 3,391 protein-encoding and 48 tRNA-encoding genes. Comparison of the predicted proteome of ZWT with those of other sphingobacteria identified 925 species-unique proteins that may contribute to the adaptation of ZWT to its native, extremely arid and inhospitable environment. As the first finished genome sequence for any Sphingobacterium, our work will serve as a useful reference for subsequent sequencing and mapping efforts for additional strains and species within this genus. PMID:25830331

Teng, Chao; Zhou, Zhengfu; Molnár, István; Li, Xinna; Tang, Ran; Chen, Ming; Wang, Lin; Su, Shiyou; Zhang, Wei; Lin, Min

2015-01-01

200

Geochemical modeling of evaporation process in Lake Qarun, Egypt  

NASA Astrophysics Data System (ADS)

Lake Qarun is an inland closed saline lake. It lies within the Fayoum Depression in the Western Desert of Egypt. Evaporation modeling has been carried out using PHREEQC to simulate the geochemical evolution of surface drainage waters inflow towards lake water. In the case of Lake Qarun, it is the first attempt to carry out such kind of modeling. Performance of this model helped to address the different sources of dissolved major ions to Lake Qarun and to identify the mechanisms control the lake's water chemistry. The model demonstrated that evaporation-crystallization process is the main mechanism controlling the evolution of lake water chemistry where major ions Na+, Mg2+, Cl- and SO42- have been built up in the lake by evaporation while Ca2+ and HCO3- are depleted by calcite precipitation. Moreover, the simulated model reproduced the real data observed in Lake Qarun except in the case of SO42- which is in real more enriched in the lake than the model output. The additional source of SO42- is reported to be from groundwater. The models result agreed well with the modified evolutionary Hardie and Eugster's scheme (1970) in which the final major composition of Lake Qarun water is Na-Mg-SO4-Cl type. In future, the monitoring of Lake Qarun chemistry with detection of any other sources of elements and/or local reactions inside the lake can be detected by performing the simulated evaporation model reported by the present study.

Abdel Wahed, Mahmoud S. M.; Mohamed, Essam A.; El-Sayed, Mohamed I.; M'nif, Adel; Sillanpää, Mika

2014-09-01

201

Geomorphology and Quaternary geology of the Dakhla Oasis Region, Egypt  

NASA Astrophysics Data System (ADS)

Dakhla Oasis (25.5°N, 29°E) occupies a structurally localized depression at 90-140 m above sea level, ˜1200 km 2 in area, below a 300 m escarpment bordering the Libyan Plateau, Western Desert of Egypt. Semi-arid intervals of the Quaternary period generated eight sedimentary formations, separated by erosion during hyper-arid intervals. Sediments comprise three generations of colluvial/fluvial fanglomerates, two generations of tabular spring-laid clastic and chemical sediments, two generations of mound springs and basinal sediments. of fluvio-lacustrine, evaporitic, pluvio-aeolian and aeolian origins. Discussion of these sediments is organized according to geomorphic region, from north to south, plateau, scarp and piedmont, lowland and cuesta plain. Chronological evidence is restricted to many radiocarbon dates of Holocene cultural material associated with playa sediments (9-4.5 ka), a {Th}/{U} isochron age of ˜62.0 ±7.6 ka for basinal evaporites, and two {Th}/{U} ages of ˜176 and ˜170 ka for a boulder of derived travertine. The regional Quaternary sequence is reconstructed from stratigraphic and geomorphic relationships of the sediments and erosion surfaces. It is broadly similar to sequences earlier reconstructed in the topographically similar Kharga Oasis region 150 km to the east, and Kurkur Oasis, 400 km to the south-southeast. Speculations on chronology and driving mechanism are offered in conclusion.

Brookes, Ian A.

202

Geography of Ancient Egypt  

NSDL National Science Digital Library

This activity focuses on the importance of geographic features and the abundance of natural resources that helped ancient Egypt become the world's first superpower. Students will learn about the geography and resources available to the ancient Egyptians. Read each question below carefully. Using the following maps: modern political map geographical features map natural resources map archaeological sites map And the following features on the Egypt's Golden Empire website: natural resources farming Answer each question below using as much detail as possible. What countries border modern-day Egypt? (modern political map) Name the major bodies of water that surround an are a part of Egypt. (modern political map) What ...

Mr. Myers

2010-09-30

203

Life in Egypt!  

NSDL National Science Digital Library

What is the difference between life in the United States and life in Egypt? Use this fact chart to record your findings! Where is Egypt? Sightseeing in Egypt Use this time to record your findings in the "places" section of your fact chart and complete any other section you can with the information you have learned! Facts about Egypt Language (with audio) A Day in the Life Use this time to record your findings in the "people" section of your fact chart and complete ...

Ms. Pendleton

2011-04-07

204

Ancient Egypt: the Mythology  

NSDL National Science Digital Library

This Website, "dedicated to supplying information about the religious beliefs of ancient Egypt," offers internally linked essays and descriptions from scholarly sources detailing the relationship between the land and ancient beliefs; glossaries with healthy descriptions of the deities and symbols; and eighteen prominent mythological stories of Ancient Egypt. An annotated list of about a dozen other pertinent sites is also posted. A simple search engine is provided and can be accessed by going to the incongruously titled "Egypt" page, which offers users an opportunity to search the site, sign the guestbook, or email the author -- a college instructor -- questions about Egyptian mythology, but which offers no additional information on Egypt itself.

205

Crustal reflectivity from the Santa Monica Mountains to the western Mojave Desert, southern California: Results from the Los Angeles Region Seismic Experiment II (LARSE II)  

NASA Astrophysics Data System (ADS)

We acquired combined refraction and low-fold reflection data along a north-south-trending profile through the epicentral regions of the 1994 M 6.7 Northridge and 1971 M 6.7 San Fernando earthquakes as part of the Los Angeles Region Seismic Experiment, Phase II (LARSE II). The profile extended from the Santa Monica Mountains to the western Mojave Desert (Antelope Valley). The chief goal of LARSE is to image sedimentary basins and faults in the Los Angeles region to better understand and assess earthquake hazards associated with these geologic features. Conventional CDP seismic data processing, extended by several steps, was used to image the crustal reflective structure below the LARSE II line. We found that stacking offsets of 20-25 km produced the most coherent reflections, especially near the bottoms of sedimentary basins, although such offsets push the limits of the CDP method. Gently to moderately dipping reflections in all regions and at all depths along the profile required migration, which was done in two ways. In the first method of migration, we constructed manual and machine line drawings of the CDP stack and then migrated the line segments in a velocity model obtained from tomographic modeling of the first arrivals. Each line segment was migrated based on its dip (? ) and local velocity v (sin ? /v = ray parameter). First, a travel time field was calculated numerically by solving the eikonal equation (using a finite-difference technique). Next rays with the appropriate ray parameters were traced from the surface to the appropriate traveltimes, and the line segments were plotted at these points. Information on reflection strength and coherency for each line segment was preserved. The second method of migration was standard poststack Kirchhoff migration. This method produced a grainy image with migration artifacts in regions of low fold (<10), chiefly at the ends of the profile and in the Santa Susana Mountains. Both migration methods produced strong, bowl-shaped reflections beneath the San Fernando, Santa Clarita, and Antelope Valleys that are interpretable as sedimentary-basin-bottom reflections. In addition, both methods showed weak to moderately strong, dipping zones of reflections at middle to lower crustal depths. One weak zone, beneath the Santa Monica Mts and southern San Fernando Valley, dips ~35o southward from the hypocenter of the Northridge mainshock. A strong zone of reflections beneath the Transverse Ranges dips ~25o northward from the hypocenter of the San Fernando mainshock to the vertical projection of the San Andreas fault. Both of these reflective zones are interpretable as the deep continuations of the Northridge and San Fernando fault systems. The connection between the San Fernando and the San Andreas faults is somewhat similar to the fault geometry seen 70 km east, along the LARSE I line, where the Sierra Madre and Whittier Narrows fault systems appear connected to the San Andreas fault by a highly reflective zone, interpretable as a decollement. The seismic images from LARSE I and II will aid in understanding how deformation is transferred from the San Andreas fault to the thrust faults of the Los Angeles region.

Ryberg, T.; Fuis, G. S.; Bauer, K.; Lutter, W. J.; Hauksson, E.

2002-12-01

206

Thar Desert  

NASA Technical Reports Server (NTRS)

This ASTER sub-scene covers an area of 12 x 15 km in NW India in the Thar Desert. The sand dunes of the Thar Desert constantly shift and take on new shapes. Located in northwestern India and eastern Pakistan, the desert is bounded on the south by a salt marsh known as the Rann of Kutch, and on the west by the Indus River plain. About 800 kilometers long and about 490 kilometers wide, the desert's terrain is mainly rolling sandhills with scattered growths of shrub and rock outcroppings. Only about 12 to 25 centimeters of rain fall on the desert each year, and temperatures rise as high as 52 degrees Celsius. Much of the population is pastoral, raising sheep for their wool. The image is located at 24.4 degrees north latitude and 69.3 degrees east longitude.

The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

2001-01-01

207

Lake Nasser and Toshka Lakes, Egypt  

NASA Technical Reports Server (NTRS)

Lake Nasser (center) and the Toshka Lakes (center left) glow emerald green and black in this MODIS true-color image acquired March 8, 2002. Located on and near the border of Egypt and Norther Sudan, these lakes are an oasis of water in between the Nubian (lower right) and Libyan Deserts (upper left). Also visible are the Red Sea (in the upper right) and the Nile River (running north from Lake Nasser). Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

2002-01-01

208

Desert Survivors!  

ERIC Educational Resources Information Center

This article describes a special third-grade classroom unit based on the reality show "Survivor." The goal of this engaging and interactive unit was to teach students about physical and behavioral adaptations that help animals survive in various desert biomes. The activity combines research, argument, and puppet play over one week of…

Horton, Jessica; Friedenstab, Steve

2013-01-01

209

Discovering Deserts.  

ERIC Educational Resources Information Center

Ranger Rick's NatureScope is a creative education series dedicated to inspiring in children an understanding and appreciation of the natural world while developing the skills they will need to make responsible decisions about the environment. The topic of this issue is "Discovering Deserts." Contents are organized into the following sections: (1)…

Braus, Judy, Ed.

1985-01-01

210

Food Deserts  

Microsoft Academic Search

Food deserts and accessibility represent a new frontier in the assault of life-threatening, dietrelated diseases, including diabetes, obesity, hypertension, and atherosclerosis. Scholars represent the research literature from diverse disciplines, such as anthropology, agriculture, sociology, economics, marketing, public policy, sociology, and social epidemiology. Applied sociology has not contributed to this important conversation. Applied sociology's integration and use of theory, methods, and

Anthony Troy Adams; Monika J. Ulrich; Amanda Coleman

2010-01-01

211

Nile behaviour and Upper Palaeolithic humans in Upper Egypt  

NASA Astrophysics Data System (ADS)

There is evidence of a decreasing human occupation of the Upper Egyptian Nile valley during the MIS 5 to MIS 3 period. Whereas very large extraction sites of the Middle Stone Age have been recorded, only very few sites of the Upper Palaeolithic have been found. The best explanation of this fact is that during the Late Middle Stone Age and the Upper Palaeolithc there was nearly no need for raw materials because there was only a very restricted population present in Upper Egypt. From about 22 ka BP an important population increase is registered by the presence of numerous Late Palaeolithic sites. During the whole LGM there is abundant presence of humans along the Nile Valley in Upper Egypt. This population was mainly living from fishing. There seems to be an abrupt end of the Palaeolithic occupation after 12.8 ka BP. Until now, no sites were found in the Valley until some rare Epipaleolithic sites occur about 8.0 ka BP. It will be suggested that these population changes are influenced by the river Nile behaviour. The best interpretation of the observations in the Upper Egyptian Nile Valley is the hypothesis that at the same time that Nile flow was reduced because of the dryness in its source area, the impact of aeolian activity was increased over Northeast Africa. The increased aeolian activity by northern winds in the Fayum and Wadi Ryan during the LGM resulted in the accumulation of aeolian sand in the valley. That aeolian sand was transported along the western Nile valley cliffs until it was accumulated when the Nile Valley change it S-N direction, such as at Nag'Hammadi. At other places sand was invading the Nile valley, directly from the Western Desert, creating a damming of the Nile at several places such as Armant and Aswan. As Nile flow was quite reduced, the Nile was unable to erode all the incoming sand and the Nile water with its important clay content was dammed. At several places large lakes were created in the Nile Valley. Those lakes were an ideal place for the settlement of the Late Palaeolithic fishers. There came an abrupt end to this situation when the Nile returned to its meandering regime at the end of the LGM. This situation created an catastrophic food crisis for the

Vermeersch, Pierre M.

2014-05-01

212

Dust Plume off the Coast of Egypt  

NASA Technical Reports Server (NTRS)

Dwarfing the Nile, a river of dust flowed out of the deserts of northern Egypt on May 19, 2007. As the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite passed overhead at 12:05 p.m. local time in Cairo, the sensor captured this image of the dust spreading northward over the Mediterranean Sea from the sandy deserts that span the country. At the margins of the plume, ribbons and ripples of dust are translucent, allowing a glimpse of the desert and water beneath, but in the center, the cloud is opaque, revealing nothing of the surface below. The part of north-central Egypt hidden by the dust plume is the Qattara Depression, the country's lowest point. Dipping down to 133 meters below sea level (436 feet), the depression is home to sandy deserts and dry lake beds that occasionally flood. The sand and fine, lake bed sediments are easily lofted into the air by strong winds that scour the area in late winter and early spring. In the eastern (right-hand) part of the image, the Nile River is lined by narrow ribbons of dull green vegetation. The fan-shaped delta is dotted with tan-colored spots, marking the location of cities and towns. The Nile Valley and Delta make up only a small fraction of the country's total land area, yet they support almost the entire population. The large image provided above has a spatial resolution (level of detail) of 250 meters per pixel. The MODIS Rapid Response Team provides this image in additional resolutions. The Earth Observatory also provides a 250-meter-resolution KMZ file of this image for use with Google Earth.

2007-01-01

213

Field and ASTER imagery data for the setting of gold mineralization in Western Allaqi-Heiani belt, Egypt: A case study from the Haimur deposit  

NASA Astrophysics Data System (ADS)

Although associated with carbonatized/listvenitized ophiolites and thrust structures, the morphology and internal structures of the auriferous quartz veins in the Haimur deposit suggest mineralization concurrent with NE-SW dextral brittle-ductile shear zones. The latter are attributed to intense transpression regime and are associated with (N)NE-trending tight to isoclinals folds that deform the early accretionary structures. Image processing techniques applicable to the Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) data are used for mapping structures and hydrothermal alteration associated with the Haimur deposit. The automated lineament extraction by LINE module on high resolution ASTER imagery provides efficient data for potential dilation loci. Emphasis is placed on reliability of mineral indices extracted from the ASTER band ratios for identification of possibly mineralized alteration zones associated with NE-trending shear zones. Field and remote sensing data, together with the structural fabrics along the lode-associated shear zones clearly constrain on the genetic relationship between the Haimur gold deposit and post-accretionary transpression/shearing. We conclude that hydrothermal alteration zones that are confined to tightly enfolded ophiolites and transpressive shear zones along the Western Allaqi-Heiani belt are most potential targets for new exploration plans.

Zoheir, Basem; Emam, Ashraf

2014-11-01

214

Structural constraints on the evolution of the Meatiq Gneiss Dome (Egypt), East-African Orogen  

NASA Astrophysics Data System (ADS)

Amphibolite-grade quartzofeldspathic gneiss domes surrounded by greenschist-grade island arc and ophiolitic assemblages is a characteristic feature of the Arabian-Nubian Shield in the Eastern Desert of Egypt. The mode of formation of these domes, including the Meatiq Gneiss Dome, is controversial, as is the protolith age of these gneisses. Reinvestigation of selected segments of the Eastern Desert Shear Zone (EDSZ), a high-strain zone separating the eugeoclinal units from the underlying quartzofeldspathic gneisses show it to be a top-to-the NW shear zone which was later folded about a NW-SE trending fold axis (long axis of the gneiss dome). Kinematic indicators (shear bands, duplex structures, etc.) along the north-eastern and south-western flanks of the dome therefore show apparent left-lateral and right-lateral strike-slip displacement across the EDSZ. These observations are in conflict with most previous tectonic models which link formation of the dome to extension in a NW-SE oriented corridor bordered by two sub-parallel left-lateral NW-SE oriented strike-slip faults. Emplacement of upper crustal, low-grade, eugeoclinal rocks tectonically on top of middle crustal amphibolite-grade quartzofeldspathic gneisses indicates that the EDSZ may represents an extensional fault with a possible break-away zone in the southern part of the Eastern Desert. Alternatively it can be explained as the result of two (or more) tectonometamorphic events with an intervening episode of erosion and exhumation of high grade rocks prior to emplacement of the eugeoclinal thrust complex. Recent U-Pb TIMS ages on syntectonic orthogneisses and post-tectonic granites in the area show that shearing and subsequent doming must be younger than 630 Ma, possibly as young as 600 Ma.

Andresen, A.; Augland, L. E.; Boghdady, G. Y.; Lundmark, A. M.; Elnady, O. M.; Hassan, M. A.; Abu El-Rus, M. A.

2010-07-01

215

Types of Deserts  

NSDL National Science Digital Library

Deserts are classified by their location and dominant weather pattern into several types: trade wind, midlatitude, rain shadow, coastal, monsoon, or polar deserts. Former desert areas presently in nonarid environments are paleodeserts, and extraterrestrial deserts exist on other planets. This site, produced by the U.S. Geological Survey, describes each type of desert using text and photographs.

216

Desert USA: Desert Animals and Wildlife  

NSDL National Science Digital Library

This great educational website about Desert Animals and Wildlife was created by DesertUSA, a publication designed to explore and educate about "the beauty, life, and culture of North American deserts." The Desert Animals and Wildlife homepage contains extensive lists of links to sites for different Mammals, Birds and Fish, Reptiles and Amphibians, and Insects and Spiders. The animal link selections include the Mexican Gray Wolf, Desert Pupfish, Desert Iguana, and Finback Whale just to name a few. The specific animal pages include photos and information categorized in areas such as Distribution, Habitat, Description, and Life Cycle. There is a feature link to a webpage on Desert Animal Survival, a list of links to relevant DesertUSA Articles and Information, and links to websites dedicated to other DesertUSA subjects such as Plants / Wildflowers, and Peoples and Cultures.

217

Geochemical and hydrological processes controlling groundwater quality in Assiut Governorate, Egypt  

NASA Astrophysics Data System (ADS)

Groundwater in Assiut area, Egypt, is an important source of fresh water for human consumption, agriculture, and domestic and industrial purposes. Due to a growing population and expansion of agricultural reclamation projects in the desert fringes of the Nile Valley, there is an increasing water demand in this arid region. This study has investigated the geochemical and hydrological processes that control groundwater quality within the Pleistocene, Plio-Pleistocene, and Eocene aquifers in Assiut, in addition to the hydraulic relationships between surface and groundwater systems and the relations among the defined groundwater aquifers. A total of 28 surface and 160 groundwater samples were collected for geochemical analysis (major and minor element chemistry, and stable isotope analyses). Total dissolved solids = 182 to 5657 mg/L, water-delta 18O = -7.5 to +6.5%, and water-delta D = -55 to +32%. Geochemical and stable isotope data indicate that the principal source of recharge to the Pleistocene and Plio-Pleistocene aquifers is the surface water system (irrigation canals), while the prevalence of Na-Cl type waters in the Eocene aquifer indicates recharge by upward leakage from the underlying Nubian sandstone aquifer which contains the same Na-Cl water type. Evaporation prior to infiltration, mixing, and mineral equilibria (dissolution and precipitation) are the main factors that affect water quality. Ion exchange plays a secondary role in controlling the water chemistry of the Pleistocene aquifer, but is more effective in controlling water quality within the Plio-Pleistocene and Eocene aquifers due to the prevalence of clay minerals within the matrices. The fresh water exploited from the Eocene aquifer may be of great importance for land reclamation projects not only at the western desert fringes, but also at the eastern desert fringes of Assiut and similar settings around the River Nile south of Assiut Governorate. Results of this study will be helpful for sustainable development, and raising the standard of living of people in the Assiut area, which is one of the poorest regions of Egypt.

Mohammad, R. G.; Tempel, R.; Gomaa, M.; Korany, E.

2011-12-01

218

Egypt: new government, old challenges  

Microsoft Academic Search

The new government in Egypt will have to deal with the following challenges in its foreign policy: the Palestinians, Sinai, the arms race between Israel and Egypt, the nuclear issue, the Suez Canal, and the Tiran Straits. Egypt has to decide what its approach would be toward these issues and as to how to maneuver between its own interests and

Ehud Eilam

2012-01-01

219

Egypt's next steps Ahmed Zewail  

E-print Network

1 Egypt's next steps Ahmed Zewail 3 Feb 2011 Mubarak must step down, a new constitution must change, writes Ahmed Zewail. CAIRO The revolt that has erupted across Egypt is in many ways historic than a better future for Egypt and its people. In this difficult time, the military has earned

Zewail, Ahmed

220

The Politics of Educational Transfer and Policymaking in Egypt  

ERIC Educational Resources Information Center

For the past two centuries, western modern education has informed education policies and practices in Egypt. However, few researchers have analyzed the historical or current politics of educational transfer in this country. This article investigates the ways in which foreign transfer has influenced Egyptian education, both historically and…

Ibrahim, Ali S.

2010-01-01

221

Geology and origin of Meatiq Dome, Egypt: A Precambrian metamorphic core complex?  

Microsoft Academic Search

Meatiq Dome, a metamorphic complex in the Precambrian basement of the Eastern Desert of Egypt, exhibits many of the essential features of Cordilleran metamorphic core complexes. It is an antiformal structure with low-dipping foliation and unidirectional mineral-slickenside lineation. The core consists of granite gneiss and is conformably overlain by a heterogeneous, isoclinally folded, mylonitic carapace. The carapace grades upward into

Neil C. Sturchio; Mohamed Sultan; Rodey Batiza

1983-01-01

222

What Makes a Desert a Desert?  

ERIC Educational Resources Information Center

Presents background information and activities which focus on definition of a desert, locations of deserts, and factors influencing locations. Activities include objective(s), recommended age level(s), subject area(s), list of materials needed, and procedures. Two ready-to-copy pages with desert landforms and temperature/rainfall data are…

NatureScope, 1985

1985-01-01

223

Desert USA: Desert Plants and Wildflowers  

NSDL National Science Digital Library

Desert plants have adapted to the extremes of heat and aridity by using both physical and behavioral mechanisms, much like desert animals. The ingenuity and variety of these many adaptations are explored in a set of links to wildflowers, cacti and succulents, trees, shrubs, and grasses. Links to related topics such as desert plant survival, wildflower articles, and others are also included.

2000-01-01

224

Desert Dust Air Mass Mapping in the Western Sahara, using Particle Properties Derived from Space-based Multi-angle Imaging  

NASA Technical Reports Server (NTRS)

Coincident observations made over the Moroccan desert during the SAhara Mineral dUst experiMent (SAMUM) 2006 field campaign are used both to validate aerosol amount and type retrieved from Multi-angle Imaging SpectroRadiometer (MISR) observations, and to place the sub-orbital aerosol measurements into the satellite's larger regional context. On three moderately dusty days for which coincident observations were made, MISR mid-visible aerosol optical thickness (AOT) agrees with field measurements point-by-point to within 0.05 to 0.1. This is about as well as can be expected given spatial sampling differences; the space-based observations capture AOT trends and variability over an extended region. The field data also validate MISR's ability to distinguish and to map aerosol air masses, from the combination of retrieved constraints on particle size, shape, and single-scattering albedo. For the three study days, the satellite observations (a) highlight regional gradients in the mix of dust and background spherical particles, (b) identify a dust plume most likely part of a density flow, and (c) show an air mass containing a higher proportion of small, spherical particles than the surroundings, that appears to be aerosol pollution transported from several thousand kilometers away.

