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Sample records for colluvium

  1. Defining Colluvium and Alluvium: An Experiment to Discuss and Consolidate Perspectives

    NASA Astrophysics Data System (ADS)

    Miller, Bradley; Juilleret, Jérôme

    2016-04-01

    Describing Earth materials with a shared terminology facilitates international collaboration because it reduces misunderstandings about the connections being made between observations and interpretations. The terms colluvium and alluvium are widely used, but their meanings vary almost as widely. Definitions for these terms can include connections to different geomorphic processes, landscape positions, or hydrology. In soil science, colluvium can be particularly influential as it is recognized in some national classification systems (e.g. France, Germany) as diagnostic material for "Colluvisols." Clarifying the meaning and diagnostic criteria of colluvium versus alluvium is especially important today because some definitions connect colluvium directly to erosion processes that are wide-spread and enhanced by anthropogenic activities. For example, the German "kolluvium" is pronounced the same as colluvium, but describes deposits at the base of hillslopes produced by water and/or tillage erosion. This contrasts with the common North American definition of colluvium describing materials transported primarily by gravity (i.e. mass movement). This poster raises awareness of the issue by illustrating the variety of published definitions for both colluvium and alluvium. Then it asks viewers to engage in the conversation by completing a survey either on paper or later online. The viewers are also invited to join the discussion on the same question, posed on the ResearchGate website (https://www.researchgate.net/post/How_do_you_define_colluvium).

  2. Geomorphic and paleoclimatic implications of latest Pleistocene radiocarbon dates from colluvium-mantled hollows, California

    SciTech Connect

    Reneau, S.L.; Dietrich, W.E.; Dorn, R.I.; Berger, C.R.; Rubin, M.

    1986-08-01

    Radiocarbon analyses of charcoal from basal colluvium in 11 California hollows show a clustering of dates between 9000 and 15,000 B.P., an indication that changes in the storage and discharge of colluvium from hillslopes accompanied the Pleistocene-Holocene transition. Hollows are sites of topographically induced convergence and deposition of colluvial debris, and evacuation of this debris was apparently more thorough and possibly more frequent in the latest Pleistocene, perhaps due to a combination of changes in vegetation and rainfall characteristics. One hypothesis is that greater storm intensities occurred in the latest Pleistocene and induced a higher frequency of landslides in hollows and a regional extension of channel heads upslope relative to the Holocene. During the last Pleistocene, California hollows apparently contained smaller volumes of colluvium in storage. The increased storage of debris during the Holocene may have resulted in a diminished supply of sediment to stream channels.

  3. The origin and its environmental significance of thick colluvium on the coast of Xiaolanyu Isle, Taiwan

    NASA Astrophysics Data System (ADS)

    Chyi, Shyh-Jeng; Jen, Chia-Hung; Ho, Lih-Der; Chen, Jia-Hong; Yen, Jiun-Yee; Liou, Ying-San; Chang, Chung-Pai; Lee, Chi-Yu; Lin, Jian-Wei; Yu, Neng-Ti; Yen, I.-Chin; Lu, Cheng-Hao

    2016-04-01

    The thick colluvium and a terrace are located at the northern and southern coast of Xiaolanyu Isle, Taiwan. Xiaolanyu Isle is the youngest volcanic island in the northern Luzon Arc, which lava was dated as 0.04 to 0.02 Ma. In its southern coast, the horizontal layers of sedimentary sequences are exposed on the 20-meter-high terrace scarp which mainly consisted of fine-grained, volcanic origin materials with soft-sediment deformation structures, which indicate the sediment layers are clarinetist origin. The sediment layers are extended to the hill of lava and covered by the thick colluvium in the southeast corner of the island. Six 14C samples collected from those sediment layers yield the dates between 1.0 ka and 1.3 ka. The results of our works show that the collapse of volcanic materials and the formation of dammed lake created the horizontal sediment layers near the edge of the exposed terrace scarp. The residual collapsed material near the eastern part of the south coast of Xiaolanyu Isle was the volcanic debris without clear layers, and the previous volcanic landform, which caused the colluvium and the nature dam was vanished. In the northern coast, the hill of lava in the northeast corner is also covered by a thick colluvium. There is an erosional surface near the bottom of the collapsed material with rounded pebbles of 1 meter diameter and coarse sand layer on the top. It should be the strath surface and sediments near the coast before the collapsing of colluvium. Five 14C samples of seashell, charcoal and coral were collected from the rounded bounder layer and the bottom of colluvium. The date of four seashell and charcoal samples were between 1.7 ka and 1.9 ka and the coral sample was about 2.7 ka. The results demonstrated that the volcano in the eastern Xiaolanyu Isle had been generated large landslides around 1.7 ka and 1.2 ka, which destroyed the volcanic landform. The main sliding bodies and dammed lake were destroyed afterwards. The coastal erosion

  4. Modeling the spatial distribution of landslide-prone colluvium and shallow groundwater on hillslopes of Seattle, WA

    USGS Publications Warehouse

    Schulz, W.H.; Lidke, D.J.; Godt, J.W.

    2008-01-01

    Landslides in partially saturated colluvium on Seattle, WA, hillslopes have resulted in property damage and human casualties. We developed statistical models of colluvium and shallow-groundwater distributions to aid landslide hazard assessments. The models were developed using a geographic information system, digital geologic maps, digital topography, subsurface exploration results, the groundwater flow modeling software VS2DI and regression analyses. Input to the colluvium model includes slope, distance to a hillslope-crest escarpment, and escarpment slope and height. We developed different statistical relations for thickness of colluvium on four landforms. Groundwater model input includes colluvium basal slope and distance from the Fraser aquifer. This distance was used to estimate hydraulic conductivity based on the assumption that addition of finer-grained material from down-section would result in lower conductivity. Colluvial groundwater is perched so we estimated its saturated thickness. We used VS2DI to establish relations between saturated thickness and the hydraulic conductivity and basal slope of the colluvium. We developed different statistical relations for three groundwater flow regimes. All model results were validated using observational data that were excluded from calibration. Eighty percent of colluvium thickness predictions were within 25% of observed values and 88% of saturated thickness predictions were within 20% of observed values. The models are based on conditions common to many areas, so our method can provide accurate results for similar regions; relations in our statistical models require calibration for new regions. Our results suggest that Seattle landslides occur in native deposits and colluvium, ultimately in response to surface-water erosion of hillstope toes. Regional groundwater conditions do not appear to strongly affect the general distribution of Seattle landslides; historical landslides were equally dispersed within and

  5. Sedimentology, petrography and early diagenesis of a travertine-colluvium succession from Chusang (southern Tibet)

    NASA Astrophysics Data System (ADS)

    Wang, Zhijun; Meyer, Michael C.; Hoffmann, Dirk L.

    2016-08-01

    The Chusang travertine is situated in southern Tibet at an altitude of ~ 4200 m asl. in a cold-arid, periglacial environment and is characterized by interbedding of hydrothermal carbonate with colluvium. Here we present sedimentological and petrographical data to elucidate the depositional environment and sedimentary processes responsible for hydrothermal carbonate precipitation and early diagenetic alteration as well as clastic sediment accumulation and provide initial 230Th/U ages to constrain the time-depth of this travertine-colluvium succession. Three main travertine lithofacies have been identified: 1) a dense laminated lithofacies, 2) a porous layered lithofacies and 3) an intraclastic lithofacies that results from erosion of pre-existing hot spring carbonate. The colluvium is composed of cohesive debris flow layers that derived from mass-wasting events from the adjacent hillslopes. Micro-fabric analyses suggest that dense laminated travertine forms via rapid calcite precipitation from hot spring water seasonally subjected to severe winter cooling, while porous layered travertine results from seasonal dilution of hot spring water with rain water during the summer monsoon months, which in turn stimulates biological productivity and gives rise to a porous summer layer. Early diagenesis in the form of recrystallization and extensive formation of pore cements is common in the Chusang travertine, but never eradicates the original crystal fabrics completely. The sedimentary architecture of the deposit is conditioned by (i) the gently dipping (~ 10°) pre-existing terrain on which hot spring water is discharged from multiple travertine mounds causing laterally extensive travertine sheets to precipitate, and (ii) the adjacent much steeper (up to 30°) periglacial hillslopes that are the source area of repeated debris flows that accumulate on the travertine surface. The resulting travertine-colluvium succession has a total thickness of ~ 24 m and 230Th/U dating

  6. A colluvium - travertine sedimentary succession from the Tibetan Plateau: dating and climatic significance

    NASA Astrophysics Data System (ADS)

    Meyer, Michael; Wang, Zhijun; Schlütz, Frank; Hoffmann, Dirk; May, Jan-Hendrik; Aldenderfer, Mark

    2014-05-01

    Morphodynamics and sedimentation on the Tibetan Plateau are strongly controlled by cold-arid climate conditions and distinct freeze-thaw cycles. In such a periglacial environment mass-wasting processes are dominant on mountain slopes, causing thick successions of talus and colluvium to accumulate. While periglacial slope dynamics are ubiquitous on the plateau today, they were probably much more intense during the various cold stages of the Late Pleistocene. However, the exact nature as well as the timing and duration of such temperature controlled slope dynamics on the Tibetan plateau are not well constrained. Travertines are secondary carbonates precipitated from hydrothermal springs. On the Tibetan Plateau these types of spring deposits form along neotectonic faults, where super-saturated ground water can penetrate onto the surface, facilitating degassing and carbonate precipitation. Spring carbonate formation further requires non-permanently frozen ground and reasonable humid conditions in order to recharge the ground water aquifer. Travertines hold potential for palaeoenvironmental reconstruction, because they are dateable via U-series techniques and their geochemical, biological and petrographic signature can be used to extract high resolution palaeoenvironmental information. Due to a dense network of neotectonic faults on the Tibetan plateau, travertines are relatively common. Nevertheless, the potential of these hydrothermal spring deposits as an archive for palaeoenvironmental change on the plateau has yet to be explored. Here we present the first results obtained for an unusual, non-continuous sediment sequence encountered in southern Tibet at an altitude of 4200 m asl. near Chusang village, i.e. a ca. 200 m thick succession of periglacial colluvium alternating with travertine deposits. Preliminary data indicate that travertine deposition at the Chusang hydrothermal spring occurred periodically throughout the Late Pleistocene and extensive travertine

  7. Subsurface flow behavior in thick colluvium and fissured bedrock in Kumano-daira, Central Japan

    NASA Astrophysics Data System (ADS)

    Hattori, S.; Onda, Y.; Tanaka, T.; Shimamura, M.; Togari-Ohta, A.; Uchida, T.; Tsujimura, M.

    2005-12-01

    Kumanodaira catchment was hypothesized; because of the thick colluvium, long time is required to infiltrate to the soil/bedrock interface and mainly composed of larger storm water. The soil water immediately above the soil/bedrock interface would infiltrate to the large fissures of the bedrock, preserving the isotopic signal and flowing quickly to the stream.

  8. Middle Pleistocene carbonate-cemented colluvium in southern Poland: Its depositional processes, diagenesis and regional palaeoenvironmental significance

    NASA Astrophysics Data System (ADS)

    Gradziński, Michał; Hercman, Helena; Staniszewski, Krzysztof

    2014-06-01

    A colluvial origin is postulated for the enigmatic relic mantle of immature, carbonate-cemented rudites on the bedrock slope of Kraków Highland, preserved in the area of Kwaczała Gullies. The deposits comprise four sedimentary facies: (A) sporadic clast-supported openwork conglomerates; (B) predominant matrix-supported massive conglomerates, some with a coarse-tail normal grading; (C) subordinate sheets of parallel stratified and/or ripple cross-laminated fine-grained sandstones; and (D) local coarse-grained sandstones with gently inclined parallel stratification. The 230Th-U dating of sparry calcite cements points to the penultimate Odranian/Warthanian interglacial. The debris was derived from local bedrock, inferred to have been frost-shattered in permafrost conditions during the Odranian glacial. Colluvial resedimentation was triggered by the rapid change in environment conditions brought by early deglaciation. Dense-snow/slush flows and slush-laden watery debris flows are thought to have transferred limestone debris from the upper to middle hillslope, where siliciclastic sand matrix was incorporated and solifluctional creep prevailed, accompanied by slope sheetwash processes. Carbonate cementation of the talus occurred in phreatic conditions during the penultimate Odranian/Warthanian interglacial (marine isotope stage 7), when soils formed and local springs supplied carbonate-saturated groundwater. The patchy preservation of cemented colluvium indicates its erosional relics. The Pleistocene colluvial mantle in the Kraków Highland was probably extensive, but was removed by subsequent erosion where non-cemented.

  9. Thermoluminescence dating of fault-scarp-derived colluvium: Deciphering the timing of paleoearthquakes on the Weber segment of the Wasatch fault zone, north central Utah

    SciTech Connect

    Forman, S.L. ); Nelson, A.R. ); McCalpin J.P. )

    1991-01-10

    The timing of middle to late Holocene faulting on the Weber segment of the Wasatch fault zone, Utah, is constrained by thermoluminescence (TL) and radiocarbon age estimates on fine-grained, fault-related colluvial sediments. The stratigraphy in two trenches excavated across fault scarps is characterized by a stack of three colluvial wedges, deposited in response to three separate faulting events, the oldest of which buried a soil developed on a middle Holocene debris flow. Thermoluminescence age estimates by the partial and total bleach methods and the regeneration method on fine-grained colluvium from the trenches agree within 1 sigma and are concordant with the radiocarbon chronology. A synthesis of the TL and {sup 14}C age estimates indicate that these three faulting events occurred sometime between 4,500 and 3,500, between 3,200 and 2,500, and between 1,400 and 1,000 years ago. Detailed investigation of a sequence of fine-grained, scarp-derived distal colluvium shows that much of the sediment was deposited during <600-year intervals immediately after faulting. The sedimentation rate of colluvium is inferred to increase shortly after faulting, and TL dating of these sediments provides additional information to constrain the timing of faulting events.

  10. Characteristics of ground motion and threshold values for colluvium slope displacement induced by heavy rainfall: a case study in northern Taiwan

    NASA Astrophysics Data System (ADS)

    Jeng, Ching-Jiang; Sue, Dar-Zen

    2016-06-01

    The Huafan University campus is located in the Ta-lun Shan area in northern Taiwan, which is characterized by a dip slope covered by colluvium soil of various depths. For slope disaster prevention, a monitoring system was constructed that consisted of inclinometers, tiltmeters, crack gages, groundwater level observation wells, settlement and displacement observation marks, rebar strain gages, concrete strain gages, and rain gages. The monitoring data derived from hundreds of settlement and displacement observation marks were analyzed and compared with the displacement recorded by inclinometers. The analysis results revealed that the maximum settlement and displacement were concentrated on the areas around the Hui-Tsui, Zhi-An, and Wu-Ming buildings and coincided with periods of heavy rainfall. The computer program STABL was applied for slope stability analysis and modeling of slope failure. For prevention of slope instability, a drainage system and tieback anchors with additional stability measures were proposed to discharge excess groundwater following rainfall. Finally, threshold value curves of rainfall based on slope displacement were proposed. The curves can be applied for predicting slope stability when typhoons are expected to bring heavy rainfall and should be significant in slope disaster prevention.

  11. Hydrogeology and simulation of source areas of water to production wells in a colluvium-mantled carbonate-bedrock aquifer near Shippensburg, Cumberland and Franklin Counties, Pennsylvania

    USGS Publications Warehouse

    Lindsey, Bruce D.

    2005-01-01

    This report presents the results of a study by the U.S. Geological Survey in cooperation with the Shippensburg Borough Authority to evaluate the source areas of water to production wells in a colluvium-mantled carbonate-bedrock aquifer in Cumberland and Franklin Counties, Pa. The areal extent of the zone of contribution was simulated for three production wells near Shippensburg, Pa. by use of a ground-water-flow model. A 111-square-mile area was selected as the model area and includes areas of the South Mountain Section and the Great Valley Section of the Valley and Ridge Physiographic Province. Within the model area, the geologic units in the South Mountain area are predominantly metamorphic rocks and the geologic units in the Great Valley are predominantly carbonate rocks. Hydrologic and geologic information were compiled to establish a conceptual model of ground-water flow. Characteristics of aquifer materials were determined, and streamflow and water levels were measured. Streamflow measurements in November 2003 showed all streams lost water as they flowed from South Mountain over the colluvium-mantled carbonate aquifer into the Great Valley. Some streams lost more than 1 cubic foot per second to the aquifer in this area. The Shippensburg Borough Authority owns three production wells in the model area. Two wells, Cu 969 and Fr 823, are currently (2004) used as production wells and produce 500,000 and 800,000 gallons per day, respectively. Well Cu 970 is intended to be brought on line as a production well in the future. Water levels were measured in 43 wells to use for model calibration. Water-level fluctuations and geophysical logs indicated confined conditions in well Cu 970. Ground-water flow was simulated with a model that consisted of two vertical layers, with five zones in each layer. The units were hydrostratigraphic units that initially were based on geologic formations, but boundaries were adjusted during model calibration. Model calibration resulted in

  12. Pedogenesis of black shale-influenced soils of the Knobs region of eastern Kentucky

    SciTech Connect

    Sobecki, T.M.

    1989-01-01

    Investigation of acid soils on forested hillslopes truncating Devonian-age black shales in the Knobs of eastern Kentucky established the impact of parent material and landscape position on colluvium occurrence and soil properties. Colluvium was thickest in headslopes, thinner in nose- and sideslopes, where illitic Typic Hapludults formed in acid gray and black shale residuum and colluvium, and sandstone colluvium. Base saturation and pH increased with depth in nose- and sideslopes, and decreased with depth in headslopes. The pH of black shale colluvium and residuum was {lt}4.0 in noseslopes, and Al saturation {gt}90%. Morphology, particle size, and TiO{sub 2}/ZrO{sub 2} ratios were used to assess parent material homogeneity and colluvium source. Compositions of soil solutions, mineral stability, and clay mineral analyses were used to evaluate illite weathering. Smectite randomly interstratified with illite was an initial illite weathering product in the noseslope black shale soil. High charge smectite (HCS), randomly interstratified with illite, predominated in noseslope pedons of black and gray shale, however. Vermiculite occurred in black and gray shale headslope pedons. Lithologic discontinuities prevented attribution of clay mineral suites solely to weathering. Soil solution compositions, clay mineral ratios, and thermodynamic stability of the clay minerals, however, suggested a weathering sequence of illite {yields} smectite {yields} HCS or vermiculite {yields} kaolinite or complete dissolution. Column leaching experiments suggested carbon, iron, and sulfur loss as the initial black shale weathering step, with silicate alteration following at a later stage. Young landscapes coupled with the loss of soluble weathering products from these soils is suggested as an explanation for the maintenance of illitic mineralogy despite undersaturation with respect to illite.

  13. 43 CFR 3832.21 - How do I locate a lode or placer mining claim?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... (deposited by gravity), or aqueous origin. (3) Establishing extralateral rights. If the minerals are... (deposited by wind), colluvium (deposited by gravity), talus, or other rock not in its original place; (iii... subject to the mineral leasing acts where a mineral subject to the General Mining Law can be extracted...

  14. 43 CFR 3832.21 - How do I locate a lode or placer mining claim?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... (deposited by gravity), or aqueous origin. (3) Establishing extralateral rights. If the minerals are... (deposited by wind), colluvium (deposited by gravity), talus, or other rock not in its original place; (iii... subject to the mineral leasing acts where a mineral subject to the General Mining Law can be extracted...

  15. 43 CFR 3832.21 - How do I locate a lode or placer mining claim?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... (deposited by gravity), or aqueous origin. (3) Establishing extralateral rights. If the minerals are... (deposited by wind), colluvium (deposited by gravity), talus, or other rock not in its original place; (iii... subject to the mineral leasing acts where a mineral subject to the General Mining Law can be extracted...

  16. A model of late quaternary landscape development in the Delaware Valley, New Jersey and Pennsylvania

    USGS Publications Warehouse

    Ridge, J.C.; Evenson, E.B.; Sevon, W.D.

    1992-01-01

    In the Delaware Valley of New Jersey and eastern Pennsylvania the late Quaternary history of colluviation, fluvial adjustment, and soil formation is based on the ages of pre-Wisconsinan soils and glacial deposits which are indicated by feld relationships and inferred from mid-latitude climate changes indicated by marine oxygen-isotope records. The area is divided into four terranes characterized by sandstone, gneiss, slate and carbonate rocks. Since the last pre-Wisconsinan glaciation (> 130 ka, inferred to be late Illinoian), each terrane responded differently to chemical and mechanical weathering. During the Sangamon interglacial stage (??? 130-75 ka) in situ weathering is inferred to have occurred at rates greater than transportation of material which resulted in the formation of deep, highly weathered soil and saprolite, and dissolution of carbonate rocks. Cold climatic conditions during the Wisconsinan, on the other hand, induced erosion of the landscape at rates faster than soil development. Upland erosion during the Wisconsinan removed pre-Wisconsinan soil and glacial sediment and bedrock to produce muddy to blocky colluvium, gre??zes lite??es, and alluvial fans on footslopes. Fluvial gravel and overlying colluvium in the Delaware Valley, both buried by late Wisconsinan outwash, are inferred to represent episodes of early and middle Wisconsinan (??? 75-25 ka) upland erosion and river aggradiation followed by river degradation and colluvium deposition. Early-middle Wisconsinan colluvium is more voluminous than later colluvium despite colder, possibly permafrost conditions during the late Wisconsinan ??? 25-10 ka). Extensive colluviation during the early and middle Wisconsinan resulted from a longer (50 kyr), generally cold interval of erosion with a greater availability of easily eroded pre-Wisconsinan surficial materials on uplands than during the late Wisconsinan. After recession of late Wisconsinan ice from its terminal position, soil formation and

  17. Active faulting on the Wallula fault within the Olympic-Wallowa Lineament (OWL), eastern Washington State

    NASA Astrophysics Data System (ADS)

    Sherrod, B. L.; Lasher, J. P.; Barnett, E. A.

    2013-12-01

    Several studies over the last 40 years focused on a segment of the Wallula fault exposed in a quarry at Finley, Washington. The Wallula fault is important because it is part of the Olympic-Wallowa lineament (OWL), a ~500-km-long topographic and structural lineament extending from Vancouver Island, British Columbia to Walla Walla, Washington that accommodates Basin and Range extension. The origin and nature of the OWL is of interest because it contains potentially active faults that are within 50 km of high-level nuclear waste facilities at the Hanford Site. Mapping in the 1970's and 1980's suggested the Wallula fault did not offset Holocene and late Pleistocene deposits and is therefore inactive. New exposures of the Finley quarry wall studied here suggest otherwise. We map three main packages of rocks and sediments in a ~10 m high quarry exposure. The oldest rocks are very fine grained basalts of the Columbia River Basalt Group (~13.5 Ma). The next youngest deposits include a thin layer of vesicular basalt, white volcaniclastic deposits, colluvium containing clasts of vesicular basalt, and indurated paleosols. A distinct angular unconformity separates these vesicular basalt-bearing units from overlying late Pleistocene flood deposits, two colluvium layers containing angular clasts of basalt, and Holocene tephra-bearing loess. A tephra within the loess likely correlates to nearby outcrops of Mazama ash. We recognize three styles of faults: 1) a near vertical master reverse or oblique fault juxtaposing very fine grained basalt against late Tertiary-Holocene deposits, and marked by a thick (~40 cm) vertical seam of carbonate cemented breccia; 2) subvertical faults that flatten upwards and displace late Tertiary(?) to Quaternary(?) soils, colluvium, and volcaniclastic deposits; and 3) flexural slip faults along bedding planes in folded deposits in the footwall. We infer at least two Holocene earthquakes from the quarry exposure. The first Holocene earthquake deformed

  18. Multiple large earthquakes in the past 1500 years on a fault in metropolitan Manila, the Philippines

    USGS Publications Warehouse

    Nelson, A.R.; Personius, S.F.; Rimando, R.E.; Punongbayan, R.S.; Tungol, N.; Mirabueno, H.; Rasdas, A.

    2000-01-01

    The first 14C-based paleoseismic study of an active fault in the Philippines shows that a right-lateral fault on the northeast edge of metropolitan Manila poses a greater seismic hazard than previously thought. Faulted hillslope colluvium, stream-channel alluvium, and debris-flow deposits exposed in trenches across the northern part of the west Marikina Valley fault record two or three surface-faulting events. Three eroded, clay-rich soil B horizons suggest thousands of years between surface faulting events, whereas 14C ages on detrital charcoal constrain the entire stratigraphic sequence to the past 1300-1700 years. We rely on the 14C ages to infer faulting recurrence of hundreds rather than thousands of years. Minimal soil development and modern 14C ages from colluvium overlying a faulted debris-flow deposit in a nearby stream exposure point to a historic age for a probable third or fourth (most recent) faulting event.

  19. Coincidence and spatial variability of geology, soils, and vegetation, Mill Run watershed, Virginia.

    USGS Publications Warehouse

    Olson, C.G.; Hupp, C.R.

    1986-01-01

    The Mill Run watershed is a structurally-controlled synclinal basin on the eastern limb of the Massanutten Mountain complex of NW Virginia. Bedrock contacts are obscured by coarse sandstone debris from exposures near basin divides. Colluvium blankets more than half the basin, masking geomorphic surfaces, affecting vegetation patterns, and contributing to the convexity of the alluvial, terrace, pediment and erosion surfaces. Vegetation is strongly interdependent with geomorphology, bedrock geology, and soils. - from Authors

  20. Variations of soil profile characteristics due to varying time spans since ice retreat in the inner Nordfjord, western Norway

    NASA Astrophysics Data System (ADS)

    Navas, A.; Laute, K.; Beylich, A. A.; Gaspar, L.