Kahn, Ralph; Petzold, Andreas; Wendisch, Manfred; Bierwirth, Eike; Dinter, Tilman; Fiebig, Marcus; Schladitz, Alexander; von Hoyningen-Huene, Wolfgang

2008-01-01

225

Desert Dust Aerosol Air Mass Mapping in the Western Sahara, Using Particle Properties Derived from Space-Based Multi-Angle Imaging  

NASA Technical Reports Server (NTRS)

Coincident observations made over the Moroccan desert during the Sahara mineral dust experiment (SAMUM) 2006 field campaign are used both to validate aerosol amount and type retrieved from multi-angle imaging spectroradiometer (MISR) observations, and to place the suborbital aerosol measurements into the satellite s larger regional context. On three moderately dusty days during which coincident observations were made, MISR mid-visible aerosol optical thickness (AOT) agrees with field measurements point-by-point to within 0.05 0.1. This is about as well as can be expected given spatial sampling differences; the space-based observations capture AOT trends and variability over an extended region. The field data also validate MISR s ability to distinguish and to map aerosol air masses, from the combination of retrieved constraints on particle size, shape and single-scattering albedo. For the three study days, the satellite observations (1) highlight regional gradients in the mix of dust and background spherical particles, (2) identify a dust plume most likely part of a density flow and (3) show an aerosol air mass containing a higher proportion of small, spherical particles than the surroundings, that appears to be aerosol pollution transported from several thousand kilometres away.

Kahn, Ralph; Petzold, Andreas; Wendisch, Manfred; Bierwirth, Eike; Dinter, Tilman; Esselborn, Michael; Fiebig, Marcus; Heese, Birgit; Knippertz, Peter; Mueller, Detlef; Schladitz, Alexander; Von Hoyningen-Huene, Wolfgang

2008-01-01

226

Safsaf Oasis, Egypt  

NASA Technical Reports Server (NTRS)

These images show two views of a region of south-central Egypt, each taken by a different type of spaceborne sensor. On the left is an optical image from the Landsat Thematic Mapper, and on the right is a radar image from the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR). This comparison shows that the visible and infrared wavelengths of Landsat are only sensitive to the materials on the surface, while the radar wavelengths of SIR-C/X-SAR can penetrate the thin sand cover in this arid region to reveal details hidden below the surface. Field studies in this area indicate that the L-band radar can penetrate as much as 2 meters (6.5 feet) of very dry sand to image buried rock structures. Ancient drainage channels, shown at the bottom of this image, are filled with sand more than 2 meters (6.5 feet) thick and therefore appear dark because the radar waves cannot penetrate them. Only the most recently active channels are visible in the Landsat scene. Some geologic structures at the surface are visible in both images. However, many buried features, such as rock fractures and the blue circular granite bodies in the upper center of the image on the right, are visible only to the radar. The Safsaf Oasis is located near the bright yellow feature in the lower left center of the Landsat image. Scientists are using the penetrating capabilities of radar imaging in desert areas to study structural geology, mineral exploration, ancient climates, water resources and archaeology. Each image is 30.8 kilometers by 25.6 kilometers (19.1 miles by 15.9 miles) and is centered at 22.7 degrees north latitude, 29.3 degrees east longitude. North is toward the upper right. In the Landsat image, the colors are assigned as follows: red is Band 7 (mid-infrared); green is Band 4 (near infrared); and blue is Band 1 (visible blue light). The colors assigned to the radar frequencies and polarizations are as follows: red is L-band, horizontally transmitted and received; green is C-band, horizontally transmitted and received; and blue is X-band, vertically transmitted and received. The radar image was acquired by the Spaceborne Imaging Radar-C/ X-band Synthetic Aperture Radar (SIR-C/X-SAR) on April 16, 1994, on board the space shuttle Endeavour. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's Earth Science Enterprise. The Landsat Program is managed jointly by NASA, the National Oceanic and Atmospheric Administration and the United States Geological Survey.

Spaceborne Imaging Radar-C and X-Band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes which are caused by nature and those changes which are induced by human activity. SIR-C was developed by NASA's Jet Propulsion Laboratory. X-SAR was developed by the Dornier and Alenia Spazio companies for the German space agency, Deutsche Agentur fuer Raumfahrtangelegenheiten (DARA), and the Italian space agency, Agenzia Spaziale Italiana (ASI), with the Deutsche Forschungsanstalt fuer Luft und Raumfahrt e.v.(DLR), the major partner in science, operations, and data processing of X-SAR.

1998-01-01

227

Egypt's disarmament initiative  

SciTech Connect

On April 16, 1990, President Mubarak of Egypt proposed to the UN that all weapons of mass destruction be prohibited in the Middle East. The proposal arises from a conviction that the very presence of such weapons in the region is a security threat not only to the Middle East but also to international peace and security one which exacerbates an already tenuous and unstable situation. Egypt believes that creating an effective zone would reduce tension and generate impetus to resolving political conflict in the region, because it would exemplify the readiness of all countries to take into account the security concerns of others. Egypt's leaders are well aware that as long as political strife prevails in the Middle East, the obstacles to concrete disarmament measures are daunting. However, the potentially catastrophic consequence of yet another outbreak of hostilities drove them to seize the initiative.

Fahmy, M.N. (United Nations, New York, NY (UN))

1990-11-01

228

Data from a Thick Unsaturated Zone Underlying Two Artificial Recharge Sites along Oro Grande Wash in the Western Part of the Mojave Desert, near Victorville, San Bernardino County, California, 2001-2006  

USGS Publications Warehouse

This report presents data on the physical and hydraulic properties of unsaturated alluvial deposits and on the chemical and isotopic composition of water collected at two recharge sites in the western part of the Mojave Desert, near Victorville, California, from 2001 to 2006. Unsaturated-zone monitoring sites were installed adjacent to the two recharge ponds using the ODEX air-hammer and air rotary method to depths of about 460 feet and 269 feet below land surface. Each of the two unsaturated-zone monitoring sites included a water-table well, matric-potential sensors, and suction-cup lysimeters installed in a single bore hole. Drilling procedures, lithologic and geophysical data, and site construction and instrumentation are described. Core material was analyzed for water content, bulk density, water potential, particle size, and water retention. The chemical composition of leachate from almost 400 samples of cores and cuttings was determined. Water from suction-cup lysimeters also was analyzed for chemical and isotopic composition. In addition, data on the chemical and isotopic composition of groundwater from the two water-table wells are reported along with chemical and isotopic composition of the surface water in the recharge ponds.

Clark, Dennis A.; Izbicki, John A.; Johnson, Russell D.; Land, Michael T.

2009-01-01

229

Astronomy at Nabta Playa, Southern Egypt  

NASA Astrophysics Data System (ADS)

Nabta Playa may contain the oldest human-made features with astronomical alignments in Egypt. In the Late and Terminal Neolithic (7,500-5,400 BP), nomadic pastoralists built a ceremonial center on the western shore of Nabta Playa, consisting of some 30 complex megalithic structures, stone circles, and lines of megaliths crossing the playa. The megaliths may once have aligned with Arcturus, the Belt of Orion, Sirius, and ? Cen. Reorientations of the northern set of megaliths suggest a response to precession. Elaborate burials at the nearby cemetery at Gebel Ramlah indicate the nomads consisted of Mediterranean and sub-Saharan populations with little social stratification.

McKim Malville, J.

230

Amphibian Declines and Environmental Change in the Eastern Mojave Desert  

Microsoft Academic Search

Eight amphibian taxa historically inhabited sparsely distributed wetlands in the Mojave Desert of western North America, habitats that have been dramatically altered or eliminated as a result of human activities. Changes in the distributions of these and two introduced amphibians, and associated environmental changes, are evaluated herein for an approximately 20,000 km2 area in the eastern Mojave Desert. Striking changes

David F. Bradford

231

Desert USA: Desert Animals And Wildlife  

NSDL National Science Digital Library

It is a miracle that life can survive in the extreme conditions of the desert. Users can learn about mammals (including wolves), insects and spiders, fish and birds(including hawks), and reptiles and amphibians (including rattlesnakes) that have adapted and, in fact, thrive in the harsh desert ecosystems. Links to related topics such as animal survival in the desert and animal rescues are included.

2000-01-01

232

Recent environmental change and prehistoric human activity in Egypt and Northern Sudan  

NASA Astrophysics Data System (ADS)

This paper reviews the various Late Quaternary records that are available from western Egypt and northern Sudan, which includes more than 500 published radiocarbon dates and various sedimentary archives from local landscape components, including palaeolakes, soils, drainages (wadis), and archaeological sites. This palaeoenvironmental compilation frames the spatial and temporal context of local cultural activities when the region was most hospitable ˜9000-6000 BP; at this time, monsoonal weather influenced the portion of the African continental interior, creating enough convective rainfall for occasional surface water storage. In this part of the modern Sahara, rapid hydroclimatic changes play a key role in geomorphic evolution and resource availability. As 'watering holes' formed and dried up in the Early to Middle Holocene, Neolithic people developed various subsistence strategies, including opportunistic hunting of small animals (e.g. gazelle and hare), and food-related (e.g. wild sorghum, millet, and legumes) activities: gathering, plant cultivation and livestock-rearing. During its wettest phases during the 'monsoonal maximum,' the area was drought-prone, sustaining a meager steppe-shrub desert flora. Further desertification and aeolian deflation during the Middle and Late Holocene fostered technological innovation, migration and settlement, as well as the further development of agrarian communities and complex culture.

Nicoll, Kathleen

2004-03-01

233

The sediments of Wadi Qena (Eastern Desert, Egypt)  

NASA Astrophysics Data System (ADS)

The first deposition of near-shore sandstones on basement rock in the northern Wadi Qena area occurred during Lower Carboniferous times. Paleozoic deposits are overlain by similar sandstones of Cretaceous age with a large but inconspicuous hiatus between them representing erosion and non-deposition. A Cenomanian transgression inundated sandstones in the north as well as basement rock in the south. The Cenomanian and Turonian sea deposited marine and near-shore material in the Wadi Qena area, and only to the south of it were fluviatile beds laid down. The extant Red Sea Hills, at that time, represented a high and formed a peninsula extending in northerly direction into the shelf sea of the Tethys ocean. The sea withdrew in or after Coniacian times and the following erosion removed almost all Coniacian marine deposits. During Campanian times, the sea returned and also flooded the Red Sea Hill peninsula. Phosphoritic marls, at times of unrest, were redeposited as phosphorite sands in the south. Carbonate deposition followed, ending in Maastrichtian times. An erosional phase during the Cretaceous-Tertiary transition removed most of these chalks and limestones from the Wadi Qena area, and Paleocene and Eocene seas deposited limestone and mmarly chalk before a final regression marked the closure of the Tethys ocean.

Bandel, Klaus; Kuss, Jochen; Malchus, Nikolaus

234

Eutrophication Problem in Egypt  

Microsoft Academic Search

\\u000a The coastal area of Egypt on the Mediterranean Sea extends for about 1,200 km. It hosts a number of important residential\\u000a and economic centres, like the cities of Alexandria, Port Said, Damietta, Rosetta, Matruh, and AL-Arish. The coastal strip\\u000a between Alexandria and Matruh hosts tens of tourist villages, which are usually crowded by visitors during summer. Many activities\\u000a are known in

Mohamed M. Dorgham

235

Desert Voices: Southwestern Children's Literature.  

ERIC Educational Resources Information Center

Examines three books with different ways of writing about the desert. Discusses: "Here Is the Southwestern Desert" by Madeline Dunphy, "The Desert Is My Mother" by Pat Mora, and "The Desert Mermaid" by Alberto Blanco. (PA)

Polette, Keith

1997-01-01

236

Where Deserts Form  

NSDL National Science Digital Library

Most of Earth's deserts can be found in dry areas created by global circulation patterns. The deserts of our world are not restricted by latitude, longitude, or elevation. This site, produced by the U.S. Geological Survey, uses text and pictures to describe how atmospheric circulation patterns influence the locations of deserts on Earth and possibly on other terrestrial planets as well.

237

ECOLOGY OF DESERT SYSTEMS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Conventional wisdom considers deserts stark, harsh regions that support few living things. Most people also believe that water alone makes the desert bloom. Ecology of Desert Systems challenges these conventional views. This volume explores a broad range of topics of interest to ecosystem, popula...

238

Nubian Complex strategies in the Egyptian high desert.  

PubMed

Systematic survey by the Abydos Survey for Paleolithic Sites project has recorded Nubian Complex artifact density, distribution, typology, and technology across the high desert landscape west of the Nile Valley in Middle Egypt. Our work contrasts with previous investigations of Nubian Complex settlement systems in Egypt, which focused on a small number of sites in the terraces of the Nile Valley, the desert oases, and the Red Sea Mountains. Earlier research interpreted the Nubian Complex, in particular, as a radiating settlement system that incorporated a specialized point production. Our high desert data, however, indicate that the Nubian Complex associated with early modern humans in this region of the high desert reflects a circulating, rather than a radiating, settlement system, and that point production has been over-emphasized. Data available from our work, as well as sites investigated by others, do not conclusively identify Nubian Complex behavioral strategies as modern. These data, however, do contribute to the understanding of landscape use by early modern human populations living along the Nile Valley Corridor route out of Africa. PMID:20659756

Olszewski, Deborah I; Dibble, Harold L; McPherron, Shannon P; Schurmans, Utsav A; Chiotti, Laurent; Smith, Jennifer R

2010-08-01

239

The status of agricultural lands in Egypt: The use of multitemporal NDVI features derived from landsat TM  

Microsoft Academic Search

Agricultural production in Egypt is limited by soil salinity and by the encroachment of urban settlements onto previously cultivated lands. In contrast, reclamation efforts in the desert and coastal areas increase the amount of land cultivated. In this study, field-calibrated, multi-temporal NDVI features derived from 10 Landsat TM images dating from 1984 to 1993 were used to assess the status

Mary Pax Lenney; Curtis E. Woodcock; John B. Collins; Hassan Hamdi

1996-01-01

240

Hydrological and climatic changes in deserts of China since the late Pleistocene  

Microsoft Academic Search

Large areas in western China were wetlands or less arid between 40 and 30 ka, corresponding to the “Greatest Lake Period” on the adjacent Tibetan Plateau. During the last glacial maximum, some of these western Chinese deserts again experienced wetter conditions; however, at the same time the sandy lands in the eastern Chinese desert belt experienced an activation of aeolian

Xiaoping Yang; Louis A. Scuderi

2010-01-01

241

New Paleocene Sepiid Coleoids (Cephalopoda) from Egypt: Evolutionary Significance and Origin of the Sepiid ‘Rostrum’  

PubMed Central

New coleoid cephalopods, assignable to the order Sepiida, are recorded from the Selandian/Thanetian boundary interval (Middle to Upper Paleocene transition, c. 59.2 Ma) along the southeastern margin (Toshka Lakes) of the Western Desert in Egypt. The two genera recognised, Aegyptosaepia n. gen. and ?Anomalosaepia Weaver and Ciampaglio, are placed in the families Belosaepiidae and ?Anomalosaepiidae, respectively. They constitute the oldest record to date of sepiids with a ‘rostrum-like’ prong. In addition, a third, generically and specifically indeterminate coleoid is represented by a single rostrum-like find. The taxonomic assignment of the material is based on apical parts (as preserved), i.e., guard, apical prong (or ‘rostrum-like’ structure), phragmocone and (remains of) protoconch, plus shell mineralogy. We here confirm the shell of early sepiids to have been bimineralic, i.e., composed of both calcite and aragonite. Aegyptosaepia lugeri n. gen., n. sp. reveals some similarities to later species of Belosaepia, in particular the possession of a distinct prong. General features of the phragmocone and protoconch of the new form are similar to both Belocurta (Middle Danian [Lower Paleocene]) and Belosaepia (Eocene). However, breviconic coiling and the presence of a longer ventral conotheca indicate closer ties with late Maastrichtian–Middle Danian Ceratisepia. In this respect, Aegyptosaepia n. gen. constitutes a link between Ceratisepia and the Eocene Belosaepia. The occurrence of the new genus near the Selandian/Thanetian boundary suggests an earlier origin of belosaepiids, during the early to Middle Paleocene. These earliest known belosaepiids may have originated in the Tethyan Realm. From northeast Africa, they subsequently spread to western India, the Arabian Plate and, probably via the Mediterranean region, to Europe and North America. PMID:24348918

Koš?ák, Martin; Jagt, John W. M.; Speijer, Robert P.; Stassen, Peter; Steurbaut, Etienne

2013-01-01

242

[Sexuality in Ancient Egypt].  

PubMed

The present article explores the sexuality in ancient Egypt. In particular in this article are presented the ways of concubinage (marriage, concubinage, adultery), the incest, loves of the pharaohs and of the common people, the freedom of choice in garments, the status of the hetairas and of the whores, the sexual perversions (male and female homosexuality, necrophilia, sodomism, bestiality, rape, masturbation, exhibitionism), the operations of the genitals (circumcision, excision, castration) and finally the level of knowledge in gynaecology, fertility, contraception and obstetrics that even today demands our admiration. PMID:7858632

Androutsos, G; Marketos, S

1994-10-01

243

Characteristics and functions of semi-desert soils in the Negev (Israel) depending on precipitation, relief and vegetation  

NASA Astrophysics Data System (ADS)

The Negev desert in south western Israel has been the subject of several investigations concerning soil forming processes and matter fluxes in desert soils. In order to investigate the influence of the ‘global change' on semi-desert ecosystems, study sites along a steep rainfall gradient are of great advantage. The study site "Nizzana 69", which is in the focus of this study, lies about 25 km south of the Mediterranean Sea near the border between Israel and Egypt. The area has an annual rainfall of approximately 170 mm * a-1. A catena consisting of six profiles, three under the legume Retama raetam and three in the bare interspace between shrubs was investigated in order to show the impact of this perennial plant and the relief on soil properties. The results show a strong influence of the shrub due to accumulation of nutrients, carbonates and soluble salts, which were precipitated with dust and rainfall, or which derive from mineralisation of plant litter. The interspace between the plants is covered by a biological soil crust, which also strongly influences the matter fluxes by creating runoff, nitrogen-fixation and stabilizing the soil surface and protecting it against deflation. The distribution of salts and carbonates in the profiles indicate leaching processes. All soils of the study site "Nizzana 69" are weekly developed Arenosols without horizons of carbonate or salt enrichment to a depth of 1 m. The comparison with other areas along the rainfall gradient shows higher inputs of soluble salts with increasing precipitation due to wet deposition, while carbonate contents increase with decreasing precipitation due to deposition of dust, which was generated in the lime stone Negev. On the other hand leaching of soluble soil constituents decreases and accumulation in the upper soil horizon increases with decreasing annual precipitation. Furthermore the importance of local relief aspects for plant growth decreases with increasing rainfall.

Felde, V.; Drahorad, S.; Felix-Henningsen, P.

2009-04-01

244

Forage production from three grass species under saline irrigation in Egypt  

Microsoft Academic Search

Various approaches have been taken to the treatment of salt-affected land. Use of halophytic plants for forage production on salt-affected soil was suggested and has been called saline agriculture. In Egypt about 96% of the land is desert, where the soil is sandy and most of the available ground-water is too saline to raise and sustain conventional crops.Field trails were

N. I. Ashour; M. S. Serag; A. K. Abd El-Haleem; B. B. Mekki

1997-01-01

245

Why Are Deserts Dry?  

NSDL National Science Digital Library

The deserts of the world today are not the deserts of the planet's past. Fossilized hippopotamus and elephant bones tell us that the Sahara, for instance, was a much moister and more hospitable environment 8,000 years ago than it is now. Each of the Earth's modern deserts are a consequence of one of the following mechanisms: air mass subsidence, rain shadows, distant moisture sources, or cold offshore temperatures at the sea's surface. This site uses text and scientific illustrations to describe how each of these mechanisms results in the occurrence of deserts.

246

Desert Water Keepers  

NSDL National Science Digital Library

In this outdoor, sunny day activity, learners experiment with paper leaf models to discover how some desert plants conserve water. Learners explore adaptations of various desert plants such as waxy coatings, thick stems, and spines and fine hairs to see which characteristics best help a plant hold water. Learners compare their model leaves to real desert leaves if they are available. Even in a nondesert region, the activity can be done at a local botanical garden that may include a desert plant collection or in any hot, dry area.

Lawrence Hall of Science

1980-01-01

247

Female desert bighorn sheep in the Sonora desert  

NSDL National Science Digital Library

Desert bighorn sheep use a lot of energy to regulate their internal temperature in the desert. During the summer the sheep eat plants and drink water every few days. In the winter, desert plants contain enough water for sheep survival.

Katie Hale (California State University, Fullerton; Student, Biological Sciences)

2007-01-13

248

Auditors and IT Support in Egypt Mohamed A. Wahdan, Faculty of Commerce, Menoufia University, Egypt  

E-print Network

and IT Support in Egypt Mohamed A. Wahdan, Faculty of Commerce, Menoufia University, Egypt Pieter Spronck, MICC ____________________________________________________________________________________ The paper aims at establishing the present status of the auditing profession in Egypt. The research framework in Egypt and to investigate the challenges and the possibilities of support by information

Spronck, Pieter

249

Reclaiming freshwater sustainability in the Cadillac Desert  

PubMed Central

Increasing human appropriation of freshwater resources presents a tangible limit to the sustainability of cities, agriculture, and ecosystems in the western United States. Marc Reisner tackles this theme in his 1986 classic Cadillac Desert: The American West and Its Disappearing Water. Reisner's analysis paints a portrait of region-wide hydrologic dysfunction in the western United States, suggesting that the storage capacity of reservoirs will be impaired by sediment infilling, croplands will be rendered infertile by salt, and water scarcity will pit growing desert cities against agribusiness in the face of dwindling water resources. Here we evaluate these claims using the best available data and scientific tools. Our analysis provides strong scientific support for many of Reisner's claims, except the notion that reservoir storage is imminently threatened by sediment. More broadly, we estimate that the equivalent of nearly 76% of streamflow in the Cadillac Desert region is currently appropriated by humans, and this figure could rise to nearly 86% under a doubling of the region's population. Thus, Reisner's incisive journalism led him to the same conclusions as those rendered by copious data, modern scientific tools, and the application of a more genuine scientific method. We close with a prospectus for reclaiming freshwater sustainability in the Cadillac Desert, including a suite of recommendations for reducing region-wide human appropriation of streamflow to a target level of 60%. PMID:21149727

Sabo, John L.; Sinha, Tushar; Bowling, Laura C.; Schoups, Gerrit H. W.; Wallender, Wesley W.; Campana, Michael E.; Cherkauer, Keith A.; Fuller, Pam L.; Graf, William L.; Hopmans, Jan W.; Kominoski, John S.; Taylor, Carissa; Trimble, Stanley W.; Webb, Robert H.; Wohl, Ellen E.

2010-01-01

250

Deserts and Wind  

NSDL National Science Digital Library

This site contains 20 questions on the topic of deserts and wind, which covers dunes, desert location and formation, and particle transportation. This is part of the Principles of Earth Science course at the University of South Dakota. Users submit their answers and are provided immediate feedback.

Timothy Heaton

251

Climate Change and the Fate of Desert Springs  

NASA Astrophysics Data System (ADS)

Springs are integral components of the unique web of life in desert ecosystems of the western United States. Many desert springs would not exist without local mountains to intercept and store water from rainfall and snowmelt, and many desert aquatic ecosystems would not exist without the springs, illustrating the connectivity between landscape processes (the realm of geoscientists) and ecosystem functioning (the realm of ecologists). On a human scale, early exploration, inhabitation, and survival in the arid and semiarid western United States would not have been feasible without springs. People living there today continue to value springs as dependable sources of water for irrigation, livestock, drinking, and recreational and economic uses (e.g., hot springs). Unfortunately, some desert springs may be less resistant to the effects of climate change than others. How can this resistance be quantified?

Frisbee, Marty D.; Wilson, John L.; Sada, Donald W.

2013-04-01

252

What's It Like Where You Live? Desert  

NSDL National Science Digital Library

This site provides excellent background information on deserts. Large print and superb pictures make this site very appealing to younger students. Topics include: What is a Desert Like?, Types of Deserts, What causes Deserts?, Deserts of the World, Desert Plants, Desert Animals, and links to other desert sites.

2002-01-01

253

February 2, 2011 Egypt's Next Steps  

E-print Network

1 February 2, 2011 Egypt's Next Steps By AHMED ZEWAIL CAIRO -- The revolt that has erupted across Egypt is in many ways historic and should take the nation into a hopeful future. What's unexpected, even, with no religious or ideological agenda other than a better future for Egypt and its people. In this difficult time

Zewail, Ahmed

254

Seroprevalence of Mycoplasma agassizii and tortoise herpesvirus in captive desert tortoises ( Gopherus agassizii) from the Greater Barstow Area, Mojave Desert, California  

Microsoft Academic Search

Upper respiratory tract disease (URTD) has been implicated as a cause of decline of wild populations of desert tortoises, Gopherus agassizii, in the western Mojave Desert. One explanation for outbreaks of disease may be the release or escape of diseased captive tortoises into naïve wild populations. Because Mycoplasma agassizii and tortoise herpesvirus have surfaced as important pathogens, 179 captive tortoises

A. J. Johnson; D. J. Morafka; E. R. Jacobson

2006-01-01

255

A Desert Adventure  

NSDL National Science Digital Library

I hope you\\'re wearing either sunscreen or a winter coat and brought plenty of water with you, because we\\'re about to begin an adventure in the desert! I\\'ll bet you\\'re thinking that a desert is hot with lots of sand, but did you know that it can even snow in some deserts? In this adventure you\\'ll be learning more interesting facts about deserts and especially about the animals that live there. You will be tracking a desert animal on your journey and following its path. What does it do to survive in the environment of the desert? But be careful! Some of these animals can be dangerous... And most important, remember to HAVE FUN! TASK: After a day of following in the footsteps (or tracks) of your animal, you will be able to present the information to the other desert researchers in our class (thats everybody) and give them hints on the best ways to survive according to your animal. ...

Ms. C. Christensen

2005-10-25

256

What Is A Desert?  

NSDL National Science Digital Library

Approximately one-third of the Earth's land surface is desert, arid land with meager rainfall that supports only sparse vegetation and a limited population of people and animals. Deserts are also fragile environments. The misuse of these lands is a serious and growing problem in parts of our world. This web page, produced by the U.S. Geological Survey, describes how deserts are defined and classified. It features text, photographs, and a map showing the distribution of non-polar arid land.

257

Negev: Land, Water, and Life in a Desert Environment  

NASA Astrophysics Data System (ADS)

In view of the continuing increased concern about the extreme fragility of deserts and desert margins, Negev provides a timely discussion of land-use practices compatible with the often conflicting goals of preservation and development. The success o f agricultural and hydrologic experiments in the Negev desert of Israel offers hope to the large percentage of the world's population that lives with an unacceptably low quality of life in desert margins. Deserts are the one remaining type of open space that, with proper use, has the potential for alleviating the misery often associated with expanding population.In addition to the science in the book, the author repeatedly reinforces the concept that “western civilization is inextricably bound to the Negev and its environs, from which it has drawn, via its desert-born religions—Judasium, Christianity, and Islam—many of the mores and concepts, and much of the imagery and love of the desert, including man's relation to nature and to ‘God’.” Deserts often are erroneously perceived to be areas of no water: In reality, these are areas in which a little rainfall occurs sporadically and unpredictably over time. This meager water supply can be meticulously garnered to produce nutritious crops and forage.

Back, William

258

The Desert Blooms!  

NSDL National Science Digital Library

This activity attempts to clear up the common misconception that deserts are always hot, totally dry, and uninhabitable. Learners listen to poetry and use picture books and other resources to discover that the desert is actually full of life! Learners develop group and individual poems. This activity is featured on pp.27-29 of the "One With the Earth: Native Americans and the Natural World" multidisciplinary unit of study for kindergarten through third grade.

The Children's Museum of Indianapolis

2014-04-30

259

The effect of drought on four plant communities in the northern Mojave Desert  

SciTech Connect

Desert plant communities contain many perennial plant species that are well adapted to arid environments; therefore, one would intuitively believe that perennial desert species readily survive drought conditions. Abundant research on plant-soil-water relationships in North American deserts has shown that many species can maintain water uptake and growth when the soil-water potential is low. Little research, however, has focused on how prolonged drought conditions affect plant species in vegetation associations in desert ecosystems. A prolonged and widespread drought occurred in much of the western United States, including the Northern Mojave Desert, from 1987 through 1991. During this drought period vegetation characterization studies, initiated in 1990, by the US Department of Energy (DOE) at Yucca Mountain, Nevada, allowed EG and G Energy Measurements to collect data that could be used to infer how both desert vegetation associations and desert plant species reacted to a prolonged drought. This paper presents the preliminary results.

Schultz, B.W. [Desert Research Inst., Reno, NV (United States); Ostler, W.K. [EG and G Energy Measurements, Inc., Las Vegas, NV (United States)

1993-12-31

260

Annualization of Rodent Burrow Clusters and Winterfat Decline in a Salt-Desert Community  

Microsoft Academic Search

Winterfat (Ceratoides lanata) is dominant or codomi- nant on much of the 16 million ha of salt-desert shrublands of Western North America. This species is in decline in much of the Great Basin and has been so for 20+ years at the Desert Experi- mental Range (DER), Pine Valley, UT. Previously, winterfat dominanted vegetation on rodent burrow clusters (RBCs), land-

Stanley G. Kitchen; Gary L. Jorgensen

261

The use of multifrequency and polarimetric SIR-C/X-SAR data in geologic studies of Bir Safsaf, Egypt  

USGS Publications Warehouse

Bir Safsaf, within the hyperarid 'core' of the Sahara in the Western Desert of Egypt, was recognized following the SIR-A and SIR-B missions in the 1980s as one of the key localities in northeast Africa, where penetration of dry sand by radar signals delineates previously unknown, sand-buried paleodrainage valleys ('radar-rivers') of middle Tertiary to Quaternary age. The Bir Safsaf area was targeted as a focal point for further research in sand penetration and geologic mapping using the multifrequency and polarimetric SIR-C/X-SAR sensors. Analysis of the SIR-C/X-SAR data from Bir Safsaf provides important new information on the roles of multiple SAR frequency and polarimetry in portraying specific types of geologic units, materials, and structures mostly hidden from view on the ground and on Landsat TM images by a relatively thin, but extensive blanket of blow sand. Basement rock units (granitoids and gneisses) and the fractures associated with them at Bir Safsaf are shown here for the first time to be clearly delineated using C- and L-band SAR images. The detectability of most geologic features is dependent primarily on radar frequency, as shown for wind erosion patterns in bedrock at X-band (3 cm wavelength), and for geologic units and sand and clay-filled fractures in weathered crystal-line basement rocks at C-band (6 cm) and L-band (24 cm). By contrast, Quaternary paleodrainage channels are detectable at all three radar frequencies owing, among other things, to an usually thin cover of blow sand. The SIR-C/X-SAR data investigated to date enable us to make specific recommendations about the utility of certain radar sensor configurations for geologic and paleoenvironmental reconnaissance in desert regions.Analysis of the shuttle imaging radar-C/X-synthetic aperture radar (SIR-C/X-SAR) data from Bir Safsaf provides important new information on the roles of multiple SAR frequency and polarimetry in portraying specific types of geologic units, materials, and structures mostly hidden from view on the ground and on Landsat images by a relatively thin, but extensive blanket of blow sand. Basement rock units and associated fractures at the Bir Safsaf are clearly delineated using C- and L-band SAR images. The detectability of most geologic features depend primarily on radar frequency. The SIR-C/X-SAR data also provide recommendations about the utility of certain radar configurations for geologic and paleoenvironmental reconnaissance in deserts.

Schaber, G.G.; McCauley, J.F.; Breed, C.S.

1997-01-01

262

Sonoran Desert: Fragile Land of Extremes  

USGS Publications Warehouse

'Sonoran Desert: Fragile Land of Extremes' shows how biologists with the U.S. Geological Survey work with other scientists in an effort to better understand native plants and animals such as desert tortoises, saguaro cacti, and Gila monsters. Much of the program was shot in and around Saguaro National Park near Tucson, Arizona. Genetic detective work, using DNA, focuses on understanding the lives of tortoises. Studies of saguaros over many decades clarify how these amazing plants reproduce and thrive in the desert. Threats from fire, diseases in tortoises, and a growing human population motivate the scientists. Their work to identify how these organisms live and survive is a crucial step for the sound management of biological resources on public lands. This 28-minute program, USGS Open-File Report 03-305, was shot entirely in high definition video and produced by the USGS Western Ecological Research Center and Southwest Biological Science Center; produced and directed by Stephen Wessells, Western Region Office of Communications.

Produced and Directed by Wessells, Stephen

2003-01-01

263

Range and habitats of the desert tortoise  

USGS Publications Warehouse

We determined the current range of the desert tortoise (Gopherus agassizii) based on the available latest data from government agencies, the literature, and our experience. We developed the first detailed range map of this species and summarized information about habitat preferences. New records of occurrences were incorporated, and some peripheral localities of questionable authenticity were deleted. The distribution oCG. agassizii covers the broadest range of latitude, climatic regimes, habitats, and biotic regions of any North American tortoise. The northern portion ofits range is in the Mojave Desert of sDuth"eastern California, southern Nevada, southwestern Utah, and northwestern Arizona. The central portion of the range consists of several subdivisions of the Sonaran Desert in southeastern California, western and southern Arizona, and western Sonora, Mexico. The southern edge of its range is in the semitropical Sinaloan thornscrub and Sinaloan deciduous forest of eastern Sonora and northern Sinaloa, Mexico. This species has marked geogi-aphic differences but seems to construct burrows throughout its range.

Germano, D.J.; Bury, R.B.; Esque, T.C.; Fritts, T.H.

1994-01-01

264

Constitutionalist Contention in Contemporary Egypt  

Microsoft Academic Search

This article tackles the problem of political—institutional change in undemocratic regimes commonly considered impervious to meaningful political contention. Egypt is one of the contemporary world's most stolid authoritarian regimes, a superpresidential system in which all effective power resides in the executive. It has been governed by uninterrupted emergency law since 1981 and since 1992 has experienced a further process of

Mona El-Ghobashy

2008-01-01

265

DISTRIBUTIONAL CHANGES AND POPULATION STATUS FOR AMPHIBIANS IN THE EASTERN MOJAVE DESERT  

EPA Science Inventory

A number of amphibian species historically inhabited sparsely distributed wetlands in the Mojave Desert of western North America, habitats that have been dramatically altered or eliminated as a result of human activities. The population status and distributional changes for amphi...

266

Using Generic and Pesticide DRASTIC GIS-based models for vulnerability assessment of the Quaternary aquifer at Sohag, Egypt  

Microsoft Academic Search

Groundwater resources in the Sohag area, Egypt are currently threatened by contamination from municipal and industrial activities,\\u000a and agricultural pesticides. To cope with the growing population, there has been development in the desert zone on both sides\\u000a of the Nile Valley including agricultural investment areas, wastewater disposal sites, new urban areas, and industry. Use\\u000a of agrochemicals in the old cultivated

Ayman A. Ahmed

2009-01-01

267

The Desert Environment January 26, 1999 1 The Desert Environment  

E-print Network

The Desert Environment January 26, 1999 1 The Desert Environment Revised Paper Steven P. Reiss1@cs.brown.edu Abstract The Desert software engineering environment is a suite of tools developed to enhance pro- grammer virtual files on demand to address specific tasks. All this is done in an open and extensible environment

Reiss, Steven P.

268

ASTER View of Sharm El Sheik, Egypt  

NASA Technical Reports Server (NTRS)

The Red Sea golf resort in Sharm El Sheik, Egypt, where President Clinton met with Israeli Prime Minister Ehud Barak and Palestinian Authority President Yasser Arafat, stands out against the desert landscape in this image acquired on August 25, 2000.

This image of the southern tip of the Sinai Peninsula shows an area about 30 by 40 kilometers (19 by 25 miles) in the visible and near infrared wavelength region. Vegetation appears in red. The blue areas in the water at the top and bottom of the image are coral reefs. The airport is visible just to the north of the golf resort.

Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, Calif., is the U.S. Science team leader; Moshe Pniel of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The primary goal of the ASTER mission is to obtain high-resolution image data in 14 channels over the entire land surface, as well as black and white stereo images. With revisit time of between 4 and 16 days, ASTER will provide the capability for repeat coverage of changing areas on Earth's surface.

The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical information for surface mapping, and monitoring dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats, monitoring potentially active volcanoes, identifying crop stress, determining cloud morphology and physical properties, wetlands Evaluation, thermal pollution monitoring, coral reef degradation, surface temperature mapping of soils and geology, and measuring surface heat balance.

2000-01-01

269

EVOLUTION AFTER THE FLOOD: PHYLOGEOGRAPHY OF THE DESERT FISH  

Microsoft Academic Search

The Bonneville Basin and upper Snake River drainage of western North America underwent extensive hydrological changes during the late Pleistocene, potentially influencing the geographic distribution and evolutionary trajectories of aquatic species that occupied this region. To test this hypothesis, I reconstructed the phylogeographic history of the desert fish Utah chub (Gila atraria) by examining 16 populations that span the natural

JERALD B. JOHNSON

270

Successional trajectories of a grazed salt desert shrubland  

Microsoft Academic Search

Successional trajectories through the statistical space of ordinations were used to examine response to grazing in salt desert shrub communities of western Utah, USA. Relative cover data were periodically collected over a 53 year period from grazing exclosures and pastures grazed with light or heavy stocking rates in fall or spring (4 grazing treatments). Two-way indicator species analysis was used

S. G. Whisenant; F. J. Wagstaff

1991-01-01

271

Andean uplift and Neogene climate change in the Atacama Desert  

Microsoft Academic Search

Today the Andean Cordillera and Altiplano provide a major obstacle to atmospheric circulation over South America. The Altiplano Plateau prevents moist air masses from the Amazon Basin from reaching the Atacama Desert, causing the Atacama to be one of the driest places on Earth. Although Neogene sedimentary records from the western flank of the Andes should record the dramatic shift

J. A. Rech; B. S. Currie; T. E. Jordan

2006-01-01

272

Phylogeographic diversification of antelope squirrels (Ammospermophilus) across North American deserts  

E-print Network

4 Department of Biology & Burke Museum of Natural History and Culture, University of Washington, Box Ammospermophilus, which are widely distributed across the deserts and other arid lands of western North America. We set to infer phylogenetic relationships. We then estimated divergence times within identified clades

273

The application of petrophysics to resolve fluid flow units and reservoir quality in the Upper Cretaceous Formations: Abu Sennan oil field, Egypt  

NASA Astrophysics Data System (ADS)

Petrophysical flow unit concept can be used to resolve some of the key challenges faced in the characterization of hydrocarbon reservoirs. The present study deals with petrophysical evaluation of some physical properties of the Upper Cretaceous rock samples obtained from the Abu-Roash and the Bahariya Formations at southwest of Sennan oil field in the Western Desert of Egypt. The aim of this study was achieved through carrying out some petrophysical measurements of porosity, bulk density, permeability, mean hydraulic radius (Rh), irreducible water saturation, and radius of pore throat at mercury saturation of 35% in order to determine reservoir characteristics. In this study, the relationships obtained between the measured petrophysical properties such as porosity, permeability and pore throat flow unit types were established for 53 sandstone core samples obtained from two different stratigraphic units. Flow zone indicator (FZI) has been calculated to quantify the flow character of the Abu-Roash and Bahariya reservoir rocks based on empirically derived equations of robust correlation coefficients. The correlations among porosity, permeability, bulk density, mean hydraulic radius and pore throat flow properties reflect the most important reservoir behavior characteristics. The calculated multiple regression models indicate close correlation among petrophysical properties and Rh and R35%. The obtained models are able to predict Rh and R35% by using porosity and permeability, to map reservoir performance and predict the location of stratigraphic traps.

Lala, Amir Maher Sayed; El-sayed, Nahla Abd El-Aziz

2015-02-01

274

Spatially variable sedimentary responses to orbitally driven pluvial climate during Marine Oxygen Isotope Stage 5.1, Dakhla Oasis region, Egypt  

NASA Astrophysics Data System (ADS)

Pleistocene basinal sediments (PBS) in the Dakhla region of Egypt's hyperarid Western Desert comprise four facies: (A) fluvio-lacustrine, (B) mixed lacustrine/pluvio-eolian, (C) pluvio-eolian, and (D) mixed eolian/pluvio-eolian. Contiguity of basins containing each facies, and their stratigraphic position between two bajada gravel formations, P/B-II and P/B-III, confirm their equivalence. Facies A and B, with lacustrine components, are attributed to orbitally forced poleward incursion of the Intertropical Convergence Zone (ITCZ), resulting in increased summer insolation/temperature/precipitation. Facies C and D, comprising pluvio-eolian and eolian sediments, reflect geologic/topographic influences overprinted on regional 'pluvial' conditions, eliminating lacustrine response. A Th/U age of ˜ 62 ka on lacustrine marl within Facies B is minimal, and an OSL age of 110 ± 18 ka on sediments immediately below Facies B is maximal. Since bajada gravels P/B-III are the youngest Pleistocene formation, they must represent the final strong incursion of the ITCZ into the Dakhla region at MIS 5.1, ˜ 80 ka. Because PBS Facies A pass rapidly up into P/B-III bajada gravels, PBS are assigned to the rising limb of the MIS 5.1 insolation/temperature/precipitation curve, slightly younger than 80 ka.

Brookes, Ian A.

2010-09-01

275

Analysis of groundwater flow in arid areas with limited hydrogeological data using the Grey Model: a case study of the Nubian Sandstone, Kharga Oasis, Egypt  

NASA Astrophysics Data System (ADS)

Management of groundwater resources can be enhanced by using numerical models to improve development strategies. However, the lack of basic data often limits the implementation of these models. The Kharga Oasis in the western desert of Egypt is an arid area that mainly depends on groundwater from the Nubian Sandstone Aquifer System (NSAS), for which the hydrogeological data needed for groundwater simulation are lacking, thereby introducing a problem for model calibration and validation. The Grey Model (GM) was adopted to analyze groundwater flow. This model combines a finite element method (FEM) with a linear regression model to try to obtain the best-fit piezometric-level trends compared to observations. The GM simulation results clearly show that the future water table in the northeastern part of the study area will face a severe drawdown compared with that in the southwestern part and that the hydraulic head difference between these parts will reach 140 m by 2060. Given the uncertainty and limitation of available data, the GM produced more realistic results compared with those obtained from a FEM alone. The GM could be applied to other cases with similar data limitations.

Mahmod, Wael Elham; Watanabe, Kunio; Zahr-Eldeen, Ashraf A.

2013-08-01

276

Environmental Processes and Spectral Reflectance Characteristics Associated with Soil Erosion in Desert Fringe Regions  

NASA Technical Reports Server (NTRS)

Results of analysis of spectral variation of sand dunes in El Ghorabi, Bahariya, Egypt; Tombouctou/Azaouad, Mali; and Tsodilo Hills, western Botswana are presented. Seasonal variations in dune extent and location of dune crests and their relationship to such factors as wind and weather variations are emphasized.

Jacobberger, P. A.

1987-01-01

277

Optical characteristics of desert dust as used in LOWTRAN: Mojave desert dust versus the LOWTRAN 7 dust model  

Microsoft Academic Search

As previously reported aerosol size and composition and meteorological data were collected at three sites (Tehachapi Pass and Rogers and China Lake dry lake beds) in the western Mojave Desert in the summer of 1990. Aerosol size distributions exhibit the usual accumulation and wind speed dependent dust modes. The dust mode aerosols are illite clay. Their composition is wind speed

Philip L. Walker; Larry A. Mathews

1995-01-01

278

Palynology and Stratigraphy of the Nubian Sandstone in Libya and Comparison with Egypt  

NASA Astrophysics Data System (ADS)

The so-called "Nubian Sandstone" outcrops along a wide area from Algeria to the Red Sea, forming two regressive phases. The lower phase is represented in Egypt by the Basal Clastic Unit, the Desert Rose Unit, the Abu Ballas Formation and the Matruh Shale. In Libya it is represented by the Mesak Sandstone, Sarir Sandstone, Cabao Sandstone and Kiklah Formation. In both countries, these successions are covered by a carbonate sequence, resulting from the Tethyan transgression during the Cenomanian. In Egypt however, the upper regressive phase is represented by the Taref Sandstone which was deposited during a brief period of active progradation, following the Tethyan incursion. This is not observed in Libya. Comparison of palynological studies in Libya with those documented by several authors in Egypt reveals that the "Nubian" facies in Libya were deposited before equivalent facies in Egypt. The Basal Clastic Unit, dated as Hautrauvian-Barremian, may be equivalent, at least to a part of the Neocomian Cabao Sandstone in NW Libya. Jarmah Member of the Mesak Formation in Libya was dated as Berriasian on the basis of Pilosisporites and Trilobosporites. This makes it older than any "Nubian" unit in Egypt. The Matruh Shale was assigned to the Aptian on the basis of Tricolpites, and the Abu Balls Formation 34 as Aptian-Albian on the basis of Tricolpites and Rousisporites radiatus. Whereas, there is no equivalent to the Aptian in NW Libya, the Aptian-Albian of Egypt is similar to Zone 1 of the Kiklah Formation and As Sarir Sandstone, which were dated as early Albian on the basis of Afropollis spp., and Perotriletes pannuceus, an Albian element not recorded in Egypt. The Plant Beds in southwestern Egypt were dated as Cenomanian on the basis of advanced angiosperm pollen. In Libya, equivalent bodies were considered Vraconian, representing the uppermost Albian, because it lacks Cenomanian pollen (e.g. Tricolpites mutabilis). Comparison of local sea-level changes with global sea-level curves is used to reconstruct paleogeography. Integration of palynology with geological data and tectonic implications indicates that, despite similarity in paleogeographic processes of the Nubian Sandstone, geological and structural settings remain different. The "Nubian Sandstone" provides a typical succession that can be studied in the light of sequence stratigraphy.

Tekbali, Ali; Hlal, Osama

2013-04-01

279

Sounds of the Desert.  