    2014-06-01

    In the Erdalen and Bødalen drainage basins located in the inner Nordfjord in western Norway the soils were formed after deglaciation. The climate in the uppermost valley areas is sub-arctic oceanic, and the lithology consists of Precambrian granitic orthogneisses on which Leptosols and Regosols are the most common soils. The Little Ice Age glacier advance affected parts of the valleys with the maximum glacier extent around AD 1750. In this study five sites on moraine and colluvium materials were selected to examine main soil properties, grain size distribution, soil organic carbon and pH to assess if soil profile characteristics and patterns of fallout radionuclides (FRNs) and environmental radionuclides (ERNs) are affected by different stages of ice retreat. The Leptosols on the moraines are shallow, poorly developed and vegetated with moss and small birches. The two selected profiles show different radionuclide activities and grain size distribution. The sampled soils on the colluviums outside the LIA glacier limit became ice-free during the Preboral. The Regosols present better-developed profiles, thicker organic horizons and are fully covered by grasses. Activity of 137Cs and 210Pbex concentrate at the topsoil and decrease sharply with depth. The grain size distribution of these soils also reflects the difference in geomorphic processes that have affected the colluvium sites. Significantly lower mass activities of FRNs were found in soils on the moraines than on colluviums. Variations of ERN activities in the valleys were related to characteristics of soil mineralogical composition. These results indicate differences in soil development that are consistent with the age of ice retreat. In addition, the pattern distribution of 137Cs and 210Pbex activities differs in the soils related to the LIA glacier limits in the drainage basins.

  1. Variations of soil profile characteristics due to varying time spans since ice retreat in the inner Nordfjord, western Norway

    NASA Astrophysics Data System (ADS)

    Navas, A.; Laute, K.; Beylich, A. A.; Gaspar, L.

    2014-01-01

    In the Erdalen and Bødalen drainage basins located in the inner Nordfjord in western Norway the soils have been formed after deglaciation. The climate in the uppermost valley areas is sub-arctic oceanic and the lithology consists of Precambrian granitic orthogneisses on which Leptosols and Regosols are the most common soils. The Little Ice Age glacier advance affected parts of the valleys with the maximum glacier extent around AD 1750. In this study five sites on moraine and colluvium materials were selected to examine the main soil properties to assess if soil profile characteristics and pattern of fallout radionuclides (FRNs) and environmental radionuclides (ERNs) are affected by different stages of ice retreat. The Leptosols on the moraines are shallow, poorly developed and vegetated with moss and small birches. The two selected profiles show different radionuclide activities and grain size distribution. The sampled soils on the colluviums outside the LIA glacier limit became ice-free during the Preboral. The Regosols present better-developed profiles, thicker organic horizons and are fully covered by grasses. Activity of 137Cs and 210Pbex concentrate at the topsoil and decrease sharply with depth. The grain size distribution of these soils also reflects the difference in geomorphic processes that have affected the colluvium sites. Significant lower mass activities of FRNs are found in soils on the moraines than on colluviums. Variations of ERNs activities in the valleys are related to characteristics soil mineralogical composition. These results indicate differences in soil development that are consistent with the age of ice retreat. In addition, the pattern distribution of 137Cs and 210Pbex activities differs in the soils related to the LIA glacier limits in the drainage basins.

  2. BISON ANTIQUUS OCCURRENCE AND PLEISTOCENE-HOLOCENE STRATIGRAPHY, CANADA DEL BUEY, PAJARITO PLATEAU, NEW MEXICO

    SciTech Connect

    RENEAU, STEVEN L.; DRAKOS, PAUL G.; MORGAN, GARY S.

    2007-02-12

    A Bison. (probable Bison antiguus) distal humerus fragment was found within a Pleistocene colluvial deposit on a hillslope above Canada del Buey near White Rock, New Mexico. The Bison fossil is preserved within a buried soil with an inferred age of ca. 50-100 ka, based on soil properties and on stratigraphic position below a deposit of ca. 50-60 ka EI Cajete pumice. This represents the second oldest dated Bison in New Mexico, and one of the few occurrences of this genus in the northern mountains of the state. It is also only the second record of a Pleistocene vertebrate from Los Alamos County, and is a rare occurrence of a pre-25 ka Bison fossil in good stratigraphic context. Hillslopes in the study area are underlain by a sequence of truncated Pleistocene and Holocene soils that are inferred to represent colluvial deposition and soil formation followed by erosion in the mid Pleistocene (buried soil 'b3'), the late Pleistocene (buried soil 'b2'), and the mid-to-late Holocene (buried soil 'b1'). The surface soil is developed in depOSits that overlie 600-800 year-old Ancestral Puebloan sites. Colluvium is dominated by relatively fine-grained (fine to very fine sand) slopewash colluvium deposited by overland flow, but also includes rocky colluvium on hillslopes below mesas. The fine-grained colluvium is likely derived mainly from reworking of eolian deposits. Episodic colluvial deposition appears to, at least in part, accompany and follow episodic eolian events, with intervening periods dominated by erosion and the development of truncated soils.

  3. Summary of lithologic logging of new and existing boreholes at Yucca Mountain, Nevada, March 1994 to June 1994

    SciTech Connect

    Geslin, J.K.; Moyer, T.C.

    1995-04-01

    This report summarizes lithologic logging of core from boreholes at Yucca Mountain, Nevada, conducted from March 1994 to June 1994. Units encountered during logging include Quaternary-Tertiary alluvium and colluvium, Tertiary Rainier Mesa Tuff, all units in the Tertiary Paintbrush Group, and Tertiary Calico Hills Formation. Logging results are presented in a table of contact depths for core from unsaturated zone neutron (UZN) boreholes and graphic lithologic logs for core from north ramp geology (NRG) boreholes.

  4. Transformation of dilative and contractive landslide debris into debris flows-An example from marin County, California

    USGS Publications Warehouse

    Fleming, R.W.; Ellen, S.D.; Algus, M.A.

    1989-01-01

    The severe rainstorm of January 3, 4 and 5, 1982, in the San Francisco Bay area, California, produced numerous landslides, many of which transformed into damaging debris flows. The process of transformation was studied in detail at one site where only part of a landslide mobilized into several episodes of debris flow. The focus of our investigation was to learn whether the landslide debris dilated or contracted during the transformation from slide to flow. The landslide debris consisted of sandy colluvium that was separable into three soil horizons that occupied the axis of a small topographic swale. Failure involved the entire thickness of colluvium; however, over parts of the landslide, the soil A-horizon failed separately from the remainder of the colluvium. Undisturbed samples were taken for density measurements from outside the landslide, from the failure zone and overlying material from the part of the landslide that did not mobilize into debris flows, and from the debris-flow deposits. The soil A-horizon was contractive and mobilized to flows in a process analogous to liquefaction of loose, granular soils during earthquakes. The soil B- and C-horizons were dilative and underwent 2 to 5% volumetric expansion during landslide movement that permitted mobilization of debris-flow episodes. Several criteria can be used in the field to differentiate between contractive and dilative behavior including lag time between landsliding and mobilization of flow, episodic mobilization of flows, and partial or complete transformation of the landslide. ?? 1989.

  5. Thin-section analysis as a tool to aid identification of palaeoearthquakes on the “slow”, active Geleen Fault, Roer Valley Graben

    NASA Astrophysics Data System (ADS)

    Vanneste, Kris; Mees, Florias; Verbeeck, Koen

    2008-06-01

    We analyzed thin sections from two palaeoseismic trenches across the low-slip-rate Geleen Fault in the Belgian Maas River valley to help identifying the most recent large palaeoearthquake on this fault segment. In the first trench we sampled silty sediment below and above a prehistoric stone pavement that was supposedly at or near the surface at the time of the event, and subsequently thrown down. The samples below show a well-developed in situ argillic Bt soil horizon in parent sediment containing remnants of stratification, whereas the sediment above is a structureless colluvium reworked at least partly from Bt-horizon material. Below the stone pavement, we also found evidence of contorted stratification, which is in agreement with macroscopic observations of both the sediment and the stone pavement itself, and which is attributed to co-seismic soft-sediment deformation. In the second trench, we sampled a sequence of vaguely discernible soil horizons in the hanging-wall, interpreted as a buried soil profile (Bt, E, and possibly A horizons), overlain by a featureless deposit. Thin-section analysis supports the colluvial nature of the latter, and also provides evidence that both the base of this layer and the top of the poorly developed A horizon below have occupied a shallow position in a soil profile. A sample from the same depth in the footwall is composed of very different material. Instead of colluvium, we find patches of Bt soil, most likely representing the same pedogenic level as the in situ Bt horizon at larger depth in the hanging-wall, but displaced and subsequently degraded. Furthermore, thin sections confirm that vertical structures cutting this Bt horizon are sand dykes. These dykes could be traced macroscopically upward to the base of the colluvium. In both trenches, we have thus identified a stratigraphic boundary in the hanging-wall, close to the surface, separating an in situ soil below from colluvium above. We interpret this limit and the

  6. Determination of paleoseismic activity over a large time-scale: Fault scarp dating with 36Cl

    NASA Astrophysics Data System (ADS)

    Mozafari Amiri, Nasim; Tikhomirov, Dmitry; Sümer, Ökmen; Özkaymak, Çaǧlar; Uzel, Bora; Ivy-Ochs, Susan; Vockenhuber, Christof; Sözbilir, Hasan; Akçar, Naki

    2016-04-01

    Bedrock fault scarps are the most direct evidence of past earthquakes to reconstruct seismic activity in a large time-scale using cosmogenic 36Cl dating if built in carbonates. For this method, a surface along the fault scarp with a minimum amount of erosion is required to be chosen as an ideal target point. The section of the fault selected for sampling should cover at least two meters of the fault surface from the lower part of the scarp, where intersects with colluvium wedge. Ideally, sampling should be performed on a continuous strip along the direction of the fault slip direction. First, samples of 10 cm high and 15 cm wide are marked on the fault surface. Then, they are collected using cutters, hammer and chisel in a thickness of 3 cm. The main geometrical factors of scarp dip, scarp height, top surface dip and colluvium dip are also measured. Topographic shielding in the sampling spot is important to be estimated as well. Moreover, density of the fault scarp and colluvium are calculated. The physical and chemical preparations are carried in laboratory for AMS and chemical analysis of the samples. A Matlab® code is used for modelling of seismically active periods based on increasing production rate of 36Cl following each rupture, when a buried section of a fault is exposed. Therefore, by measuring the amount of cosmogenic 36Cl versus height, the timing of major ruptures and their offsets are determined. In our study, Manastır, Mugırtepe and Rahmiye faults in Gediz graben, Priene-Sazlı, Kalafat and Yavansu faults in Büyük Menderes graben and Ören fault in Gökava half-graben have been examined in the seismically active region of Western Turkey. Our results reconstruct at least five periods of high seismic activity during the Holocene time, three of which reveal seismic ruptures beyond the historical pre-existing data.

  7. Applying Distributed, Coupled Hydrological Slope-Stability Models for Landslide Hazard Assessments

    NASA Astrophysics Data System (ADS)

    Godt, J. W.; Baum, R. L.; Lu, N.; Savage, W. Z.; McKenna, J. P.

    2006-12-01

    Application of distributed, coupled hydrological slope-stability models requires knowledge of hydraulic and material-strength properties at the scale of landslide processes. We describe results from a suite of laboratory and field tests that were used to define the soil-water characteristics of landslide-prone colluvium on the steep coastal bluffs in the Seattle, Washington area and then use these results in a coupled model. Many commonly used tests to determine soil-water characteristics are performed for the drying process. Because most soils display a pronounced hysteresis in the relation between moisture content and matric suction, results from such tests may not accurately describe the soil-water characteristics for the wetting process during rainfall infiltration. Open-tube capillary-rise and constant-flow permeameter tests on bluff colluvium were performed in the laboratory to determine the soil-water characteristic curves (SWCC) and unsaturated hydraulic conductivity functions (HCF) for the wetting process. Field-tests using a borehole permeameter were used to determine the saturated hydraulic conductivity of colluvial materials. Measurements of pore-water response to rainfall were used in an inverse numerical modeling procedure to determine the in-situ hydraulic parameters of hillside colluvium at the scale of the instrument installation. Comparison of laboratory and field results show that although both techniques generally produce SWCCs and HCFs with similar shapes, differences in bulk density among field and lab tests yield differences in saturated moisture content and saturated hydrologic conductivity. We use these material properties in an application of a new version of a distributed transient slope stability model (TRIGRS) that accounts for the effects of the unsaturated zone on the infiltration process. Applied over a LiDAR-based digital landscape of part of the Seattle area for an hourly rainfall history known to trigger shallow landslides, the

  8. Utilization of humus-rich forest soil (mull) in geochemical exploration for gold

    USGS Publications Warehouse

    Curtin, Gary C.; Lakin, H.W.; Neuerburg, G.J.; Hubert, A.E.

    1968-01-01

    Distribution of gold in humus-rich forest soil (mull) reflects the known distribution of gold deposits in bedrock in the Empire district, Colorado. Gold from the bedrock is accumulated by pine and aspen trees and is concentrated in the mull by the decay of organic litter from the trees. Anomalies in mull which do not coincide with known gold deposits merit further exploration. The gold anomalies in soil (6- to 12-inch depth) and in float pebbles and cobbles poorly reflect the known distribution of gold deposits in bedrock beneath the extensive cover of colluvium and glacial drift.

  9. LIDAR Helps Identify Source of 1872 Earthquake Near Chelan, Washington

    NASA Astrophysics Data System (ADS)

    Sherrod, B. L.; Blakely, R. J.; Weaver, C. S.

    2015-12-01

    One of the largest historic earthquakes in the Pacific Northwest occurred on 15 December 1872 (M6.5-7) near the south end of Lake Chelan in north-central Washington State. Lack of recognized surface deformation suggested that the earthquake occurred on a blind, perhaps deep, fault. New LiDAR data show landslides and a ~6 km long, NW-side-up scarp in Spencer Canyon, ~30 km south of Lake Chelan. Two landslides in Spencer Canyon impounded small ponds. An historical account indicated that dead trees were visible in one pond in AD1884. Wood from a snag in the pond yielded a calibrated age of AD1670-1940. Tree ring counts show that the oldest living trees on each landslide are 130 and 128 years old. The larger of the two landslides obliterated the scarp and thus, post-dates the last scarp-forming event. Two trenches across the scarp exposed a NW-dipping thrust fault. One trench exposed alluvial fan deposits, Mazama ash, and scarp colluvium cut by a single thrust fault. Three charcoal samples from a colluvium buried during the last fault displacement had calibrated ages between AD1680 and AD1940. The second trench exposed gneiss thrust over colluvium during at least two, and possibly three fault displacements. The younger of two charcoal samples collected from a colluvium below gneiss had a calibrated age of AD1665- AD1905. For an historical constraint, we assume that the lack of felt reports for large earthquakes in the period between 1872 and today indicates that no large earthquakes capable of rupturing the ground surface occurred in the region after the 1872 earthquake; thus the last displacement on the Spencer Canyon scarp cannot post-date the 1872 earthquake. Modeling of the age data suggests that the last displacement occurred between AD1840 and AD1890. These data, combined with the historical record, indicate that this fault is the source of the 1872 earthquake. Analyses of aeromagnetic data reveal lithologic contacts beneath the scarp that form an ENE

  10. Soils, surficial geology, and geomorphology of the Bear Creek Valley Low-Level Waste Disposal Development and Demonstration Program site

    SciTech Connect

    Lietzke, D.A.; Lee, S.Y.; Lambert, R.E.

    1988-04-01

    An intensive soil survey was conducted on the proposed Low-Level Waste Disposal Development and Demonstration Program site (LLWDDD) in Bear Creek Valley. Soils on the site were related to the underlying residuum and to the surficial colluvium and alluvium. Within any particular geologic formation, soils were subdivided based mostly on the degree of weathering, as reflected by saprolite weathering and morphologic features of the soils. Degree of weathering was related both to slope shape and gradient and to the joint-fracture system. Erosion classes were also used to make further subdivisions of any particular soil. Deep pits were dug in each of the major Conasauga Group formations (Pumpkin Valley, Rogersville, Maryville, and Nolichucky) for soil and saprolite characterization. Because of the widespread presence of alluvium and colluvium, which are potential sources of fill and final cover material, pits and trenches were dug to characterize the properties of these soils and to try to understand the past geomorphic history of the site. The results of the soil survey investigation indicated that the deeply weathered Pumpkin Valley residuum has good potential for the construction of tumuli or other types of belowground or aboveground burial of prepackaged compacted waste. 11 refs., 30 figs., 3 tabs.

  11. Magnetic survey of the Risher Road Open Metal Pit Waste Unit

    SciTech Connect

    Cumbest, R.J.

    1995-07-01

    The Risher Road Waste Unit is located at the base of a small bluff (approximately 30 ft high) composed of sand and gravel. Due to collapse of the face of the bluff a steep slope of colluvium has formed at the base. The area of investigation is located on the slope of colluvium, and is marked by the presence of two pin flags spaced approximately 25 ft apart parallel to the bluff face. In order to investigate the presence of buried metallic material that might indicate waste containers or other wash beneath the colluvial slope a magnetometer survey was conducted in and around the vicinity of the pin flags. The survey consisted of a 5-ft by 5-ft square grid node pattern in a 40-ft by 60-ft rectangle. Magnetic field and gradient anomalies were detected in the locations of the pin flags and can be attributed to the ferric composition of the pin flag shafts. Other magnetic field and gradient variations are at background levels and do not indicate the presence of buried ferric objects of any significant size.

  12. Identifying Colluvial Slopes by Airborne LiDAR Analysis

    NASA Astrophysics Data System (ADS)

    Kasai, M.; Marutani, T.; Yoshida, H.

    2015-12-01

    Colluvial slopes are one of major sources of landslides. Identifying the locations of the slopes will help reduce the risk of disasters, by avoiding building infrastructure and properties nearby, or if they are already there, by applying appropriate counter measures before it suddenly moves. In this study, airborne LiDAR data was analyzed to find their geomorphic characteristics to use for extracting their locations. The study site was set in the suburb of Sapporo City, Hokkaido in Japan. The area is underlain by Andesite and Tuff and prone to landslides. Slope angle and surface roughness were calculated from 5 m resolution DEM. These filters were chosen because colluvial materials deposit at around the angle of repose and accumulation of loose materials was considered to form a peculiar surface texture differentiable from other slope types. Field survey conducted together suggested that colluvial slopes could be identified by the filters with a probability of 80 percent. Repeat LiDAR monitoring of the site by an unmanned helicopter indicated that those slopes detected as colluviums appeared to be moving at a slow rate. In comparison with a similar study from the crushed zone in Japan, the range of slope angle indicative of colluviums agreed with the Sapporo site, while the texture was rougher due to larger debris composing the slopes.

  13. Hydrogeology, geochemistry, and quality of water of The Basin and Oak Spring areas of the Chisos Mountains, Big Bend National Park, Texas

    USGS Publications Warehouse

    Baker, E.T., Jr.; Buszka, P.M.

    1993-01-01

    Test-drilling, water-chemistry data, and isotopic data indicate that the water at Oak Spring originates as recharge from precipitation onto the Oak Spring area west of The Basin--the principal tourist area in the park--and possibly onto the fractured igneous rocks of the western Basin. Tritium activity of Oak Spring water indicates that the average age of the water is less than 14 years. Test drilling in the vicinity of Oak Spring has shown that Oak Spring issues from bedrock, the aquifer being a sand bed 5-feet thick. Test drilling near two sewage lagoons in The Basin area has shown that the alluvium and colluvium, on which the lagoons are located, is not saturated at and near the lagoons. Previous hypotheses suggested that seepage from the lagoons might pollute shallow ground water moving westward toward Window Pouroff, the only surface outlet of The Basin, in the direction of Oak Spring, Oak Spring, almost 2 miles downgradient of the lagoons, is the sole source of water for The Basin. The test borings completed in bedrock below the alluvium and colluvium are dry, which indicates that no substandal leakage from the lagoons is occurring and no contaminant plume is identifiable.

  14. Alluvial and colluvial sediment storage in the Geul River catchment (The Netherlands) — Combining field and modelling data to construct a Late Holocene sediment budget

    NASA Astrophysics Data System (ADS)

    de Moor, J. J. W.; Verstraeten, G.

    2008-03-01

    We used a combined approach of a two-dimensional erosion and hillslope sediment delivery model (WATEM/SEDEM) and detailed geomorphological reconstructions to quantify the different components in a sediment budget for the Geul River catchment (southern Netherlands) since the High Middle Ages. Hillslope erosion and colluvium deposition were calculated using the model, while floodplain storage was estimated using field data. Our results show that more than 80% of the total sediment production in the catchment has been stored as colluvium (mostly generated by hillslope erosion), while almost 13% is stored in the floodplain since the High Middle Ages (this situation resembles a capacity-limited system). Model results for the period prior to the High Middle Ages (with a nearly completely forested catchment) show that far less sediment was generated and that most of the sediments were directly transported to the main river valleys or out of the catchment (a supply-limited system). Geomorphological analysis of a large alluvial fan shows the sensitivity of the study area to changes in the percentage of arable land. Our combined field data-modeling study presents an elegant method to calculate a catchment sediment budget for a longer period and is able to identify and quantify the most important sediment storage elements. Furthermore, it provides a valuable tool to calculate a sediment budget while only limited dated fluvial sediment sequences are available.

  15. Comparative stability calculations of the Pleistocene landslide in France

    NASA Astrophysics Data System (ADS)

    Fabre, R.; Martins Campina, B.; Riss, J.; Bertran, P.

    2003-04-01

    Remnants of the Petit-Bost landslide that occurred during the Pleistocene have been observed during field investigations in Quaternary alluvial formations, southwestern France. The work presented demonstrates how field observations can be used to calculate slope stability. A sliding surface and other related features due to soil deformation have been discovered within a clay layer that overlays the gravel. Abundant periglacial features such as ice-wedge casts have also been found in the colluvium and testify to a former permafrost, suggesting that sliding may be closely linked with Pleistocene periglacial conditions. The surface of rupture is located in a 0.5 m thick, very plastic mottled clay at the top of an alluvial gravel. The initial topography at the time of sliding is not known, but the gradient was thought to be close to that of the present soil surface. This ranges between 3 and 4°; a value of 3° has been used in the following stability calculations. The landslide corresponds to a 2-m-thick colluvium formations with 1.5-m thick permafrost that has been subjected to gravity-induced instability in saturated soil in a periglacial environment. The stability calculations for the Petit-Bost landslide have been performed using an infinite plane sliding and according to two complementary methods. The first one has been usually used for plane sliding, the Carter method. The second one used also for plane sliding with the FLAC computer method (Fast Lagrangian Analysis of Continua method). Following the first one Carter method, calculations were made for an impermeable upper layer, that leads to the development of high pore water pressure in the clay layer. These first results show that instability in the clay only occurs for very low angle of internal friction and cohesion values. Under such conditions, artesian water pressures may have triggered sliding. This could have occurred if the thawed clay layer was trapped between a permafrost table and an overlying

  16. Field and laboratory rainfall simulation as a tool to investigate Quaternary badland geomorphic development

    NASA Astrophysics Data System (ADS)

    Kuhn, Nikolaus; Kasanin-Grubin, Milica; Yair, Aaron; Rorke, Brian; Schwanghart, Wolfgang

    2010-05-01

    . However, the stability is achieved in different ways. In the Dinosaur Badlands, weathering rates are low compared to erosion capacity, maintaining continuous evacuation of sediment from slopes to the flood planes of the Red Deer River system. Only a very pronounced contrast between winter weathering and drier summers would generate a colluvium and thus change slope hydrology. In the Zin Valley, the development of a thick colluvium at the foot of the slopes has increased infiltration capacity, reducing runoff and sediment yield into the floodplain. Only an increase in rainfall magnitude would improve runoff continuity and induce the erosion of the colluvium. The somewhat surprising, long-term resilience of the badland slope systems identified in this study illustrates the versatility combining rainfall simulation experiments with numerical modeling in landscape evolution studies.

  17. Experimental investigation into Quaternary badland geomorphic development

    NASA Astrophysics Data System (ADS)

    Kasanin-Grubin, Milica; Kuhn, Nikolaus; Yair, Aaron; Bryan, Rorke; Schwanghart, Wolfgang

    2010-05-01

    to the flood planes of the Red Deer River system. Only a very pronounced contrast between winter weathering and drier summers would generate a colluvium and thus change slope hydrology. In the Zin Valley the development of a thick colluvium at the foot of the slopes has increased infiltration capacity, reducing runoff and sediment yield into the floodplain. Here, only an increase in rainfall magnitude would improve runoff continuity and induce the erosion of the colluvium. This would in turn reduce infiltration capacity and thus initiate a positive feedback on runoff and sediment yield into the Zin River. Overall, Holocene climate change appears to be insufficient to change the geomorphic development in both badlands. However, this stability is achieved not despite of climate, but because of the specific history of geomorphic development. In addition, the combination of erosion and weathering experiments with numerical modeling demonstrates the versatility of Experimental Geomorphology in landscape evolution studies.

  18. Variations of soil profile characteristics due to varying time spans since ice retreat in the inner Nordfjord, western Norway

    NASA Astrophysics Data System (ADS)

    Navas, Ana; Laute, Katja; Beylich, Achim A.; Gaspar, Leticia

    2013-04-01

    In the Erdalen and Bødalen drainage basins located in the inner Nordfjord in western Norway the soils have been formed after deglaciation. The climate in the upper valley part is sub-arctic oceanic with an annual areal precipitation of ca 1500 mm. The lithology in Erdalen and Bødalen consists of Precambrian granitic orthogneisses on which Leptosols and Regosols are the most common soils. Parts of the valleys were affected by the Little Ice Age glacier advance with the maximum glacier extent around 1750 BP. In this study five sites on moraine and colluvium materials were selected to examine the main soil properties of the most representative soils found in the region. The objective was to assess if soil profile characteristics and pattern of fallout radionuclides (FRN's) and environmental radionuclides (ERN's) are affected by different stages of ice retreat. Soil profiles were sampled at 5 cm depth interval increments until 20 cm depth. The Leptosols on the moraines are shallow, poorly developed and vegetated with moss and small birches. The two selected profiles show different radionuclide activities and grain size distribution. At P2 profile where ice retreated earlier (ca., 1767) depth profile activities of FRŃs are more homogenous than in P1 that became ice-free since ca. 1930. The sampled soils on the colluviums outside the LIA glacier limit became ice free during the Preboral. The Regosols present better developed profiles, thicker organic horizons and are fully covered by grasses. Activity of 137Cs and 210Pbex concentrate at the topsoil and decrease sharply with depth. The grain size distribution of these soils also reflects the difference in geomorphic processes that have affected the colluvium sites. Lower activities of FRŃs in soils on the moraines are related to the predominant sand material that has less capacity to fix the radionuclides. Lower 40K activities in Erdalen as compared to Bødalen are likely related to soil mineralogical composition. All

  19. Summary of lithologic logging of new and existing boreholes at Yucca Mountain, Nevada, August 1993 to February 1994

    SciTech Connect

    Geslin, J.K.; Moyer, T.C.; Buesch, D.C.