ERIC Educational Resources Information Center

Discusses the program called "Sounds of the Desert" that celebrates the Southwest indigenous culture and focuses on understanding music in relation to history and culture. Emphasizes the study of Mariachi music that is being taught alongside band, orchestra, and chorus from the third grade to senior high in many Tucson (Arizona) schools. (CMK)

McCullough-Brabson, Ellen; Achilles, Elayne; Ashcraft, Joan

1997-01-01

280

Tectonic framework of northeast Egypt and its bearing on hydrocarbon exploration  

SciTech Connect

Detailed structural study of northern and central Sinai, the northern Eastern Desert, and the northern Gulf of Suez clarified the tectonic framework of northeast Egypt. This framework is related to the movements between the African Plate and the Eurasian and Arabian Plates. Late Cretaceous folding and thrusting in response to oblique convergence between the African and Eurasian Plates formed NE-ENE oriented, doubly plunging, en echelon folds of the northern Egypt fold belt. This fold belt is well exposed in northern Sinai and a few other places but is concealed under younger sediments in the other parts of northern Egypt. Younger folding of local importance is related to dextral slip on the Themed Fault (Central Sinai) in post Middle Eocene-pre Miocene time. Early Miocene rifting of the Afro-Arabian Plate led to the opening of the Suez rift and deposition of significant syn-rift facies. Half grabens and tilted fault blocks dominate the rift. Slightly tilted fault blocks characterize the competent Middle Eocene limestones of the Eastern Desert south of the Cairo-Suez road but north of this road, Middle Eocene rocks are locally dragged on nearby E-W and NW-SE oriented faults forming fault-drag folds. Ductile Upper Eocene and Miocene rocks are also folded about gentle NW-SE oriented doubly plunging folds. The different stages of tectonic activity in northern Egypt contributed to the development of different types of structural traps as well as different source, reservoir, and cap rocks. The sedimentary history of the region indicates well developed marine sediments of Jurassic, Cretaceous, Eocene, and Miocene ages. Basin development in structurally low areas provided good sites for hydrocarbon generation and maturation.

Khalil, M. [Gulf of Suez Petroleum Company, Cairo (Egypt); Moustafa, A.R.

1995-08-01

281

Regional geothermal exploration in Egypt  

NASA Technical Reports Server (NTRS)

A study is presented of the evaluation of the potential geothermal resources of Egypt using a thermal gradient/heat flow technique and a groundwater temperature/chemistry technique. Existing oil well bottom-hole temperature data, as well as subsurface temperature measurements in existing boreholes, were employed for the thermal gradient/heat flow investigation before special thermal gradient holes were drilled. The geographic range of the direct subsurface thermal measurements was extended by employing groundwater temperature and chemistry data. Results show the presence of a regional thermal high along the eastern margin of Egypt with a local thermal anomaly in this zone. It is suggested that the sandstones of the Nubian Formation may be a suitable reservoir for geothermal fluids. These findings indicate that temperatures of 150 C or higher may be found in this reservoir in the Gulf of Suez and Red Sea coastal zones where it lies at a depth of 4 km and deeper.

Morgan, P.; Boulos, F. K.; Swanberg, C. A.

1983-01-01

282

Egypt: Social Responsibility Disclosure Practices  

Microsoft Academic Search

This paper offers updated evidence on social disclosure trends in Egypt. It examines whether Egyptian companies care about\\u000a the community as an important stakeholder in their Internet social reporting. In doing so, the paper employs content analysis\\u000a to measure and explore the social responsibility self-disclosure practices of major Egyptian companies in their online annual\\u000a reports and\\/or Websites. The analysis shows

Aly Salama

283

Cataract surgery in ancient Egypt.  

PubMed

Ophthalmology was one of the most important specialties in Egyptian medicine, and more specialists are known in this field than in any other. This specialization seems, however, to have been of a purely noninvasive nature. Even though it has been claimed that cataract surgery was performed in pharaonic Egypt, careful analysis of the sources does not support the claim. No example of cataract surgery or of any other invasive ophthalmologic procedure can be found in the original sources. PMID:24485861

Blomstedt, Patric

2014-03-01

284

Orthopedic surgery in ancient Egypt  

PubMed Central

Background — Ancient Egypt might be considered the cradle of medicine. The modern literature is, however, sometimes rather too enthusiastic regarding the procedures that are attributed an Egyptian origin. I briefly present and analyze the claims regarding orthopedic surgery in Egypt, what was actually done by the Egyptians, and what may have been incorrectly ascribed to them. Methods — I reviewed the original sources and also the modern literature regarding surgery in ancient Egypt, concentrating especially on orthopedic surgery. Results — As is well known, both literary sources and the archaeological/osteological material bear witness to treatment of various fractures. The Egyptian painting, often claimed to depict the reduction of a dislocated shoulder according to Kocher’s method, is, however, open to interpretation. Therapeutic amputations are never depicted or mentioned in the literary sources, while the specimens suggested to demonstrate such amputations are not convincing. Interpretation — The ancient Egyptians certainly treated fractures of various kinds, and with varying degrees of success. Concerning the reductions of dislocated joints and therapeutic amputations, there is no clear evidence for the existence of such procedures. It would, however, be surprising if dislocations were not treated, even though they have not left traces in the surviving sources. Concerning amputations, the general level of Egyptian surgery makes it unlikely that limb amputations were done, even if they may possibly have been performed under extraordinary circumstances. PMID:25140982

Blomstedt, Patric

2014-01-01

285

A study of Desert Dermatoses in the Thar Desert Region  

PubMed Central

Introduction: Desert dermatology describes the cutaneous changes and the diseases affecting those living in the desert. Diurnal variation in temperature is high and is characteristic of the deserts. The lack of water affects daily activities and impacts dermatological conditions. Adaptation to the desert is therefore important to survival. This original article focuses on dermatoses occurring in a population in the Thar desert of India, predominantly located in Rajasthan. Materials and Methods: This is a descriptive study involving various dermatoses seen in patients residing in the Thar desert region over a duration of 3 years. Results: Infections were the most common condition seen among this population and among them fungal infections were the most common. The high incidence of these infections would be accounted for by the poor hygienic conditions due to lack of bathing facilities due to scarcity of water and the consequent sweat retention and overgrowth of cutaneous infective organisms. Pigmentary disorders, photodermatoses, leishmaniasis and skin tumors were found to be more prevalent in this region. Desert sweat dermatitis was another specific condition found to have an increased incidence. Conclusion: The environment of the desert provides for a wide variety of dermatoses that can result in these regions with few of these dermatoses found in much higher incidence than in other regions. The concept of desert dermatology needs to be understood in more details to provide better care to those suffering from desert dermatoses and this article is a step forward in this regard. PMID:25657392

Chatterjee, Manas; Vasudevan, Biju

2015-01-01

286

Benchmarking performance: Environmental impact statements in Egypt  

Microsoft Academic Search

Environmental impact assessment (EIA) was formally introduced in Egypt in 1994. This short paper evaluates “how well” the EIA process is working in practice in Egypt, by reviewing the quality of 45 environmental impact statements (EISs) produced between 2000 and 2007 for a variety of project types. The Lee and Colley review package was used to assess the quality of

El-Sayed A. Badr; Ashraf A. Zahran; Matthew Cashmore

2011-01-01

287

Ideology, politics and sport in Egypt  

Microsoft Academic Search

This paper discusses the status of sport in contemporary Egypt, providing a brief background from Ancient Egypt through its Roman period and Islamic era. The British are credited with the introduction of modern organized sport into Eygpt. With the rise of nationalism and relative affluence of middle-class Egyptians, the number of athletic clubs increased between the two world wars. Nasser's

Hilmi M. Ibrahim; Nahed F. Asker

1984-01-01

288

Egypt: Beyond Pharaohs, Feluccas and Fellahin.  

ERIC Educational Resources Information Center

In a random study of five middle school social studies textbooks available for adoption in the state of Indiana in 1984, great variation in the treatment of Egypt was noted. Coverage of contemporary history was incomplete in all cases. All texts dealt with Egypt's ancient history, but what was reported was questionable. Only one text addressed in…

Holt, Evelyn R.

289

Inclusiveness in Higher Education in Egypt  

ERIC Educational Resources Information Center

In Egypt, before 1952, education, especially higher education, was the province of a privileged few. After the 1952 Revolution, in pursuit of social justice and economic development, Egypt's leaders eliminated fees, instituted a universal admission examination, promised government employment to all graduates of higher education, and expanded the…

Cupito, Emily; Langsten, Ray

2011-01-01

290

Sphinx and Great Pyramid of Giza, Egypt  

USGS Multimedia Gallery

The Spinx and the Great Pyramid of Giza, Egypt are pictured here. USGS and University of Pennsylvania research shows that ancient pollen and charcoal preserved in deeply buried sediments in Egypt's Nile Delta document the region’s ancient droughts and fires, including a huge drought 4,200...

291

Annual variations of desert dust size distribution over Israel.  

NASA Astrophysics Data System (ADS)

The annual variation of the desert dust aerosol loading above the Eatsren Mediterranean is studied. Three periods are identified - March-May, July-August, and September-November - for which the properties of dust particles are distinctly different. The dust layers are at higher altitudes and consist of larger particles in summer and autumn than in spring. The real part of the refractive index of the particles is the same for summer and autumn periods and exceeds the real part of the refractive index measured during the spring. The imaginary part of the refractive index is negligible both in spring and in summer, whereas the imaginary refractive index becomes significant in September-November indicating the presence of absorbing aerosols. The difference is attributed to different sources and desert dust trajectories in these periods. In spring, the desert aerosol from the source in Chad is transported to the Eastern Mediterranean predominantly along the North African coast. This is the motion associated with Sharav cyclones. The aerosols come to the Eastern Mediterranean via Egypt from the sources near the Red Sea in July-August. In autumn, the dust arrives to the Eastern Mediterranean from the Libyan coast.

Israelevich, P. L.; Ganor, E.; Levin, Z.; Joseph, J. H.

2003-04-01

292

Wind modeling of Chihuahuan Desert dust outbreaks  

NASA Astrophysics Data System (ADS)

The Chihuahuan Desert region of North America is a significant source of mineral aerosols in the Western Hemisphere, and Chihuahuan Desert dust storms frequently impact the Paso del Norte (El Paso, USA/Ciudad Juarez, Mexico) metropolitan area. A statistical analysis of HYSPLIT back trajectory residence times evaluated airflow into El Paso on all days and on days with synoptic (non-convective) dust events in 2001-2005. The incremental probability—a measure of the areas most likely to have been traversed by air masses arriving at El Paso during dusty days—was only strongly positively associated with the region west-southwest of the city, a zone of known dust source areas. Focused case studies were made of major dust events on 15 April and 15 December 2003. Trajectories approached the surface and MM5 (NCAR/Penn State Mesoscale Model) wind speeds increased at locations consistent with dust sources observed in satellite imagery on those dates. Back trajectory and model analyses suggested that surface cyclones adjacent to the Chihuahuan Desert were associated with the extreme dust events, consistent with previous studies of dust storms in the Southern High Plains to the northeast. The recognition of these meteorological patterns serves as a forecast aid for prediction of dust events likely to impact the Paso del Norte.

Rivera Rivera, Nancy I.; Gill, Thomas E.; Gebhart, Kristi A.; Hand, Jennifer L.; Bleiweiss, Max P.; Fitzgerald, Rosa M.

293

The Rise of Egypt: New Beginnings or Same Old Story  

E-print Network

The Rise of Egypt: New Beginnings or Same Old Story Monday March 28th - 2011 Course # 846A, Tuition dramatic than the change in government in Egypt. What does this mean for the workers of Egypt in this transition? Will the revolution in Egypt take the path of the failed revolutions in Iran or are we witnessing

Thompson, Michael

294

Deserts of China  

USGS Publications Warehouse

Improving arid land quality requires an understanding of the original state of the land and its relationship to wind, water, and plant regimes, as well as understanding of interactions within the present ecosystem.  Chinese scientists and local residents have made significant advances in improving arid environments in gobi and sandy deserts and in less arid sandy lands.  Wind patterns are being changed by planting forest belts to protect oases and sandy lands, and on a smaller scale by planting grasses and shrubs or constructing straw grids.  Research on reclamation of deserts is now focusing on how sand-fixing plants may be adapted to local environments, and how the resources of grazing land and water may be effectively exploited without being overused.

Walker, Alta S.

1982-01-01

295

Metal and fluid sources in a potential world-class gold deposit: El-Sid mine, Egypt  

NASA Astrophysics Data System (ADS)

Lode gold mineralization at the El-Sid mine area is associated with the ca. 600 Ma Fawakhir granite intrusion, which cuts the ~737 Ma ophiolite nappes in the Central Eastern Desert of Egypt. The mineralized quartz veins are hosted by ~E- and NE-trending fault/fracture sets cutting the western boundary of the intrusion and sheared ophiolites. The results of electron microprobe analyses of gold-associated hydrothermal sulfide and silicate minerals suggest that Au was mobilized alongside Ni, Co, Cr and As from the adjacent ophiolitic serpentinite. After granite emplacement, hydrothermal fluids interacted with the sheared serpentinite, leaching metals and re-depositing them in the faults/fractures and adjacent wall rock in a cyclic process. Low-salinity aqueous-carbonic fluids with significant quantities of volatile species (CO2, CH4, and N2 ± H2S) leached and transported Au from deep to shallow crustal levels. Carbon dioxide had a buffering effect on the Au-bearing hydrothermal solution, maintaining its pH within a narrow near-neutral range, where elevated gold concentration was transported by complexation with reduced magmatic sulfur in a reducing environment. Gold deposition along fault/fracture conduits in the Fawakhir granite and adjacent serpentinite resulted from interplay of pressure drop, fluctuations in oxygen and sulfur fugacities, and exsolution of the volatile phases. Infiltration of meteoric water may have contributed to the formation of the late stage gold-sulfide mineralization that formed at shallower levels during terrane uplift. Sulfidation of the Fe-rich magmatic minerals was, on the other hand, the overriding process in the wall rock as evidenced by abundant disseminated sulfides with gold inclusions. Considering the structural control by regional shear zones (fluid conduits) and the voluminous granitic and ophiolitic rocks (metal sources), a high tonnage gold deposit amenable to open pit mining at the El-Sid mine area is very likely.

Helmy, Hassan; Zoheir, Basem

2014-11-01

296

A Desert Park  

NSDL National Science Digital Library

This National Park Service site describes the desert and oasis ecosystems of Joshua Tree National Park as well as the cultural history of humans occupying the area. Nature sections describe the animals, plants, cryptobiotic crusts, and the geology of the park. There are sections on environmental factors such as air quality, disturbed lands, exotic species and fire ecology. There is also information on natural history and cultural history education programs provided for different grade levels.

297

Cenozoic Climates in Deserts  

Microsoft Academic Search

Deserts are superb repositories of geological, geomorphic and archaeological evidence. The very aridity to which they owe\\u000a their existence has enabled them to preserve a remarkably good record of past depositional and erosional events. The fossil\\u000a river valleys of the Sahara, the great salt lakes of Australia, China, and Patagonia, the dissected volcanic mountains of\\u000a the Arabian peninsula and the

M. A. J. Williams

298

Unchanging Desert Sand Dunes  

NASA Astrophysics Data System (ADS)

Deserts are one of the major landforms on earth. They occupy nearly 20% of the total land area but are relatively less studied. With the rise in human population, desert regions are being gradually occupied for settlement posing a management challenge to the concerned authorities. Unrestrained erosion is generally a feature of bare dunes. Stabilized dunes, on the other hand, do not undergo major changes in textures, and can thus facilitate the growth of vegetation. Keeping in view of the above factors, better mapping and monitoring of deserts and particularly of sand dunes is needed. Mapping dunes using field instruments is very arduous and they generate relatively sparse data. In this communication, we present a method of clustering and monitoring sand dunes through imagery captured by remote sensing sensors. Initially Radon spectrum of an area is obtained by decomposition of the image into various projections sampled at finer angular directions. Statistical features such as mode, entropy and standard deviation of Radon spectrum are used in delineation and clustering of regions with different dune orientations. These clustered boundaries are used to detect if there are any changes occurring in the dune regions. In the experiment's, remote sensing data covering various dune regions of the world are observed for possible changes in dune orientations. In all the cases, it is seen that there are no major changes in desert dune orientations. While these findings have implications for understanding of dune geomorphology and changes occurring in dune directions, they also highlight the importance of a wider study of dunes and their evolution both at regional and global scales. Results for Dataset 1 & Dataset 2 Results for Dataset 3

Gadhiraju, S.; Banerjee, B.; Buddhiraju, K.; Shah, V.

2013-12-01

299

Cathedrals in the Desert  

NSDL National Science Digital Library

The California Museum of Photography at the University of California-Riverside, (last mentioned in the May 30, 2000 Scout Report for Social Sciences) is a site worth visiting again and again; there is always something new to look at in a variety of areas: photography history, California lifestyle and culture, fine art photography, and photo journalism. Jean Ruiter's exhibition, Cathedrals in the Desert, is a show based on "borrowing classic images to offer ironic commentary on the present."

Ruiter, Jean.

300

Deserts and Arid Lands  

NASA Astrophysics Data System (ADS)

The exponential growth of global population and often concomitant degradation of the environment has forced human expansion into the more hostile and less well-known terrains of arid lands and deserts. Drought in the African Sahel, with recent wholesale movement of tribes seeking survival, has focused interest in such regions. However, geologic and geomorphic knowledge of deserts has expanded slowly until the last few decades. For instance, the arid cycle of erosion, as conceived by William Morse Davis (now deceased; formerly, Harvard University, Cambridge, Mass.), with modifications by W. Penck (now deceased; formerly, Leipzig University, Leipzig, German Democratic Republic), and L. C. King (University of Natal and Durban, South Africa), has dominated desert geomorphological deductions until recently. Since World War II and the verification of plate tectonics, the knowledge of arid lands has increased dramatically, especially in synoptic mapping from remote sensing data and space photography, which transcends political boundaries, thanks to the open skies policy of the U.S. space pioneers.

Brown, Glen F.

301

Snow, the Great River, and the Desert  

NASA Astrophysics Data System (ADS)

While many major rivers around the world originate from alpine snowpacks in mountain regions, some experience the extreme contrast of flowing through harsh desert environments downriver. One such stream is the Rio Grande which rises in the San Juan and the Sangre de Christo mountains of southern Colorado and northern New Mexico. Eventually, the snow fed Rio Grande flows through North America's largest desert, the Chihuahuan Desert in New Mexico, Texas, and Mexico, and simultaneously becomes part of the border between the United States and Mexico. As is often true, urban areas develop along the river corridors rather than in more inaccessible mountain regions. This demographic preference tends to isolate the vast majority of population in the Rio Grande, who are dependent on water for their livelihoods, from the mountain snowpacks where the flow is generated. Ironically then, snow is seldom viewed as the source of the much needed water flowing through the desert by the majority of the basin's population. In arid regions of the western U.S., water demand far exceeds the water supply, and water use is apportioned under the doctrine of prior appropriation with the oldest right getting the first use of water. The increasing population in urban areas does not usually have a right to use the water flowing through the desert unless water rights have been purchased by municipalities from the major category of water user in these basins, namely, irrigated agriculture. In the entire Rio Grande basin, irrigation makes up 80% of the consumptive use of water. Additionally, basin compacts and international treaties apportion water between states and countries. Because these formal agreements were based on above average runoff years, there is little flexibility in changing the use of water, particularly in dry to normal runoff years. Most of the older water rights in the Rio Grande, especially the upper basin, are supplied by snowmelt. This leaves the lower basin to depend upon rainfall-produced runoff occurring mostly during the sporadic summer monsoon season. Water harvesting techniques which promote heterogeneous water accumulation or production can effectively make more water available in certain areas at the expense the expense of nearby areas. The use of water ponding dikes on arid rangeland can promote increased native vegetation productivity through increases in soil moisture. Stock tanks lined with impervious material are also used to collect whatever runoff that is generated for later use. Desert dwellers living along rivers must rely on conservation measures and ingenuity in order to come up with a very limited water resource to survive. This survival is continually in doubt because population(and consequently water demand) continues to grow in these arid regions while the water supply remains relatively constant.

Rango, A.

2005-12-01

302

The Kamil Crater in Egypt.  

PubMed

We report on the detection in southern Egypt of an impact crater 45 meters in diameter with a pristine rayed structure. Such pristine structures are typically observed on atmosphereless rocky or icy planetary bodies in the solar system. This feature and the association with an iron meteorite impactor and shock metamorphism provides a unique picture of small-scale hypervelocity impacts on Earth's crust. Contrary to current geophysical models, ground data indicate that iron meteorites with masses of the order of tens of tons can penetrate the atmosphere without substantial fragmentation. PMID:20651117

Folco, Luigi; Di Martino, Mario; El Barkooky, Ahmed; D'Orazio, Massimo; Lethy, Ahmed; Urbini, Stefano; Nicolosi, Iacopo; Hafez, Mahfooz; Cordier, Carole; van Ginneken, Matthias; Zeoli, Antonio; Radwan, Ali M; El Khrepy, Sami; El Gabry, Mohamed; Gomaa, Mahomoud; Barakat, Aly A; Serra, Romano; El Sharkawi, Mohamed

2010-08-13

303

Arizona-Sonora Desert Museum  

NSDL National Science Digital Library

The Arizona-Sonora Desert Museum is a zoo, natural history museum and botanical garden, whose mission is to inspire people to live in harmony with the natural world by fostering love, appreciation, and understanding of the Sonoran Desert. The Center for Sonoran Desert Studies conducts the educational and scientific functions of the Museum and is a hub for research, education and conservation of the Sonoran Desert Region. The Center's activities range from on-grounds and outreach education programs for school children and adults, to conducting ecological research in the Sonoran Desert region and advising museum staff, other conservation organizations, and the public on scientific and educational matters. The website has extensive information about desert ecology, environments, animals, and plants, with some content presented in Spanish. There are numerous programs and classes presented, hiking clubs, tours, and activities for Scouts.

304

Jeeps Penetrating a Hostile Desert  

ERIC Educational Resources Information Center

Several jeeps are poised at base camp on the edge of a desert aiming to escort one of them as far as possible into the desert, while the others return to camp. They all have full tanks of gas and share their fuel to maximize penetration. In a friendly desert it is best to leave caches of fuel along the way to help returning jeeps. We solve the…

Bailey, Herb

2009-01-01

305

Comparison of Growth and Stress in Resident Redband Trout Held in Laboratory Simulations of Montane and Desert Summer Temperature Cycles  

Microsoft Academic Search

Within their native range in western North America, resident redband trout Oncorhynchus mykiss gairdneri occupy stream habitat from high mountains to low desert. To better understand the temperature tolerance, growth, and stress physiology of native redband trout populations and compare the resilience and responses to reciprocal environments of stocks adapted to desert or montane conditions, we conducted controlled laboratory trials.

John D. Cassinelli; Christine M. Moffitt

2010-01-01

306

Inclusion -Exclusion: Recasting the Issue of Boundaries for the Western Laurent DOUSSET  

E-print Network

1 Inclusion - Exclusion: Recasting the Issue of Boundaries for the Western Desert Laurent DOUSSET, Laurent 2013. « Inclusion-Exclusion: Recasting the Issue of Boundaries for the Western Desert, the concept that has vaguely been translated as `family' and which is the idiosyncratic expression

Paris-Sud XI, Université de

307

Space Radar Image of Safsaf Oasis, Egypt  

NASA Technical Reports Server (NTRS)

This three-frequency space radar image of south-central Egypt demonstrates the unique capability of imaging radar to penetrate thin sand cover in arid regions to reveal hidden details below the surface. Nearly all of the structures seen in this image are invisible to the naked eye and to conventional optical satellite sensors. Features appear in various colors because the three separate radar wavelengths are able to penetrate the sand to different depths. Areas that appear red or orange are places that can be seen only by the longest wavelength, L-band, and they are the deepest of the buried structures. Field studies in this area indicate L-band can penetrate as much as 2 meters (6.5 feet) of very dry sand to image buried rock structures. Ancient drainage channels at the bottom of the image are filled with sand more than 2 meters (6.5 feet) thick and therefore appear dark because the radar waves cannot penetrate them. The fractured orange areas at the top of the image and the blue circular structures in the center of the image are granitic areas that may contain mineral ore deposits. Scientists are using the penetrating capabilities of radar imaging in desert areas in studies of structural geology, mineral exploration, ancient climates, water resources and archaeology. This image is 51.9 kilometers by 30.2 kilometers (32.2 miles by 18.7 miles) and is centered at 22.7 degrees north latitude, 29.3degrees east longitude. North is toward the upper right. The colors are assigned to different radar frequencies and polarizations as follows: red is L-band, horizontally transmitted and received; green is C-band, horizontally transmitted and received; and blue is X-band, vertically transmitted and received. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) on April 16, 1994, on board the space shuttle Endeavour. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's Mission to Planet Earth program.

1994-01-01

308

Lost in the Desert!  

NSDL National Science Digital Library

Students learn about the interconnectedness of the body, with a particular focus on the skin as one of the most important homeostatic organ systems, in this case study in which the protagonist sets out on a three-hour drive across the Arizona desert to meet his fiancee in California, and never shows up. The case was designed to be used with students in a lower-level anatomy and physiology class who are interested in pursuing careers in nursing, occupational therapy, and other health related fields.

David L. Evans

2002-01-01

309

Desert Research Institute: Research  

NSDL National Science Digital Library

Operating as the nonprofit research campus of the University and Community College System of Nevada, the Desert Research Institute (DRI) conducts more than $27 million in environmental research each year with the help of its approximately 400 research faculty and support staff. The informational research page of the main Web site offers descriptions; publications; links; and other relevant facts from the various arms of the institute, which include the Division of Atmospheric Sciences, Division of Earth and Ecosystem, Division of Hydrologic Sciences, Center for Arid Lands Environmental Management, Center for Watersheds and Environmental Sustainability, and several others.

1969-12-31

310

Desert-Tropicals.com  

NSDL National Science Digital Library

Created by plant enthusiast Philippe Faucon, Desert-Tropicals.com is a well-designed website with information about, and pictures of, over 3,500 plants. Plant lists are organized by scientific and common name, succulents, xeriscape plants, palm trees, herbs, and trees. The plant lists are quite extensive, and each species receives its own description page with a nice close-up photo as well as brief information about family, frost and heat tolerance, sun exposure, origin, propagation, and more. The site also connects to articles, a Bulletin Board, Bookstore, and relevant links.

Faucon, Philippe

311

Center for Desert Archaeology Archaeology Southwest  

E-print Network

Center for Desert Archaeology Archaeology Southwest Center for Desert Archaeology Archaeology Southwest Archaeology Southwest is a Quarterly Publication of the Center for Desert Archaeology Volume 22 ongoing archaeological investigation of Ancestral Pueblo community organization

Kohler, Tim A.

312

Mars Desert Research Station  

NASA Astrophysics Data System (ADS)

The Mars Desert Research Station (MDRS) located in southern Utah presents an invaluable opportunity for researchers to become personally involved in the quest for the human exploration of Mars. MDRS is owned and operated by the Mars Society. Crews from across the nation and around the globe rotate in every two weeks to do a simulation of a human crew on Mars. The location and nature of the Mars Desert Research Station provide a unique opportunity for scientists from the Southwest to propose and do research pertaining to the human exploration of Mars. Being the closest major university to the research station, Brigham Young University has become a worthy asset to the Mars Society in their long-term goals for MDRS. The Mars Research Group at Brigham Young University has spent the past nine months proving their usefulness by making four trips down to the habitat to provide support whenever needed. In the upcoming year we plan to finish modifications on the habitat's greenhouse, get the habitat's new 14-inch telescope running, and provide technical briefings for incoming crews on the use of the habitat, greenhouse, and telescope.

Farnsworth, Nicole; Allred, David D.

2003-10-01

313

Desert landscape irrigation  

SciTech Connect

Industrialization can take place in an arid environment if a long term, overall water management program is developed. The general rule to follow is that recharge must equal or exceed use. The main problem encountered in landscape projects is that everyone wants a lush jungle setting, tall shade trees, ferns, with a variety of floral arrangements mixed in. What we want, what we can afford, and what we get are not always the same. Vegetation that requires large quantities of water are not native to any desert. Surprisingly; there are various types of fruit trees, and vegetables that will thrive in the desert. Peaches, plums, nut trees, do well with drip irrigation as well as tomatoes. Shaded berry plans will also do well, the strawberry being one. In summary; if we match our landscape to our area, we can then design our irrigation system to maintain our landscape and grow a variety of vegetation in any arid or semiarid environment. The application of science and economics to landscaping has now come of age.

Quinones, R.

1995-06-01

314

Desert Farming Benefits from Microbial Potential in Arid Soils and Promotes Diversity and Plant Health  

PubMed Central

Background To convert deserts into arable, green landscapes is a global vision, and desert farming is a strong growing area of agriculture world-wide. However, its effect on diversity of soil microbial communities, which are responsible for important ecosystem services like plant health, is still not known. Methodology/Principal Findings We studied the impact of long-term agriculture on desert soil in one of the most prominent examples for organic desert farming in Sekem (Egypt). Using a polyphasic methodological approach to analyse microbial communities in soil as well as associated with cultivated plants, drastic effects caused by 30 years of agriculture were detected. Analysing bacterial fingerprints, we found statistically significant differences between agricultural and native desert soil of about 60%. A pyrosequencing-based analysis of the 16S rRNA gene regions showed higher diversity in agricultural than in desert soil (Shannon diversity indices: 11.21/7.90), and displayed structural differences. The proportion of Firmicutes in field soil was significantly higher (37%) than in the desert (11%). Bacillus and Paenibacillus play the key role: they represented 96% of the antagonists towards phytopathogens, and identical 16S rRNA sequences in the amplicon library and for isolates were detected. The proportion of antagonistic strains was doubled in field in comparison to desert soil (21.6%/12.4%); disease-suppressive bacteria were especially enriched in plant roots. On the opposite, several extremophilic bacterial groups, e.g., Acidimicrobium, Rubellimicrobium and Deinococcus-Thermus, disappeared from soil after agricultural use. The N-fixing Herbaspirillum group only occurred in desert soil. Soil bacterial communities were strongly driven by the a-biotic factors water supply and pH. Conclusions/Significance After long-term farming, a drastic shift in the bacterial communities in desert soil was observed. Bacterial communities in agricultural soil showed a higher diversity and a better ecosystem function for plant health but a loss of extremophilic bacteria. Interestingly, we detected that indigenous desert microorganisms promoted plant health in desert agro-ecosystems. PMID:21912695

Köberl, Martina; Müller, Henry; Ramadan, Elshahat M.; Berg, Gabriele

2011-01-01

315

Aspects of Mycorrhizae in Desert Plants  

Microsoft Academic Search

\\u000a Mycorrhizal symbioses are critical to desert plants since they face the challenges of scarce, sporadic precipitation, nutrient\\u000a deficiencies, intense solar radiation, and the high temperatures found in hot deserts. Deserts are covering increasingly more\\u000a of the Earth's surface area as desertification increases globally. Mycorrhizal desert plants have a greater chance of survival\\u000a in the harsh desert environment. Desert plants form

Martha E. Apple

316

Raising Questions Central Mojave Desert  

E-print Network

. A. Vazquez The Rainbow Loop Flora from the Mud Hills, Mojave Desert, California 39 Robert E. Jackson #12;32013 desert symposium New records of fish from southern exposures of the Imperial Formation of San Diego County, California 165 Mark A. Roeder Hydrographic significance of fishes from the Early

de Lijser, Peter

317

Physiological Adaptation in Desert Birds  

NSDL National Science Digital Library

This peer-reviewed article from BioScience journal is about adaptations desert birds. We call into question the idea that birds have not evolved unique physiological adaptations to desert environments. The rate at which desert larks metabolize energy is lower than in mesic species within the same family, and this lower rate of living translates into a lower overall energy requirement in the wild. We argue that selection has reduced oxygen consumption at the tissue level under basal conditions for birds living in deserts. We document that total evaporative water loss--the sum of cutaneous water loss (CWL) and respiratory water loss--is reduced in desert birds, and present evidence that changes in CWL are responsible for this pattern. The diminution in CWL is attributable to changes in the lipid structure of the stratum corneum of the skin, the physical barrier to diffusion of water vapor. Finally, we show linkages between physiology and life-history attributes of larks along an aridity gradient; birds from deserts have not only a reduced rate of metabolism but also a small clutch size and slow nestling development. Hence, attributes of physiology are correlated with traits that directly affect reproductive success. Our hope is that we will prompt students to question the notion that birds do not possess physiological adaptations to the desert environment, and raise the specter of doubt about "preadaptation" in birds living in deserts.

JOSEPH B. WILLIAMS and B. IRENE TIELEMAN (; )

2005-05-01

318

Space Radar Image of Giza Egypt - with enlargement  

NASA Technical Reports Server (NTRS)

This radar image shows the area west of the Nile River near Cairo, Egypt. The Nile River is the dark band along the right side of the image and it flows approximately due North from the bottom to the right. The boundary between dense urbanization and the desert can be clearly seen between the bright and dark areas in the center of the image. This boundary represents the approximate extent of yearly Nile flooding which played an important part in determining where people lived in ancient Egypt. This land usage pattern persists to this day. The pyramids at Giza appear as three bright triangles aligned with the image top just at the boundary of the urbanized area. They are also shown enlarged in the inset box in the top left of the image. The Great Pyramid of Khufu (Cheops in Greek) is the northern most of the three Giza pyramids. The side-looking radar illuminates the scene from the top, the two sides of the pyramids facing the radar reflect most of the energy back to the antenna and appear radar bright; the two sides away from the radar reflect less energy back and appear dark Two additional pyramids can be seen left of center in the lower portion of the image. The modern development in the desert on the left side of the image is the Sixth of October City, an area of factories and residences started by Anwar Sadat to relieve urban crowding. The image was taken on April 19, 1994 by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the shuttle Endeavour. SIR-C/X-SAR, a joint mission of the German, Italian and the United States space agencies, is part of NASA's Mission to Planet Earth. The image is centered on latitude 29.72 degrees North latitude and 30.83 degrees East longitude. The area shown is approximately 20 kilometers by 30 kilometers. The colors in the image are assigned to different frequencies and polarizations of the radar as follows: red is L-band horizontally transmitted, horizontally received; green is C-band horizontally transmitted, horizontally received; blue is C-band horizontally transmitted, vertically received.

1994-01-01

319

Rising Water Table Threatens Egypt's Monuments  

NSDL National Science Digital Library

This article from National Geographic News examines the threat posed to Egyptian monuments by a rising water table. The article details the problems facing antiquities throughout Egypt and presents possible solutions.

Chad Cohen

320

Developing a solar energy industry in Egypt  

E-print Network

This paper assesses Egypt's current energy infrastructure and its problems, the available solar energy resource, and the technologies required to harness this resource. After this assessment, an industry based on high ...

AbdelMessih, Sherife (Sherife Mohsen)

2009-01-01

321

USGS Scientists in Wadi Degla, Northern Egypt  

USGS Multimedia Gallery

USGS scientists looking at Eocene sandstones and limestones in Wadi Degla, northern Egypt. This area was studied to understand the Levant Basin Province, as both regions have similar rock formations....

322

Ancient Egypt, Sacred Science, and Transatlantic Romanticism  

E-print Network

science and theology, describing a natural process and atNatural and Spiritual Mysteries, By Way of Representations and Correspondences (the link to Egypt is evident from the title), presents a visionary theology

Redd, Marques Jerard

2011-01-01

323

Factors influencing the rates, processes and magnitude of accumulation of carbon in desert soils  

NASA Astrophysics Data System (ADS)

This report summarizes research funded through NASA's Soil Landscape Climate Program which includes studies of the systematics of carbon storage and flux in the terrestrial environment, specifically terrestrial soils. Efforts focussed on the nature of carbon behavior in arid environments, where the majority of the carbon is present as inorganic carbon stored as pedogenic carbonate in desert calcic soils. Studies were supported of soils in two areas of western North America's major deserts: the Mojave Desert and the Chihuahuan Desert. Part 1 of this report summarizes the results of research conducted in the area of the Providence Mountains, California in the eastern Mojave Desert. Part 2 of this report summarizes the results of research in the Sevilleta Wildlife Refuge in central New Mexico, one of the sites of the UMN Biology Department's Long Term Ecological Research.

McFadden, Leslie D.

324

Factors influencing the rates, processes and magnitude of accumulation of carbon in desert soils  

NASA Technical Reports Server (NTRS)

This report summarizes research funded through NASA's Soil Landscape Climate Program which includes studies of the systematics of carbon storage and flux in the terrestrial environment, specifically terrestrial soils. Efforts focussed on the nature of carbon behavior in arid environments, where the majority of the carbon is present as inorganic carbon stored as pedogenic carbonate in desert calcic soils. Studies were supported of soils in two areas of western North America's major deserts: the Mojave Desert and the Chihuahuan Desert. Part 1 of this report summarizes the results of research conducted in the area of the Providence Mountains, California in the eastern Mojave Desert. Part 2 of this report summarizes the results of research in the Sevilleta Wildlife Refuge in central New Mexico, one of the sites of the UMN Biology Department's Long Term Ecological Research.

Mcfadden, Leslie D.

1994-01-01

325

Faunal remains from a Middle Pleistocene lacustrine marl in Dakhleh Oasis, Egypt: palaeoenvironmental reconstructions  

Microsoft Academic Search

Vertebrates and invertebrates associated with lithic artifacts are reported from a later middle Pleistocene horizon in Dakhleh Oasis, probably dating to isotope stage 7. This represents the first middle Pleistocene fauna of this stage from a site in the Egyptian Western Desert and demonstrates the presence of extensive permanent lakes along the margin of the Libyan Escarpment. The fauna includes

C. S Churcher; M. R Kleindienst; H. P Schwarcz

1999-01-01

326

Impact of highway geometry and posted speed on operating speed at multi-lane highways in Egypt  

PubMed Central

The paper presents an analysis of roadway factors and posted speed limits that affect the operating speed at multi-lane highways in Egypt. Field data on multi-lane highways in Egypt are used in this investigation. The analysis considers two categories of highways. The first consists of two desert roads (Cairo–Alexandria and Cairo–Ismailia desert roads) and the second consists of two agricultural roads (Cairo–Alexandria and Tanta–Damietta agricultural roads). The paper includes three separate relevant analyses. The first analysis uses the regression models to investigate the relationships between operating speed (V85) as dependent variable, and roadway factors and posted speed as independent variables. The road factors are lane width, shoulder width, pavement width, median width, number of lanes in each direction, and existence of side access along each section. The second analysis uses the Artificial Neural Network (ANN) to explore the previous relationships while the third one examines the suitability of the posted speed limits on the roads under study. It is found that the ANN modeling gives the best model for predicting the operating speed and the most influential variables on V85 are the pavement width, followed by the median width and the existence of side access along section. It is also found that the posted speed limit has a very small effect on the operating speed due to the bad behavior of drivers in Egypt. These results are so important for controlling V85 on multi-lane rural highways in Egypt. PMID:25685460

Semeida, Ahmed M.

2012-01-01

327

Evolutionary hotspots in the Mojave Desert  

USGS Publications Warehouse

Genetic diversity within species provides the raw material for adaptation and evolution. Just as regions of high species diversity are conservation targets, identifying regions containing high genetic diversity and divergence within and among populations may be important to protect future evolutionary potential. When multiple co-distributed species show spatial overlap in high genetic diversity and divergence, these regions can be considered evolutionary hotspots. We mapped spatial population genetic structure for 17 animal species across the Mojave Desert, USA. We analyzed these in concurrence and located 10 regions of high genetic diversity, divergence or both among species. These were mainly concentrated along the western and southern boundaries where ecotones between mountain, grassland and desert habitat are prevalent, and along the Colorado River. We evaluated the extent to which these hotspots overlapped protected lands and utility-scale renewable energy development projects of the Bureau of Land Management. While 30–40% of the total hotspot area was categorized as protected, between 3–7% overlapped with proposed renewable energy project footprints, and up to 17% overlapped with project footprints combined with transmission corridors. Overlap of evolutionary hotspots with renewable energy development mainly occurred in 6 of the 10 identified hotspots. Resulting GIS-based maps can be incorporated into ongoing landscape planning efforts and highlight specific regions where further investigation of impacts to population persistence and genetic connectivity may be warranted.

Vandergast, Amy G.; Inman, Richard D.; Barr, Kelly R.; Nussear, Kenneth E.; Esque, Todd C.; Hathaway, Stacie A.; Wood, Dustin A.; Medica, Philip A.; Breinholt, Jesse W.; Stephen, Catherine L.; Gottscho, Andrew D.; Marks, Sharyn B.; Jennings, W. Bryan; Fisher, Robert N.

2013-01-01

328

Western Foot Patrol Western University  

E-print Network

Western Foot Patrol Western University Room 57, University Community Centre London, Ontario N6A 3K7 August 2013 Get involved! Volunteer with Western Foot Patrol Welcome to Western! Thank you for your interest in volunteering for Western Foot Patrol (WFP)! WFP is a free service that promotes

Lennard, William N.

329

77 FR 71777 - Trade Mission to Egypt and Kuwait  

Federal Register 2010, 2011, 2012, 2013, 2014

...Administration Trade Mission to Egypt and Kuwait AGENCY: International Trade Administration...regarding the Trade Mission to Egypt and Kuwait March 10-14, 2013, published at 77...the U.S. Trade Mission to Egypt and Kuwait March 10-14, 2013, published at...

2012-12-04

330

Post-Mubarak Egypt: The Dark Side of Islamic Utopia  

E-print Network

23 Post-Mubarak Egypt: The Dark Side of Islamic Utopia Robert S. Wistrich Robert S. Wistrich victor in the first two rounds of the democratic elections currently taking place in post-Mubarak Egypt. Though they did not initiate the wider popular movement toward democracy, the Islamist forces in Egypt

Anat, Maril,

331

Published: 20 May 2012 Egypt's March Toward Democracy  

E-print Network

1 Published: 20 May 2012 Egypt's March Toward Democracy Op-Ed by Ahmed H. Zewail CAIRO -- A few candidates among the 13 running for president of Egypt. This stunning debate went on for more than four hours and was watched by millions of Egyptians and other Arabs. Contrary to the perception around the world that Egypt

Zewail, Ahmed

332

Opportunities for woody crop production using treated wastewater in Egypt  

Technology Transfer Automated Retrieval System (TEKTRAN)

The Nile River provides nearly 97% of Egypt's freshwater supply. Egypt's share of Nile waters is allocated according to international treaty obligations and is fixed at 55.5 billion cubic meters annually. As a result, Egypt will not be able to meet increasing water demand using freshwater from the N...

333

The Effect of Child Work on Schooling: Evidence from Egypt  

E-print Network

The Effect of Child Work on Schooling: Evidence from Egypt Ragui Assaad Humphrey Institute of Minnesota Nadia Zibani Centre d'Etudes et de Documentation Economiques et Juridiques Cairo, Egypt Revised Growth (ICEG) through its Economic Policy Initiative Consortium project in Egypt, which is funded

Levinson, David M.

334

Profil de poste Reprsentant de l'IRD en Egypte  

E-print Network

Profil de poste N°3999 Représentant de l'IRD en Egypte Catégorie A - Directeur de recherche détachement sur un emploi de chercheur1 AFFECTATION STRUCTURELLE Le représentant de l'IRD en Egypte est déléguées. AFFECTATION GEOGRAPHIQUE Le représentant de l'IRD en Egypte sera affecté au Caire à compter du 1

335

THE EGYPT LABOR MARKET PANEL SURVEY: INTRODUCING THE 2012 ROUND  

E-print Network

#12;THE EGYPT LABOR MARKET PANEL SURVEY: INTRODUCING THE 2012 ROUND Ragui Assaad and Caroline Egypt www.erf.org.eg Copyright © The Economic Research Forum, 2013 All rights reserved. No part our data to other statistical sources for Egypt to evaluate the representativeness of the sample

Levinson, David M.

336

SIX NEW SPECIES OF ANTS (INSECTA: HYMENOPTERA: FORMICIDAE) FROM EGYPT  

E-print Network

SIX NEW SPECIES OF ANTS (INSECTA: HYMENOPTERA: FORMICIDAE) FROM EGYPT HASSAN H. FADL, REDA F. BAKR, RAWDA M. BADAWY AND MOSTAFA R. SHARAF Entomology Dept., Fac. Science, Ain Shams University, Cairo, Egypt. ABSTRACT Six new ant species from Egypt Cerapachys collingwoodi, Cataglyphis agostii, Messor eglalae

Villemant, Claire

337

Demographic Surprises Foreshadow Change in Neoliberal Egypt Eric Denis, CNRS  

E-print Network

Demographic Surprises Foreshadow Change in Neoliberal Egypt Eric Denis, CNRS Eric.denis@univ-paris-diderot.fr Final Draft, Middle East Report, Spring 2008, Number 246 In the Egypt of 2008, half the population has. These demographic surprises have important implications for the stability of Egypt and the regimes economic

Paris-Sud XI, Université de

338

Archaeological Institute of America-Milwaukee Society Napoleon in Egypt  

E-print Network

Archaeological Institute of America-Milwaukee Society Presents Napoleon in Egypt The Beginning Egypt in 1798, along with his army he brought 150 artists, linguists, and scientists of all kinds to describe Egypt. Together they conducted the first ethnographic study of its kind but also laid

Saldin, Dilano

339

Proefschrift: Occidentalisms. Images of `the West' in Egypt Robbert Woltering  

E-print Network

Proefschrift: Occidentalisms. Images of `the West' in Egypt Robbert Woltering Nederlandse onderzoek naar Occidentalisme in hedendaags Egypte. In het bijzonder is onderzocht welke beelden van het) en tientallen boeken, waarin de relatie van Egypte (of breder: de Arabische wereld, of zelfs `de

van den Brink, Jeroen

340

Experience Ancient Egypt Uncover the secrets of the ancient world...  

E-print Network

Experience Ancient Egypt Uncover the secrets of the ancient world... A day event for Children in Care in school years 7 - 9 Discover the secrets of Ancient Egypt at this FREE taster day. Explore the incredible Ancient Egypt Gallery at the Fitzwilliam Museum and create some Egyptian artwork. Plus enjoy

Travis, Adrian

341

Information Herodotus called by many "The Father of History" traveled to Egypt around 450 BC to study Egypt.  

E-print Network

© 2012 Information Age Herodotus called by many "The Father of History" traveled to Egypt around 450 BC to study Egypt. Herodotus indicated that each of the four "perfectly triangle faces in 24 BC wrote forty-seven books about the History of Egypt. Unfortunately, most of his work was lost

Bardsley, John

342

Egypt Centre and The Department of History and Classics Swansea Experiment and Experience: Ancient Egypt in the Present  

E-print Network

Egypt Centre and The Department of History and Classics Swansea University Experiment and Experience: Ancient Egypt in the Present Monday 10th-Wednesday 12th May 2010 Early bookings (pre 15th are included in the price. Tickets are available from Carolyn Graves-Brown at, The Egypt Centre, Swansea

Martin, Ralph R.