    1995-05-01

    Yucca Mountain, Nevada, is being investigated as a potential site for a high-level radioactive waste repository. This report summarizes the lithologic logging of new and existing boreholes at Yucca Mountain that was done from August 1993 to February 1994 by the Rock Characteristics Section, Yucca Mountain Project Branch, US Geological Survey (USGS). Units encountered during logging include Quaternary-Tertiary alluvium/colluvium, Tertiary Rainier Mesa Tuff, all units in the Tertiary Paintbrush Group, Tertiary Calico Hills Formation and Tertiary Prow Pass Tuff. We present criteria used for recognition of stratigraphic contacts, logging results as tables of contact depths for core from neutron (UZN) boreholes and graphical lithologic logs for core from non-UZN boreholes, and descriptions of several distinctive nonwelded tuffs recognized in the PTn hydrogeologic unit of the Paintbrush Group.

  20. Debris flows in Grand Canyon National Park, Arizona: magnitude, frequency and effects on the Colorado River

    USGS Publications Warehouse

    Melis, Theodre S.; Webb, Robert H.

    1993-01-01

    Debris flows are recurrent sediment-transport processes in 525 tributaries of the Colorado River in Grand Canyon. Arizona. Initiated by slope failures in bedrock and (or) colluvium during intense rainfall, Grand Canyon debris flows are high-magnitude, short-duration floods. Debris flows in these tributaries transport very large boulders into the river where they accumulate on debris fans and form rapids. The frequency of debris flows range from less than 1 per century to 10 or more per century in these tributaries. Before regulation by Glen Canyon Dam in 1963, high-magnitude floods on the Colorado River reworked debris fans by eroding all particles except large boulders. Because flow regulation has substantially decreased the river's competence, debris flows occurring after 1963 have increased accumulation of finer-grained sediments on debris fans and in rapids.

  1. A comparative analysis of simulated and observed landslide locations triggered by Hurricane Camille in Nelson County, Virginia

    USGS Publications Warehouse

    Morrissey, M.M.; Wieczorek, G.F.; Morgan, B.A.

    2008-01-01

    In 1969, Nelson County, Virginia received up to 71 cm of rain within 12 h starting at 7 p.m. on August 19. The total rainfall from the storm exceeded the 1000-year return period in the region. Several thousands of landslides were induced by rainfall associated with Hurricane Camille causing fatalities and destroying infrastructure. We apply a distributed transient response model for regional slope stability analysis to shallow landslides. Initiation points of over 3000 debris flows and effects of flooding from this storm are applied to the model. Geotechnical data used in the calculations are published data from samples of colluvium. Results from these calculations are compared with field observations such as landslide trigger location and timing of debris flows to assess how well the model predicts the spatial and temporal distribution. of landslide initiation locations. The model predicts many of the initiation locations in areas where debris flows are observed. Copyright ?? 2007 John Wiley & Sons, Ltd.

  2. Quaternary geology of Avery Island, Louisiana

    SciTech Connect

    Autin, W.J.; McCulloh, R.P.; Davison, A.T.

    1986-09-01

    Avery Island, one of the Five Islands salt domes of south-central Louisiana, is a piercement-type dome that has been uplifted from several kilometers' depth. It is nearly circular in plan with a maximum elevation approximately 50 m above the surrounding coastal marsh. Dissection has produced a terrain of gullies and steep slopes. The features identified indicate a complex geologic history for Avery Island. Deposition of late Pleistocene sediments in a low-relief alluvial plain and subsequent soil development predate domal uplift. The stratigraphy of loess and colluvial silts indicates the island was emergent during loess depositions. The degree of dissection, distribution of colluvium, and shearing of Quaternary sediments reflects continual uplift after loess deposition.

  3. A mass balance model for the hydrologic response of fine-grained hillside soils to rainfall

    SciTech Connect

    Haneberg, W.C. . New Mexico Bureau of Mines and Mineral Resources)

    1992-01-01

    For a sloping soil layer of uniform thickness D, length L, and angle of inclination B, slope-normal influx per unit breadth is given by Q[sub in] = R L cos B, where R is net recharge. Slope-parallel discharge is given by Q[sub out] = K D sin B, where K is saturated hydraulic conductivity. If the long-term ratio of discharge to influx is > 1, then the slope is self-draining. If the ratio is < 1, then the slope is self-filling. Self-filling slopes will be more susceptible to failure because they cannot easily dissipate infiltration-induced pore pressure increases. For time-variant recharge, the rate of change in volumetric soil moisture content is given by d[Theta]/dt = (R/D) cos B--(K/L) sin B. Calculations using data from a thin colluvium landslide along the Ohio River give an average annual steady-state value of Q[sub out]/Q[sub in] = 1.06. A finite difference solution of the transient mass balance equation agrees fairly well with observed daily mean pressure heads from spring 1988. Stochastic simulations using temporally uncorrelated rainfall distributions fitted to the observed data tend to produce smoother hydrographs than simulations using observed rainfall values. This is due to a mismatch between the observed and fitted distributions, which caused the frequency of large storms to be underestimated and the frequency of small storms to be overestimated. Long-term trends in the stochastic simulations, however, were self-draining in three out of five trials. The mildly self-draining nature of thin colluvium hillsides along the Ohio River may explain why these slopes are marginally stable to unstable, and the general agreement between observed and simulated values suggests that mass balance models may be useful for assessing the susceptibility of hillside soils to precipitation-induced landsliding.

  4. Holocene debris flows on the Colorado Plateau: The influence of clay mineralogy and chemistry

    USGS Publications Warehouse

    Webb, R.H.; Griffiths, P.G.; Rudd, L.P.

    2008-01-01

    Holocene debris flows do not occur uniformly on the Colorado Plateau province of North America. Debris flows occur in specific areas of the plateau, resulting in general from the combination of steep topography, intense convective precipitation, abundant poorly sorted material not stabilized by vegetation, and the exposure of certain fine-grained bedrock units in cliffs or in colluvium beneath those cliffs. In Grand and Cataract Canyons, fine-grained bedrock that produces debris flows contains primarily single-layer clays - notably illite and kaolinite - and has low multilayer clay content. This clay-mineral suite also occurs in the colluvium that produces debris flows as well as in debris-flow deposits, although unconsolidated deposits have less illite than the source bedrock. We investigate the relation between the clay mineralogy and major-cation chemistry of fine-grained bedrock units and the occurrence of debris flows on the entire Colorado Plateau. We determined that 85 mapped fine-grained bedrock units potentially could produce debris flows, and we analyzed clay mineralogy and major-cation concentration of 52 of the most widely distributed units, particularly those exposed in steep topography. Fine-grained bedrock units that produce debris flows contained an average of 71% kaolinite and illite and 5% montmorillonite and have a higher concentration of potassium and magnesium than nonproducing units, which have an average of 51% montmorillonite and a higher concentration of sodium. We used multivariate statistics to discriminate fine-grained bedrock units with the potential to produce debris flows, and we used digital-elevation models and mapped distribution of debris-flow producing units to derive a map that predicts potential occurrence of Holocene debris flows on the Colorado Plateau. ?? 2008 Geological Society of America.

  5. Evidence for Late Holocene earthquakes on the Utsalady Point fault, Northern Puget Lowland, Washington

    USGS Publications Warehouse

    Johnson, S.Y.; Nelson, A.R.; Personius, S.F.; Wells, R.E.; Kelsey, H.M.; Sherrod, B.L.; Okumura, K.; Koehler, R., III; Witter, R.C.; Bradley, L.-A.; Harding, D.J.

    2004-01-01

    Trenches across the Utsalady Point fault in the northern Puget Lowland of Washington reveal evidence of at least one and probably two late Holocene earthquakes. The "Teeka" and "Duffers" trenches were located along a 1.4-km-long, 1-to 4-m-high, northwest-trending, southwest-facing, topographic scarp recognized from Airborne Laser Swath Mapping. Glaciomarine drift exposed in the trenches reveals evidence of about 95 to 150 cm of vertical and 200 to 220 cm of left-lateral slip in the Teeka trench. Radiocarbon ages from a buried soil A horizon and overlying slope colluvium along with the historical record of earthquakes suggest that this faulting occurred 100 to 400 calendar years B.P. (A.D. 1550 to 1850). In the Duffers trench, 370 to 450 cm of vertical separation is accommodated by faulting (???210 cm) and folding (???160 to 240 cm), with probable but undetermined amounts of lateral slip. Stratigraphic relations and radiocarbon ages from buried soil, colluvium, and fissure fill in the hanging wall suggest the deformation at Duffers is most likely from two earthquakes that occurred between 100 to 500 and 1100 to 2200 calendar years B.P., but deformation during a single earthquake is also possible. For the two-earthquake hypothesis, deformation at Teeka trench in the first event involved folding but not faulting. Regional relations suggest that the earthquake(s) were M ??? ???6.7 and that offshore rupture may have produced tsunamis. Based on this investigation and related recent studies, the maximum recurrence interval for large ground-rupturing crustal-fault earthquakes in the Puget Lowland is about 400 to 600 years or less.

  6. Paleoseismic investigations of the Paintbrush Canyon fault in southern Midway Valley, Yucca Mountain, Nevada: Preliminary results

    SciTech Connect

    Swan, F.H.; Wesling, J.R.; Thomas, A.P. )

    1993-04-01

    Trench mapping in southern Midway Valley provides evidence of multiple surface-faulting events on a western splay of the Paintbrush Canyon fault during the middle to late Pleistocene. The 6-m-wide fault zone exposed in the trench strikes N30-45E and dips steeply ([approximately]78[degree]) to the west, although some shears within the zone dip to the east. Tertiary volcanic bedrock is exposed only on the footwall block within the trench. Unconsolidated colluvial and eolian deposits are present in the hanging-wall block and above bedrock in the footwall block. These deposits tentatively are assigned, respectively, mid Pleistocene and late Pleistocene ages based on correlations with surficial map units in Midway Valley. Three to five displacement events are inferred based on faulted colluvial and eolian deposits, and scarp-derived colluvial wedges. Total cumulative dip-slip displacement of the oldest middle Pleistocene subunit is estimated to be about 170 to 270 cm. The dip-slip displacement associated with the youngest event is about 15 cm. The earlier displacements are estimated to have produced between 40 and 85 cm of dip-slip displacement per event. The most recent event occurred after deposition of late Pleistocene colluvium deposited against the fault scarp but before deposition of an overlying hillslope-derived colluvium of probable late pleistocene age. Based on the preliminary results of the authors study, the middle to late Quaternary rate of dip-slip displacement is approximately 0.01 m/kyr or less. Ongoing work, including soil-stratigraphic studies and numerical dating of deposits, should better constrain the timing and a rate of faulting along this western splay of the Paintbrush Canyon fault.

  7. Geohydrologic data collected from shallow neutron-access boreholes and resultant-preliminary geohydrologic evaluations, Yucca Mountain area, Nye County, Nevada

    SciTech Connect

    Blout, D.O.; Hammermeister, D.P.; Loskot, C.L.; Chornack, M.P.

    1994-12-31

    In cooperation with the US Department of Energy, 74 neutron-access boreholes were drilled in and near the southwestern part of the Nevada Test Site, Nye County, Nevada. Drilling, coring, sample collection and handling, and lithologic and preliminary geohydrologic data are presented in this report. The boreholes were drilled in a combination of alluvium/colluvium, ash-flow tuff, ash-fall tuff, or bedded tuff to depths of 4.6 to 36.6 meters. Air was used as a drilling medium to minimize disturbance of the water content and water potential of drill cuttings, core, and formation rock. Drill cuttings were collected at approximately 0.6-meter intervals. Core was taken at selected intervals from the alluvium/colluvium using drive-coring methods and from tuff using rotary-coring methods. Nonwelded and bedded tuffs were continuously cored using rotary-coring methods. Gravimetric water-content and water-potential values of core generally were greater than those of corresponding drill cuttings. Gravimetric water-content, porosity, and water-potential values of samples generally decreased, and bulk density values increased, as the degree of welding increased. Grain-density values remained fairly constant with changes in the degree of welding. A high degree of spatial variability in water-content and water-potential profiles was noted in closely spaced boreholes that penetrate similar lithologic subunits and was also noted in adjacent boreholes located in different topographic positions. Variability within a thick lithologic unit usually was small. 18 refs., 21 figs., 17 tabs.

  8. Aggradation-incision transition in arid environments at the end of the Pleistocene: An example from the Negev Highlands, southern Israel

    NASA Astrophysics Data System (ADS)

    Faershtein, Galina; Porat, Naomi; Avni, Yoav; Matmon, Ari

    2016-01-01

    One of the most significant environmental processes that occurred at the transition from the last glacial phase into the present inter-glacial phase in arid regions was the shift from aggradation to incision in the drainage systems. This is evident by the sharp transition from a fluvial regime depositing fine-grained sediment within the wadis to intensive incision which formed gullies and narrow channels that dissected the late Pleistocene sediments. In order to investigate this transition, we studied three small-scale basins in the arid region of the Negev Highlands, southern Israel. Although the selected basins drain toward different base levels, their geomorphological parameters, particle size distribution of alluvial units and their OSL ages are similar. Sediments from the penultimate glacial cycle are found in patches in the bigger catchments. Fluvial loess was widely deposited since at least 67 ka until after 28 ka, covering valleys and slopes. Between ~ 28 and ~ 24 ka, loess was washed from the slopes into the channels, exposing the underlying colluvium. At ~ 24 ka erosion began with the transport of slope colluvium as gravels into the valleys that eroded the underlying loess sediments. Incision became dominant at ~ 12 ka and is still ongoing and intensifying. Dust and reworked loess continued to be deposited during the main incision stages. It is proposed that the transition from aggradation to incision was controlled by rates of loess supply and removal. Until ~ 24 ka dust choked the drainage system and only after reduction in dust supply was erosion and incision possible. It began first on the slopes and then in the channels. Our results show that an increase in precipitation is not a prerequisite for initiation of incision as is often assumed. Similar processes are described in other arid zones around the world.

  9. How does biological and anthropogenic soil mixing contribute to morphologic evolution of landscapes and terrestrial carbon cycles? (Invited)

    NASA Astrophysics Data System (ADS)

    Yoo, K.; Mudd, S. M.; Chen, C.; Aufdenkampe, A. K.; Weinman, B.; Ji, J.; Hurst, M. D.; Klaminder, J.

    2009-12-01

    The generation of sediment and its transport occurs within and at the boundaries of colluvial soils. Models that predict the evolution of soil mantled landscapes are most commonly based on statements of mass conservation that quantify mass fluxes (i.e., sediment transport) and mass sources (e.g., soil production) within colluvial soil. Traditionally these models consider soil mixing to be an internal process which does not affect sediment transport and therefore has no impact on landscape evolution. It is known, however, that physical, biological, and anthropogenic soil mixing triggers the lateral movement of soil. Here, by emphasizing that the boundary between physically mobile colluvium and immobile saprolite is defined by the depth that mixing agents are able to penetrate, we provide theoretical and empirical supports that animal burrowing, tree throw, and agricultural plowing have distinct impacts on the morphologic evolution of landscapes and the terrestrial carbon cycles. First, where colluvial flux is proportional to both colluvial thickness and slope gradient, soil mixing agents, by affecting the thickness, contribute to determining the flux. Second, soil mixing drives the physical production of colluvium in thin soils where mixing agents actively disturb underlying saprolite. In this case the depth to which mixing agents are active determines colluvial thickness and increased soil erosion rates may not translate to reduced colluvial thickness. Furthermore, by simultaneously assessing soil mixing and erosion accelerated by agricultural activities, we can better predict how land use changes may affect the contacts between organic matter and minerals during their travel from hillslopes to channels and to floodplains, which may control the production of mineral-bound carbon pools with longer turnover times and thus carbon sequestration. In biologically productive landscapes, soil mixing agents may hold important keys to unlock the black box of colluvial

  10. OFAI: 3D block tracking for a real-size rockfall experiment in the weathered volcanic context of Tahiti, French Polynesia

    NASA Astrophysics Data System (ADS)

    Dewez, Thomas; Nachbaur, Aude; Mathon, Christian; Sedan, Olivier; Berger, Frédéric; Des Garets, Emmanuel

    2010-05-01

    The Land Management Authority of French Polynesia contracted BRGM to run a real-size rockfall experiment name-coded OFAI in September 2009. The purposes of the experiment are two fold: first observe real-size rock trajectories in a context of variably weathered volcanic rock slopes; and second, use observed rockfall trajectories to calibrate block propagation numerical models (see Mathon et al., EGU 2010, this session). 90 basalt blocks were dropped down a 150-m-long slope made of hard basalt veins, lenses of colluvium and erosion channels covered in blocks of various sizes. Parameters of the experiment concerned the shape (from nearly perfect sphere to elongated cubes) and mass of the blocks (from 300 kg to >5000 kg), and the launching point, in order to bounce the blocks both off stiff basalt veins and colluvium lenses. The presentation addresses the monitoring technique developed to measure block trajectories in 3D and the variables extracted from them. A set of two 50-frame-per-second digital reflex cameras (Panasonic GH1) were installed on two prominent vantage points in order to record block motion in stereoscopy. A series of ground control points, surveyed with centimetre accuracy, served to orient pairs of images in the local topographic reference frame. This enabled the computation of block position at 50 Hz along a section of ca. 30-m-long slope, constrained by the cameras field of view. These results were then processed to extract parameters, such as velocity (horizontal, vertical, rotational, incident and reflected), number of impacts, and height of rebounds in relation with ground cover properties.

  11. Soil profile dynamics in an eroding soil landscape - a catena through a kettle hole

    NASA Astrophysics Data System (ADS)

    Gerke, Horst H.; Kaczorek, Danuta; Hierold, Wilfried; Deumlich, Detlef; Koszinski, Sylvia; Ellerbrock, Ruth H.; Sommer, Michael

    2015-04-01

    The arable hummocky ground moraine soil landscapes are characterized by a spatial continuum of more or less eroded soils at hilltops and slopes, and by colluviated soils in topographic depressions. After removal of forest in the middle ages, colluvium started covering the pre-existing Histosols and Gleysols within and Luvisols in the vicinity of kettle holes. A catena through originally peat-filled kettle-hole has hardly been described with respect to ongoing pedological modifications according to changes in landscape and hydrology. The objective was to derive the lateral continuum of soil horizons by identifying the location of the lateral boundaries between regions of clay mobilization/migration and gleisation (gleyic conditions), peat accumulation, and secondary carbonate accumulation. Data from an intensively-sampled field in northeastern Germany are presented. The start of colluviation could be dated by tree ring analyses of a buried stem. The location of the fossil topsoil A and peat horizons was determined from a dense grid of auger holes and geophysical explorations. In addition to older processes in the landscape, also younger redoximorphic processes were indicating changes in soil hydraulic properties and a modified hydrology of the arable soil landscape. We found in micromorphological analyses of soil thin sections that clay migration is an ongoing process; samples indicated vertical gradients in C-contents and secondary carbonate accumulation. The clay mobilization in the colluvium and the migration into the fossil horizons seemed to depend on the direction of soil water movement; anisotropic hydraulic conductivity indicated a potential for lateral water movement. The catena data suggest that the soil landscape development was relatively dynamic; the results may allow the reconstruction of former land surfaces, soil distributions, and erosion rates and may help predicting future developments.

  12. A comparative analysis of hazard models for predicting debris flows in Madison County, VA

    USGS Publications Warehouse

    Morrissey, Meghan M.; Wieczorek, Gerald F.; Morgan, Benjamin A.

    2001-01-01

    During the rainstorm of June 27, 1995, roughly 330-750 mm of rain fell within a sixteen-hour period, initiating floods and over 600 debris flows in a small area (130 km2) of Madison County, Virginia. Field studies showed that the majority (70%) of these debris flows initiated with a thickness of 0.5 to 3.0 m in colluvium on slopes from 17 o to 41 o (Wieczorek et al., 2000). This paper evaluated and compared the approaches of SINMAP, LISA, and Iverson's (2000) transient response model for slope stability analysis by applying each model to the landslide data from Madison County. Of these three stability models, only Iverson's transient response model evaluated stability conditions as a function of time and depth. Iverson?s model would be the preferred method of the three models to evaluate landslide hazards on a regional scale in areas prone to rain-induced landslides as it considers both the transient and spatial response of pore pressure in its calculation of slope stability. The stability calculation used in SINMAP and LISA is similar and utilizes probability distribution functions for certain parameters. Unlike SINMAP that only considers soil cohesion, internal friction angle and rainfall-rate distributions, LISA allows the use of distributed data for all parameters, so it is the preferred model to evaluate slope stability over SINMAP. Results from all three models suggested similar soil and hydrologic properties for triggering the landslides that occurred during the 1995 storm in Madison County, Virginia. The colluvium probably had cohesion of less than 2KPa. The root-soil system is above the failure plane and consequently root strength and tree surcharge had negligible effect on slope stability. The result that the final location of the water table was near the ground surface is supported by the water budget analysis of the rainstorm conducted by Smith et al. (1996).

  13. A Detailed Study of Debris Flow Source Areas in the Northern Colorado Front Range.

    NASA Astrophysics Data System (ADS)

    Arana-Morales, A.; Baum, R. L.; Godt, J.

    2014-12-01

    Nearly continuous, heavy rainfall occurred during 9-13 September 2013 causing flooding and widespread landslides and debris flows in the northern Colorado Front Range. Whereas many recent studies have identified erosion as the most common process leading to debris flows in the mountains of Colorado, nearly all of the debris flows mapped in this event began as small, shallow landslides. We mapped the boundaries of 415 September 2013 debris flows in the Eldorado Springs and Boulder 7.5-minute quadrangles using 0.5-m-resolution satellite imagery. We characterized the landslide source areas of six debris flows in the field as part of an effort to identify what factors controlled their locations. Four were on a dip slope in sedimentary rocks in the Pinebrook Hills area, near Boulder, and the other two were in granitic rocks near Gross Reservoir. Although we observed no obvious geomorphic differences between the source areas and surrounding non-landslide areas, we noted several characteristics that the source areas all had in common. Slopes of the source areas ranged from 28° to 35° and most occurred on planar or slightly concave slopes that were vegetated with grass, small shrubs, and sparse trees. The source areas were shallow, irregularly shaped, and elongated downslope: widths ranged from 4 to 9 m, lengths from 6 to 40 m and depths ranged from 0.7 to 1.2 m. Colluvium was the source material for all of the debris flows and bedrock was exposed in the basal surface of all of the source areas. We observed no evidence for concentrated surface runoff upslope from the sources. Local curvature and roughness of bedrock and surface topography, and depth distribution and heterogeneity of the colluvium appear to have controlled the specific locations of these shallow debris-flow source areas. The observed distribution and characteristics of the source areas help guide ongoing efforts to model initiation of the debris flows.

  14. Preliminary Geotechnical Investigation of Two Basaltic Landslide Sites in Mauritius, Offshore Africa

    NASA Astrophysics Data System (ADS)

    Dabycharun, Bhoopendra; Kuwano, Takeshi; Ichikawa, Kensuke; Fukuoka, Hiroshi

    2016-04-01

    Landslide hazards in developing areas in Mauritius became a great challenge as well as a fundamental concern for the government and the citizen of the country. In recent years, landslide disasters have caused losses of both public and private properties. In 2005, a large-scale landslide at Chitrakoot affected 54 houses and infrastructures, and it was reactivated in 2006, damaging another 14 houses. Vallee Pitot landslide is frequently reactivated in these years and threatening several houses in densely-populated zone. Although the long-term annual precipitation show slightly decreasing trend, number of tropical cyclone over Mauritius is clearly increasing at least in the past 3 decades. Being of volcanic origin, Mauritius has observed dramatic and quick weathering of the soil which may partly contributes to creating landslide-prone geo-environment. This study focuses on the preliminary geotechnical investigation of the above-mentioned two basaltic landslide areas in Mauritius. Recent investigation was conducted jointly by JICA (Japan International Cooperation Agency) and Ministry of Public Infrastructure and Land Transport of Government of Mauritius on both sites from 2012 to 2015 to survey the landslide surface and to implement countermeasures works. In the field investigation, aerial photo interpretation was used to investigate the zone of cracks and scarps for both sites. The landslide areas for Chitrakoot and Vallee Pitot were estimated to 1.8 km2 and 5,000 m2 respectively. Both sites are located in the highly populated area in the capital city of Mauritius. The geological features of the sites were studied with the borehole core logging data obtained from 6 boreholes and it was found that possible sliding surface was observed in the colluvium layer consisting of gravels and stiff silty-clays, at depths from 6 to 10 m below the ground surface. The rate of landslide movement during heavy rainfall amount exceeding 100 mm/hr was elaborated with past records of

  15. The River Mondego terraces at the Figueira da Foz coastal area (western central Portugal): Geomorphological and sedimentological characterization of a terrace staircase affected by differential uplift and glacio-eustasy

    NASA Astrophysics Data System (ADS)

    Ramos, Anabela M.; Cunha, Pedro P.; Cunha, Lúcio S.; Gomes, Alberto; Lopes, Fernando C.; Buylaert, Jan-Pieter; Murray, Andrew S.

    2012-09-01

    A geomorphological and sedimentological characterization of the River Mondego terraces in the Figueira da Foz coastal area, Portugal, is presented. The relief is dominated by a Pliocene a marine sandy unit ~ 10-15 m thick, reaching ~ 250 m a.s.l., that covers a shore platform surface. The River Mondego has incised into the Pliocene relief and its long drainage evolution is recorded within a series of inset river terrace landforms. These river terraces are better preserved on the right-hand (northern) bank, where they form a staircase developed against the uplifted Serra da Boa Viagem structure. A set of five river terraces, represented by sedimentary deposits or erosional straths, are identified, namely: T1 at 128-125 m; T2 at 101-90 m; T3 at 70-60 m; T4 at 29-24 m; T5 at 11-10 m a.s.l. Some luminescence dating ages were obtained from the river terrace deposits: > 390 ka from the middle of T4; > 170 ka from the top of T4; ~ 120 ka from the base of T5; ~ 109 ka from T5 (average age for three samples); and 53 ± 3 ka from a colluvium at 35 m a.s.l. Some differences in altitude of the uppermost sedimentary unit and of the terraces are here interpreted as resulting from vertical displacements of active faults during the Quaternary. The main tectonic structure is the WNW-ESE trending Quiaios fault, responsible for the regional tilting towards SW. Other probably active faults and tectonic lineaments trend NNW-SSE to N-S, NNE-SSW to NE-SW and WNW-ESE. This study reports a long-term uplift rate of 0.004-0.055 m/ka for the last 3.6 Ma, but 0.017-0.118 m/ka for the last ~ 1.8 Ma (using as references, respectively, the base and the surface of the uppermost sedimentary unit). The facies associations that characterize the older terrace deposits (T1 and T2) consist of poorly sorted fluvial sandy-gravels and silts, but also some colluvium at the top of each terrace. The younger terraces (T3, T4 and T5) show better developed sedimentary structures and less sedimentary matrix; the

  16. Soils of Walker Branch Watershed

    SciTech Connect

    Lietzke, D.A.