343

Women's position and family planning in Egypt.  

PubMed

In this report, data from the 1988 Egypt Demographic and Health Survey are used to address some of the most frequently raised questions about the relationship between gender inequality and reproductive behavior. The findings from binomial and multinomial logit models show that while the relationship between women's position and fertility control in Egypt is complex, some clear, broad patterns exist that have important theoretical and policy implications. First, although women's status in Egypt is clearly multidimensional, the reproductive aspect of women's position has a strong connection with the nonreproductive dimensions. Second, the case of the continued use of education and employment as proxies of women's position, especially in relationship to fertility control, is considerably discredited by the results. Finally, the findings indicate that Egyptian culture supports gender equality in the form of interaction and negotiation rather than women's autonomy. PMID:8986031

Govindasamy, P; Malhotra, A

1996-01-01

344

Notes on the synanthropic plants of Egypt  

Microsoft Academic Search

Red and blue flowered pimpernels commonly referred toAnagallis arvensis s. 1. were studied in Egypt, Iraq, and adjacent territories. Key, description, taxonomic, chorological, ecological notes,\\u000a and phytocartograms of the following taxa growing or expected in Egypt are given:Anagallis arvensis L. var.arvensis, A. latifolia L.,A. arvensis L. var.caerulea (L.)Gouan, andA. foemina\\u000a Mill. New hybridAnagallis×hadidii\\u000a Chrtek etOsbornová-Kosinová (A. arvensis L. var.arvensis ×

Jind?ich Chrtek; Jana Osbornová-Kosinová

1986-01-01

345

Desert Life in the American Southwest  

NSDL National Science Digital Library

DesertUSA.com (DUSA) provides this interesting site, offering a plethora of general information on the deserts of the United States. Designed as an educational tool for discovering "the beauty, life and culture of North American deserts," the site contains illustrated text, factual summaries, virtual reality tours, movie/audio clips, and stories. All materials focus on desert-related topics, including plants, animals, geology, cultural and natural history, and parks, among others. The site has much to offer -- from the basics of the desert environment, to a photo-illustrated guide of desert flora and fauna, to details on specific arid and semi-arid deserts of the American Southwest. A glossary of desert terms and brief descriptions of features of the Chihuahuan, Great Basin, Mojave and Sonoran Deserts round out the site.

346

From (b)edouin to (a)borigine: the myth of the desert noble savage.  

PubMed

This article examines the myth of the supposed superiority of the desert noble savage over civilized man. With the Bedouin of Arabia and the Aborigines of Australia as its two prime examples, the article argues that two versions of this myth can be traced: one in which the desert noble savage is valorized due to his valour, physical prowess and martial skill (Bedouin); and another, later version, where the desert noble savage is valorized as a pacifist, an ecologist and a mythmaker/storyteller (Aborigines). The article concludes by examining the way in which this turn from one type of desert noble savage to another reflects the manner in which western modernity has shifted its values from Cartesian dualities and Enlightenment rationalism to that of networks, potentialities, ecology and myth. PMID:19886291

Graulund, Rune

2009-01-01

347

Phytoremediation for Oily Desert Soils  

NASA Astrophysics Data System (ADS)

This chapter deals with strategies for cleaning oily desert soils through rhizosphere technology. Bioremediation involves two major approaches; seeding with suitable microorganisms and fertilization with microbial growth enhancing materials. Raising suitable crops in oil-polluted desert soils fulfills both objectives. The rhizosphere of many legume and non-legume plants is richer in oil-utilizing micro-organisms than non-vegetated soils. Furthermore, these rhizospheres also harbour symbiotic and asymbiotic nitrogen-fixing bacteria, and are rich in simple organic compounds exuded by plant roots. Those exudates are excellent nutrients for oil-utilizing microorganisms. Since many rhizospheric bacteria have the combined activities of hydrocarbon-utilization and nitrogen fixation, phytoremediation provides a feasible and environmentally friendly biotechnology for cleaning oil-polluted soils, especially nitrogen-poor desert soils.

Radwan, Samir

348

Analysis of utilization of desert habitats with dynamic simulation  

USGS Publications Warehouse

The effects of climate and herbivores on cool desert shrubs in north-western Utah were investigated with a dynamic simulation model. Cool desert shrublands are extensively managed as grazing lands, and are defoliated annually by domestic livestock. A primary production model was used to simulate harvest yields and shrub responses under a variety of climatic regimes and defoliation patterns. The model consists of six plant components, and it is based on equations of growth analysis. Plant responses were simulated under various combinations of 20 annual weather patterns and 14 defoliation strategies. Results of the simulations exhibit some unexpected linearities in model behavior, and emphasize the importance of both the pattern of climate and the level of plant vigor in determining optimal harvest strategies. Model behaviors are interpreted in terms of shrub morphology, physiology and ecology.

Williams, B.K.

1986-01-01

349

Rainbows in the Indian rock art of desert western America.  

PubMed

For thousands of years the image of the rainbow was pecked and painted by native Americans onto the rocks of the Great Basin and the Southwest. This long-lived tradition, which transcended major developments in lifestyles and cultures, underscores the important symbolic significance of the rainbow to the inhabitants of this arid region. The rainbow rock art depictions were usually associated with humanlike ceremonial figures, snakes, clouds, rain, and lightning bolts, suggesting that the rainbow symbol was employed as part of an elaborate sacred tradition. Although such ceremonial usage of the rainbow image tends to lead to abstraction and symbolic representation, there are examples, including a properly colorized rainbow painting from central Utah (approximately a thousand years old), that indicate observationally based rainbow reproductions of relatively great antiquity. PMID:20706421

Sassen, K

1991-08-20

350

Egypt, Morocco, and the United States  

Microsoft Academic Search

The political importance of the Middle East to the United States is evident from the willingness of the United States to wage a war in Iraq, the polit- ical capital some US administrations have invested in resolving the Pales- tinian-Israeli conflict, and the amount of aid extended to such countries as Egypt and Israel. It is not surprising, therefore, that

AHMED GALAL; ROBERT Z. LAWRENCE

2003-01-01

351

Numerical taxonomy of Galium (Rubiaceae) in Egypt  

Microsoft Academic Search

On the basis of fifty morphological characters, including vegetative parts, flowers, fruits, seeds, pollen grains, and anatomical structure, a systematic study of 13 taxa belonging to genus Galium (Rubiaceae) from Egypt was conducted by means of numerical analysis. Four branches and clusters were distinguished. Representatives of these groups were clustered together according to characters with high factor loading in the

Kadry N. Abdel Khalik; Monier M. Abd El-Ghani; Ahmed El Kordy

352

Women's "Justification" of Domestic Violence in Egypt  

ERIC Educational Resources Information Center

We explored the influences of women's social learning, marital resources and constraints, and exposure to norms about women's family roles on their views about wife hitting or beating among 5,450 participants in the 2005 Egypt Demographic and Health Survey. One half justified wife hitting or beating for some reason. Women from rural areas who were…

Yount, Kathryn M.; Li, Li

2009-01-01

353

Directory of Adult Education Agencies in Egypt.  

ERIC Educational Resources Information Center

The directory of Adult Education Agencies in Egypt is a listing of six different types of organizations: national bodies and central agencies; teachers' training institutes and research institutions; adult education institutions (governmental); adult education institutions (non-governmental); central libraries and documentation centers; and…

El-Bashary, Ahmed, Comp.

354

Censorship and Security Agents Pervade Egypt's Universities  

ERIC Educational Resources Information Center

This article offers a glimpse into one of the many ways in which the Egyptian government and the campus administrators it appoints are slowly and persistently squeezing the life out of universities in Cairo, Egypt. Classroom discussions are monitored, faculty appointments and academic research are scrutinized, and faculty participation in outside…

Mills, Andrew

2008-01-01

355

Detection of Strawberry Viruses in Egypt  

Technology Transfer Automated Retrieval System (TEKTRAN)

As part of a USAID-MERC funded project, ‘Disease-indexing and mass propagation of superior strawberry cultivars’, an effort was made to evaluate the virus status of strawberries in Egypt. Diagnostic reverse transcription-polymerase chain reaction (RT-PCR) tests for Strawberry mottle, Strawberry cri...

356

Journey to Egypt: A Board Game  

ERIC Educational Resources Information Center

This author describes how her elementary students first became interested in studying ancient Egypt. Her students' interest in the ancient Egyptian studies began when a student checked out a library book on Egyptology that contained colorful images and was soon swarmed by interested classmates. Many of her students began practicing writing…

Selvidge, Ellen

2006-01-01

357

Review of Parasitic Zoonoses in Egypt  

PubMed Central

This review presents a comprehensive picture of the zoonotic parasitic diseases in Egypt, with particular reference to their relative prevalence among humans, animal reservoirs of infection, and sources of human infection. A review of the available literature indicates that many parasitic zoonoses are endemic in Egypt. Intestinal infections of parasitic zoonoses are widespread and are the leading cause of diarrhea, particularly among children and residents of rural areas. Some parasitic zoonoses are confined to specific geographic areas in Egypt, such as cutaneous leishmaniasis and zoonotic babesiosis in the Sinai. Other areas have a past history of a certain parasitic zoonoses, such as visceral leishmaniasis in the El-Agamy area in Alexandria. As a result of the implementation of control programs, a marked decrease in the prevalence of other zoonoses, such as schistosomiasis and fascioliasis has been observed. Animal reservoirs of parasitic zoonoses have been identified in Egypt, especially in rodents, stray dogs and cats, as well as vectors, typically mosquitoes and ticks, which constitute potential risks for disease transmission. Prevention and control programs against sources and reservoirs of zoonoses should be planned by public health and veterinary officers based on reliable information from systematic surveillance. PMID:24808742

Youssef, Ahmed I.; Uga, Shoji

2014-01-01

358

New leaf diseases of barley in Egypt.  

PubMed

Leaf diseases of barley were observed also in Egypt. From leaves of barley were isolated: Helminthosporium teres, H. gramineum, Stemphylium vesicarium, Alternaria triticina, Vlocladium chartarum, Acnemonium kiliense, Stemphylium spec. accompanied with the Pleospora stage. Inoculations on both attached and detached leaves showed that all the tested fungi were pathogenic, except Acremonium kiliense and Ulocladium chartarum. PMID:1037183

Mehiar, F F; El-Deen, E; Wasfy, H; El-Samra, I A

1976-01-01

359

Phytoremediation for Oily Desert Soils  

Microsoft Academic Search

\\u000a This chapter deals with strategies for cleaning oily desert soils through rhizosphere technology. Bioremediation involves\\u000a two major approaches; seeding with suitable microorganisms and fertilization with microbial growth enhancing materials. Raising\\u000a suitable crops in oil-polluted desert soils fulfills both objectives. The rhizosphere of many legume and non-legume plants\\u000a is richer in oil-utilizing micro-organisms than non-vegetated soils. Furthermore, these rhizospheres also harbour

Samir Radwan

2009-01-01

360

Prickly pear desert cactus flower in the Mojave desert  

NSDL National Science Digital Library

The prickly pear cactus is a desirable meal for many desert organisms because of its water storing capability. Cacti have no leaves which reduces water loss. However, it has many spines and thorns for shade and to keep predators from eating it.

Katie Hale (California State University, Fullerton; Student, Biological Sciences)

2007-01-13

361

In Texas, the distributions of desert mule deer (Odocoileus hemionus eremicus) and  

E-print Network

-tailed deer (Odocoileus virginianus) over- lap in portions of the Trans-Pecos region, the western edge hemionus eremicus) and white-tailed deer (Odocoileus virginianus) in west central Texas. We captured 18In Texas, the distributions of desert mule deer (Odocoileus hemionus eremicus) and white

McIntyre, Nancy E.

362

Native Perennial Grass Communities of the Carson Desert of Northwestern Nevada  

Microsoft Academic Search

Ahstract-A generalized distribution of the perennial grasses in the western Great Basin reveals an inter-mixing of species of the two grass Tribes Hordeae and Agrostideae (following the nomencla­ ture of Hitchcock 1950). The dominant genera are Agropyron and Achnatherum -Hesperostipa. In the Lahontan trough of the Carson Desert, a third Tribe of grasses, Zoysieae, is represented by Hilaria jamesii. The

James A. Young; Charlie D. Clements

1999-01-01

363

Water relations and photosynthesis of a barrel cactus, Ferocactus acanthodes , in the Colorado desert  

Microsoft Academic Search

The structural characteristics, water relations, and photosynthesis of Ferocactus acanthodes (Lemaire) Britton and Rose, a barrel cactus exhibiting Crassulacean acid metabolism (CAM), were examined in its native habitat in the western Colorado desert. Water storage in its succulent stem permitted nighttime stomatal opening ot continue for about 40 days after the soil water potential became less than that of the

Park S. Nobel

1977-01-01

364

Hematologic, plasma biochemistry, and acid-base analysis of adult Negev Desert tortoises (Testudo werneri) in Israel.  

PubMed

The Negev Desert tortoise (Testudo werneri) is one of the smallest tortoise species in the Mediterranean region. This is a critically endangered species (CITES I) in its native habitat, which includes the Saharo-Arabian sands of northern Egypt, Sinai, and the Negev Desert in Israel. Great efforts have been invested in captive breeding and reintroduction of this tortoise to the wild. The purpose of this study was to collect blood samples from healthy Negev Desert tortoises kept in well-managed zoologic collections in order to describe hematologic, plasma biochemistry, and acid-base analytes for this species. Data of 36 different blood analytes were collected using the Abaxis Vetscan bench-top analyzer and i-STAT handheld analyzer, and a significant difference was observed between males and females in 13 of the measured analytes. To the authors' knowledge, this is the first report of blood analytes for the Negev Desert tortoise; however, the data do not fully meet the strict ASVCP guidelines required for reference range determination and thus can only provide a rough estimate for evaluating the health status of Negev Desert tortoises using similar testing methodology. PMID:25632697

Eshar, David; Gancz, Ady Y; Avni-Magen, Nili; King, Roni; Beaufrére, Hugues

2014-12-01

365

Diversity and adaptations in the Mojave desert  

NSDL National Science Digital Library

Deserts are characterized by low humidity, little rainfall, extreme temperatures, and a small amount of vegetation. However, deserts are not "dead zones" and host a variety of organisms adapted to these conditions.

Katie Hale (California State University, Fullerton; Student, Biological Sciences)

2007-01-13

366

Intercalibration of GOES Imager visible channels over the Sonoran Desert  

NASA Astrophysics Data System (ADS)

The Geostationary Operational Environmental Satellites (GOES) have been observing the Western Hemisphere since the late 1970s, providing valuable information for weather forecast and climate change studies. Due to the lack of an onboard calibration device for the visible channel, accurate reflectance of the visible channel data depends on vicarious calibration methods to provide postlaunch calibration coefficients to compensate for the degraded responsivity. In this study, the Sonoran Desert, which can be viewed by both GOES-East and GOES-West satellites, is used to intercalibrate the visible channels on board the three-axis stabilized GOES satellite Imagers traceable to the Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 6 (C6) calibration standard. It was found that when the anomalous reflectance in 2004 and 2005 are excluded, the Sonoran Desert is radiometrically, spatially, and spectrally stable at the GOES viewing geometries and thus can be considered as a pseudo-invariant calibration site to develop long-term GOES Imager visible data set. To characterize the desert target reflectance with the MODIS data, GOES observations over 1 year period are used to convert the MODIS reflectance to the GOES viewing and solar illumination geometries. The spectral band adjustment factor for each GOES Imager visible channel is generated with a set of clear-sky Hyperion measurements. A trending algorithm, which consists of a polynomial function for the description of instrument degradation performance and two sine terms for the impacts of the seasonal variations of the solar zenith angle and atmospheric components, is applied to fit the time series of prelaunch calibrated reflectance. The combined calibration uncertainty of the desert calibration method is less than 4% at the Aqua MODIS C6 calibration standard. The difference of the postlaunch calibration coefficients between the desert calibration and the current GOES visible operational calibration methods is mainly within 5%.

Yu, Fangfang; Wu, Xiangqian; Grotenhuis, Michael; Qian, Haifeng

2014-07-01

367

78 FR 26682 - Culturally Significant Objects Imported for Exhibition Determinations: “Hall of Ancient Egypt”  

Federal Register 2010, 2011, 2012, 2013, 2014

...Exhibition Determinations: ``Hall of Ancient Egypt'' AGENCY: Department of State. ACTION...pertaining to the exhibition ``Hall of Ancient Egypt.'' The referenced notice is corrected...included in the exhibition ``Hall of Ancient Egypt,'' imported from abroad for...

2013-05-07

368

Last date modified 1/15/13 Location and Institution EGYPT -CAIRO  

E-print Network

Last date modified 1/15/13 Location and Institution EGYPT - CAIRO AMERICA trips through Egypt, service learning activities, and/or Scholarships forums will need a student visa to enter and study in Egypt. You must apply as soon

Galles, David

369

DR. MELINDA HARTWIG A Lecture by the American Research Center in Egypt Northwest Chapter  

E-print Network

. MELINDA HARTWIG A Lecture by the American Research Center in Egypt of ancient Egypt and the ancient Mediterranean basin. She received her Ph chapel of Menna (TT 69) is one of the finest painted tombs in Egypt

Hochberg, Michael

370

Last date modified 7/9/13 Location and Institution EGYPT -CAIRO  

E-print Network

Last date modified 7/9/13 Location and Institution EGYPT - CAIRO AMERICA trips through Egypt, service learning activities, and/or Scholarships forums will need a student visa to enter and study in Egypt. You must apply as soon

Galles, David

371

Department of Pharmacognosy1 , Faculty of Pharmacy, University of Alexandria, Alexandria, Egypt; Department of Pharma-  

E-print Network

Department of Pharmacognosy1 , Faculty of Pharmacy, University of Alexandria, Alexandria, Egypt Ela, Pharmacognosy Department, Faculty of Pharmacy, Alexandria University, 21521 Alexandria, Egypt of air-dried powdered roots of Artemisia monosperma growing in Egypt afforded two new compounds; 6

372

Magneto U Seismic Studies On The Estern, Part of Qattara Depression, Northwestern Desert, Egypt  

NASA Astrophysics Data System (ADS)

The potential field data considered main factor in supporting the geo- physical exploration process in detection and evaluation the subsurface structures. In this respect a detailed land magnetic survey was performed to the studied area that was subjected to seismic investigation. The geomagnetic data was corrected and reduced to the North magnetic Pole. Since this work dealing with the tectonics, therefore a trend analysis technique has performed to the reduced map and a tectonic map was deduced. Moreover the two dimensional filtering technique was applied to the reduced data us- ing different order of coefficients (8, 16, 21, filter units) to define the continuation of these structures at different depths. Three maps (16-unit residual, 21-unit band-pass and 8-unit regional filtered maps,)were chosen to represent the geomagnetic field at shallow, intermediate and deep depths and trend analysis technique was applied to these maps. The results show that the main dominant tectonic trends is N35-45W, N45-65E, E-Wand Aqaba trends . Two seismic lines 39 and 127 were interpreted and the location of these lines was matched with the deduced tectonic map. The results showing that there are complete matching between the location of the faults deduced from the geomagnetic and seismic data. Moreover quantitative interpretation was per- formed to the geomagnetic data using spectral analysis and three dimensions models techniques. The deduced results show a complete agreement with seismic and well logging data. The area was subjected into two sets of structures fault lines divide the area into a horst in the middle and two grabens in both sides of the studied area.

Rabeh, T. T.

373

Diagenetic history of Cambrian quartzarenites, Ras Dib Zeit Bay area, Gulf of Suez, eastern desert, Egypt  

NASA Astrophysics Data System (ADS)

In the northern corner of the El Zeit range, 370 m of sandstone overlie Precambrian granite and underlie Cretaceous marine strata. The sandstones include the marine Lower Cambrian(?) Araba Formation and the overlying, dominantly fluvial, Upper Cambrian(?) Naqus Formation. The framework compositions of both sandstones are almost entirely quartz, with trace amounts of muscovite, K-feldspar and heavy minerals. Up to 21% oversize pores, some filled with younger cements, attest to extensive dissolution loss of detrital grains. Because the final mineralogical maturation of these quartzarenites reflects diagenesis, they are diagenetic quartzarenites. During burial diagenesis, the introduction of up to 8% quartz cement (inhomogeneously distributed, mean = 3%) was followed by local, pore-occluding calcite cement, which halted compaction. Sandstones without calcite cement underwent additional mechanical and chemical compaction sufficient to develop sutured quartz grain contacts and reduce porosity (˜27%). These events were followed by: (1) extensive dissolution loss of carbonate cement, detrital feldspars, micas, and heavy minerals; (2) formation of local patches of kaolinite (mean = 3%); and (3) formation of extensive iron-oxide cements, including specular hematite. These features suggest extensive invasion by oxidizing meteoric water. The timing of this event can only be dated as post-Cambrian(?) and pre-Cenomanian. Some outcrop samples contain pore-occluding gypsum cement, or mixtures of gypsum and halite. Sr 87/Sr 86 ratios of four samples of gypsum cement have values (0.7079 and 0.7085) that indicate Miocene and slightly younger seawater. Evaporites were evidently leached by modern meteoric water from nearby outcrops of Miocene and younger marine evaporite-bearing strata, transported in surface and ground water to the topographically low terrain where the Cambrian sandstones crop out, and reprecipitated by evaporation. Initial primary porosity (45%) was reduced to ˜27% by compaction in sands with minor quartz cement; compaction ceased where calcite was precipitated. Subsequent dissolution of some calcite cement and unstable detrital grains generated considerable secondary porosity.

Abdel Wahab, Antar

1998-10-01

374

Thermal Performance of Exposed Composed Roofs in Very Hot Dry Desert Region in Egypt (Toshky)  

E-print Network

that the thermal transmittance (UValue) has a major role in chosen the constructed materials. Also the thermal insulation considered the suitable manner for damping the thermal stresses through day time and makes the interior environment of the building near...

Khalil, M. H.; Sheble, S.; Morsey, M. S.; Fakhry, S.

2010-01-01

375

Evaluation of natural radionuclides at Um-Greifat area, eastern desert of Egypt.  