    1994-01-01

    The soil survey of Walker Branch Watershed (WBW) utilized the most up-to-date knowledge of soils, geology, and geohydrology in building the soils data base needed to reinterpret past research and to begin new research in the watershed. The soils of WBW were also compared with soils mapped elsewhere along Chestnut Ridge on the Oak Ridge Reservation to (1) establish whether knowledge obtained elsewhere could be used within the watershed, (2) determine whether there were any soils restricted to the watershed, and (3) evaluate geologic formation lateral variability. Soils, surficial geology, and geomorphology were mapped at a scale of 1:1200 using a paper base map having 2-ft contour intervals. Most of the contours seemed to reasonably represent actual landform configurations, except for dense wooded areas. For example, the very large dolines or sinkholes were shown on the contour base map, but numerous smaller ones were not. In addition, small drainageways and gullies were often not shown. These often small but important features were located approximately as soil mapping progressed. WBW is underlain by dolostones of the Knox Group, but only a very small part of the surface area contains outcroppings of rock and most outcrops were located in the lower part. Soil mapping revealed the presence of both ancient alluvium and ancient colluvium deposits, not recognized in previous soil surveys, that have been preserved in high-elevation stable portions of present-day landforms. An erosional geomorphic process of topographic inversion requiring several millions of years within the Pleistocene is necessary to bring about the degree of inversion that is expressed in the watershed. Indeed, some of these ancient alluvial and colluvial remnants may date back into the Tertiary. Also evident in the watershed, and preserved in the broad, nearly level bottoms of dolines, are multiple deposits of silty material either devoid or nearly devoid of coarse fragments. Recent research

  17. Water supply for the Nuclear Rocket Development Station at the U.S. Atomic Energy Commission's Nevada Test Site

    USGS Publications Warehouse

    Young, Richard Arden

    1972-01-01

    The Nuclear Rocket Development Station, in Jackass Flats, occupies about 123 square miles in the southwestern part of the U.S. Atomic Energy Commission's Nevada Test Site. Jackass Flats, an intermontane valley bordered by highlands on all sides except for a drainage outlet in the southwestern corner, has an average annual rainfall of 4 inches. Jackass Flats is underlain by alluvium, colluvium, and volcanic rocks of Cenozoic age and, at greater depth, by sedimentary rocks of Paleozoic age. The alluvium and the colluvium lie above the saturated zone throughout nearly all of Jackass Flats. The Paleozoic sedimentary rocks contain limestone and dolomite units that are excellent water producers elsewhere ; however, these units are too deep in Jackass Flats to be economic sources of water. The only important water-producing unit known in the vicinity of the Nuclear Rocket Development Station is a welded-tuff aquifer, the Topopah Spring Member of the Paintbrush Tuff, which receives no significant recharge. This member contains about 500 feet of highly fractured rock underlying an area 11 miles long and 3 miles wide in western Jackass Flats. Permeability of the aquifer is derived mostly from joints and fractures; however, some permeability may be derived from gas bubbles in the upper part of the unit. Transmissivity, obtained from pumping tests, ranges from 68,000 to 488,000 gallons per day per foot. Volume of the saturated part of the aquifer is about 3.5 cubic miles, and the average specific yield probably ranges from 1 to 5 percent. The volume of ground water in storage is probably within the range of 37-187 billion gallons. This large amount of water should be sufficient to supply the needs of the Nuclear Rocket Development Station for many years. Water at the Nuclear Rocket Development Station is used for public supply, construction, test-cell coolant, exhaust cooling, and thermal shielding during nuclear reactor and engine testing, and washdown. Present (1967) average

  18. Wildfire impacts on the processes that generate debris flows in burned watersheds

    USGS Publications Warehouse

    Parise, M.; Cannon, S.H.

    2012-01-01

    Every year, and in many countries worldwide, wildfires cause significant damage and economic losses due to both the direct effects of the fires and the subsequent accelerated runoff, erosion, and debris flow. Wildfires can have profound effects on the hydrologic response of watersheds by changing the infiltration characteristics and erodibility of the soil, which leads to decreased rainfall infiltration, significantly increased overland flow and runoff in channels, and movement of soil. Debris-flow activity is among the most destructive consequences of these changes, often causing extensive damage to human infrastructure. Data from the Mediterranean area and Western United States of America help identify the primary processes that result in debris flows in recently burned areas. Two primary processes for the initiation of fire-related debris flows have been so far identified: (1) runoff-dominated erosion by surface overland flow; and (2) infiltration-triggered failure and mobilization of a discrete landslide mass. The first process is frequently documented immediately post-fire and leads to the generation of debris flows through progressive bulking of storm runoff with sediment eroded from the hillslopes and channels. As sediment is incorporated into water, runoff can convert to debris flow. The conversion to debris flow may be observed at a position within a drainage network that appears to be controlled by threshold values of upslope contributing area and its gradient. At these locations, sufficient eroded material has been incorporated, relative to the volume of contributing surface runoff, to generate debris flows. Debris flows have also been generated from burned basins in response to increased runoff by water cascading over a steep, bedrock cliff, and incorporating material from readily erodible colluvium or channel bed. Post-fire debris flows have also been generated by infiltration-triggered landslide failures which then mobilize into debris flows. However

  19. The synergetic effect of moisture protection, substrate quality and biotic acclimation on soil organic carbon persistence along a cultivated loamy hillslope

    NASA Astrophysics Data System (ADS)

    Wiaux, François; Vanclooster, Marnik; Cornelis, Jean-Thomas; Van Oost, Kristof

    2014-05-01

    The combination of hydrologic, geomorphic and biogeochemical approaches is required to determine organic carbon (OC) persistence and dynamics within landscapes. Here, we used soil in-situ surface heterotrophic respiration measurement as an indicator of OC persistence along a hillslope (crop field on the loess belt under temperate climate), characterized by an important erosion-induced OC stock colluvium downslope. Along this topographical gradient, we quantified the space-time structure of soil water and temperature, and soil OC amount and quality (from a chemical point of view based on NaOCl oxidation) in relation to CO2 fluxes. We used a Generalized Least Square (GLS) regression model to identify the role of each abiotic factor as well as their interactions on observed soil respiration rates, and to calculate time-average values of these CO2 fluxes at each studied slope positions. We observed significant differences between the observed respiration rates along the topographical gradient (up to 30% more CO2 emissions downslope and 50% backslope, relative to un-eroded summit position). Despite mean CO2 fluxes (standardized at 15°C) at the bottom of the slope are significantly higher (p<0.05) than at the top of the hillslope, this difference is lower than expected given the high OC stock found downslope (c.2 times higher than at the summit position). In the cultivated loamy hillslope, the soil OC persistence is mainly controlled by the stabilizing effect of the high moisture content, implying large amount of OC. This provides evidence that soil OC dynamic (sink or source) can be mainly governed by site-specific abiotic conditions (e.g. soil moisture). On the other hand, OC found downslope was showed to be especially vulnerable for OC mineralization (it would emit 26% to c.40% more CO2 in case of temperature increase), due to both (i) improved efficiency of soil-micro-organisms in stabilizing conditions, and (ii) high quality of OC stock (easy to decompose for soil

  20. Fire-related debris flows in the Iberian Range, Spain

    NASA Astrophysics Data System (ADS)

    García-Ruiz, José M.; Arnáez, José; Gómez-Villar, Amelia; Ortigosa, Luis; Lana-Renault, Noemí

    2013-08-01

    Debris flows occurred three weeks after a wildfire in August 1986 in the Najerilla River valley in the Iberian Range, northern Spain. The flows were triggered by a brief, intense rainstorm (approximately 25 mm h- 1 over 15 min) in a small area with steep slopes covered by a thick colluvium of quartzite clasts. This storm resulted in the development of several unconfined hillslope debris flows and the formation of an alluvial fan at the mouth of the Pítare stream, which partially blocked the Najerilla River. We analysed the conditions that led to the development of the debris flows, and estimated the rainfall threshold for the debris flows to occur as well as the total volume of mobilised sediment. Four factors contributed to the debris flows: (i) the occurrence of a rainstorm three weeks after a wildfire, which had removed the plant cover from the soil; (ii) the steep slopes in the area (> 30°), which were the most affected by debris flows; (iii) the presence of quartzite scarps on the hillslopes, which favoured the development of a 'firehose effect' involving channelised surface runoff; and (iv) the low plasticity index values of the fine material of the colluvium (indices of 7 to 8), which enabled rapid liquefaction. Estimates of rainfall intensity derived from the estimated peak flow in the Pítare stream suggests that around 80 mm of rainfall fell in approximately 15 min, although this is clearly an overestimated value given the high proportion of sediment load transported during the peak flow. Various equations estimated a rainfall-threshold of approximately 25 mm h- 1 considering a concentration time of 15 min. The total sediment transported by the debris flows was 10,500 m3 (15,750 Mg, 6800 Mg km- 2), and the Pítare stream alone transported a minimum of 4000 m3 (6000 Mg, 2500 Mg km- 2). These results suggest that the rainfall threshold for initiating debris flows decreases following a wildfire, such that an ordinary rainstorm is able to trigger a severe

  1. Detection of early stage large scale landslides in forested areas by 2 m LiDAR DEM analysis. The example of Portainé (Central Pyrenees)

    NASA Astrophysics Data System (ADS)

    Guinau, Marta; Ortuño, Maria; Calvet, Jaume; Furdada, Glòria; Bordonau, Jaume; Ruiz, Antonio; Camafort, Miquel

    2016-04-01

    Mass movements have been classically detected by field inspection and air-photo interpretation. However, airborne LiDAR has significant potential for generating high-resolution digital terrain models, which provide considerable advantages over conventional surveying techniques. In this work, we present the identification and characterization of six slope failures previously undetected in the Orri massif, at the core of the Pyrenean range. The landforms had not been previously detected and were identified by the analysis of high resolution 2 m LiDAR derived bared earth topography. Most of the scarps within these failures are not detectable by photo interpretation or the analysis of 5 m resolution topographic maps owing to their small heights (ranging between 0.5 and 2 m) and their location within forest areas. 2D and 3D visualization of hillshade maps with different sun azimuths, allowed to obtain the overall picture of the scarp assemblage and to analyze the geometry and location of the scarps with respect to the slope and the structural fabric. Near 120 scarps were mapped and interpreted as part of slow gravitational deformation, incipient slow flow affecting a colluvium, rotational rock-sliding and slope creep. Landforms interpreted as incipient slow flow affecting a colluvium have headscarps with horse-shoe shape and superficial (< 20 m) basal planes whereas sackung features have open headscarps and basal planes that are likely located at 200-250 m maximum depth. Other distinctive features are toppling or extensive scarps, double ridges and rock rotational landslides. The sharpness of the scarps suggests their recent activity, which may pose a potential risk for the Port-Ainé sky resort users and facilities. These results suggest that the systematic analysis of 2 m LIDAR derived bared earth topography would significantly help in the rapid detection and mapping of early stage slope deformations in high mountain areas, which could contribute to 1) a better

  2. High permafrost ice contents in Holocene slope deposits as observed from shallow geophysics and a coring program in Pangnirtung, Nunavut, Canada

    NASA Astrophysics Data System (ADS)

    Carbonneau, A.; Allard, M.; L'Hérault, E.; LeBlanc, A.

    2011-12-01

    A study of permafrost conditions was undertaken in the Hamlet of Pangnirtung, Nunavut, by the Geological Survey of Canada (GSC) and Université Laval's Centre d'études nordiques (CEN) to support decision makers in their community planning work. The methods used for this project were based on geophysical and geomorphological approaches, including permafrost cores drilled in surficial deposits and ground penetrating radar surveys using a GPR Pulse EKKO 100 extending to the complete community area and to its projected expansion sector. Laboratory analysis allowed a detailed characterization of permafrost in terms of water contents, salinity and grain size. Cryostratigraphic analysis was done via CT-Scan imagery of frozen cores using medical imaging softwares such as Osiris. This non destructive method allows a 3D imaging of the entire core in order to locate the amount of the excess ice, determine the volumetric ice content and also interpret the ice-formation processes that took place during freezing of the permafrost. Our new map of the permafrost conditions in Pangnirtung illustrates that the dominant mapping unit consist of ice-rich colluvial deposits. Aggradationnal ice formed syngenitically with slope sedimentation. Buried soils were found imbedded in this colluvial layer and demonstrates that colluviation associated with overland-flow during snowmelt occurred almost continuously since 7080 cal. BP. In the eastern sector of town, the 1 to 4 meters thick colluviums cover till and a network of ice wedges that were revealed as spaced hyperbolic reflectors on GPR profiles. The colluviums also cover ice-rich marine silt and bedrock in the western sector of the hamlet; marine shells found in a permafrost core yielded a radiocarbon date of 9553 cal. BP which provides a revised age for the local deglaciation and also a revised marine submergence limit. Among the applied methods, shallow drilling in coarse grained permafrost, core recovery and CT-Scan allowed the

  3. Using a 2.5D Electrical Resistivity Imaging Method for Locating the House Remnants and Possible Landslide Victims of Typhoon Morak

    NASA Astrophysics Data System (ADS)

    Chang, S.; Chang, P.; Chen, H.; Jan, P.

    2009-12-01

    The Typhoon Morak hits Taiwan on August 8th, 2009, and pours huge amount of precipitation (over 2000 mm in just three days) into the southern part of the island. The heavy precipitation induces many landslides in the mountain area and costs over 500 deaths. To help searching the remnants of the buildings and possible victims that may be buried under the buildings, we utilized the 2.5D electrical resistivity tomography (2.5D) technique in one landslide location near the Baolai village area in the Kaohsiung County. A family of 5 was reported missing in the landslide and only parts of the bodies were recovered in the rescue mission. We conducted 2.5D electrical resistivity tomography in two possible areas marked by the rescue team along four 20-meter long parallel lines. The remnants of the house and bodies were believed to be buried under the thick colluvium sediments. To search for possible anomalies from these man-made objects, we chose dipole-dipole method and the 0.5-m electrode spacing for the survey.

  4. Reconstructing paleo- and initial landscapes using a multi-method approach in hummocky NE Germany

    NASA Astrophysics Data System (ADS)

    van der Meij, Marijn; Temme, Arnaud; Sommer, Michael

    2016-04-01

    The unknown state of the landscape at the onset of soil and landscape formation is one of the main sources of uncertainty in landscape evolution modelling. Reconstruction of these initial conditions is not straightforward due to the problems of polygenesis and equifinality: different initial landscapes can change through different sets of processes to an identical end state. Many attempts have been done to reconstruct this initial landscape. These include remote sensing, reverse modelling and the usage of soil properties. However, each of these methods is only applicable on a certain spatial scale and comes with its own uncertainties. Here we present a new framework and preliminary results of reconstructing paleo-landscapes in an eroding setting, where we combine reverse modelling, remote sensing, geochronology, historical data and present soil data. With the combination of these different approaches, different spatial scales can be covered and the uncertainty in the reconstructed landscape can be reduced. The study area is located in north-east Germany, where the landscape consists of a collection of small local depressions, acting as closed catchments. This postglacial hummocky landscape is suitable to test our new multi-method approach because of several reasons: i) the closed catchments enable a full mass balance of erosion and deposition, due to the collection of colluvium in these depressions, ii) significant topography changes only started recently with medieval deforestation and recent intensification of agriculture and iii) due to extensive previous research a large dataset is readily available.

  5. Regoliths of the middle-Atlantic Piedmont and evolution of a polymorphic landscape

    USGS Publications Warehouse

    Cleaves, E.T.

    2000-01-01

    The regolith overlying the alumino-silicate rocks of the middle-Atlantic Piedmont Province consists primarily of saprolite with a thin veneer of diamictons of colluvial origin. Thickness and distribution of the saprolite is related to landform and lithology. For example, on uplands isovolumetric weathering of the Loch Raven Schist produces saprolite averaging 55 ft (17 m) thick. On Port Deposit Gneiss, saprolite beneath uplands averages 42 ft (13 m) in thickness. The saprolite results from the reaction of alumino-silicate rocks with through-flowing groundwater. Chemical weathering of the rock results in clay and resistate minerals, residual rock layers, corestones, and pinnacles. Surface erosion of saprolite with quartzite and metagraywacke residual layers may produce a 'washboard' topography. Surface erosion of a metagabbro saprolite containing corestones and pinnacles results in a surface with lag deposits of corestones and emergent pinnacles. The diamicton material comes from the underlying saprolite, weathered rock and bedrock. Generally, diamictons are thinner on uplands and upper slopes, and thicker at the base of slopes and in hollows and gathering areas of first-order streams. The saprolite and colluvium reflect response of geomorphic processes (chemical weathering, fluvial incision, and periglacial processes) to rock lithology and landscape. The modifications to the landscape have been driven by neotectonic crustal warping and alternating periglacial-humid temperate climates. Altogether these varied interactions have resulted in a Holocene polymorphic landscape.

  6. Landslides triggered by the September 4, 1984, Nagano-ken-Seibu earthquake in Japan

    SciTech Connect

    Harp, E.L.; Keefer, D.K.

    1985-01-01

    The September 14, 1984, Nagano-ken-Seibu earthquake (M 6.9) triggered several hundred landslides, including four particularly destructive slope failures-- three soil flows and one of the largest earthquake-generated rock avalanches in history. The rock avalanche originated on the flank of a historically active volcano. The initial basal sliding surface (whose slope was 25/sup 0/) was in weathered rhyolitic tuff. The soil flows had volumes as great as 5 x 10/sup 5/ m/sup 3/ and occurred in unconsolidated to weakly cemented colluvium and alluvium, weathered rhyolitic tuff, and ash. Liquefaction of saturated, unconsolidated ash deposits that are hydraulically confined by impermeable, weathered rhyolitic tuff may have triggered two of the soil flows. One of the flows was reported by an eyewitness to have attained speeds of 20 to 60 kph; another destroyed houses and killed 13 people. The extreme runnout distance of the rock avalanche and the fact that all of the deaths in the earthquake were from landslides point of the hazards posed by these types of destructive landslides. The presence of volcanic layers subparallel to surface slopes and interbedded with highly altered layers indicates that the geologic conditions under which the rock avalanche and soil flows occurred are similar to conditions which produced similar landslides in other historical earthquakes. The occurrence of these landslides emphasizes the fact that similar hazards may exist in volcanic and seismically active areas in the western US (such as the Cascade Range), even without the presence of active volcanism.

  7. Mine seepage problems in drift mine operations

    SciTech Connect

    DeRossett, C.; Johnson, D.E.; Bradshaw, D.B.

    1996-12-31

    Extensive mining in the Eastern Kentucky Coal Region has occurred in coal deposits located above valley floors. Underground mines present unique stability problems resulting from the creation of mine pools in abandoned works. {open_quotes}Blowouts{close_quotes} occur when hydrostatic pressures result in the cataclysmic failure of an outcrop-barrier. Additionally, seepage from flooded works results in saturation of colluvium, which may ultimately mobilize as landslides. Several case studies of both landslides and blowouts illustrate that considerations should be taken into account to control or prevent these problems. Underground mine maps and seepage conditions at the individual sites were examined to determine the mine layouts, outcrop-barrier widths, and structure of the mine floors. Discharge monitoring points were established in and near the landslides. These studies depict how mine layout, operation, and geology influence drainage conditions. The authors suggest that mine designs should incorporate drainage control to insure long-term stability and limit liability. The goal of the post-mining drainage plan is control of the mine drainage, which will reduce the size of mine pools and lower the hydrostatic pressure. Recommendations are made as to several methods that may be useful in controlling mine drainage.

  8. Surficial deposits of the United States

    SciTech Connect

    Hunt, C.

    1986-01-01

    This volume is the culmination of efforts to provide an explanation for the 1:7,500,000 scale (1 inch = 120 miles) overview map of the country's surficial deposits prepared by the US Geological Survey for the National Atlas of the United States of America. Because the scale is small, the map is of only limited use to specialists. The map information is technical and nonspecialist needs an explanation that is more complete than can appear on the map. In this book surficial deposits are divided into four major categories: (1) untransported deposits - those formed more or less in place by weathering (residuum) or by organic activity) as in marshes and swamps); (2) transitional deposits - those displaced by gravity, such as colluvium, landslides, debris, avalanches, or mudflows; (3) transported deposits, which include shore, glacial, stream, lake, and wind deposits; and (4) miscellaneous kinds of deposits including basalt, clinker due to the burning of coal beds, hot spring deposits, and small patches of bedrock shown on the overview map.

  9. Frequency and initiation of debris flows in Grand Canyon, Arizona

    NASA Astrophysics Data System (ADS)

    Griffiths, Peter G.; Webb, Robert H.; Melis, Theodore S.

    2004-12-01

    Debris flows from 740 tributaries transport sediment into the Colorado River in Grand Canyon, Arizona, creating rapids that control its longitudinal profile. Debris flows mostly occur when runoff triggers failures in colluvium by a process termed "the fire hose effect." Debris flows originate from a limited number of geologic strata, almost exclusively shales or other clay-rich, fine-grained formations. Observations from 1984 through 2003 provide a 20 year record of all debris flows that reached the Colorado River in Grand Canyon, and repeat photography provides a 100 year record of debris flows from 147 tributaries. Observed frequencies are 5.1 events/year from 1984 to 2003, and historic frequencies are 5.0 events/year from 1890 to 1983. Logistic regression is used to model historic frequencies based on drainage basin parameters observed to control debris flow initiation and transport. From 5 to 7 of the 16 parameters evaluated are statistically significant, including drainage area, basin relief, and the height of and gradient below debris flow source areas, variables which reflect transport distance and potential energy. The aspect of the river channel, which at least partially reflects storm movement within the canyon, is also significant. Model results are used to calculate the probability of debris flow occurrence at the river over a century for all 740 tributaries. Owing to the variability of underlying geomorphic controls, the distribution of this probability is not uniform among tributaries of the Colorado River in Grand Canyon.

  10. Geologic map of the White Hall quadrangle, Frederick County, Virginia, and Berkeley County, West Virginia

    USGS Publications Warehouse

    Doctor, Daniel H.; Orndorff, Randall C.; Parker, Ronald A.; Weary, David J.; Repetski, John E.

    2010-01-01

    The White Hall 7.5-minute quadrangle is located within the Valley and Ridge province of northern Virginia and the eastern panhandle of West Virginia. The quadrangle is one of several being mapped to investigate the geologic framework and groundwater resources of Frederick County, Va., as well as other areas in the northern Shenandoah Valley of Virginia and West Virginia. All exposed bedrock outcrops are clastic and carbonate strata of Paleozoic age ranging from Middle Cambrian to Late Devonian. Surficial materials include unconsolidated alluvium, colluvium, and terrace deposits of Quaternary age, and local paleo-terrace deposits possibly of Tertiary age. The quadrangle lies across the northeast plunge of the Great North Mountain anticlinorium and includes several other regional folds. The North Mountain fault zone cuts through the eastern part of the quadrangle; it is a series of thrust faults generally oriented northeast-southwest that separate the Silurian and Devonian clastic rocks from the Cambrian and Ordovician carbonate rocks and shales. Karst development in the quadrangle occurs in all of the carbonate rocks. Springs occur mainly near or on faults. Sinkholes occur within all of the carbonate rock units, especially where the rocks have undergone locally intensified deformation through folding, faulting, or some combination.

  11. Geologic map of the Jam Up Cave and Pine Crest quadrangles, Shannon, Texas, and Howell Counties, Missouri

    USGS Publications Warehouse

    Weary, David J.; Orndorff, Randall C.; Repetski, John E.

    2013-01-01

    The Jam Up Cave and Pine Crest 7.5-minute quadrangles are located in south-central Missouri within the Salem Plateau region of the Ozark Plateaus physiographic province. About 2,400 to 3,100 feet (ft) of flat-lying to gently dipping Lower Paleozoic sedimentary rocks, mostly dolomite, chert, sandstone, and orthoquartzite, overlie Mesoproterozoic igneous basement rocks. Unconsolidated residuum, colluvium, terrace deposits, and alluvium overlie the sedimentary rocks. Numerous karst features, such as sinkholes, caves, and springs, have formed in the carbonate rocks. Many streams are spring fed. The topography is a dissected karst plain with elevations ranging from about 690 ft where the Jacks Fork River exits the northeastern corner of the Jam Up Cave quadrangle to about 1,350 ft in upland areas along the north-central edge and southwestern corner of the Pine Crest quadrangle. The most prominent physiographic feature is the valley of the Jacks Fork River. This reach of the upper Jacks Fork, with its clean, swiftly-flowing water confined by low cliffs and bluffs, provides one of the most beautiful canoe float trips in the nation. Most of the land in the quadrangles is privately owned and used primarily for grazing cattle and horses and growing timber. A large minority of the land within the quadrangles is publicly owned by the Ozark National Scenic Riverways of the National Park Service. Geologic mapping for this investigation was conducted in 2005 and 2006.

  12. Aeromagnetic maps with geologic interpretations for the Tularosa Valley, south-central New Mexico

    USGS Publications Warehouse

    Bath, G.D.

    1977-01-01

    An aeromagnetic survey of the Tularosa Valley in south-central New Mexico has provided information on the igneous rocks that are buried beneath alluvium and colluvium. The data, compiled as residual magnetic anomalies, are shown on twelve maps at a scale of 1:62,500. Measurements of magnetic properties of samples collected in the valley and adjacent highlands give a basis for identifying the anomaly-producing rocks. Precambrian rocks of the crystalline basement have weakly induced magnetizations and produce anomalies having low magnetic intensities and low magnetic gradients. Late Cretaceous and Cenozoic intrusive rocks have moderately to strongly induced magnetizations. Precambrian rocks produce prominent magnetic anomalies having higher amplitudes and higher gradients. The Quaternary basalt has a strong remanent magnetization of normal polarity and produces narrow anomalies having high-magnetic gradients. Interpretations include an increase in elevation to the top of buried Precambrian rock in the northern part of the valley, a large Late Cretaceous and Cenozoic intrusive near Alamogordo, and a southern extension of the intrusive rock exposed in the Jarilla Mountains. Evidence for the southern extension comes from a quantitative analysis of the magnetic anomalies..