PubMed

Air borne radiometric maps and remote sensing techniques were used to explore for the occurrence of radioactive materials. The previous techniques recorded radioactive mineralization for the first time along the NW-SE trending fault zones within the Miocene clastic-carbonate sediments. In the present study, gamma-ray spectrometry was used to confirm the presence of this mineralization. Concentrations of radionuclides, associated within the iron ochre at Um-Greifat area, have been measured, using a hyper-pure germanium spectrometer. The variation in concentration of radionuclides for the area under investigation can be classified into A, B and C regions of high, medium and low natural radioactivity. In region A, average concentration in Bqkg(-1) has been observed to range from 1858 to 4062 for 238U, between 29 and 151 for 232Th, from 60 to 136 for 235U and between 46 and 409 Bqkg(-1) for 40K. Radium equivalent activities (Ra(eq)) in addition to external and internal hazard indices (H(ex), H(in)) have also been determined. Ra(eq) varies between 1901 and 4307Bqkg(-1), which exceeds the permitted value (370Bqkg(-1)) and H(ex) and H(in) are higher than 1. The high activity concentration within region A points to an environmental hazard, while regions B and C have less exposure effect on human beings. PMID:12573328

Nada, A

2003-02-01

376

Geometry and texture of quartz veins in Wadi Atalla area, Central Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

Several quartz vein sets with varying orientation, geometry and internal structure were recognized in the Atalla area. The veins were associated with the deformation phases affecting the area. En echelon and extensional veins are the main geometrical types. Syn-kinematic veins associated with the major northeast-over-southwest thrust faults were later boudinaged, folded and re-folded. En echelon veins, fibrous veins, and extensional veins are associated with the NNW-SSE faults. Other veins are associated with the NW-SE, N-S, NE-SW and E-W faults. Veins are concentrated at the intersection zones between faults. The internal structure of the veins comprises syntaxial, antitaxial, and composite types and reflects a change from a compressive stress regime to an extensional one. Chocolate-tablet structures and synchronous and co-genetic vein networks indicate later multi-directional extension of the area. Interaction between cracking and sealing of fractures is a common feature in the study area indicating that it was easy for the pore pressure to open pre-existing fractures instead of creating new ones. The reopening of pre-existing fractures rather than creating new ones is also indicated by the scattering of vein data around ?3. There is an alteration and change in characteristics of the wall rock due to increase in fluid flow rate. Fault-valving probably is also a cause of the complex geometry of some veins.

Akawy, Ahmed

2007-02-01

377

Prehistoric occupation of the eastern desert, Egypt: a key to landform analysis  

SciTech Connect

Surface scatters of lithic artifacts on Quaternary faulted relict surfaces and terrace flights represent the first Prehistoric sites reported from the west bank, Gulf of Suez. These aid in analyzing the geomorphifc history of the Gulf, a Neogene rift valley. Diagnostic artifacts include Lower Palaeolithic choppers and Acheulean hand axes; Middle Palaeolithic Levallois flakes and points, denticulate scrapers, and a discoidal core; Late Palaeolithic blade and scrapers and blades; and a Neolithic tanged point, side scraper, and chipped axe. Tectonic and climatic changes are indicated by vertical distribution of Prehistoric sites. Similar artifact assemblages at different relative elevations on bedrock horsts imply laterally varying tectonic uplift rates. Large elevation differences between Middle and Late Palaeolithic-bearing alluvial terraces indicate rapid erosional landscape change. This allows tentative correlation of widely separated terrace flights and indicates the latest possible age of drainage abandonment. Considerable climatic amelioration would have been required for Prehistoric occupation of this arid region. Sites were probably situated above then-active drainages. Additionally, today's limited rainfall cannot account for the amount of erosion since Prehistoric occupation. Therefore, at least three pluvials, corresponding to the Lower, Middle, and Late Palaeolithic, are postulated; these apparently controlled both landscape development and human occupation of this marginal ecosystem. Archaeological analysis can thus be useful as a tool for semiquantitative evaluation of erosion cycles and uplift rates.

Gawarecki, S.L.; Hoffman, M.A.; Perry, S.K.

1985-01-01

378

Spectral reflectance of biogenic crust developed on desert dune sand along the Israel-Egypt border  

Microsoft Academic Search

The effect of biogenic crust on imagery acquired by spaceborne sensors is demonstrated. The crust consists mostly of microphytes such as cyanobacteria. The macrophytes (higher vegetation) on the sand dunes are sparse and have a relatively low spectra! reflectance response. However, since a considerable ponton of the ground is covered by this biogenic crust, (which has a different spectral reflectance

A. Karnieli; H. Tsoar

1995-01-01

379

Paleoclimatic and Tectonic History of the Eastern Desert, Egypt and Surroundings  

NASA Technical Reports Server (NTRS)

This report covers work for the Planetary Geology and Geophysics Program, which has focused on three areas: analysis of the tectonics and paleoclimatic conditions in north eastern Africa, analysis of surficial geology and damage associated with the 1993 Missouri River floods and rates of lava flow degradation at Lunar Crater volcanic field in Nevada. Work has resulted in several dozen abstracts, several dissertations and a number of papers.

Arvidson, Raymond E.

1997-01-01

380

Moss nutrient plasticity in desert ecosystems: a hot-cold desert comparison  

E-print Network

of water and nutrients. Projections of future climate change suggest that many deserts will experienceMoss nutrient plasticity in desert ecosystems: a hot-cold desert comparison Becky A. Ball1.ball@asu.edu Introduction: · Desert biology live close to the physical limitations for life, constrained by low availability

Hall, Sharon J.

381

Desert-Adapted Crocs Found in Africa  

NSDL National Science Digital Library

This National Geographic site details the discovery of several small communities of crocodiles living on the southern edge of Africa's Sahara in desert conditions. The desert crocodiles have apparently adapted to the changing environment in northern Africa; 8,000 to 10,000 years ago, what is now desert was probably lush savannah and grasslands.

Hillary Mayell

382

Desert Babies Face Harsh Childhood  

NSDL National Science Digital Library

The phenomenon is the relationships between the animals and plants that inhabit the Sonoran Desert. The video shows a wide variety of animals raising their young, feeding, sheltering and protecting them. The video includes numerous examples of interactions between living things in this environment.

383

Factors determining desert dune type  

Microsoft Academic Search

While most observers recognize four elemental types of desert dunes (longitudinal, transverse, barchan and star1-3) there is little agreement about which factors determine these types. The angular relationships between the resultant of sand shifting winds and both the crest and principal slipfaces of the elemental types have been discussed qualitatively for many decades. These relationships have been quantified but the

R. J. Wasson; R. Hyde

1983-01-01

384

Regional and Seasonal Diet of the Western Burrowing Owl in South-Central Nevada  

Microsoft Academic Search

We examined diets of Western Burrowing Owls (Athene cunicularia hypugaea) based on contents of pellets and large prey remains collected year-round at burrows in each of the 3 regions in south central Nevada (Mojave Desert, Great Basin Desert, and Transition region). The most common prey items, based on percent frequency of occurrence, were crickets and grasshoppers, beetles, rodents, sun spiders,

Derek B. Hall; Paul D. Greger; Jeffrey R. Rosier

2009-01-01

385

Mesozoic evolution of the northeast African shelf margin, Libya and Egypt  

SciTech Connect

The present tectonic features of the northeast African shelf margin between the Nile delta and the Gulf of Sirte are products of (1) precursory late Paleozoic basement arches, (2) early Mesozoic rifting and plate separation, and (3) Late Cretaceous structural inversion. Isopach and structural maps, cross sections, and sediment accumulation (geohistory) curves constructed from 89 wells in the Western Desert and 27 wells in northeastern Libya depict the structural and stratigraphic development of the northeast African shelf margin.

Aadland, R.K.; Schamel, S.

1988-08-01

386

Management of Disused Radioactive Sealed Sources in Egypt - 13512  

SciTech Connect

The future safe development of nuclear energy and progressive increasing use of sealed sources in medicine, research, industry and other fields in Egypt depends on the safe and secure management of disused radioactive sealed sources. In the past years have determined the necessity to formulate and apply the integrated management program for radioactive sealed sources to assure harmless and ecological rational management of disused sealed sources in Egypt. The waste management system in Egypt comprises operational and regulatory capabilities. Both of these activities are performed under legislations. The Hot Laboratories and Waste Management Center HLWMC, is considered as a centralized radioactive waste management facility in Egypt by law 7/2010. (authors)

Mohamed, Y.T.; Hasan, M.A.; Lasheen, Y.F. [Hot Laboratories and Waste Management Center, Egyptian Atomic Energy Authority, 11787, Cairo (Egypt)] [Hot Laboratories and Waste Management Center, Egyptian Atomic Energy Authority, 11787, Cairo (Egypt)

2013-07-01

387

Modeling Soil Moisture in the Mojave Desert  

USGS Publications Warehouse

The Mojave Desert is an arid region of southeastern California and parts of Nevada, Arizona, and Utah; the desert occupies more than 25,000 square miles (fig. 1). Ranging from below sea level to over 5,000 feet (1,524 m) in elevation, the Mojave Desert is considered a ?high desert.? On the west and southwest it is bounded by the Sierra Nevada, the San Gabriel, and the San Bernardino Mountains. These imposing mountains intercept moisture traveling inland from the Pacific Ocean, producing arid conditions characterized by extreme fluctuations in daily temperatures, strong seasonal winds, and an average annual precipitation of less than six inches. The Mojave Desert lies farther south and at a lower elevation than the cooler Great Basin Desert and grades southward into the even lower and hotter Sonoran Desert.

Miller, David M.; Hughson, Debra; Schmidt, Kevin M.

2008-01-01

388

Rheum palaestinum (desert rhubarb), a self-irrigating desert plant  

NASA Astrophysics Data System (ADS)

The rare plant Rheum palaestinum (Polygonaceae) is a perennial hemicryptophyte that grows during the rainy winter in desert mountainous areas in Israel and Jordan that receive an average annual rainfall of ca. 75 mm. It produces between one and four large round leaves that are tightly attached to the ground and form large rosettes of up to 1 m2. These leaves differ markedly from the typical small leaves of most desert plants. Moreover, they have a unique 3D morphology resembling a scaled-down mountainous area with well-developed steep drainage systems, raising the question which selective agents were involved in their evolution. We propose that the large leaves collect rainwater that then infiltrates the soil surrounding the root. We measured the seasonal course of leaf growth, examined the area of wet soil surrounding the root after actual and simulated rain, and modeled the water harvesting capacity using the plant leaf area and the weekly precipitation. We show that even in the slightest rains, water flows above the veins to the leaf’s base where it irrigates the vertical root. A typical plant harvests more than 4,100 cm3 of water per year, and enjoys a water regime of about 427 mm/year, equivalent to the water supply in a Mediterranean climate. This is the first example of self-irrigation by large leaves in a desert plant, creating a leaf-made mini oasis.

Lev-Yadun, Simcha; Katzir, Gadi; Ne`Eman, Gidi

2009-03-01

389

Textural parameters of desert sediments — Thar desert (India)  

NASA Astrophysics Data System (ADS)

The textural study of a sizable number of samples from the various microenvironments of the Thar Desert reveals that the overall size of the desert sediments corresponds to fine sand (2-3 ?); the crests of the dunes are coarser than the flanks; the sediments have bimodal and/or polymodal population, they show a high sand/silt ratio, are well sorted, and are fine-skewed to strongly-fine-skewed; most of the sediments show platykurtic and very platykurtic curves, exhibit subangular to subrounded outlines, and show a moderate to high degree of sphericity. It is concluded that the scatter plots between moment mean ( overline?) and moment skewness ( ?3), moment mean ( overline?) and first percentile, graphic mean ( Mz) and inclusive graphic skewness ( SkI), moment standard deviation ( ?) and moment mean ( overline?), moment standard deviation ( ?) and first percentile, cubed standard deviation and mean cubed deviation ( ?3?3), moment standard deviation ( ?) and moment skewness ( ?3), and moment standard deviation ( ?) and mean cubed deviation ( ?3?3), can safely be used to distinguished the desert sediments from those accumulated in river and beach environments.

Chaudhri, R. S.; Khan, H. M. M.

1981-01-01

390

Anthropogenic enhancement of Egypt's Mediterranean fishery.  

PubMed

The highly productive coastal Mediterranean fishery off the Nile River delta collapsed after the completion of the Aswan High Dam in 1965. But the fishery has been recovering dramatically since the mid-1980s, coincident with large increases in fertilizer application and sewage discharge in Egypt. We use stable isotopes of nitrogen (delta(15)N) to demonstrate that 60%-100% of the current fishery production may be from primary production stimulated by nutrients from fertilizer and sewage runoff. Although the establishment of the dam put Egypt in an ideal position to observe the impact of rapid increases in nutrient loading on coastal productivity in an extremely oligotrophic sea, the Egyptian situation is not unique. Such anthropogenically enhanced fisheries also may occur along the northern rim of the Mediterranean and offshore of some rapidly developing tropical countries, where nutrient concentrations in the coastal waters were previously very low. PMID:19164510

Oczkowski, Autumn J; Nixon, Scott W; Granger, Stephen L; El-Sayed, Abdel-Fattah M; McKinney, Richard A

2009-02-01

391

Ostrich (Struthio camelus) production in Egypt.  

PubMed

This review discusses the historical, developmental and practices of ostrich farming in Egypt. In the early 20th century, ostrich farming was very important for production of ostrich feathers and documents were produced to perfect the art of procuring the plumes from the birds and subsequently processing them. Pharaohs used ostrich feathers for adornment. Of 43 provinces, 12 were featured in 2003-2004 as farming ostriches: Alexandria, Al-Behera, Al-Dakahlia, Al-Wadi Al-Gadid, Aswan, Cairo, El-Sharkia, Geiza, Ismailia, Kafr-El-Sheikh, Matrouh and Nubaria. Abattoirs and tanneries specialising in ostrich handling are limited to two. Egypt has numerous strengths and opportunities to develop its ostrich sector. Rising meat prices suggest that fresh ostrich meat is unaffordable to many locals. Funds may be allocated to local advertising campaigns to promote ostrich meat; provision of incentives to farmers; and improving the capacity of abattoirs. PMID:18509943

Cooper, R G; Mahrose, K M A; El-Shafei, M; Marai, I F M

2008-06-01

392

Benchmarking performance: Environmental impact statements in Egypt  

SciTech Connect

Environmental impact assessment (EIA) was formally introduced in Egypt in 1994. This short paper evaluates 'how well' the EIA process is working in practice in Egypt, by reviewing the quality of 45 environmental impact statements (EISs) produced between 2000 and 2007 for a variety of project types. The Lee and Colley review package was used to assess the quality of the selected EISs. About 69% of the EISs sampled were found to be of a satisfactory quality. An assessment of the performance of different elements of the EIA process indicates that descriptive tasks tend to be performed better than scientific tasks. The quality of core elements of EIA (e.g., impact prediction, significance evaluation, scoping and consideration of alternatives) appears to be particularly problematic. Variables that influence the quality of EISs are identified and a number of broad recommendations are made for improving the effectiveness of the EIA system.

Badr, El-Sayed A., E-mail: ebadr@mans.edu.e [Environmental Sciences Department, Faculty of Science at Damietta, Mansoura University, New Damietta City, PO Box 103 (Egypt); Zahran, Ashraf A., E-mail: ashraf_zahran@yahoo.co [Environmental Studies and Research Institute, Minufiya University, Sadat City, Sixth Zone, PO 32897 (Egypt); Cashmore, Matthew, E-mail: m.cashmore@uea.ac.u [InteREAM, School of Environmental Sciences, University of East Anglia, Norwich, Norfolk, NR4 7TJ (United Kingdom)

2011-04-15

393

Murder or Not and other Egypt Stuff  

NSDL National Science Digital Library

The students will discover information about Egypt and decide if the, boy king, Tutankhamun, was murdered or died of natural causes. The first two sites will lead the students to discover all about: *Geography *Egyptian People and their Life Styles *Death and Burial *Egyptian Mythology *Pyramids *Temples and the Pharaohs *Egyptian Writing On the third site the students will learn all about King Tut and write a persuasive essay; taking a stand on if he was murdered or not. The ...

Mrs. Niebergall

2007-11-06

394

MERS Coronaviruses in Dromedary Camels, Egypt  

PubMed Central

We identified the near-full-genome sequence (29,908 nt, >99%) of Middle East respiratory syndrome coronavirus (MERS-CoV) from a nasal swab specimen from a dromedary camel in Egypt. We found that viruses genetically very similar to human MERS-CoV are infecting dromedaries beyond the Arabian Peninsula, where human MERS-CoV infections have not yet been detected. PMID:24856660

Chu, Daniel K.W.; Poon, Leo L.M.; Gomaa, Mokhtar M.; Shehata, Mahmoud M.; Perera, Ranawaka A.P.M.; Abu Zeid, Dina; El Rifay, Amira S.; Siu, Lewis Y.; Guan, Yi; Webby, Richard J.; Ali, Mohamed A.

2014-01-01

395

MERS coronaviruses in dromedary camels, Egypt.  

PubMed

We identified the near-full-genome sequence (29,908 nt, >99%) of Middle East respiratory syndrome coronavirus (MERS-CoV) from a nasal swab specimen from a dromedary camel in Egypt. We found that viruses genetically very similar to human MERS-CoV are infecting dromedaries beyond the Arabian Peninsula, where human MERS-CoV infections have not yet been detected. PMID:24856660

Chu, Daniel K W; Poon, Leo L M; Gomaa, Mokhtar M; Shehata, Mahmoud M; Perera, Ranawaka A P M; Abu Zeid, Dina; El Rifay, Amira S; Siu, Lewis Y; Guan, Yi; Webby, Richard J; Ali, Mohamed A; Peiris, Malik; Kayali, Ghazi

2014-06-01

396

Household income and child survival in Egypt  

Microsoft Academic Search

This article uses household-level economic and fertility survey data to examine the relationship between household income\\u000a and child survival in Egypt. Income has little effect on infant mortality but is inversely related to mortality in early childhood.\\u000a The relationship persists with other associated socioeconomic variables controlled. The mechanisms underlying the income effects\\u000a are not evident from this analysis: income differentials

John B. Casterline; Elizabeth C. Cooksey; Abdel Fattah E. Ismail

1989-01-01

397

Ostrich ( Struthio camelus ) production in Egypt  

Microsoft Academic Search

This review discusses the historical, developmental and practices of ostrich farming in Egypt. In the early 20th century,\\u000a ostrich farming was very important for production of ostrich feathers and documents were produced to perfect the art of procuring\\u000a the plumes from the birds and subsequently processing them. Pharaohs used ostrich feathers for adornment. Of 43 provinces,\\u000a 12 were featured in

R. G. Cooper; Kh. M. A. Mahrose; M. El-Shafei; I. F. M. Marai

2008-01-01

398

Mortality, Recruitment and Change of Desert Tree Populations in a Hyper-Arid Environment  

PubMed Central

Background Long-term vegetation changes in hyper-arid areas have long been neglected. Mortality, recruitment and change in populations of the ecologically and culturally important and drought persistent Acacia tortilis and Balanites aegyptiaca are therefore estimated in the Eastern Desert of Egypt, and are related to the primary agents of change, water conditions and human intervention. Methodology A change analysis using high-resolution Corona images (1965) in combination with field data (2003) is the basis for recruitment, mortality and change estimates. For assessing the influence of water conditions on patterns in recruitment and survival, different types of generalized linear models are tested. Conclusions The overall trend in population size in that part of the Eastern Desert studied here is negative. At some sites this negative trend is alarming, because the reduction in mature trees is substantial (>50%) at the same time as recruitment is nearly absent. At a few sites there is a positive trend and better recruitment. Frequent observations of sprouting in saplings indicate that this is an important mechanism to increase their persistence. It is the establishment itself that seems to be the main challenge in the recruitment process. There are indications that hydrological variables and surface water in particular can explain some of the observed pattern in mortality, but our results indicate that direct human intervention, i.e., charcoal production, is the main cause of tree mortality in the Eastern Desert. PMID:17299588

Andersen, Gidske L.; Krzywinski, Knut

2007-01-01

399

Phylogeography of Beck's Desert Scorpion, Paruroctonus becki, reveals Pliocene diversification in the Eastern California Shear Zone and postglacial expansion in the Great Basin Desert.  

PubMed

The distribution of Beck's Desert Scorpion, Paruroctonus becki (Gertsch and Allred, 1965), spans the 'warm' Mojave Desert and the western portion of the 'cold' Great Basin Desert. We used genetic analyses and species distribution modeling to test whether P. becki persisted in the Great Basin Desert during the Last Glacial Maximum (LGM), or colonized the area as glacial conditions retreated and the climate warmed. Phylogenetic and network analyses of mitochondrial cytochrome c oxidase 1 (cox1), 16S rDNA, and nuclear internal transcribed spacer (ITS-2) DNA sequences uncovered five geographically-structured groups in P. becki with varying degrees of statistical support. Molecular clock estimates and the geographical arrangement of three of the groups suggested that Pliocene geological events in the tectonically dynamic Eastern California Shear Zone may have driven diversification by vicariance. Diversification was estimated to have continued through the Pleistocene, during which a group endemic to the western Great Basin diverged from a related group in the eastern Mojave Desert and western Colorado Plateau. Demographic and network analyses suggested that P. becki underwent a recent expansion in the Great Basin. According to a landscape interpolation of genetic distances, this expansion appears to have occurred from the northwest, implying that P. becki may have persisted in part of the Great Basin during the LGM. This prediction is supported by species distribution models which suggest that climate was unsuitable throughout most of the Great Basin during the LGM, but that small patches of suitable climate may have remained in areas of the Lahontan Trough. PMID:23933071

Graham, Matthew R; Jaeger, Jef R; Prendini, Lorenzo; Riddle, Brett R

2013-12-01

400

Desert Dust Kills Florida Fish  

NSDL National Science Digital Library

This news article details a red tide event that was spread across the Atlantic by a combination of storms in the Sahara Desert region and easterly trade winds that spread fertilized or nutrient overloaded soils to the Gulf of Mexico and Florida coastal regions. The article includes options to listen to the story via streaming audio and downloading capability. It also features colorful pictures and animations provided by NASA satellites. Related weblinks are included.

Patrick L. Barry

401

African Historical Religions: A Conceptual and Ethnical Foundation for "Western Religions."  

ERIC Educational Resources Information Center

This paper attempts to set the record straight with regard to the following assumptions: (1) the Africans of the antiquities of Ethiopia and Egypt were black people; and (2) the same black people developed the foundation that provides the basis for the so-called major Western religions of Judaism, Christianity, and Islam. There are two parts to…

Alexander, E. Curtis

402

Western Skink  

USGS Multimedia Gallery

The Western skink (Plestiodon skiltonianus) is a relatively common and widespread lizard in Southern California. It is more secretive and prefers more grassy habitat than the Western fence lizard or the side-blotched lizard, yet USGS and National Park Service biologists are finding signs of genetic ...

403

Enabling Entrepreneurship in Egypt: Toward a Sustainable Dynamic Model  

Microsoft Academic Search

The objective of this report is to assess the current status of entrepreneurship in Egypt, and to offer strategic and actionable recommendations that will enable entrepreneurship and significantly impact the Egyptian economy. The report offers a fresh look at entrepreneurship in Egypt and the support mechanisms currently at play, assesses the initiatives and challenges at hand, and provides multilevel recommendations

Mohamed El Dahshan; Ahmed H. Tolba; Tamer Badreldin

2012-01-01

404

Separate but Equal: Segregated Religious Education in Egypt's Public Schools  

ERIC Educational Resources Information Center

The Arab Spring exposed the hidden secrets of Egyptian society to the global community. In spite of the insatiable media attention paid to the Mubarak regime and the toll it took on the entire country, Egypt's education system received little attention. For decades, Egypt's public schools have forced students to attend segregated classes, based on…

Isaac, John

2012-01-01

405

Power and Gender in Ancient Egypt: The Case of Hatshepsut  

ERIC Educational Resources Information Center

Hatshepsut (1479-1458 B.C.E) ruled New Kingdom Egypt for roughly 20 years as one of the few female pharaohs in the history of ancient Egypt. Her rule began when her husband died and her stepson was too young to be pharaoh. To legitimize her role as pharaoh, Hatshepsut began a significant building campaign by constructing numerous images, temples,…

Hilliard, Kristina; Wurtzel, Kate

2009-01-01

406

A SURVEY OF CYST NEMATODES (HETERODERA SPP.) IN NORTHERN EGYPT  

Technology Transfer Automated Retrieval System (TEKTRAN)

Information concerning the occurrence and distribution of cyst nematodes (Heterodera spp.) in Egypt is important to assess their potential to cause economic damage to crop plants. A nematode survey was conducted in Alexandria and El-Behera Governorates in northern Egypt to identify the species of cy...