  13. A preliminary case study of potential ceramic raw materials in the Aileu area of Timor Leste

    NASA Astrophysics Data System (ADS)

    Lisboa, J. V.; Carvalho, J. M. F.; Oliveira, A.; Carvalho, C.; Grade, J.

    2007-03-01

    The newly independent country of Timor Leste is located in the eastern half of Timor Island (Indonesian archipelago). Geological studies of the country's mineral resources and extractive activities are practically non-existent. There is evidence of the exploitation of ceramic raw materials at outcrop level and two small brick kilns, nowadays inactive, in the Dili and Aileu areas. Near Aileu, there are light-coloured silt-rich deposits, interpreted as overbank deposits, interbedded with ancient river terraces (post-Pliocene) overlying metamorphic bedrock. These sediments are the subject of this study, which encompassed geological mapping and preliminary characterisation. Tectonically, the area is a graben, preserving alluvium and colluvium deposits. Five channel samples representative of the silt-rich deposits were collected. Semi-quantitative mineralogical analysis shows that the samples are made of illite, quartz and kaolinite clays, with accessory illite/vermiculite interstratified minerals and K-feldspar. The chemical data show agreement with the estimated mineralogical composition. The grain size distribution points to a silt-dominated assemblage. Most samples have a satisfactory extrudability but deficient moulding properties. After firing, the sampled raw materials form a final product with possible ceramic capability for whiteware production.

  14. Reinterpretation of the Robein and Plano Silts, northeastern Illinois

    SciTech Connect

    Curry, B.B.; Kempton, J.P.

    1985-01-01

    Reinterpretation of till stratigraphy in northern Illinois and recently obtained radiocarbon dates suggest the Plano Silt is lithologically and stratigraphically indistinguishable from the Robein Silt. These recent data suggest colluvial silt and organic-rich sediment were deposited in most of the northern Illinois between >50,000 and 23,000 RCBP. This age range agrees with radiocarbon dates from the Mid-Wisconsinan Sidney Interstadial Soil of the Huron-Erie Lobe. Altonian (Early to Mid-Wisconsinan)-age till associated with the Lake Michigan Lobe has not yet been identified. Horberg and others recognize in northeastern Illinois a single basal Wisconsinan organic-rich zone; peat, silt and loess of the Farmdalian Substage were interpreted to overlie Sangamon Soil developed in Illinoian drift. They also interpreted a reddish-brown diamicton overlying the Plano Silt at its type section as the Capron Till Member of late Altonian age. The new data support the earlier interpretation of a single organic-rich deposit between Wisconsinan and Illinoian drifts. The Plano Silt should be abandoned as a rock-stratigraphic unit. The Robein Silt includes colluvium and organic-rich sediment not only of Farmdalian age, but also Altonian age in most of northern Illinois, similar to the rest of the upper Mississippi River Valley. The evidence of nearly continuous Robein deposition restricts possible Altonian-age glacial deposits to a narrow band on Capron Ridge in northern Illinois and southern Wisconsin.

  15. Roman, Visigothic and Islamic evidence of earthquakes recorded in the archaeological site of “El Tolmo de Minateda” (Prebetic Zone, southeast of Spain)

    USGS Publications Warehouse

    Rodríguez-Pascua, M.A.; Abad Casal, L.; Pérez-López, R.; Gamo Parra, B.; Silva, P.G.; Garduño-Monroy, V.H.; Giner-Robles, J.L.; Perucha, M.A.; Israde-Alcántara, I.; Bischoff, J.; Calvo, J.P.

    2013-01-01

    The archaeological site of “El Tolmo de Minateda” is located within the Albacete province (SE of Spain) and shows a continuous time record of ancient civilizations from 3500 yr BP onwards. However, three temporal gaps were identified in this archaeological record, all of them in relationship with a sudden and unclear abandonment of the city (Centuries 1st, 7th and 9-10th). The Archaeological Earthquake Effects (EAEs) supports the possibility that moderate to strong earthquakes were the cause of such abandonments: oriented columns fallen, collapsed walls and arches, abandonment of irrigation systems and fresh-water supplies, crashed pottery, etc. Despite of the scarce of instrumental seismicity and a few historical chronicles, paleoseismic studies performed in the neighbouring zone (Tobarra) suggest the presence of closer seismic sources as faults (Pozohondo Fault) affecting Quaternary alluvial, lacustrine deposits and colluviums. In this work, we propose the possibility that three moderate earthquakes devastated the ancient Roman city of Ilunum (Century 1st AD), the Visigothic city of Elo (Century 7th AD) and the Islamic city of Madinat Iyih (Century 9th-10thAD), all of them the same place: “El Tolmo de Minateda”.

  16. Landslide susceptibility in the Tully Valley area, Finger Lakes region, New York

    USGS Publications Warehouse

    Jager, Stefan; Wieczorek, Gerald E.

    1994-01-01

    As a consequence of a large landslide in the Tully Valley, Onondaga County, New York, an investigation was undertaken to determine the factors responsible for the landslide in order to develop a model for regional landslide susceptibility. The April 27, 1993 Tully Valley landslide occurred within glacial lake clays overlain by till and colluvium on gentle slopes of 9-12 degrees. The landslide was triggered by extreme climatic events of prolonged heavy rainfall combined with rapid melting of a winter snowpack. A photoinventory and field checking of landslides within a 415 km2 study area, including the Tully Valley, revealed small recently-active landslides and other large dormant prehistoric landslides, probably Pleistocene in age. Similar to the larger Tully Valley landslide, the smaller recently-active landslides occurred in red, glacial lake clays very likely triggered by seasonal rainfall. The large dormant landslides have been stable for long periods as evidenced by slope denudational processes that have modified the landslides. These old and ancient landslides correspond with proglacial lake levels during the Pleistocene, suggesting that either inundation or rapid drainage was responsible for triggering these landslides. A logistic regression analysis was performed within a Geographic Information System (GIS) environment to develop a model of landslide susceptibility for the Tully Valley study area. Presence of glacial clays, slope angle, and glacial lake levels were used as explanatory variables for landslide incidence. The spatial probability of landsliding, categorized as low, moderate and high, is portrayed within 90-m square cells on the susceptibility map.

  17. Geology of five small Australian impact craters

    USGS Publications Warehouse

    Shoemaker, E.M.; Macdonald, F.A.; Shoemaker, C.S.

    2005-01-01

    Here we present detailed geological maps and cross-sections of Liverpool, Wolfe Creek, Boxhole, Veevers and Dalgaranga craters. Liverpool crater and Wolfe Creek Meteorite Crater are classic bowlshaped, Barringer-type craters, Liverpool was likely formed during the Neoproterozoic and was filled and covered with sediments soon thereafter. In the Cenozoic, this cover was exhumed exposing the crater's brecciated wall rocks. Wolfe Creek Meteorite Crater displays many striking features, including well-bedded ejecta units, crater-floor faults and sinkholes, a ringed aeromagnetic anomaly, rim-skirting dunes, and numerous iron-rich shale balls. Boxhole Meteorite Crater, Veevers Meteorite Crater and Dalgaranga crater are smaller, Odessa-type craters without fully developed, steep, overturned rims. Boxhole and Dalgaranga craters are developed in highly follated Precambrian basement rocks with a veneer of Holocene colluvium. The pre-existing structure at these two sites complicates structural analyses of the craters, and may have influenced target deformation during impact. Veevers Meteorite Crater is formed in Cenozoic laterites, and is one of the best-preserved impact craters on Earth. The craters discussed herein were formed in different target materials, ranging from crystalline rocks to loosely consolidated sediments, containing evidence that the impactors struck at an array of angles and velocities. This facilitates a comparative study of the influence of these factors on the structural and topographic form of small impact craters. ?? Geological Society of Australia.

  18. Geohydrology of Monitoring Wells Drilled in Oasis Valley near Beatty, Nye County, Nevada, 1997

    USGS Publications Warehouse

    Robledo, Armando R.; Ryder, Philip L.; Fenelon, Joseph M.; Paillet, Frederick L.

    1999-01-01

    Twelve monitoring wells were installed in 1997 at seven sites in and near Oasis Valley, Nevada. The wells, ranging in depth from 65 to 642 feet, were installed to measure water levels and to collect water-quality samples. Well-construction data and geologic and geophysical logs are presented in this report. Seven geologic units were identified and described from samples collected during the drilling: (1) Ammonia Tanks Tuff; (2) Tuff of Cutoff Road; (3) tuffs, not formally named but informally referred to in this report as the 'tuff of Oasis Valley'; (4) lavas informally named the 'rhyolitic lavas of Colson Pond'; (5) Tertiary colluvial and alluvial gravelly deposits; (6) Tertiary and Quaternary colluvium; and (7) Quaternary alluvium. Water levels in the wells were measured in October 1997 and February 1998 and ranged from about 18 to 350 feet below land surface. Transmissive zones in one of the boreholes penetrating volcanic rock were identified using flowmeter data. Zones with the highest transmissivity are at depths of about 205 feet in the 'rhyolitic lavas of Colson Pond' and 340 feet within the 'tuff of Oasis Valley.'

  19. Geologic controls on movement of produced-water releases at US geological survey research Site A, Skiatook lake, Osage county, Oklahoma

    USGS Publications Warehouse

    Otton, J.K.; Zielinski, R.A.; Smith, B.D.; Abbott, M.M.

    2007-01-01

    Highly saline produced water was released from multiple sources during oil field operations from 1913 to 1973 at the USGS research Site A on Skiatook Lake in northeastern Oklahoma. Two pits, designed to hold produced water and oil, were major sources for release of these fluids at the site. Produced water spills from these and other features moved downslope following topography and downdip by percolating through permeable eolian sand and colluvium, underlying permeable sandstone, and, to a lesser extent, through shales and mudstones. Saline water penetrated progressively deeper units as it moved through the gently dipping bedrock to the north and NW. A large eroded salt scar north of the pits coincides with underlying fine-grained rocks that have retained substantial concentrations of salt, causing slow revegetation. Where not eroded, thick eolian sand or permeable sandstone bedrock is near the surface, and vegetation has been little affected or has reestablished itself after the introduced salt was flushed by precipitation. The extent of salt-contaminated bedrock extends well beyond existing surface salt scars. These results indicate that one of the legacies of surface salt spills can be a volume of subsurface salinization larger than the visible surface disturbance. ?? 2007.

  20. Large quaternary landslides in the central appalachian valley and ridge province near Petersburg, West Virginia

    NASA Astrophysics Data System (ADS)

    Scott Southworth, C.

    1988-12-01

    Geological mapping and photointerpretation of side-looking airborne radar images and color-infrared aerial photographs reveal two large Quaternary landslides in the Valley and Ridge province of the central Appalachians near Petersburg, W. Va. The Elkhorn Mountain rock avalanche occurs on the thrust-faulted northwestern flank of the Elkhorn Mountain anticlinorium. A minimum of 7 × 10 6 m 3 of quartzite colluvium was transported more than 3 km from a 91 m high escarpment of Silurian Tuscarora Quartzite. The extensively vegetated deposit may owe, in part, its transport and weathering to periglacial conditions during the Pleistocene. In contrast, the Gap Mountain rock block slide is a single allochthonous block that is 1.2 km long, 0.6 km wide, and at least 60 m thick. The 43 × 10 6 m 3 block is composed of limestone of the Helderberg Group and the Oriskany Sanstone of Early Devonian age. Planar detachment probably occurred along a dissolution bedding plane near the Shriver Chert and the Oriskany Sandstone contact. Failure probably was initiated by downcutting of the South Branch Potomac River during the Pleistocene. Landslides of this magnitude suggest accelerated erosion during periglacial climates in the Pleistocene. The recognition of these large slope failures may provide evidence of paleoclimatic conditions and, thereby, increase our understanding of the geomorphologic development of the Valley and Ridge province.

  1. Evidence for Regional Stream Aggradation in the Central Oregon Coast Range during the Pleistocene-Holocene Transition

    USGS Publications Warehouse

    Personius, S.F.; Kelsey, H.M.; Grabau, P.C.

    1993-01-01

    Low, nearly continuous terraces of similar age are present along streams in drainage basins that range in size from Drift Creek (190 km2) to the Umpqua River (11,800 km2) in the Oregon Coast Range. Radiocarbon ages from near the bose of fluvial sediments underlying these terraces are clustered at about 9000-11,000 14C yr B.P. Beveled bedrock surfaces (straths) that underlie the fluvial sediments are 1-8 m above summer stream levels and are present along most of the nontidal reaches of the rivers that we studied. Where exposed, the bedrock straths are overlain by 2-11 m of fluvial sediment that consists of a bottom-stratum (channel) facies of sandy pebble-cobble gravel and a top-stratum (overbank) facies of sandy silt or silt. Eight radiocarbon ages from the fluvial sediments allow correlation of the lowest continuous terrace over a wide area and thus indicate that a regional aggradation episode occurred in Coast Range drainage basins during the Pleistocene-Holocene transition. The cause of such widespread aggradation is unknown but may be related to climate-induced changes in the frequency of evacuation of colluvium from hollows, which are common in all drainage basins in the region.

  2. Hydrogeologic characterization report for the Rocky Flats environmental technology site

    SciTech Connect

    Reeder, D.C.; Burcar, S.; Smith, R.

    1996-12-31

    The Denver groundwater basin encompasses approximately 6,700 square miles, extending east from the Front Range of the Rocky Mountains. This structural basin contains four Cretaceous bedrock aquifers overlain by a regional Quaternary alluvial aquifer. The Rocky Flats Site is located on the northwest margin of the basin. The shallow groundwater system at the Rocky Flats Site is divided into upper and lower hydrostratigraphic units (UHSU and LHSU, respectively). The UHSU at the Rocky Flats site comprises Quaternary alluvium, colluvium, valley-fill alluvium, artificial fill, weathered bedrock of the undifferentiated Arapahoe and Laramie formations and all sandstones that are hydraulically connected with overlying surficial groundwater. The LHSU comprises unweathered claystone with interbedded siltstones and sandstones of the undifferentiated Arapahoe and Laramie formations. The contact separating the UHSU and LHSU is identified as the base of the weathered zone. The separation of hydrostratigraphic units is supported by the contrasting permeabilities of the units comprising the UHSU and LHSU, well hydrograph data indicating that the units respond differently to seasonal recharge events, and geochemical data reflecting distinct major ion chemistries in the groundwaters of the UHSU and LHSU. Surface-water/groundwater interactions at the Rocky Flats site generally respond to seasonal fluctuations in precipitation, recharge, groundwater storage, and stream and ditch flow. Effluent conditions are dominant in the spring along western stream segments and influent conditions are common in the late summer and fall along most stream reaches.

  3. Antimony and other metal anomalies south of Stibnite, Valley County, Idaho

    USGS Publications Warehouse

    Curtin, Gary C.; King, Harley D.; Leonard, B.F.

    1974-01-01

    Results of geochemical investigations south of Stibnite, Valley County, Idaho, show that the distribution of Sb, As, Au, Zn, Ag, and Mo in mull ash and of Hg, in soil forms a highly anomalous area which is more than 1.5 km long and 1 km wide along the trace of the Meadow Creek fault, a major northstriking fault zone. In the report area the Meadow Creek fault is covered by deposits of Quaternary glacial debris ranging in thickness from several meters to more than 30 meters. Two other highly anomalous areas--one of Au, Zn, and Hg, and one of Zn, Ag, Hg, and Mo--correlate with silicified granodiorite along the trace of the Meadow Creek fault. These anomalies are not related to hnown Ore deponits and merit further investigation. The enrichment of metals in mull ash in the area of thick glacial debris suggests that the metals migrate from bedrock upward through the glacial debris, are taken up by the forest vegetation, and are concentrated in the mull as the litter from the vegetation-decays. The findings indicate that mull is the most useful geochemical sampling medium in the stibnite area because the bedrock is deeply buried beneath deposits of transported material such as colluvium or glacial debris.

  4. The Uranium-trend dating method: Principles and application for southern California marine terrace deposits

    USGS Publications Warehouse

    Muhs, D.R.; Rosholt, J.N.; Bush, C.A.

    1989-01-01

    Uranium-trend dating is an open-system method for age estimation of Quaternary sediments, using disequilibrium in the 238U234U230Th decay series. The technique has been applied to alluvium, colluvium, loess, till, and marine sediments. In this study we tested the U-trend dating method on calcareous marine terrace deposits from the Palos Verdes Hills and San Nicolas Island, California. Independent age estimates indicate that terraces in these areas range from ???80 ka to greater than 1.0 Ma. Two low terraces on San Nicolas Island yielded U-trend plots that have a clustered array of points and the ages of these deposits are indeterminate or highly suspect. Middle Pleistocene terraces and one early Pleistocene terrace on San Nicolas Island and all terraces on the Palos Verdes Hills gave reasonably linear U-trend plots and estimated ages that are stratigraphically consistent and in agreement with independent age estimates. We conclude that many marine terrace deposits are suitable for U-trend dating, but U-trend plots must be carefully evaluated and U-trend ages should be consistent with independent geologic control. ?? 1989.

  5. Geochemical and C, O, Sr, and U-series isotopic evidence for the meteoric origin of calcrete at Solitario Wash, Crater Flat, Nevada, USA

    NASA Astrophysics Data System (ADS)

    Neymark, L. A.; Paces, J. B.; Marshall, B. D.; Peterman, Z. E.; Whelan, J. F.

    2005-08-01

    Calcite-rich soils (calcrete) in alluvium and colluvium at Solitario Wash, Crater Flat, Nevada, USA, contain pedogenic calcite and opaline silica similar to soils present elsewhere in the semi-arid southwestern United States. Nevertheless, a ground-water discharge origin for the Solitario Wash soil deposits was proposed in a series of publications proposing elevation-dependent variations of carbon and oxygen isotopes in calcrete samples. Discharge of ground water in the past would raise the possibility of future flooding in the unsaturated zone at Yucca Mountain, Nevada, site of a proposed high-level nuclear waste repository. New geochemical and carbon, oxygen, strontium, and uranium-series isotopic data disprove the presence of systematic elevation-isotopic composition relations, which are the main justification given for a proposed ground-water discharge origin of the calcrete deposits at Solitario Wash. Values of δ13C (-4.1 to -7.8 per mil [‰]), δ18O (23.8-17.2‰), 87Sr/86Sr (0.71270-0.71146), and initial 234U/238U activity ratios of about 1.6 in the new calcrete samples are within ranges previously observed in pedogenic carbonate deposits at Yucca Mountain and are incompatible with a ground-water origin for the calcrete. Variations in carbon and oxygen isotopes in Solitario Wash calcrete likely are caused by pedogenic deposition from meteoric water under varying Quaternary climatic conditions over hundreds of thousands of years.

  6. Applications of in situ cosmogenic nuclides in the geologic site characterization of Yucca Mountain, Nevada

    SciTech Connect

    Gosse, J.C.; Harrington, C.D.; Whitney, J.W.

    1996-08-01

    The gradual buildup of rare isotopes from interactions between cosmic rays and atoms in an exposed rock provides a new method of directly determining the exposure age of rock surfaces. The cosmogenic nuclide method can also provide constraints on erosion rates and the length of time surface exposure was interrupted by burial. Numerous successful applications of the technique have been imperative to the complete surface geologic characterization of Yucca Mountain, Nevada, a potential high level nuclear waste repository. The {sup 10}Be exposure age of Black Cone lava, within a ten mile radius of the proposed repository site, is 840 {+-} 210 kyr (in agreement with previous K/Ar dates of 1.0 {+-} 0.1 Ma). Rates of erosion of the tuff bedrock (< 0.4 cm/kyr from 7 {sup 10}Be measurements) and of hillslope colluvium ({approximately} 0.5 cm/kyr from {sup 10}Be dates on boulder deposits) preclude denudation of the mountain as a concern. Neotectonic concerns (rate of slip and timing of last significant movement along faults) are also being addressed with in situ {sup 14}C and {sup 10}Be measurements on scarp surfaces and on fault-dissected landforms where no surficial expression of the fault is preserved.

  7. Natural versus anthropogenic genesis of mardels (closed depressions) on the Gutland plateau (Luxembourg); archaeometrical and palynological evidence of Roman clay excavation from mardels.

    NASA Astrophysics Data System (ADS)

    van Mourik, Jan; Braekmans, Dennis; Doorenbosch, Marieke; Kuijper, Wim; van der Plicht, Hans

    2016-04-01

    Mardels, small closed depressions, are distinctive landforms on the Luxembourger Gutland plateau. In the present landscape most mardels are shallow fens, filled with colluvial sediments. The genesis of mardels has been studied intensively, inside and outside Luxembourg. Some researchers suggested a natural development and consider mardels as subsidence basins due to subsurface solution of gypsum veins, other researchers suggested cultural causes and consider mardels as prehistorical quarries. In the Gutland, mardels occur on various substrates. Mardels on the Strassen marls (li3) are abandoned quarries, related to clay excavation in Roman Time. Mardels on the Luxembourger sandstone (li2) are sinkholes, related to joint patterns in the sandstone formation. Mardels on the Keuper marls (km1,3) are originally subsidence basins, related to subsurface dissolutions of gypsum lenses and veins, filled with colluvial clay. The results of pollen analysis and archaeometrical tests demonstrate Roman extraction of clay for the production of ancient ceramics. So, the natural depressions have been enlarged to the present mardels. After excavation, the sedimentation of colluvium restarted in the abandoned quarries.

  8. Paleoseismology of a newly discovered scarp in the Yakima fold-and-thrust belt, Kittitas County, Washington

    USGS Publications Warehouse

    Barnett, Elizabeth A.; Sherrod, Brian L.; Norris, Robert; Gibbons, Douglas

    2013-01-01

    The Boylston Mountains anticlinal ridge is one of several that are cored by rocks of the Columbia River Basalt Group and, with the interceding synclinal valleys, constitute the Yakima fold-and-thrust belt of central Washington. Lidar data acquired from the U.S. Army's Yakima Training Center reveal a prominent, northwest-side-up, 65°- to 70°-trending, 3- to 4-meter-high scarp that cuts across the western end of the Boylston Mountains, perpendicular to the mapped anticline. The scarp continues to the northeast from the ridge on the southern side of Park Creek and across the low ridges for a total length of about 3 kilometers. A small stream deeply incises its flood plain where it projects across Johnson Canyon. The scarp is inferred to be late Quaternary in age based on its presence on the modern landscape and the incised flood-plain sediments in Johnson Canyon. Two trenches were excavated across this scarp. The most informative of the two, the Horned Lizard trench, exposed shallow, 15.5-Ma Grande Ronde Basalt, which is split by a deep, wide crack that is coincident with the base of the scarp and filled with wedges of silty gravels that are interpreted to represent at least two generations of fault colluvium that offset a buried soil.

  9. Geochemical and C, O, Sr, and U-series isotopic evidence for the meteoric origin of calcrete at Solitario Wash, Crater Flat, Nevada, USA

    USGS Publications Warehouse

    Neymark, L.A.; Paces, J.B.; Marshall, B.D.; Peterman, Z.E.; Whelan, J.F.

    2005-01-01

    Calcite-rich soils (calcrete) in alluvium and colluvium at Solitario Wash, Crater Flat, Nevada, USA, contain pedogenic calcite and opaline silica similar to soils present elsewhere in the semi-arid southwestern United States. Nevertheless, a ground-water discharge origin for the Solitario Wash soil deposits was proposed in a series of publications proposing elevation-dependent variations of carbon and oxygen isotopes in calcrete samples. Discharge of ground water in the past would raise the possibility of future flooding in the unsaturated zone at Yucca Mountain, Nevada, site of a proposed high-level nuclear waste repository. New geochemical and carbon, oxygen, strontium, and uranium-series isotopic data disprove the presence of systematic elevation-isotopic composition relations, which are the main justification given for a proposed ground-water discharge origin of the calcrete deposits at Solitario Wash. Values of ??13C (-4.1 to -7.8 per mil [???]), ??18O (23.8-17.2???), 87Sr/ 86Sr (0.71270-0.71146), and initial 234U/238U activity ratios of about 1.6 in the new calcrete samples are within ranges previously observed in pedogenic carbonate deposits at Yucca Mountain and are incompatible with a ground-water origin for the calcrete. Variations in carbon and oxygen isotopes in Solitario Wash calcrete likely are caused by pedogenic deposition from meteoric water under varying Quaternary climatic conditions over hundreds of thousands of years. ?? Springer-Verlag 2005.

  10. The impact of glacial/interglacial climate changes on fluvial and mass-wasting processes in the Taiwan's mountains

    NASA Astrophysics Data System (ADS)

    Li, W. L.; Hsieh, M. L.; Tsui, H. K.; Hsiao, Y. T.

    2014-12-01

    The Taiwan orogenic belt, located in Southeastern Asia, is under monsoon climate, frequently attacked by tropical typhoons, and characterized by rapid tectonic uplift with high seismicity. Researchers have been linking the Taiwan's landscapes to active tectonic uplift. In this study, we show the significance of glacial/interglacial climate changes in shaping the landscapes. We focus on the mountain areas that have never been glaciated. Based on >400 radiocarbon dates (70 of which >12 ka), we find that both the slope and fluvial activities were generally low during the glacial time. Still, extensive alluviation had occurred at certain time periods, forming large debris slopes or alluvial fans (typically along mountain fronts), and causing significant aggradation along some major rivers. In contrast, with numerous landslides and debris flows, river incision has dominated during the postglacial time. Episodic river aggradation with alluvial-terrace development (typically at tributary mouths) also occurred during this time period, but was less extensive than previously. Some huge postglacial alluvial terraces have been proved sourced from the colluviums deposited in the glacial time. We attribute the low landscape activities of the glacial period to the dryness during the period. However, even in this time rare but severe rainfall events must have occurred to trigger some extensive alluviation. In contrast, the increase in both rainfall and typhoon frequency during the postglacial time drastically increased the slope instability and sediment yield. The great stream power, along with the sufficient coarse debris acting as erosion tools, ensured the rapid river incision during this time.