407

Egypt's Bounty via the Humble Potstand Maria A. Gutierrez, McNair Scholar, Pennsylvania State University  

E-print Network

120 Egypt's Bounty via the Humble Potstand Maria A. Gutierrez, McNair Scholar, Pennsylvania State thing in Upper Egypt, in Lower Egypt, all life, stability and power..." Sesostris I pavilion at Karnak to their king Sesostris (fig. 1) the bounty of Egypt as also connoting the best in life. In looking at various

Omiecinski, Curtis

408

Published: 3 November 2014 Don't Cut Aid to Egypt: The Hopeful Case for  

E-print Network

1 Published: 3 November 2014 Don't Cut Aid to Egypt: The Hopeful Case for Supporting Egyptian President Sisi Today, the U.S. needs Egypt's partnership more than ever. Op-Ed by Ahmed H. Zewail Some support him. And I believe that cutting foreign aid to Egypt at this point would harm the U.S.-Egypt

Zewail, Ahmed

409

Education, Social Mobility and Religious Movements: A Theory of the Islamic Revival in Egypt  

E-print Network

Education, Social Mobility and Religious Movements: A Theory of the Islamic Revival in Egypt on changes to Egypt's educational system over the past half-century as well as about the employment guarantee century must be viewed against Egypt's high population growth. Egypt's population increased from 22

Brody, James P.

410

Influence of surface roughness of a desert  

NASA Technical Reports Server (NTRS)

A numerical simulation study, using the current GLAS climate GCM, was carried out to examine the influence of low bulk aerodynamic drag parameter in the deserts. The results illustrate the importance of yet another feedback effect of a desert on itself, that is produced by the reduction in surface roughness height of land once the vegetation dies and desert forms. Apart from affecting the moisture convergence, low bulk transport coefficients of a desert lead to enhanced longwave cooling and sinking which together reduce precipitation by Charney's (1975) mechanism. Thus, this effect, together with albedo and soil moisture influence, perpetuate a desert condition through its geophysical feedback effect. The study further suggests that man made deserts is a viable hypothesis.

Sud, Y. C.; Smith, W. E.

1984-01-01

411

Recoverability and Vulnerability of Desert Ecosystems  

NSDL National Science Digital Library

USGS scientists are taking an interdisciplinary approach to understanding the physical and biological processes that influence the vulnerability of the desert ecosystem to disturbance and its ability to recover. They are studying historical information, conducting experimental studies on physical and biological processes, and mapping and modeling the existing landscape. These data can be synthesized into maps and predictive models that show how ecosystem components respond to imposed stress, providing valuable tools for desert land managers. Such tools will help land managers make decisions that sustain the desert even as economic, recreation, and military uses continue. The site includes links to publications, maps, a glossary and links to other materials on Mojave desert ecosystems.

412

Plants--Desert Studies Center + -Common names from Edmund Jaeger's Desert Wild Flowers  

E-print Network

Plants--Desert Studies Center + - Common names from Edmund Jaeger's Desert Wild Flowers * - Common *Colorado Desert-marigold, +Lax-flower Baileya pleniradiata *+Woolly-marigold Bebbia juncea asper carphoclinia *+Pebble-pincushion Chaenactis fremontii *+Fremont-pincushion Chaenactis stevioides *Broad-flowered

de Lijser, Peter

413

Desert Dust Kills Florida Fish  

NSDL National Science Digital Library

This National Aeronautics and Space Administration (NASA) article discusses the connection between dust storms in Africa, and red tides along the Florida coast. Red tides are blooms of toxic algae that kill fish, birds, and mammals, as well as cause health problems in humans. Storm activity in the Sahara Desert region kicks up topsoil that winds transport into the Gulf of Mexico. These clouds fertilize the water with iron, which bacteria named Trichodesmium use to create nitrogen. The nitrogen makes the water a friendly environment for the toxic algae. This article discusses this process and research that is going on to help solve the problem. Audio version is available as well.

414

Boats of Egypt before the old kingdom  

E-print Network

-Salaam and the earlier phases of El-Omari, probably predate the Predynastic of Upper Egypt. The Fayum cultures settled on the banks of Lake Moeris in a depression west of the Nile (Casini, 1984: 203; Arkell and Ucko, 1965: 145). No copper has been found ln a neolithic... lower date for at least some "Bedarien" cultures, According to Hays. a charcoal sample assocated with a Bedarian burial at El Khettara yielded e date of 4810 B. P. plus or minus 80, or between 3400 and 3470 on the HASCA calllbration (T. R. Hays, 1984...

Vinson, Steve

1987-01-01

415

Pillow form morphology of selected Neoproterozoic metavolcanics in the Egyptian Central Eastern Desert and their implications  

NASA Astrophysics Data System (ADS)

This study discusses the features of well-preserved pillow forms of seven Neoproterozoic metavolcanic occurrences found in the Central Eastern Desert of Egypt and compares them to modern and ancient tectonic environments. The aim is to present a mode of origin model, parent magma composition and eruption environment of these lavas. Categorized on size and shape, three different pillow types have been recognized: elongated pillows (type A), in the Muweilih and Wadi Beririq; bulbous pillows (type B) in Wadi Ghadir, Gabal Ghadir and Wadi Um Seleimat; and spherical pillows (type C) in Wadi Kareim and Gabal Semna. Absent in the studied pillow forms are the tubular type pillow, connection between pillows, and radial crack features. The most prominent features of the studied pillows are flattening, tight packing with development of chilled margins, small size, and the abundance of vesicular structure. These features indicate their accumulation at high initial temperature and hydrostatic pressure, low viscosity, and rapid eruption when compared to modern mid-oceanic ridge pillows. The significant features of the studied pillow forms show they differ from pillows of the modern mid-oceanic ridge environments, and are akin to pillows found in ancient marginal basin environments (especially types A and B). The small size of type C pillows is considered a by-product of the felsic composition, which suggests formation in an island-arc environment. The deduced paleotectonic environments are supported by geochemical data and the resulting regional implication is that the central part of the Eastern Desert of Egypt could represent a SE subducted arc-back-arc system.

Farahat, E. S.; El Mahallawi, M. M.; Hoinkes, G.; Abdel Aal, A. Y.; Hauzenberger, C. A.

2010-04-01

416

12007 Desert Symposium Wild,scenic and rapid  

E-print Network

Desert State Park, San Diego County, California, compiler California State University,Desert Studies Consortium and LSA Associates,Inc. April 2007 #12 Colorado River, Anza-Borrego Desert State Park, California: a review

de Lijser, Peter

417

Optical characteristics of desert dust  

NASA Astrophysics Data System (ADS)

We have been conducting research aimed at enabling prediction of desert optical environments from meteorological and satellite observations. To this end we have been collecting aerosol size distributions, visibility and meteorological data continuously for the past year at 2 sites in the Mojave Desert of California. Optical properties of dust are calculated from these data for a great variety of meteorological conditions. The concentration of dust particles is strongly dependent on wind speed for speeds greater than a threshold (7 m/s at Edwards and 15 m/s at China Lake). For individual wind episodes there is a clear relationship between wind speed and dust mass. However, that relationship changes from event to event leading to noisy summary plots; thus, indicating that other factors, such as dust sources, also influence dust loading. The HYPACT program is used to map out the sources, concentration and flow of dust. HYPACT is a pollution transport program that uses RAMS meteorological code output for input. HYPACT can calculate concentration forward in time from an assumed emission source or backward in time from an observation site. This facilitates the location of dust sources and the calculation of dust concentrations along air streams. Once dust concentrations are known and assuming the particle size distributions are the same as at the measurement sites knowledge of IR extinction is no longer confined to just the measurement sites.

Walker, Philip L.; Blomshield, Fred

2002-08-01

418

Deformation History Of Jabal Muqsim Ophiolitic Nappe And Environs, Allaqi District: Implications For The Tectonic Evolution Of The South Eastern Desert Tectonic Terrane In NE Nubian Shield Zakaria Hamimi*, Yahia El-Kazzaz** and Abdelhamid El-Fakharani* * Department of Structural Geology and Remote Sensing, Faculty of Earth Sciences, King Abdulaziz University, Jeddah 21589, P.O.B 80206 ** Geology Department, Faculty of Science, Helwan University, Egypt  

NASA Astrophysics Data System (ADS)

The Neoproterozoic basement rocks exposed in Jabal Muqsim area and environs are discriminated, based on field relations and petrographic investigations, into three main tectono-stratigraphic units; dismembered ophiolitic suite, metavolcaniclastics and syn- to post-tectonic intrusives. The ophiolitic rocks comprise variably-sized slices of metaultramaifcs, amphibolites and metagabbros, thrusted from SE to NW over, and incorporated within, highly sheared metasediments. The metavolcaniclastics consist of clastic sequence varies from poorly sorted proximal to well developed laminated distal tuffs. These rocks suffered a prolonged history of deformation resulted in remarkable change in the clasts into NW-plunged oriented deformed pebbles. The intrusives embrace layered gabbros and syn- to post-tectonic granitoids. Structural analysis of mesoscopic structures indicated that the area has undergone a poly-phase deformation history involving three phases of deformation (D1-D3). D1 was a N-S to NNW-SSE shortening phase, led to the formation of tight to isoclinal and intrafolial folds (F1), penetrative foliation (S1), and subhorizontal crenulation and mineral lineation (L1). D2 was a progressive phase of D1 and both of them were most probably the consequence of the accretion between the South Eastern Desert tectonic terrane and the Gabgaba tectonic terrane along the conspicuous Allaqi-Heiani Shear Zone. D2 dominated by S- to SSE-dipping imbricated thrusts and thrust duplexes, as well as N- to NNW-verging F2 thrust-related folds. D3 was an E-W to ENE-WSW shortening phase, accompanied with the later collision between East- and West-Gondwana blocks in the late Cryogenian-Ediacaran (650-542 Ma). It was responsible for the formation of F3 open folds and subvertical S3 foliation. Progressive convergence between East and West Gondwana was accommodated in the study area by distinct reverse displacements along S1.

Hamimi, Z. E.

2012-12-01

419

ECOLOGY OF DESERT SYSTEMS BOOK REVIEW  

Technology Transfer Automated Retrieval System (TEKTRAN)

The 12 chapters of Whitford's book, Ecology of Desert Systems, summarize the comprehensive experiences and knowledge of a scientist with an extensive research background on a wide variety of physical and biological aspects of desert ecology. The author illustrates facts and concepts presented in th...

420

Magnetic Analysis Techniques Applied to Desert Varnish  

NASA Technical Reports Server (NTRS)

Desert varnish is a black or reddish coating commonly found on rock samples from arid regions. Typically, the coating is very thin, less than half a millimeter thick. Previous research has shown that the primary components of desert varnish are silicon oxide clay minerals (60%), manganese and iron oxides (20-30%), and trace amounts of other compounds [1]. Desert varnish is thought to originate when windborne particles containing iron and manganese oxides are deposited onto rock surfaces where manganese oxidizing bacteria concentrate the manganese and form the varnish [4,5]. If desert varnish is indeed biogenic, then the presence of desert varnish on rock surfaces could serve as a biomarker, indicating the presence of microorganisms. This idea has considerable appeal, especially for Martian exploration [6]. Magnetic analysis techniques have not been extensively applied to desert varnish. The only previous magnetic study reported that based on room temperature demagnetization experiments, there were noticeable differences in magnetic properties between a sample of desert varnish and the substrate sandstone [7]. Based upon the results of the demagnetization experiments, the authors concluded that the primary magnetic component of desert varnish was either magnetite (Fe3O4) or maghemite ( Fe2O3).

Schmidgall, E. R.; Moskowitz, B. M.; Dahlberg, E. D.; Kuhlman, K. R.

2003-01-01

421

Before you arrive... Drylands, Deserts & Desertification 2012  

E-print Network

1 Before you arrive... Drylands, Deserts & Desertification 2012 November 12-15, 2012 Sede Boqer that you can use to layer. Sde Boqer is part of the Negev desert, and will be cool in the mornings, warm on spending the weekend in any of the conference venues, please make sure to order food in advance, as almost

Prigozhin, Leonid

422

Being Logical About Desert Island Reading  

Microsoft Academic Search

To begin with, I refuse to be stranded on a desert island: sand without vegetation, hot sun, and salty water are just not conducive to good thinking. So let’s get into deserted tropical island mood, which is what everyone else has been doing. First, let’s wind time back to around 1978. This is important because our bodies can do without

Alex Borgida

2002-01-01

423

Desert Amplification of Greenhouse Gas Warming  

NASA Astrophysics Data System (ADS)

Surface temperatures over the Sahara and Arabian Deserts are increasing at a rate that is 3.5 times that of the global mean. These regions have warmed by 1.4 K between 1980 and 2012. In the tropical (and global) mean, added energy incident at the surface due to increased concentrations of greenhouse gases is used partly to increase the surface temperature, and partly to evaporate water. The resulting atmospheric water vapor anomaly is effectively mixed vertically and horizontally throughout the tropics on annual time scales, and amplifies the greenhouse effect (increased longwave back radiation to the surface) everywhere, including over the deserts. But, on the desert surface, evaporative cooling is disabled and the enhanced longwave energy incident on the surface serves only to increase surface temperature. Despite the fact that this desert amplification mechanism should operate over any dry surface, the other deserts of the world are not exhibiting accelerated warming. Each of these deserts is smaller than the Sahara/Arabian Desert area, and various regional processes dominate over the desert amplification mechanism.

Cook, K. H.

2013-12-01

424

The age of the Sahara desert.  

PubMed

In the Sahara region, the age of onset of the desert condition has been uncertain until now. Here we report on the discovery of 7,000,000-year-old eolian dune deposits from the northern Chad Basin. This geological archive is the oldest known evidence for desert occurrence in the Sahara. PMID:16469920

Schuster, Mathieu; Duringer, Philippe; Ghienne, Jean-François; Vignaud, Patrick; Mackaye, Hassan Taisso; Likius, Andossa; Brunet, Michel

2006-02-10

425

Notes from the Great American Desert  

ERIC Educational Resources Information Center

In the good old days, the state that is Nebraska was identified as part of the Great American Desert. In many ways, in climate and terrain, it still bears a resemblance to a desert. As a frontier or a land of pioneers, it deserves recognition. Invisibility may be one of the greatest challenges women face. One of the great flaws in the writing of…

Grady, Marilyn L.; LaCost, Barbara Y.

2005-01-01

426

Is the Sonoran Desert losing its cool?  

Microsoft Academic Search

Freezing temperatures strongly influence vegetation in the hottest desert of North America, in part determining both its overall boundary and distributions of plant species within. To evaluate recent variability of freezing temperatures in this context, minimum temperature data from weather stations in the Sonoran Desert are examined. Data show widespread warming trends in winter and spring, decreased frequency of freezing

JEREMY L. W EISS; J ONA; T HAN T. O VERPECK

427

On carbon sequestration in desert ecosystems  

USGS Publications Warehouse

Recent reports of net ecosysytem production >100 g C m-2 yr-1 in deserts are incompatible with existing measurements of net primary production and carbon pools in deserts. The comparisions suggest that gas exchange measurements should be used with caution and better validation if they are expected to indicate the magnitude of carbon sink in these ecosysytems. ?? 2009 Blackwell Publishing.

Schlesinger, W.H.; Belnap, J.; Marion, G.

2009-01-01

428

Sea Breezes over the Red Sea: Affect of topography and interaction with Desert Convective Boundary Layer  

NASA Astrophysics Data System (ADS)

Thermodynamic structure of sea-breeze, its interaction with coastal mountains, desert plateau and desert convective boundary layer have been investigated in the middle region of the Red Sea around 25°N, at the Western coast of Saudi Arabia. Sea and land breeze is a common meteorological phenomenon in most of the coastal regions around the world. Sea-Breeze effects the local meteorology and cause changes in wind speed, direction, cloud cover and sometimes precipitation. The occurrence of sea-breeze, its intensity and landward propagation are important for wind energy resource assessment, load forecasting for existing wind farms, air pollution, marine and aviation applications. The thermally induced mesoscale circulation of sea breeze modifies the desert Planetary Boundary Layer (PBL) by forming Convective Internal Boundary Layer (CIBL), and propagates inland as a density current. The leading edge of the denser marine air rapidly moves inland undercutting the hot and dry desert air mass. The warm air lifts up along the frontal boundary and if contains enough moisture a band of clouds is formed along the sea breeze front (SBF). This study focuses on the thermodynamic structure of sea-breeze as it propagates over coastal rocky mountain range of Al-Sarawat, east of the Red Sea coast, and the desert plateau across the mountain range. Additional effects of topographical gaps such as Tokar gap on the dynamics of sea-land breezes have also been discussed. Interaction of SBF with the desert convective boundary layer provide extra lifting that could further enhance the convective instability along the frontal boundary. This study provides a detailed analysis of the thermodynamics of interaction of the SBF and convective internal boundary layer over the desert. Observational data from a buoy and meteorological stations have been utilized while The Advanced Research WRF (ARW) modeling system has been employed in real and 2D idealized configuration.

Khan, Basit A.; Stenchikov, Georgiy; Abualnaja, Yasser

2014-05-01

429

Associations between Leaf Structure, Orientation, and Sunlight Exposure in Five Western Australian Communities  

Microsoft Academic Search

Five plant communities in Western Australia, as well as selected desert and Rocky Mountain species of the western USA, were surveyed to evaluate associations among leaf structure, orientational properties, and the sunlight exposure and precipitation characteristic of each community. Selected leaf structural features have been associated previously with photosynthetic function and included shape, thickness, the ratio of thickness to width,

William K. Smith; David T. Bell; Kelly A. Shepherd

1998-01-01

430

Characterization of the Sonoran desert as a radiometric calibration target for Earth observing sensors  

USGS Publications Warehouse

To provide highly accurate quantitative measurements of the Earth's surface, a comprehensive calibration and validation of the satellite sensors is required. The NASA Moderate Resolution Imaging Spectroradiometer (MODIS) Characterization Support Team, in collaboration with United States Geological Survey, Earth Resources Observation and Science Center, has previously demonstrated the use of African desert sites to monitor the long-term calibration stability of Terra MODIS and Landsat 7 (L7) Enhanced Thematic Mapper plus (ETM+). The current study focuses on evaluating the suitability of the Sonoran Desert test site for post-launch long-term radiometric calibration as well as cross-calibration purposes. Due to the lack of historical and on-going in situ ground measurements, the Sonoran Desert is not usually used for absolute calibration. An in-depth evaluation (spatial, temporal, and spectral stability) of this site using well calibrated L7 ETM+ measurements and local climatology data has been performed. The Sonoran Desert site produced spatial variability of about 3 to 5% in the reflective solar regions, and the temporal variations of the site after correction for view-geometry impacts were generally around 3%. The results demonstrate that, barring the impacts due to occasional precipitation, the Sonoran Desert site can be effectively used for cross-calibration and long-term stability monitoring of satellite sensors, thus, providing a good test site in the western hemisphere.

Angal, Amit; Chander, Gyanesh; Xiong, Xiaoxiong; Choi, Tae-young; Wu, Aisheng

2011-01-01

431

Seed polymorphism in two western Nevada Indian ricegrass communities  

Technology Transfer Automated Retrieval System (TEKTRAN)

Indian ricegrass (Achnatherum hymenoides) is a dominant perennial grass species in salt desert communities and lower elevations of the sagebrush (Artemisia) vegetation zone of western North America. This perennial bunchgrass reaches its heaviest densities on sandy soils and is an important winter f...

432

EVOLUTION AFTER THE FLOOD: PHYLOGEOGRAPHY OF THE DESERT FISH UTAH CHUB  

Microsoft Academic Search

Abstract. The Bonneville Basin and upper,Snake River drainage,of western,North America,underwent,extensive hydrological changes during the late Pleistocene, potentially influencing the geographic distribution and evolutionary trajectories of aquatic species that occupied this region. To test this hypothesis, I reconstructed the phylogeographic history of the desert fish Utah chub (Gila atraria) by examining,16 populations,that span the natural distribution of this species across the

Jerald B. Johnson

2002-01-01

433

Proc. ICCS-X, Cairo, Egypt December 20-23, 2009, Vol. 18, pp. xx-xx ASTROCLADISTICS  

E-print Network

Proc. ICCS-X, Cairo, Egypt December 20-23, 2009, Vol. 18, pp. xx-xx ASTROCLADISTICS: MULTIVARIATE on Statistical Sciences, Cairo : Egypt (2009)" #12;Proc. ICCS-X, Cairo, Egypt December 20-23, 2009, Vol. 18, pp

Paris-Sud XI, Université de

434

Are ocean deserts getting larger?  

NASA Astrophysics Data System (ADS)

The spatial and temporal dynamics of ocean biomes and their provincial subdivisions are affected by the dynamics of Earth's climate system, but the effect of climate change on the distribution and variability of ocean biomes and provinces is largely unknown. A time-series analysis from multiple satellite platforms shows that the lowest productivity provinces have been growing over the last decade and that the growth rates of these provinces increase as they get larger, and decrease as they get smaller. The most oligotrophic provinces of the ocean grow by reducing the size of the slightly less oligotrophic provinces. As a consequence, while the ocean's most extreme deserts are increasing at an accelerating rate, some oligotrophic areas are simultaneously shrinking. The aggregate area of the oligotrophic provinces oscillated in phase with the Pacific Decadal Oscillation Index from 1998-2007.

Irwin, Andrew J.; Oliver, Matthew J.

2009-09-01

435

Desert potholes: Ephemeral aquatic microsystems  

USGS Publications Warehouse

An enigma of the Colorado Plateau high desert is the "pothole", which ranges from shallow ephemeral puddles to deeply carved pools. The existence of prokaryotic to eukaryotic organisms within these pools is largely controlled by the presence of collected rainwater. Multivariate statistical analysis of physical and chemical limnologic data variables measured from potholes indicates spatial and temporal variations, particularly in water depth, manganese, iron, nitrate and sulfate concentrations and salinity. Variation in water depth and salinity are likely related to the amount of time since the last precipitation, whereas the other variables may be related to redox potential. The spatial and temporal variations in water chemistry affect the distribution of organisms, which must adapt to daily and seasonal extremes of fluctuating temperature (0-60 ??C), pH changes of as much as 5 units over 12 days, and desiccation. For example, many species become dormant when potholes dry, in order to endure intense heat, UV radiation, desiccation and freezing, only to flourish again upon rehydration. But the pothole organisms also have a profound impact on the potholes. Through photosynthesis and respiration, pothole organisms affect redox potential, and indirectly alter the water chemistry. Laboratory examination of dried biofilm from the potholes revealed that within 2 weeks of hydration, the surface of the desiccated, black biofilm became green from cyanobacterial growth, which supported significant growth in heterotrophic bacterial populations. This complex biofilm is persumably responsible for dissolving the cement between the sandstone grains, allowing the potholes to enlarge, and for sealing the potholes, enabling them to retain water longer than the surrounding sandstone. Despite the remarkable ability of life in potholes to persist, desert potholes may be extremely sensitive to anthropogenic effects. The unique limnology and ecology of Utah potholes holds great scientific value for understanding water-rock-biological interactions with possible applications to life on other planetary bodies. ?? Springer 2005.

Chan, M.A.; Moser, K.; Davis, J.M.; Southam, G.; Hughes, K.; Graham, T.

2005-01-01

436