  11. Geologic map of the greater Denver area, Front Range urban corridor, Colorado

    USGS Publications Warehouse

    Trimble, Donald E.; Machette, Michael N.

    1979-01-01

    This digital map shows the areal extent of surficial deposits and rock stratigraphic units (formations) as compiled by Trimble and Machette from 1973 to 1977 and published in 1979 under the Front Range Urban Corridor Geology Program. Trimble and Machette compiled their geologic map from published geologic maps and unpublished geologic mapping having varied map unit schemes. A convenient feature of the compiled map is its uniform classification of geologic units that mostly matches those of companion maps to the north (USGS I-855-G) and to the south (USGS I-857-F). Published as a color paper map, the Trimble and Machette map was intended for land-use planning in the Front Range Urban Corridor. This map recently (1997-1999) was digitized under the USGS Front Range Infrastructure Resources Project. In general, the mountainous areas in the western part of the map exhibit various igneous and metamorphic bedrock units of Precambrian age, major faults, and fault brecciation zones at the east margin (5-20 km wide) of the Front Range. The eastern and central parts of the map (Colorado Piedmont) depict a mantle of unconsolidated deposits of Quaternary age and interspersed outcroppings of Cretaceous or Tertiary-Cretaceous sedimentary bedrock. The Quaternary mantle comprises eolian deposits (quartz sand and silt), alluvium (gravel, sand, and silt of variable composition), colluvium, and a few landslides. At the mountain front, north-trending, dipping Paleozoic and Mesozoic sandstone, shale, and limestone bedrock formations form hogbacks and intervening valleys.

  12. Infinite slope stability under steady unsaturated seepage conditions

    USGS Publications Warehouse

    Lu, N.; Godt, J.

    2008-01-01

    [1] We present a generalized framework for the stability of infinite slopes under steady unsaturated seepage conditions. The analytical framework allows the water table to be located at any depth below the ground surface and variation of soil suction and moisture content above the water table under steady infiltration conditions. The framework also explicitly considers the effect of weathering and porosity increase near the ground surface on changes in the friction angle of the soil. The factor of safety is conceptualized as a function of the depth within the vadose zone and can be reduced to the classical analytical solution for subaerial infinite slopes in the saturated zone. Slope stability analyses with hypothetical sandy and silty soils are conducted to illustrate the effectiveness of the framework. These analyses indicate that for hillslopes of both sandy and silty soils, failure can occur above the water table under steady infiltration conditions, which is consistent with some field observations that cannot be predicted by the classical infinite slope theory. A case study of shallow slope failures of sandy colluvium on steep coastal hillslopes near Seattle, Washington, is presented to examine the predictive utility of the proposed framework. Copyright 2008 by the American Geophysical Union.

  13. Earthquake recurrence and fault behavior on the Homestead Valley fault -- Central segment of the 1992 Landers surface rupture sequence

    SciTech Connect

    Cinti, F.R. ); Fumal, T.E.; Garvin, C.D.; Hamilton, J.C.; Powers, T.J.; Schwartz, D.P. )

    1993-04-01

    The 1992 M 7.5 Landers earthquake produced complex surface rupture on sections of the previously mapped Johnson Valley, Homestead Valley, and Emerson faults. The earthquake has raised questions about new faulting, characteristic earthquakes, and fault segmentation. To address these issues the authors initiated a study of both ruptured and unruptured fault segments, and report initial observations on the Homestead Valley fault (HVF). The authors site is located at the distal end of a large alluvial fan where 1992 right slip was 3 m, vertical slip was 40 cm, and the rupture followed pre-existing NE-facing scarps. Two trenches provide clear evidence of the two most recent pre-1992 surface faulting events. The trenches exposed alluvial fan and scarp derived colluvial deposits that are displaced and locally warped by both vertical strike-slip and low angle reverse-oblique( )-slip faults. At the main fault trace two pre-1992 colluvial wedges overlie a distinctive Bt soil horizon of late( ) Pleistocene age. Colluvium from the penultimate event has weak soil development, indicating a Holocene age for this faulting; apparent vertical displacement from this event is 35 cm, essentially the same as 1992. Preliminary observations indicate that recurrence of large magnitude earthquakes on faults of the Eastern California Shear Zone is one to two orders of magnitude longer than on major faults of the San Andreas system. The length of the HVF is short for this amount of offset, which suggests prior events may have also involved the rupture of multiple fault segments.

  14. Flood geomorphology of Arthurs Rock Gulch, Colorado: paleoflood history

    USGS Publications Warehouse

    Waythomas, C.F.; Jarrett, R.D.

    1994-01-01

    Episodic late Quaternary flooding is recorded by bouldery deposits and slackwater sediments along Arthurs Rock Gulch, an ephemeral stream west of Fort Collins, Colorado. Flood deposits consist of individual granodiorite and pegmatite boulders, boulder bars, and coarse overbank sediment that rest on erosional terrace segments along the channel. We identified evidence for at least five flood in the lower two thirds of the 1.84 km2 drainage basin. Flood deposits are differentiated by their position above the active channel, weathering characteristics, degree of boulder burial by colluvium, amount of lichen cover, and position with respect to terrace and colluvial deposits. Age estimates for the flood deposits are based on radiocarbon dating, tree-ring analyses, and relative-age criteria from four sites in the basin. At least two floods occurred in the last 300 years; a third flood is at least 5000 years old, but likely younger than 10,000 yr BP; and the two oldest floods occurred at least 40,000 years BP. ?? 1994.

  15. Analyzing debris flows with the statistically calibrated empirical model LAHARZ in southeastern Arizona, USA

    USGS Publications Warehouse

    Magirl, Christopher S.; Griffiths, Peter G.; Webb, Robert H.

    2010-01-01

    Hazard-zone delineation for extreme events is essential for floodplain management near mountain fronts in arid and semiarid regions. On 31 July 2006, unprecedented debris flows occurred in the Santa Catalina Mountains of southeastern Arizona following extreme multiday precipitation (recurrence interval > 1000 years for 4-day precipitation). Most mobilized sediment contributing to debris flows was derived from shallow-seated failures of colluvium on steep slopes. A total of 435 slope failures in the southern Santa Catalina Mountains released 1.34 million Mg of sediment into the channels of 10 drainage basins. Five drainages produced debris flows that moved to the apices of alluvial fans on the southern edge of the mountain front, damaging infrastructure and aggrading channels to reduce future flood conveyance. Using the statistically calibrated, empirical debris-flow model LAHARZ and modified model coefficients developed to better match conditions in southeastern Arizona, we predicted the approximate area of deposition and travel distance in comparison to observed depositional areas and travel distance for seven debris flows. Two of the modeled debris flows represented single slope failures that terminated downslope with no additive influence of other debris flows or streamflow flooding. Five of the simulated debris flows represented the aggregation of multiple slope failures and streamflow flooding into multiple debris-flow pulses. Because LAHARZ is a debris-flow hazard-zone delineation tool, the complexity of alternating transport and deposition zones in channels with abrupt expansions and contractions reduces the applicability of the model in some drainage basins.

  16. Borehole-calibration methods used in cased and uncased test holes to determine moisture profiles in the unsaturated zone, Yucca Mountain, Nevada

    SciTech Connect

    Hammermeister, D.P.; Kneiblher, C.R.; Klenke, J.

    1985-12-31

    The use of drilling and coring methods that minimize the disturbance of formation rock and core has permitted field calibration of neutron-moisture tools in relatively large diameter cased and uncased boreholes at Yucca Mountain, Nevada. For 5.5-inch diameter cased holes, there was reasonable agreement between a field calibration in alluvium-colluvium and a laboratory calibration in a chamber containing silica sand. There was little difference between moisture-content profiles obtained in a neutron-access hole with a hand-held neutron-moisture meter and an automated borehole-logging tool using laboratory-generated calibration curves. Field calibrations utilizing linear regression analyses and as many as 119 data pairs show a good correlation between neutron-moisture counts and volumetric water content for sections of uncased 6-inch diameter boreholes in nonwelded and bedded tuff. Regression coefficients ranged from 0.80 to 0.94. There were only small differences between calibration curves in 4.25- and 6-inch uncased sections of boreholes. Results of analyzing field calibration data to determine the effects of formation density on calibration curves were inconclusive. Further experimental and theoretical work is outlined.

  17. Sagging and collapse sinkholes over hypogenic hydrothermal karst in a carbonate terrain

    NASA Astrophysics Data System (ADS)

    Frumkin, Amos; Zaidner, Yossi; Na'aman, Israel; Tsatskin, Alexander; Porat, Naomi; Vulfson, Leonid

    2015-01-01

    We show that clusters of karst sinkholes can occur on carbonate hypogene karst terrains. Unlike common doline karst of dissolution origin, the studied sinkholes form mainly by sagging and collapse. Thermal survey, OSL dating and morphologic analysis during quarrying and excavations are applied to study the sinkholes at the Ayyalon karst, Israel. The thermal survey shows the spatial pattern of rising warm water plumes, whose temperature is > 2 °C warmer than the surrounding aquifer water. These plumes dissolve the limestone, creating large voids and maze caves. Mass wasting forms surface sinkholes mainly by sagging and collapse. Both types of deformation often occur within the same depression. Lack of hydrologic connection between the surface and underground voids constrain drainage and promote rapid accumulation of colluvium, dust and pedogenic clays. These have filled the sinkholes up to their rim before the late Holocene. OSL dating constrains the rate of sediment accumulation within the sinkholes. The average filling rate (thickness divided by elapsed time) is ~ 47 mm ka- 1 for the last 53 ± 4 ka in Sinkhole 1, while in Sinkhole 2 ("Nesher Ramla karst depression"), the rate is ~ 61 mm ka- 1 from ~ 200 to 78 ka, and ~ 173 mm ka- 1 since ~ 78 ka. Between ~ 170 and 78 ka, Sinkhole 2 was intensively used by Middle Paleolithic hominins. The studied sinkholes may be considered as a type locality for hypogene sinkhole terrain on carbonate rocks.

  18. Terrain, vegetation, and landscape evolution of the R4D research site, Brooks Range Foothills, Alaska

    USGS Publications Warehouse

    Walker, D. A.; Binnian, Emily F.; Evans, B. M.; Lederer, N. D.; Nordstrand, E.; Webber, P. J.

    1989-01-01

    Maps of the vegetation and terrain of a 22 km2 area centered on the Department of Energy (DOE) R4D (Response, Resistance, Resilience to and Recovery from Disturbance in Arctic Ecosystems) study site in the Southern Foothills Physiographic Province of Alaska were made using integrated geobotanical mapping procedures and a geographic-information system. Typical land forms and surface f orms include hillslope water tracks, Sagavanirktok-age till deposits, nonsorted stone stripes, and colluvial-basin deposits. Thirty-two plant communities are described; the dominant vegetation (51% of the mapped area) is moist tussock-sedge, dwarf-shrub tundra dominated by Eriophorum vaginatum or Carex bigelowii. Much of the spatial variation in the mapped geobotanical characters reflects different-aged glaciated surfaces. Shannon-Wienerin dices indicate that the more mature landscapes, represented by retransported hillslope deposits and basin colluvium, are less heterogeneous than newer landscapes such as surficial till deposits and floodplains. A typical toposequence on a mid-Pleistocene-age surface is discussed with respect to evolution of the landscape. Thick Sphagnum moss layers occur on lower hillslopes, and the patterns of moss-layer development, heat flux, active layer thickness, and ground-ice are seen as keys to developing thermokarst-susceptibility maps.

  19. Geologic Map of the Abiquiu Quadrangle, Rio Arriba County, New Mexico

    USGS Publications Warehouse

    Maldonado, Florian

    2008-01-01

    The Abiquiu 1:24,000-scale quadrangle is located along the Colorado Plateau-Rio Grande rift margin in north-central New Mexico. The map area lies within the Abiquiu embayment, an early (pre-Miocene) extensional basin of the Rio Grande rift. Rocks exposed include continental Paleozoic and Mesozoic rocks of the Colorado Plateau and Cenozoic basin-fill deposits and volcanic rocks of the Rio Grande rift. Paleozoic units include the Late Pennsylvanian to Early Permian Cutler Group, undivided. Mesozoic units are Upper Triassic Chinle Group, undivided, middle Jurassic Entrada Sandstone, and Todilto Limestone Member of the Wanakah Formation. Mesozoic rocks are folded in some areas and overlain disconformably by Cenozoic rocks. Cenozoic sedimentary rocks are composed of the Eocene El Rito Formation, Oligocene Ritito Conglomerate, Oligocene-Miocene Abiquiu Formation, and Miocene Chama-El Rito and Ojo Caliente Sandstone Members of the Tesuque Formation of the Santa Fe Group. Volcanic rocks include the Lobato Basalt, the El Alto Basalt, and dacite of the Tschicoma Formation. Quaternary deposits consist of inset ancestral axial and tributary Rio Chama deposits and Holocene floodplain alluvium, fan and pediment alluvium, and landslide colluvium.

  20. Generalized surficial geologic map of the Denver 1 degree by 2 degrees quadrangle, Colorado

    USGS Publications Warehouse

    Moore, D.W.; Straub, A.W.; Berry, M.E.; Baker, M.L.; Brandt, T.R.

    2000-01-01

    Thirty-nine types of surficial geologic deposits and residual materials of Quaternary age are described and mapped in the greater Denver area, in part of the Front Range, and in the piedmont and plains east of Denver, Boulder, and Castle Rock. Descriptions appear in the pamphlet that accompanies the map. Landslide deposits, colluvium, residuum, alluvium, and other deposits or materials are described in terms of predominant grain size, mineral or rock composition (e.g., gypsiferous, calcareous, granitic, andesitic), thickness of deposits, and other physical characteristics. Origins and ages of the deposits and geologic hazards related to them are noted. Many lines between geologic units on our map were placed by generalizing contacts on published maps. However, in 1997-1999 we mapped new boundaries, as well. The map was projected to the UTM projection. This large map area extends from the Continental Divide near Winter Park and Fairplay (on the west edge), eastward about 107 mi (172 km); and extends from Boulder on the north edge to Woodland Park at the south edge (68 mi; 109 km).

  1. Generalized surficial geology map of the Pueblo 1 degree by 2 degrees quadrangle, Colorado

    USGS Publications Warehouse

    Moore, D.W.; Straub, A.W.; Berry, M.E.; Baker, M.L.; Brandt, T.R.

    2002-01-01

    Fifty-three types of surficial geologic deposits and residual materials of Quaternary age are described in a pamphlet and located on a map of the greater Pueblo area, in part of the Front Range, in the Wet and Sangre de Cristo Mountains, and on the plains east of Colorado Springs and Pueblo. Deposits formed by landslides, wind, and glaciers, as well as colluvium, residuum, alluvium, and others are described in terms of predominant grain size, mineral or rock composition (e.g., gypsiferous, calcareous, granitic, andesitic), thickness, and other physical characteristics. Origins and ages of the deposits and geologic hazards related to them are noted. Many lines drawn between units on our map were placed by generalizing contacts on published maps. However, in 1997-1999 we mapped new boundaries as well. The map was projected to the UTM projection. This large map area extends from near Salida (on the west edge), eastward about 107 mi (172 km), and from Antero Reservoir and Woodland Park on the north edge to near Colorado City at the south edge (68 mi; 109 km).

  2. The Use of Statistical End-Member Mixing Analysis (EMMA) of Grain Size Distributions to Characterize Site Deposition of a Deeply Stratified Paleoindian Rock Shelter, Harney Basin, Eastern Oregon

    NASA Astrophysics Data System (ADS)

    Collins, J. D., Jr.

    2014-12-01

    Sedimentological investigations were conducted on Excavation Unit 2 of Rimrock Draw Rockshelter (35HA3855), a deeply stratified, multi-component Paleoindian site located along the western margin of the Harney Basin, eastern Oregon. Field descriptions and end-member mixing analysis (EMMA) of grain-size distributions (GSD) of 13 sediment samples identified six stages of site formation: three stratigraphic units (SU), two unconformities, and a relict Bt soil horizon. EMMA resulted in the characterization of three end-members (EM) that correlate with field descriptions. EM's 1 and 2 represent 88.4% of the total variance among samples and are present within the upper-most stratigraphic unit, SU1, and the lower-most stratigraphic unit, SU3. EM 3 correlates with the poorly developed Bt horizon within the middle stratigraphic unit, SU2. EM 1 is a well-sorted coarse to medium sand interpreted as fluvial deposition. EM 2 is a trimodal deposit of poorly sorted sand, silt, and clay, interpreted as a predominantly aeolian deposition occasionally punctuated by colluvium derived from the colluvial wedge to the east of the Unit and from the brow of the rockshelter. EM 3 is a bimodal distribution of medium sand to fine silts and clays that represent a predominately aeolian deposit overprinted by a Bt horizon. The results of this study demonstrate the applicability of EMMA to distinguish between depositional units within an archaeological context and provide geologically meaningful interpretations of paleoenvironments for the development of hypotheses related to human environmental interactions.

  3. Hydrogeologic investigation of the Maxey Flats radioactive waste burial site, Fleming County, Kentucky

    USGS Publications Warehouse

    Zehner, H.H.

    1983-01-01

    Burial trenches at the Maxey Flats radioactive waste burial site cover an area of about 20 acres, and are located on a plateau, about 300 to 400 feet above surrounding valleys. All waste is buried in the Nancy Member of the Borden Formation, and most is in the weathered shale (regolith) part of this member. Recharge to the rocks is probably by infiltration of rainfall through regolith at the top of the hill. At least two water tables are present: near the base of the regolith, at a depth of about 25 feet and; in the Ohio Shale, at a depth of about 300 feet. About 95 percent of ground-water discharge to streams is from colluvium on hillsides and valley alluvium. The remaining 5 percent is discharge from bedrock, of which about 0.5 percent is from rocks underlying the burial area. Waste radionuclides in the subsurface, other than tritium, were observed only in the regolith of the Nancy Member. Only tritium was observed with certainty in deeper rocks and in the adjacent valley alluvium. Other waste radionuclides were in streamwater and stream sediment, and may have been transported with overland runoff from the surface of the burial site. (USGS)

  4. Genesis and continuity of quaternary sand and gravel in glacigenic sediment at a proposed low-level radioactive waste disposal site in east-central Illinois

    USGS Publications Warehouse

    Troost, K.G.; Curry, B. Brandon

    1991-01-01

    The Illinois Department of Nuclear Safety has characterized the Martinsville Alternative Site (MAS) for a proposed low-level radioactive waste disposal facility. The MAS is located in east-central Illinois approximately 1.6 km (1 mi) north of the city of Martinsville. Geologic investigation of the 5.5-km2 (1380-acre) site revealed a sequence of chiefly Illinoian glacigenic sediments from 6 to 60 m (20-200 ft) thick overlying two major bedrock valleys carved in Pennsylvanian strata. Relatively permeable buried units include basal, preglacial alluvium; a complex of intraglacial and subglacial sediment; englacial deposits; and supraglacial fluvial deposits. Postglacial alluvium underlies stream valleys on and adjacent to the site. In most areas, the buried sand units are confined by low-permeability till, lacustrine sediment, colluvium, and loess. The distribution and thickness of the most extensive and continuous buried sand units have been modified considerably by subglacial erosion, and their distributions have been influenced by the buried bedrock valleys. The most continuous of the various sand units were deposited as preglacial and postglacial alluvium and are the uppermost and lowermost stratigraphic units at the alternative site. Sand units that were deposited in englacial or ice-marginal environments are less continuous. Aquifer pumping tests, potentiometric head data, and groundwater geochemistry analyses indicate minimal interaction of groundwater across localized interconnections of the permeable units. ?? 1991 Springer-Verlag New York Inc.

  5. Evidence of multiple late-Wisconsin floods from glacial Lake Missoula in Badger Coulee, Washington

    NASA Astrophysics Data System (ADS)

    Bunker, Russell C.

    1982-07-01

    Catastrophic floods from glacial Lake Missoula entered the Pasco Basin in south-central Washington and backflooded its marginal valleys. Badger Coulee, one such valley, contains beds of fine-grained slackwater sediment deposited by these floods. The slackwater sediment contains two ash layers of the Mount St. Helens set S tephra, about 13,000 yr old. The ash was deposited on a ground surface developed atop slackwater sediment deposited during preash flooding. Evidence of the former ground surface includes the reworked ash, inferred trace fossils, stream and debris-flow deposits, slopewash and/or eolian sediment, and colluvium at the ash horizon. These features and the ash were buried by slackwater sediment deposited during postash flooding. Nonflood, subaerial deposits are not present atop other beds. Instead, beds commonly are reversely graded across "contacts," suggesting that multiple beds were continuously deposited. The exposed beds thus record at least two late-Wisconsin floods, one preash, the other postash. The pre- and postash floods may be correlative with earlier-reported floods thought to have occurred 17,500-14,000 and 14,000-13,000 yr B.P., respectively.

  6. Cultural and Climatic History of Cobá, a Lowland Maya City in Quintana Roo, Mexico

    NASA Astrophysics Data System (ADS)

    Leyden, Barbara W.; Brenner, Mark; Dahlin, Bruce H.

    1998-01-01

    Lake Cobá, within the archaeological site of Cobá, provides evidence bearing on lowland Maya development. Palynological and geochemical data record multidecadal precipitation cycles from a 8.80-m, >8370-yr lake-sediment sequence terminating on bedrock. Late Classic sedimentation rates are rapid, but an anthropogenically derived colluvium layer is lacking. Initial vegetation was medium semi-deciduous and swamp forest. Forest clearance began 1650 B.C. (Early Preclassic) and maize first occurred at 850 B.C. (Middle Preclassic). Lakeside milpas existed until A.D. 720 (Late Classic) and then were moved from the city center as urbanization intensified and Lake Cobá was diked as a reservoir. Cobá was at most briefly vacated during the Classic Collapse and was abandoned after A.D. 1240, although some habitation persisted. The paleoecological record matches the archaeological history for Cobá, but pervasive disturbance muted the climatic signal, as the Late Classic drought is barely evident. The question whether economic trees were maintained within the city is unresolved. Maize cultivation allowed the Maya to develop a complex society and support a large population, but dependence on maize was ultimately doomed by variable rainfall. Precipitation in extreme years was insufficient to support crops, while native vegetation was not directly affected by drought that devastated Maya agriculture.

  7. The Role of Debris Flows in Long-term Denudation and Landscape Evolution in the central Appalachians

    NASA Astrophysics Data System (ADS)

    Eaton, L. S.

    2004-12-01

    Four major storms spanning a 46 year period from 1949 to 1995 that triggered debris flows in the Virginia-West Virginia Appalachians provided new insights into the role of high-magnitude, low-frequency storm events in long-term denudation and landscape evolution in mountainous terrain. Storm denudation measured in five Blue Ridge Mountain drainage basins (mean=3.7 cm) was approximately an order of magnitude greater compared to four basins located in the mountains of the Valley and Ridge province (mean=0.2cm). This difference is probably the result of higher storm rainfall from the Blue Ridge storms. Long-term (103 yrs) denudation rates were estimated using several lines of evidence, including 1) studies of the volume of sediment deposited in, or offshore of, the Atlantic Coastal Plain; 2) findings of parallel rates of continental uplift and denudation; and 3) historic sediment-load data. Using these estimates and subtracting the denudation attributed to chemical load, the mechanical denudation rate of the central Blue Ridge is approximated as 2.4 cm/k.y. Whereas debris flows recur at a frequency of approximately one event each three years somewhere in the unglaciated terrain of the Appalachians, the return interval is much greater when only individual mountainous basins are considered. Radiocarbon dating of debris-flow deposits in mountainous first- and second-order river basins of the Blue Ridge indicates a debris-flow return interval of not more than 2000 to 4000 yr. These data on debris flow frequency, combined with measurements of storm-induced upland basin denudation, suggests that approximately half of the long-term denudation from mechanical load occurs episodically by debris-flows. Although floods of moderate magnitude are largely responsible for mobilizing sediment in low-gradient streams, the data suggest that high-magnitude, low-frequency events are the most significant component in delivering coarse-grained colluvium from mountainous hollows and

  8. Lipid biomarker and compound-specific isotope analysis of cave sediments: a new approach to investigating past vegetation change

    NASA Astrophysics Data System (ADS)

    Blyth, A.; Griffiths, T.; Robson, S.

    2009-12-01

    Caves are vital archives for records of terrestrial palaeoenvironmental change, as they form sheltered sediment traps capable of preserving long environmental sequences. Due to their unique role in the landscape, they are also intimately connected to the archaeology and palaeoecology of the parent region. Chemical proxy records preserved in speleothems (chemically precipitated cave deposits) have long been used as a tool in palaeoclimatic research, but clastic sediments deposited by air, water, and breakdown of the surrounding rock also have much to contribute. However, although well researched in a sedimentary context, the geochemical records contained in these deposits, especially organic parameters, have been less well-studied. Here we present the first in-depth study of the organic geochemistry of cave sediment sequences, using samples from two south-east Asian caves, and focusing on plant-derived lipid biomarkers and their associated compound-specific carbon isotope records. The work aimed to establish: whether routine extraction and analysis of compounds was feasible in this context at acceptable sample sizes; whether there was a significant vegetation-derived contribution to the record; whether the depositional mode of the sediment (colluvium, midden, channel fill etc) affects the organic composition; and whether the records show coherent and interpretable variation through time. Two sites were studied: Niah Cave in Borneo, where the sediments recovered are a mixture of colluvium and channel fill and date back to >40 ka; and Hang Boi in Vietnam, where the principal deposit is a Holocene occupation midden dominated by land-snail shells. To recover the lipid fraction 7 g aliquots of freeze-dried sediment were extracted by sonication in 95:5 dichloromethane:methanol. Excess solvent was then removed via rotary evaporation and the extracts derivatised with BF3-Methanol and BSTFA prior to analysis by GC-MS. The lipid extracts contain a range of compounds including

  9. Preliminary Assessment of Landslides Along the Florida River Downstream from Lemon Reservoir, La Plata County, Colorado

    USGS Publications Warehouse

    Schulz, William H.; Coe, Jeffrey A.; Ellis, William L.; Kibler, John D.

    2006-01-01

    Nearly two-dozen shallow landslides were active during spring 2005 on a hillside located along the east side of the Florida River about one kilometer downstream from Lemon Reservoir in La Plata County, southwestern Colorado. Landslides on the hillside directly threaten human safety, residential structures, a county roadway, utilities, and the Florida River, and indirectly threaten downstream areas and Lemon Dam. Most of the area where the landslides occurred was burned during the 2002 Missionary Ridge wildfire. We performed geologic mapping, subsurface exploration and sampling, radiocarbon dating, and shallow ground-water and ground-displacement monitoring to assess landslide activity. Active landslides during spring 2005 were as large as 35,000 m3 and confined to colluvium. Debris flows were mobilized from most of the landslides, were as large as 1,500 m3, and traveled as far as 250 m. Landslide activity was triggered by elevated ground-water pressures within the colluvium caused by infiltration of snowmelt. Landslide activity ceased as ground-water pressures dropped during the summer. Shallow landslides on the hillside appear to be much more likely following the Missionary Ridge fire because of the loss of tree root strength and evapotranspiration. We used monitoring data and observations to develop preliminary, approximate rainfall/snowmelt thresholds above which shallow landslide activity can be expected. Landslides triggered during spring 2005 occurred within a 1.97 x 107 m3 older landslide that extends, on average, about 40 m into bedrock. The south end of this older landslide appears to have experienced deep secondary landsliding. Radiocarbon dating of sediments at the head of the older landslide suggests that the landslide was active about 1,424-1,696 years ago. A relatively widespread wildfire may have preceded the older landslide, and the landslide may have occurred during a wetter time. The wetter climate and effects of the wildfire would likely have

  10. Chemical vs. Physical Contributions to Grainsize Distributions in Hillslope Soils along a Denudation Gradient in the Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Weinman, B. A.; Yoo, K.; Mudd, S. M.; Attal, M.; Hurst, M. D.; Maher, K.; Kouba, C. M.; Bern, C.; Singhvi, A. K.

    2011-12-01

    An important part of understanding how soil forms consists of understanding grainsize evolution. How much of a soil's grainsize distribution comes from physical (i.e., fracturing or treethrow) and/or chemical (i.e., secondary mineral production) weathering remains poorly understood. In order to evaluate the effect and magnitude of physical and chemical weathering on soil-grainsize, we used a geochemical mass balance and grainsize approach on soils from the Feather River basin in the Sierra Nevada. Three hillslopes in the basin were chosen to reflect 3 different degrees of channel erosion at their bases-a hillslope with active channel incision (60% slope, below the knickpoint), a hillslope reflecting the transition between the relict and modern-day incising areas (50% slope, at the knickpoint), and a 30% hillslope in the relict landscape (an area that has not yet "felt" the 5Mya increase in erosion). Our results show that soil particle sizes increase with both hillslope slope gradient and soil-depth, following a soil grainsize increase (μm/cm) = 0.036e^{6×Slope} (R^2 = 0.9995). The Zr from the tonalite (100 ppm) up to the saprolite (100-250ppm) and into the soil (soil approx saprolite) along the 3 slopes indicate that the basin's soil geochemistry is set at depths below the soil-saprolite boundary. The mean grainsize of particles at the soil-saprolite boundary increases with slope from 78 to 181 to 275μm. Thus, in terms of elemental compositions, colluvial soils appear virtually identical to the underlying saprolite, and soil grainsize differentiation within the colluvium is mostly a physical process. However, colluvial soils do show significantly finer size distributions in the hillslopes with lower erosion rates (which also have saprolites with a greater degree of weathering loss). Therefore, the degree of chemical denudation in the saprolite appears to dictate the susceptibility of the materials to physical breakdown to finer particle sizes in the overlying

  11. A comparison of rating and dating techniques to estimate the threat of soil erosion to archaeological monuments under agricultural fields

    NASA Astrophysics Data System (ADS)

    van Soest, Maud; Huisman, Hans; Schoorl, Jeroen; Reimann, Tony; Temme, Arnaud; Wallinga, Jakob; de Kort, Jan-Willem; van der Heiden, Menno; van Os, Bertil; van Egmond, Fenny; Ketteren, Michael

    2015-04-01

    For the protection of Dutch archaeological sites against degradation, the TOPsites project is investigating the rate, extent and mitigation of the most important processes involved. One of these processes is soil translocation or soil redistribution. For many Dutch archaeological sites the actual extent and rate of soil erosion is not yet known. In this study different techniques for dating and estimating rates have been compared on three archaeological sites on tilled fields with gentle slopes: (multi-temporal LiDar, profiles and spatial distribution of 137Cs, anthropogenic Pb, and 239+240Pu, and moreover OSL. In addition, the added value of the combination of several of these techniques together will be evaluated. Preliminary results show evidence for colluvium formation (deposition) on two of the sites. Lead contents in a buried soil on one of these sites suggest a subrecent to recent date. 137Cs profiles and spatial mapping, however, do not show clear evidence for recent erosion or re-deposition patterns. These first results suggest that in these agricultural settings with typical Dutch gentle slopes, erosion may only occur in rare, catastrophic, events with local high erosion and re-deposition rates instead of a more or less continuous process with lower rates. Consequently, the impact of ploughing might be limited to mixing of the plough layer, while the effect of damaging soil translocation, for these selected archaeological sites, seems less important. Forthcoming analysis and results of Pu and OSL will provide enough data for further discussion and possible falsification of these preliminary conclusions.

  12. Integrating Near-Real Time Hydrologic-Response Monitoring and Modeling for Improved Assessments of Slope Stability Along the Coastal Bluffs of the Puget Sound Rail Corridor, Washington State

    NASA Astrophysics Data System (ADS)

    Mirus, B. B.; Baum, R. L.; Stark, B.; Smith, J. B.; Michel, A.

    2015-12-01

    Previous USGS research on landslide potential in hillside areas and coastal bluffs around Puget Sound, WA, has identified rainfall thresholds and antecedent moisture conditions that correlate with heightened probability of shallow landslides. However, physically based assessments of temporal and spatial variability in landslide potential require improved quantitative characterization of the hydrologic controls on landslide initiation in heterogeneous geologic materials. Here we present preliminary steps towards integrating monitoring of hydrologic response with physically based numerical modeling to inform the development of a landslide warning system for a railway corridor along the eastern shore of Puget Sound. We instrumented two sites along the steep coastal bluffs - one active landslide and one currently stable slope with the potential for failure - to monitor rainfall, soil-moisture, and pore-pressure dynamics in near-real time. We applied a distributed model of variably saturated subsurface flow for each site, with heterogeneous hydraulic-property distributions based on our detailed site characterization of the surficial colluvium and the underlying glacial-lacustrine deposits that form the bluffs. We calibrated the model with observed volumetric water content and matric potential time series, then used simulated pore pressures from the calibrated model to calculate the suction stress and the corresponding distribution of the factor of safety against landsliding with the infinite slope approximation. Although the utility of the model is limited by uncertainty in the deeper groundwater flow system, the continuous simulation of near-surface hydrologic response can help to quantify the temporal variations in the potential for shallow slope failures at the two sites. Thus the integration of near-real time monitoring and physically based modeling contributes a useful tool towards mitigating hazards along the Puget Sound railway corridor.

  13. The Temporal and Spatial Quantification of Holocene Sediment Dynamics in a meso-scale catchment in northern Bavaria/Germany

    NASA Astrophysics Data System (ADS)

    Fuchs, Markus; Will, Mathias; Kreutzer, Sebastian

    2013-04-01

    The Aufsess River catchment (97 km2) in northern Bavaria, Germany, is studied to establish a Holocene sediment budget and to investigate the sediment dynamics since the early times of farming in the 3rd millennium BCE. The temporal characterization of the sediment dynamics is based on an intensive dating program with 73 OSL and 14 14C ages. To estimate soil erosion and deposition, colluvial and alluvial archives are investigated in the field by piling and trenching, supported by laboratory analyses. The sediment budget shows that 58% of these sediments are stored as colluvium in on- and foot-slope positions, 9% are stored as alluvium in the floodplains and 33% are exported from the Aufsess River catchment. Colluviation starts in the End-Neolithic (ca. 3100 BCE), while first indicators of soil erosion derived alluviation is recorded ca. 2-3 ka later. The pattern of sedimentation rates also displays differences between the colluvial and alluvial system, with a distinct increase in the Middle Ages (ca. 1000 CE) for the alluvial system, while the colluvial system records low sedimentation rates for this period. A contrast is also observed since Modern Times (ca. 1500 CE), with increasing sedimentation rates for the colluvial system, whereas the alluvial system records decreasing rates. The different behavior of the colluvial and alluvial system clearly shows the non-linear behavior of the catchment's fluvial system. The results further suggest that human impact is most probably the dominant factor influencing the sediment dynamics of the catchment since the introduction of farming. Fuchs, M., Will, M., Kunert, E., Kreutzer, S., Fischer, M. & Reverman, R. 2011. The temporal and spatial quantification of Holocene sediment dynamics in a meso-scale catchment in northern Bavaria / Germany. The Holocene 21, 1093-1104. Fuchs, M., Fischer, M. & Reverman, R. 2010. Colluvial and alluvial sediment archives temporally resolved by OSL dating: Implications for reconstructing soil

  14. Inventory of landslides in southern Illinois near the New Madrid Seismic Zone and the possible failure mechanism at three sites

    SciTech Connect

    Su, Wen June . Engineering Geology Section)

    1992-01-01

    A total of 221 landslides was inventoried along a 200-kilometer reach of the Ohio and the Mississippi Rivers from Olmsted to Chester, IL using Side-Looking Airborne Radar imagery, vertical, stereoscopic, black and white aerial photography at various scales, and low altitude, oblique color and color infrared photography. Features observed on aerial photographs were used to classify landslides into three types (rock/debris fall, block slide, and rotational/translational slide) at three levels of confidence: certain, probable, or possible. Some landslides combined two or more types at a single site. Only a few of the landslides showed evidence of repeated activity; most are ancient landforms. Most of the landslides were developed in the loess, alluvium, colluvium, and weak clay layers of the Chesterian Series or in the Porter's Creek Clay and McNairy Formation. Failure of three representative landslides was modeled under static (aseismic) and dynamic (seismic) situations using three different sliding mechanisms. Both the pseudo-static method and a simplified method of the Newmark displacement analysis were used to determine the stability of the slope under earthquake conditions. The three representative landslides selected for detailed slope stability analysis were the Ford Hill, Jones Ridge, and Olmsted landslides. The Ford Hill and Jones Ridge landslides have similar slope geometries. Their modes of failure were recognized as a translational block slide on a weak clay layer. The Olmsted landslide is a complex of several rotational slides of different ages and a mega block slide on weak clay layers. The stability analyses of these three landslides suggest that they would not have occurred under aseismic conditions. However, under earthquake loadings similar to those generated by the 1811-12 earthquakes, most of the slopes could have experienced large displacements leading to landslide initiation.

  15. Relations between rainfall amount, soil moisture and landslides in Hamilton County, Ohio, measured by strain survey and tensiometers

    SciTech Connect

    Bechtel, B.; Mayer, L. . Dept. of Geology)

    1993-03-01

    The movement of water through fill material and natural colluvium in a cut slope is being monitored at two sites with past landslide activity adjacent to I-275 in Hamilton County, Ohio. Quadrilaterals and an array of wooden stakes were placed immediately adjacent to the slide area to monitor movement of the slope at Site 1. To correlate any movement with soil moisture levels, rain gauges were installed. Changes in line-length measurements over a 3-month period are < 14 mm, and most differences average about 4 mm. Since measurement errors of up to 5--6 mm can be expected using a steel tape, more measurements over time will be needed to determine if significant displacement is occurring. Tensiometers were placed at 12 and 36 inches depth in the soil from mid-September through early November 1992, in order to measure matric suction. The 36 inch tensiometer indicated that the soil remained saturated at that depth. The 12 inch tensiometer measured 8 centibars, which occurred following a week of rain-free weather. Gravimetric measurements of soil samples show that surface soil moisture ranges from 14--39% immediately following a storm to 7--29% following at least 10 days of dry weather. At Site 2, quadrilaterals were set up in mid-August 1992; resurveys of the quadrilaterals shows very little, if any, movement. Movement of 38 mm occurred in one quadrilateral; movement in other quadrilaterals averaged close to 5 mm. The slide is not steadily moving, and may be following a pattern, where slides in Hamilton County were more likely to move in late winter or early spring.

  16. Reorganization of vegetation, hydrology and soil carbon after permafrost degradation across heterogeneous boreal landscapes

    USGS Publications Warehouse

    Jorgenson, M. Torre; Harden, Jennifer; Kanevskiy, Mikhail; O'Donnell, Jonathan; Wickland, Kim; Ewing, Stephanie; Manies, Kristen; Zhuang, Qianlai; Shur, Yuri; Striegl, Robert; Koch, Josh

    2013-01-01

    The diversity of ecosystems across boreal landscapes, successional changes after disturbance and complicated permafrost histories, present enormous challenges for assessing how vegetation, water and soil carbon may respond to climate change in boreal regions. To address this complexity, we used a chronosequence approach to assess changes in vegetation composition, water storage and soil organic carbon (SOC) stocks along successional gradients within four landscapes: (1) rocky uplands on ice-poor hillside colluvium, (2) silty uplands on extremely ice-rich loess, (3) gravelly–sandy lowlands on ice-poor eolian sand and (4) peaty–silty lowlands on thick ice-rich peat deposits over reworked lowland loess. In rocky uplands, after fire permafrost thawed rapidly due to low ice contents, soils became well drained and SOC stocks decreased slightly. In silty uplands, after fire permafrost persisted, soils remained saturated and SOC decreased slightly. In gravelly–sandy lowlands where permafrost persisted in drier forest soils, loss of deeper permafrost around lakes has allowed recent widespread drainage of lakes that has exposed limnic material with high SOC to aerobic decomposition. In peaty–silty lowlands, 2–4 m of thaw settlement led to fragmented drainage patterns in isolated thermokarst bogs and flooding of soils, and surface soils accumulated new bog peat. We were not able to detect SOC changes in deeper soils, however, due to high variability. Complicated soil stratigraphy revealed that permafrost has repeatedly aggraded and degraded in all landscapes during the Holocene, although in silty uplands only the upper permafrost was affected. Overall, permafrost thaw has led to the reorganization of vegetation, water storage and flow paths, and patterns of SOC accumulation. However, changes have occurred over different timescales among landscapes: over decades in rocky uplands and gravelly–sandy lowlands in response to fire and lake drainage, over decades to

  17. Conditions for generation of fire-related debris flows, Capulin Canyon, New Mexico

    USGS Publications Warehouse

    Cannon, S.H.; Reneau, S.L.

    2000-01-01

    Comparison of the responses of three drainage basins burned by the Dome fire of 1996 in New Mexico is used to identify the hillslope, channel and fire characteristics that indicate a susceptibility specifically to wildfire-related debris flow. Summer thunderstorms generated three distinct erosive responses from each of three basins. The Capulin Canyon basin showed widespread erosive sheetwash and rilling from hillslopes, and severe flooding occurred in the channel; the North Tributary basin exhibited extensive erosion of the mineral soil to a depth of 5 cm and downslope movement of up to boulder-sized material, and at least one debris flow occurred in the channel; negligible surface runoff was observed in the South Tributary basin. The negligible surface runoff observed in the South Tributary basin is attributed to the limited extent and severity of the fire in that basin. The factors that best distinguish between debris-flow producing and flood-producing drainages are drainage basin morphology and lithology. A rugged drainage basin morphology, an average 12 per cent channel gradient, and steep, rough hillslopes coupled with colluvium and soil weathered from volcaniclastic and volcanic rocks promoted the generation of debris flows. A less rugged basin morphology, an average gradient of 5 per cent, and long, smooth slopes mantled with pumice promoted flooding. Flood and debris-flow responses were produced without the presence of water-repellent soils. The continuity and severity of the burn mosaic, the condition of the riparian vegetation, the condition of the fibrous root mat, accumulations of dry ravel and colluvial material in the channel and on hillslopes, and past debris-flow activity, appeared to have little bearing on the distinctive responses of the basins. Published in 2000 by John Wiley and Sons, Ltd.

  18. Thrusting Rates in the Early Eocene from the Sevier Hinterland, Idaho, USA

    NASA Astrophysics Data System (ADS)

    Anastasio, D. J.; Latta, D.; Kodama, K. P.; Idleman, B. D.

    2011-12-01

    The terminal motion on the Wildhorse thrust system was reconstructed from the Smiley Creek Formation in eastern Idaho, USA (UTM coordinates 11T 739950 m E, 4865190 m N). During the last 100 m of fault slip the calculated slip rate varied between 0.05 to 1.2 mm/yr averaged over time intervals of 300-800 kyrs. The emergent thrust fault overrode proximal fault scarp colluvium deposited as water poor debris flows and was buried by braided stream sheet flood facies sourced by out-of-sequence thrust motion further west. Paleomagnetic data (~100 cores from 27 horizons spaced ~5-60 m apart) showed both normal and reversed directions during progressive step-wise thermal demagnetization to 670° C. Principal component analysis was used to calculate characteristic remanent magnetization directions from which sample polarities were assigned. Correlation of the Smiley Creek Formation to the Geomagnetic Polarity Timescale requires an age older than 49.39±0.27 (n=7) Ma determined by 40Ar/39Ar dating of overlying Challis Volcanic samples and younger than 57±9 Ma, the youngest U/Pb zircon age from an included andesite cobble from a near by Smiley Creek conglomerate exposure (11T 766548 m E, 4874382 m N). The favored magnetostratigraphic correlation is most consistent with expected terrestrial fan facies accumulation rates, the reversal pattern, and calculated paleopole positions. The 183 m of Smiley Creek Formation west of Stag Creek, Idaho was deposited in 4.48 myrs during polarity chrons 24.3n to 23n2n. The terminal emplacement of the Wildhorse thrust was associated with the development of the Pioneer Metamorphic Core complex in the hinterland of the Montana Recess of the Idaho-Wyoming-Montana thrust belt.

  19. Eolian Signal of the Onset of the Late Paleozoic Ice Age in North America Re-Deposited and Preserved As Paleo-Cave Sediments, Southwestern Colorado, U.S.a.

    NASA Astrophysics Data System (ADS)

    Evans, J. E.; Soreghan, M. J.

    2014-12-01

    The Molas Formation is a loessite consisting of reddish silt of Early Pennsylvanian (Bashkirian) age. U-Pb age spectra of accessory zircons indicate long-distance (>2000 km) transport from the Grenville province in northeastern North America plus sources from the peri-Gondwanan terranes in southeastern North America and local sources in the Ancestral Rocky Mountains uplift. These eolian sediments formed a blanket deposit <30 m thick above a paleokarst landscape in southwestern Colorado, infilling solution valleys and burying karst towers developed on the underlying Mississippian (Tournaisian-Visean) Leadville Limestone. The loessite is an eolian signal for the probable onset of glaciation at multiple locations in tectonically uplifted mountainous areas in North America. However, the loessite is easily eroded and has low preservation potential. Prior to lithification, significant amounts of the loess were remobilized and transported into the underlying karst system. As paleo-cave deposits, encased in limestone and dolostone, the silt-rich deposits have a higher preservation potential, and the eolian signal of the onset of the Late Paleozoic Ice Age in North America is still recognizable. However, the following signal modification processes need to be understood: (1) source area weathering and pedogenesis; (2) land-atmosphere transfer processes; (3) deposition effects of paleotopography, vegetation and moisture conditions, and infiltration into open fractures and/or the matrix of colluvium; (4) remobilization by surface runoff into open fractures and/or groundwater piping/sapping processes in loess soils; (5) transport into vadose and phreatic karst passageways by episodic ("streamflood") hydrologic events, forming event deposits (debrites, inundites, and jointites); (6) breakout dome collapse (forming interbedded cave sediments, karst breccias, and speleothems); (7) lithification and diagenesis; (8) post-lithification modification including pervasive hydrothermal

  20. Terrestrial sedimentation and the carbon cycle: coupling weathering and erosion to carbon burial

    USGS Publications Warehouse

    Stallard, R.F.

    1998-01-01

    This paper examines the linkages between the carbon cycle and sedimentary processes on land. Available data suggest that sedimentation on land can bury vast quantities of organic carbon, roughly 1015 g C yr-1. To evaluate the relative roles of various classes of processes in the burial of carbon on land, terrestrial sedimentation was modeled as a series of 864 scenarios. Each scenario represents a unique choice of intensities for seven classes of processes and two different global wetland distributions. Comparison was made with presumed preagricultural conditions. The classes of processes were divided into two major component parts: clastic sedimentation of soil-derived carbon and organic sedimentation of autochthonous carbon. For clastic sedimentation, masses of sediment were considered for burial as reservoir sediment, lake sediment, and combined colluvium, alluvium, and aeolian deposits. When the ensemble of models is examined, the human-induced burial of 0.6-1.5.1015 g yr-1 of carbon on land is entirely plausible. This sink reaches its maximum strength between 30 ?? and 50??N. Paddy lands stand out as a type of land use that warrants future study, but the many faces of rice agriculture limit generalization. In an extreme scenario, paddy lands alone could be made to bury about 1.1015 g C yr-1. Arguing that terrestrial sedimentation processes could be much of the sink for the so called 'missing carbon' is reasonable. Such a hypothesis, however, requires major redesign of how the carbon cycle is modeled. Unlike ecosystem processes that are amenable to satellite monitoring and parallel modeling, many aspects of terrestrial sedimentation are hidden from space.

  1. Comparison of Logistic Regression and Random Forests techniques for shallow landslide susceptibility assessment in Giampilieri (NE Sicily, Italy)

    NASA Astrophysics Data System (ADS)

    Trigila, Alessandro; Iadanza, Carla; Esposito, Carlo; Scarascia-Mugnozza, Gabriele

    2015-11-01

    The aim of this work is to define reliable susceptibility models for shallow landslides using Logistic Regression and Random Forests multivariate statistical techniques. The study area, located in North-East Sicily, was hit on October 1st 2009 by a severe rainstorm (225 mm of cumulative rainfall in 7 h) which caused flash floods and more than 1000 landslides. Several small villages, such as Giampilieri, were hit with 31 fatalities, 6 missing persons and damage to buildings and transportation infrastructures. Landslides, mainly types such as earth and debris translational slides evolving into debris flows, were triggered on steep slopes and involved colluvium and regolith materials which cover the underlying metamorphic bedrock. The work has been carried out with the following steps: i) realization of a detailed event landslide inventory map through field surveys coupled with observation of high resolution aerial colour orthophoto; ii) identification of landslide source areas; iii) data preparation of landslide controlling factors and descriptive statistics based on a bivariate method (Frequency Ratio) to get an initial overview on existing relationships between causative factors and shallow landslide source areas; iv) choice of criteria for the selection and sizing of the mapping unit; v) implementation of 5 multivariate statistical susceptibility models based on Logistic Regression and Random Forests techniques and focused on landslide source areas; vi) evaluation of the influence of sample size and type of sampling on results and performance of the models; vii) evaluation of the predictive capabilities of the models using ROC curve, AUC and contingency tables; viii) comparison of model results and obtained susceptibility maps; and ix) analysis of temporal variation of landslide susceptibility related to input parameter changes. Models based on Logistic Regression and Random Forests have demonstrated excellent predictive capabilities. Land use and wildfire

  2. Tartarus Colles: A sampling of the Martian highlands

    NASA Technical Reports Server (NTRS)

    Murchie, Scott; Treiman, Allan

    1994-01-01

    Several of the most fundamental issues about the geology of Mars can be addressed using information on composition and structure of the plateau plains ('highlands') that cover approximately half the planet. The units that compose the highlands are interpreted as a mixture of volcanic, fluvial, lacustrine, and impact ejecta deposits. A more precise inventory of differing of igneous and sedimentary lithologies in highland rock units would not only lead to a better understanding of how the plateau plains formed, but would also clarify the nature of the surface environment during the first 800 m.y. of martian history. Structural features including bedforms, joints, and small faults that are unresolved from orbit record a history of the emplacement and deformation of the highlands. In addition, weathering products present in this very ancient terrain represent a mineralogic record of past climate and of the pathways by which bedrock is altered chemically. Their similarity or dissimilarity to bright soils observed spectroscopically and in situ at the Viking Lander sites will be evidence for the relative roles of regional sources and global eolian transport in producing the widespread cover of 'dust.' Unfortunately, these issues are difficult to address in the plateau plains proper, because bedrock is covered by mobile sand and weathering products, which dominate both surface composition and remotely measurable spectral properties. However, the 'Tartarus Colles' site, located at 11.41 deg N, 197.69 deg W at an elevation of -1 km, provides an excellent opportunity to address the highland geology within the mission constraints of Mars Pathfinder. The site is mapped as unit HNu, and consists of knobby remnants of deeply eroded highlands. It contains rolling hills, but lacks steep escarpments and massifs common in most highland remnants, and is free of large channels that would have removed colluvium from eroded upper portions of the stratigraphic column. These

  3. Characterizing the Iron Wash fault: A fault line scarp in Utah

    NASA Astrophysics Data System (ADS)

    Kozaci, O.; Ostenaa, D.; Goodman, J.; Zellman, M.; Hoeft, J.; Sowers, J. M.; Retson, T.

    2015-12-01

    The Iron Wash fault (IWF) is an approximately 30 mile-long, NW-SE trending structure, oriented perpendicular to the San Rafael Monocline near Green River in Utah. IWF exhibits well-expressed geomorphic features such as a linear escarpment with consistently north side down displacement. The fault coincides with an abrupt change in San Rafael Monocline dip angle along its eastern margin. The IWF is exposed in incised drainages where Jurassic Navajo sandstone (oldest) and Lower Carmel Formation (old), are juxtaposed against Jurassic Entrada sandstone (younger) and Quaternary alluvium (youngest). To assess the recency of activity of the IWF we performed detailed geomorphic mapping and a paleoseismic trenching investigation. A benched trench was excavated across a Quaternary fluvial terrace remnant across the mapped trace of the IWF. The uppermost gravel units and overlying colluvium are exposed in the trench across the projection of the fault. In addition, we mapped the basal contact of the Quaternary gravel deposit in relation to the adjacent fault exposures in detail to show the geometry of the basal contact near and across the fault. We find no evidence of vertical displacement of these Quaternary gravels. A preliminary U-series date of calcite cementing unfaulted fluvial gravels and OSL dating of a sand lens within the unfaulted fluvial gravels yielded approximately 304,000 years and 78,000 years, respectively. These preliminary results of independent dating methods constrains the timing of last activity of the IWF to greater than 78,000 years before present suggesting that IWF not an active structure. Its distinct geomorphic expression is most likely the result of differential erosion, forming a fault-line scarp.

  4. Ground-water geology of the Dickson, Lawrenceburg, and Waverly areas in the western Highland Rim, Tennessee

    USGS Publications Warehouse

    Marcher, Melvin V.; Bingham, Roy H.; Lounsbury, Richard Edwin

    1964-01-01

    Ground-water supplies in the Dickson, Lawrenceburg, and Waverly areas are obtained from wells and springs in limestone and chert formations of Missisippian age. In the Dickson area most of the wells and springs are in Warsaw Limestone. In the Lawrenceburg and Waverly areas, ground-water supplies are obtained from Fort Payne Chert and from residuum. In all three areas a few wells obtain small amounts of water from gravel stringers in the residuum. Yields of well range from a few to 300 gpm (gallons per minute). Wells having the largest yields obtain water from residual material (colluvium) in the valley of Trace Creek in the Waverly area. Fewer than 10 percent of all wells inventoried yield more than 25 gpm. Springs are common in all the areas studied and yield as much as 1,000 gpm. The quality of water from wells and springs iv the areas studied generally is good. The water is of the calcium bicarbonate type, and most of it is moderately hard to hard. The constituents in water from springs and from wells are about the same, although water from springs tends to be softer and slightly lower in dissolved-solids content. Springs constitute the largest potential source of water in the three areas. Twenty-one of the large springs discharge approximately 12 million gallons per day, or about 8,000 gpm. Another potential source of water is residuum underlying the valley of Trace Creek in the Waverly area. Wells yielding as much as 500 gpm probably could be developed in this aquifer.

  5. Evidence for a twelfth large earthquake on the southern hayward fault in the past 1900 years

    USGS Publications Warehouse

    Lienkaemper, J.J.; Williams, P.L.; Guilderson, T.P.

    2010-01-01

    We present age and stratigraphic evidence for an additional paleoearthquake at the Tyson Lagoon site. The acquisition of 19 additional radiocarbon dates and the inclusion of this additional event has resolved a large age discrepancy in our earlier earthquake chronology. The age of event E10 was previously poorly constrained, thus increasing the uncertainty in the mean recurrence interval (RI), a critical factor in seismic hazard evaluation. Reinspection of many trench logs revealed substantial evidence suggesting that an additional earthquake occurred between E10 and E9 within unit u45. Strata in older u45 are faulted in the main fault zone and overlain by scarp colluviums in two locations.We conclude that an additional surfacerupturing event (E9.5) occurred between E9 and E10. Since 91 A.D. (??40 yr, 1??), 11 paleoearthquakes preceded the M 6:8 earthquake in 1868, yielding a mean RI of 161 ?? 65 yr (1??, standard deviation of recurrence intervals). However, the standard error of the mean (SEM) is well determined at ??10 yr. Since ~1300 A.D., the mean rate has increased slightly, but is indistinguishable from the overall rate within the uncertainties. Recurrence for the 12-event sequence seems fairly regular: the coefficient of variation is 0.40, and it yields a 30-yr earthquake probability of 29%. The apparent regularity in timing implied by this earthquake chronology lends support for the use of time-dependent renewal models rather than assuming a random process to forecast earthquakes, at least for the southern Hayward fault.

  6. Chemical weathering and runoff chemistry in a steep headwater catchment

    NASA Astrophysics Data System (ADS)

    Anderson, Suzanne Prestrud; Dietrich, William E.

    2001-07-01

    We present here deductions about the location, rate, and mechanisms of chemical weathering in a small catchment based on a catchment-scale sprinkling experiment. In this experiment demineralized water was applied at an approximately steady rate in the CB1 catchment in the Oregon Coast Range to reach and maintain a quasi-steady discharge for a period of 4 days. Because of nearly steady flow conditions within the catchment, the contribution to solute fluxes from soil and bedrock could be partitioned. One half of the solute flux from the catchment derived from colluvial soil, and one half from weathering in bedrock. This implies more intense weathering in the thin colluvium mantling the catchment than in the thick underlying weathered bedrock. The annual solute flux from the catchment, scaled to the annual runoff from the catchment, is 32 +/- 10 t km-2 year-1, equivalent to published chemical denudation rates for nearby rivers with drainage areas 106 times greater than the experiment site. Soil waters sampled during the sprinkling experiment had steady compositions following a period of transient water flow conditions, implying steady-state chemical evolution in the soil. The waters leached organic anions from shallow depths in the soil, which solubilized aluminium and iron, indicating that podzolization is occurring in these soils. Carbonate dissolution appears to be an important source of solutes from the bedrock, despite being present as only a minor phase in the rock. Water balance suggests that the residence time of water in the catchment is about 2 months, and that typical 24 h storms displace only a fraction of the stored water. A consequence is that runoff chemistry is dominated by old water, which imposes strong limits on the variability of runoff composition.

  7. Post-wildfire erosion response in two geologic terrains in the western USA

    USGS Publications Warehouse

    Moody, J.A.; Martin, D.A.; Cannon, S.H.

    2008-01-01

    Volumes of eroded sediment after wildfires vary substantially throughout different geologic terrains across the western United States. These volumes are difficult to compare because they represent the response to rainstorms and runoff with different characteristics. However, by measuring the erosion response as the erodibility efficiency of water to detach and transport sediment on hillslopes and in channels, the erosion response from different geologic terrains can be compared. Specifically, the erodibility efficiency is the percentage of the total available stream power expended to detach, remobilize, or transport a mass of sediment. Erodibility efficiencies were calculated for the (i) initial detachment, and for the (ii) remobilization and transport of sediment on the hillslopes and in the channels after wildfire in two different geological terrains. The initial detachment efficiencies for the main channel and tributary channel in the granitic terrain were 10 ?? 9% and 5 ?? 4% and were similar to those for the volcanic terrain, which were 5 ?? 5% and 1 ?? 1%. No initial detachment efficiency could be measured for the hillslopes in the granitic terrain because hillslope measurements were started after the first major rainstorm. The initial detachment efficiency in the volcanic terrain was 1.3 ?? 0.41%. The average remobilization and transport efficiencies associated with flash floods in the channels also were similar in the granitic (0.18 ?? 0.57%) and volcanic (0.11 ?? 0.41%) terrains. On the hillslope the remobilization and transport efficiency was greater in the volcanic terrain (2.4%) than in the granitic terrain (0.65%). However, this may reflect the reduced sediment availability after the first major rainstorm (30-min maximum rainfall intensity ??? 90??mm h- 1) in the granitic terrain, while easily erodible fine colluvium remained on the hillslope after the first rainstorm (30-min maximum rainfall intensity = 7.2??mm h- 1) in the volcanic terrain. The

  8. A record of large earthquakes on the southern Hayward fault for the past 1800 years

    USGS Publications Warehouse

    Lienkaemper, J.J.; Williams, P.L.

    2007-01-01

    This is the second article presenting evidence of the occurrence and timing of paleoearthquakes on the southern Hayward fault as interpreted from trenches excavated within a sag pond at the Tyson's Lagoon site in Fremont, California. We use the information to estimate the mean value and aperiodicity of the fault's recurrence interval (RI): two fundamental parameters for estimation of regional seismic hazard. An earlier article documented the four most recent earthquakes, including the historic 1868 earthquake. In this article we present evidence for at least seven earlier paleoruptures since about A.D. 170. We document these events with evidence for ground rupture, such as the presence of blocky colluvium at the base of the main trace fault scarp, and by corroborating evidence such as simultaneous liquefaction or an increase in deformation immediately below event horizons. The mean RI is 170 ?? 82 yr (1??, standard deviation of the sample), aperiodicity is 0.48, and individual intervals may be expected to range from 30 to 370 yr (95.4% confidence). The mean RI is consistent with the recurrence model of the Working Group on California Earthquake Probabilities (2003) (mean, 161 yr; range, 99 yr [2.5%]; 283 yr [97.5%]). We note that the mean RI for the five most recent events may have been only 138 ?? 58 yr (1??). Hypothesis tests for the shorter RI do not demonstrate that any recent acceleration has occurred compared to the earlier period or the entire 1800-yr record, principally because of inherent uncertainties of the event ages.

  9. An examination of the factors governing the development of karst topography in the Cumberland Valley of Pennsylvania

    SciTech Connect

    Ackerman, R.V. . Dept. of Geological Sciences)

    1993-03-01

    The landscape of the Cumberland Valley of South Central Pennsylvania is dominated by karst topography. A study was initiated to determine if the development of karst was controlled primarily by geologic structure or by lithologic differences. Existing data concerning the geographic locations of karst features, the hydrogeologic characteristics of the Cumberland Valley, and the chemistry of the eleven carbonate formations within the 518 km[sup 2] study area were compiled. Data concerning 366 mapped sinkholes and over 9,000 additional karst features and their relations to the structural, lithological and spatial characteristics of the study area were collected and compiled into the database. Other factors contributing to karst development such as groundwater flow, soil and colluvium characteristics, and geographic distribution were considered. The data suggest that structure dominates lithology in the development of karst features within the study area. Structural features such as fractures, joints and folds, which create secondary porosity, are prerequisite for solution of the carbonate bedrock. Joint systems, fold axes, igneous intrusions, caves, springs and groundwater flow have a significant impact on the development of karst features. The presence of faults proved inconclusive. There are a greater number of karst features per unit area in areas of purer limestones (units with a lower percentage of acid insoluble residue). Lithological variations impact karst development only when structural features are present to provide secondary porosity that enhances chemical weathering. The distribution of karst features and the geologic factors governing their development and distribution should be taken into account when land-use decisions in karst terrains are made.

  10. Land use history, floodplain development, and soil erosion in the vicinity of a millstone production center since the Iron Age in the Segbachtal near Mayen (eastern Eifel, Germany)

    NASA Astrophysics Data System (ADS)

    Dotterweich, Markus; Wenzel, Stefan; Schreg, Rainer; Fülling, Alexander; Engel, Max

    2015-04-01

    In Roman times, the stone and pottery production near Mayen in western Germany reached a very high intensity which would have satisfied the needs of a much wider area. The rate and volume of production was unprecedented and never reached the same level thereafter. The Segbach valley study site with an area of only a few square kilometres offers a very special geoarchaeological archive. The Roman land use structures were completely preserved under a 2 meter thick layer of sediment and are now partially exposed in a gully due to erosion. Pedological, sedimentological and geophysical studies at the colluvium and floodplain sediments as well as relict field structures showed that in the last 2500 years there has been a considerable human impact on both water and sediment budgets. This also had various implications on the further development of water courses, soils and relief. Evidence for the development of flood plain sediments can be traced as far back as the late La Tène period, the Roman Iron Age, and since the Middle Ages. On one particular south-facing slope we found evidence of recultivation measures on a former quarry tailing heap dating from the Middle Ages. This and other human construction activities and land uses lead to a significant change in erosion and sedimentation patterns. It is surprising that sedimentation in flood plains was largely absent during the Roman Iron Age despite intensive land use. Evidence shows that flash flood events with intensive accumulation of soil matter in flood plains only occurred during the High Middle Ages. Sediments from the late Middle ages and the Modern Times are largely missing. The research undertaken in Segbach valley not only offers new insights into specific local historical land uses and land use changes but also fundamental knowledge about the principles and impacts of long-term human-environment interactions.

  11. Geologic map of the South Sierra Wilderness and South Sierra Roadless area, southern Sierra Nevada, California

    SciTech Connect

    Diggles, M.F. ); Carter, K.E. )

    1993-04-01

    The study area is underlain predominantly by granitoid rocks of the Sierra Nevada batholith. Metamorphic rocks are present in roof pendants mainly in the southwest corner of the study area and consist of quartz-biotite schist, phyllite, quartzite, marble, calc-silicate hornfels, and meta-dacite. Among the seven Triassic and (or) Jurassic plutons are three newly described units that consist of the gabbro of Deer Mountain, the tonalite of Falls Creek, and the quartz diorite of Round Mountain. The map shows one newly described unit that intrudes Triassic rocks: the granodiorite of Monache Creek which is a leucocratic, medium-grained, equi-granular, locally porphyritic biotite hornblende granodiorite. Among the seven Cretaceous plutons are two newly described units. The Cretaceous rocks are generally medium- to coarse-grained, potassium-feldspar porphyritic granite with biotite and minor hornblende; it includes abundant pods of alaskite. The granite of Haiwee Creek is similar but only locally potassium-feldspar porphyritic and with only minor hornblende. Major-element data plotted on Harker diagrams show the older rocks to be higher in iron and magnesium and lower in silica than the younger rocks. There are abundant local pods of alaskite throughout the study area that consist of medium- to coarse-grained, leucocratic granite, alkali-feldspar granite and associated aplite and pegmatite bodies occurring as small pods and highly leucocratic border phases of nearby plutons. Tertiary and Quaternary volcanic rock include the rhyolite of Monache Mountain and Quaternary surficial deposits: fan, stream-channel, colluvium, talus, meadow-filling, rock-glacier, and glacial-moraine deposits. Important structures include the Sierran front fault and a possible extensional feature along which Bacon (1978) suggests Monache Mountain erupted.

  12. Geology of the Harpers Ferry Quadrangle, Virginia, Maryland, and West Virginia

    USGS Publications Warehouse

    Southworth, Scott; Brezinski, David K.

    1996-01-01

    The Harpers Ferry quadrangle covers a portion of the northeast-plunging Blue Ridge-South Mountain anticlinorium, a west-verging allochthonous fold complex of the late Paleozoic Alleghanian orogeny. The core of the anticlinorium consists of high-grade paragneisses and granitic gneisses that are related to the Grenville orogeny. These rocks are intruded by Late Proterozoic metadiabase and metarhyolite dikes and are unconformably overlain by Late Proterozoic metasedimentary rocks of the Swift Run Formation and metavolcanic rocks of the Catoctin Formation, which accumulated during continental rifting of Laurentia (native North America) that resulted in the opening of the Iapetus Ocean. Lower Cambrian metasedimentary rocks of the Loudoun, Weverton, Harpers, and Antietam Formations and carbonate rocks of the Tomstown Formation were deposited in the rift-to-drift transition as the early Paleozoic passive continental margin evolved. The Short Hill fault is an early Paleozoic normal fault that was contractionally reactivated as a thrust fault and folded in the late Paleozoic. The Keedysville detachment is a folded thrust fault at the contact of the Antietam and Tomstown Formations. Late Paleozoic shear zones and thrust faults are common. These rocks were deformed and metamorphosed to greenschist-facies during the formation of the anticlinorium. The Alleghanian deformation was accompanied by a main fold phase and a regional penetrative axial plane cleavage, which was followed by a minor fold phase with crenulation cleavage. Early Jurassic diabase dikes transected the anticlinorium during Mesozoic continental rifting that resulted in the opening of the Atlantic Ocean. Cenozoic deposits that overlie the bedrock include bedrock landslides, terraces, colluvium, and alluvium.

  13. Assessing landslide potential on coastal bluffs near Mukilteo, Washington—Geologic site characterization for hydrologic monitoring

    USGS Publications Warehouse

    Mirus, Benjamin B.; Smith, Joel B.; Benjamin Stark; York Lewis; Abigail Michel; Baum, Rex L.

    2016-01-01

    During the summer 2015, the U.S. Geological Survey collected geologic and geotechnical data for two sites on coastal bluffs along the eastern shore of Puget Sound, Washington. The U.S. Geological Survey also installed hydrologic instrumentation at the sites and collected specimens for laboratory testing. The two sites are located on City of Mukilteo open-space land and are about 0.6 kilometers apart. The bluffs at each site are approximately 42 meters high, and rise steeply from the shoreline with 32–35° slopes. The more northerly of the two sites occupies an active landslide and is mostly unvegetated. The other site is forested, and although stable during the preparation of this report, shows evidence of historical and potential landslide activity. The slopes of the bluffs at both sites are mantled by a thin, nonuniform colluvium underlain by clay-rich glacial deposits and tills of the Whidbey Formation or Double Bluff Drift. Till consisting of sand, gravel, and cobbles caps the bluffs and rests on finer grained glacial deposits of sand, silt, and clay. These types of different glacial deposits are dense, vertically fractured, and generally have low permeability, but field observations indicate that locally the deposits are sufficiently permeable to allow lateral flow of water along fractures and subhorizontal boundaries between deposits of different texture. Laboratory tests indicate that many of the deposits are highly plastic, with low hydraulic conductivity, and moderate shear strength. Steep slopes combined with the strength and hydraulic characteristics of the deposits leave the bluffs prone to slope instability, particularly during the wet season when infiltrating rainfall changes moisture content, pore-water pressure, and effective stress within the hillslope. The instrumentation was designed to primarily observe rainfall variability and hydrologic changes in the subsurface that can affect stability of the bluffs, and also to compare the hydrologic

  14. Evidence for debris flow gully formation initiated by shallow subsurface water on Mars

    USGS Publications Warehouse

    Lanza, N.L.; Meyer, G.A.; Okubo, C.H.; Newsom, Horton E.; Wiens, R.C.

    2010-01-01

    The morphologies of some martian gullies appear similar to terrestrial features associated with debris flow initiation, erosion, and deposition. On Earth, debris flows are often triggered by shallow subsurface throughflow of liquid water in slope-mantling colluvium. This flow causes increased levels of pore pressure and thus decreased shear strength, which can lead to slide failure of slope materials and subsequent debris flow. The threshold for pore pressure-induced failure creates a distinct relationship between the contributing area supplying the subsurface flow and the slope gradient. To provide initial tests of a similar debris flow initiation hypothesis for martian gullies, measurements of the contributing areas and slope gradients were made at the channel heads of martian gullies seen in three HiRISE stereo pairs. These gullies exhibit morphologies suggestive of debris flows such as leveed channels and lobate debris fans, and have well-defined channel heads and limited evidence for multiple flows. Our results show an area-slope relationship for these martian gullies that is consistent with that observed for terrestrial gullies formed by debris flow, supporting the hypothesis that these gullies formed as the result of saturation of near-surface regolith by a liquid. This model favors a source of liquid that is broadly distributed within the source area and shallow; we suggest that such liquid could be generated by melting of broadly distributed icy materials such as snow or permafrost. This interpretation is strengthened by observations of polygonal and mantled terrain in the study areas, which are both suggestive of near-surface ice. ?? 2009 Elsevier Inc.

  15. Surficial geologic maps along the riparian zone of the Animas River and its headwater tributaries, Silverton to Durango, Colorado, with upper Animas River watershed gradient profiles

    USGS Publications Warehouse

    Blair, R.W.; Yager, D.B.; Church, S.E.

    2002-01-01

    This product consists of Adobe Acrobat .PDF format documents for 10 surficial geologic strip maps along the Animas River watershed from its major headwater tributaries, south to Durango, Colorado. The Animas River originates in the San Juan Mountains north of the historic mining town of Silverton, Colorado. The surficial geologic maps identify surficial deposits, such as flood-plain and terrace gravels, alluvial fans, glacial till, talus, colluvium, landslides, and bogs. Sixteen primary units were mapped that included human-related deposits and structures, eight alluvial, four colluvial, one glacial, travertine deposits, and undifferentiated bedrock. Each of the surficial geologic strip maps has .PDF links to surficial geology photographs, which enable the user to take a virtual tour of these deposits. Geochemical data collected from mapped surficial deposits that pre- and postdate mining activity have aided in determining the geochemical baseline in the watershed. Several photographs with their corresponding geochemical baseline profiles are accessible through .PDF links from several of the maps. A single coverage for all surficial deposits mapped is included as an ArcInfo shape file as an Arc Export format .e00 file. A gradient map for major headwater tributary streams to the Animas River is also included. The gradient map has stream segments that are color-coded based on relative variations in slope and .PDF format links to each stream gradient profile. Stream gradients were derived from U.S. Geological Survey 10-m digital elevation model data. This project was accomplished in support of the U.S. Geological Survey's Abandoned Mine Lands Initiative in the San Juan Mountains, Colorado.

  16. Nivation landforms in the western Great Basin and their paleoclimatic significance

    USGS Publications Warehouse

    Dohrenwend, J.C.

    1984-01-01

    More than 10,000 nivation landforms occur in the higher mountain ranges of the western Great Basin. They range from small, subtle hollows with head scarps a few meters high and a few tens of meters long to broad, clearly defined terraces as much as 220 m wide bounded by bold, steeply sloping head scarps as much as 30 m high and 1600 m long. Distribution of these nivation hollows is strongly influenced by elevation, slope orientation, local relief, and substrate lithology. About 95% occur between 2200 and 3000 m elevation, and nearly 80% are situated on north-northwest-to east-northeast-facing slopes. They occur mainly in areas of moderately sloping terrain and moderate local relief, and they are preferentially developed on relatively incompetent substrates including terrigenous sedimentary deposits, volcanic and metavolcanic rocks of intermediate composition, and deeply weathered granitoid rocks. Nearly all of these nivation hollows are relict. They are most abundant near areas of late Pleistocene glaciation but rarely occur within such areas. Most are veneered with colluvium and are well vegetated, and many hollows in the Mono Basin area are veneered with volcanic ash at least 700 yr old. Distribution of nivation hollows suggests that (1) the full-glacial nivation threshold altitude (NTA) rose from north to south at 190 m per degree of latitude, subparallel to, and approximately 740 m lower than, the full-glacial equilibrium-line altitude (ELA) and about 1370 m lower than the estimated modern ELA; (2) the difference between the full-glacial and modern ELAs indicates an approximate 7??C full-glacial mean-annual-temperature depression throughout the Great Basin; and (3) the full-glacial mean annual temperature at the NTA is estimated to have been approximately 0?? to 1??C, assuming little change in accumulation-season precipitation. ?? 1984.

  17. Soil survey of Solid Waste Storage Area 6

    SciTech Connect

    Lietzke, D.A.; Lee, S.Y.

    1986-06-01

    An intensive soil survey was made of Solid Waste Storage Area (SWSA) 6 (Oak Ridge National Laboratory) at a scale of 1:1200. The amount of chemical weathering, the thickness of upland soils, and the depth to unoxidized rock are dependent on slope gradient, water-flow pathways, degree of rock fracturing, and the extent of soil and rock erosion by late Pleistocene and Holocene geomorphic processes. Foot-slope landforms have generally concave slope shapes where sediment accumulates. Colluvium stratigraphy exhibits at least one lithologic discontinuity, but there may be two discontinuities preserved in some thicker colluvia. One or more paleosols, either complete or partially truncated, are preserved in these concave landforms. Alluvial soils were not examined in detail but were separated from colluvial soils because of their wetness. A small area of ancient alluvium was located on a stable upland summit that formed the highest elevation in SWSA-6. On the nearly level summit, a thin loess cap was preserved on the older alluvial soil. Upland and colluvial soils are all highly leached and strongly acid even though they are formed from a calcareous parent rock. The highly fractured rock, being relatively permeable, has been leached free of carbonates in the upper levels so that there is a wide pH gradient from the surface downward. Most of the soils were classified as Ultisols, with minimal areas of Alfisols, Inceptisols, and Entisols. Based on the soil survey, representative landforms and soils will be selected to study physical, chemical, and mineralogical properties of the soil and weathered rock. Those properties will be used to predict both the amount and duration of leachate filtration and purification in downward migration to the water table or lateral migration through colluvial and alluvial soils to ground-water seeps.

  18. Field and Laboratory Data From an Earthquake History Study of Scarps in the Hanging Wall of the Tacoma Fault, Mason and Pierce Counties, Washington

    USGS Publications Warehouse

    Nelson, Alan R.; Personius, Stephen F.; Sherrod, Brian L.; Buck, Jason; Bradley, Lee-Ann; Henley, Gary, II; Liberty, Lee M.; Kelsey, Harvey M.; Witter, Robert C.; Koehler, R.D.; Schermer, Elizabeth R.; Nemser, Eliza S.; Cladouhos, Trenton T.

    2008-01-01

    As part of the effort to assess seismic hazard in the Puget Sound region, we map fault scarps on Airborne Laser Swath Mapping (ALSM, an application of LiDAR) imagery (with 2.5-m elevation contours on 1:4,000-scale maps) and show field and laboratory data from backhoe trenches across the scarps that are being used to develop a latest Pleistocene and Holocene history of large earthquakes on the Tacoma fault. We supplement previous Tacoma fault paleoseismic studies with data from five trenches on the hanging wall of the fault. In a new trench across the Catfish Lake scarp, broad folding of more tightly folded glacial sediment does not predate 4.3 ka because detrital charcoal of this age was found in stream-channel sand in the trench beneath the crest of the scarp. A post-4.3-ka age for scarp folding is consistent with previously identified uplift across the fault during AD 770-1160. In the trench across the younger of the two Stansberry Lake scarps, six maximum 14C ages on detrital charcoal in pre-faulting B and C soil horizons and three minimum ages on a tree root in post-faulting colluvium, limit a single oblique-slip (right-lateral) surface faulting event to AD 410-990. Stratigraphy and sedimentary structures in the trench across the older scarp at the same site show eroded glacial sediments, probably cut by a meltwater channel, with no evidence of post-glacial deformation. At the northeast end of the Sunset Beach scarps, charcoal ages in two trenches across graben-forming scarps give a close maximum age of 1.3 ka for graben formation. The ages that best limit the time of faulting and folding in each of the trenches are consistent with the time of the large regional earthquake in southern Puget Sound about AD 900-930.

  19. An establishment on the hazard mitigation system of large scale landslides for Zengwen reservoir watershed management in Taiwan

    NASA Astrophysics Data System (ADS)

    Tsai, Kuang-Jung; Lee, Ming-Hsi; Chen, Yie-Ruey; Huang, Meng-Hsuan; Yu, Chia-Ching

    2016-04-01

    Extremely heavy rainfall with accumulated rainfall amount more than 2900mm within continuous 3 day event occurred at southern Taiwan has been recognized as a serious natural hazard caused by Morakot typhoon in august, 2009. Very destructive large scale landslides and debris flows were induced by this heavy rainfall event. According to the satellite image processing and monitoring project was conducted by Soil & Water Conservation Bureau after Morakot typhoon. More than 10904 sites of landslide with total sliding area of 18113 ha were significantly found by this project. Also, the field investigation on all landslide areas were executed by this research on the basis of disaster type, scale and location related to the topographic condition, colluvium soil characteristics, bedrock formation and geological structure after Morakot hazard. The mechanism, characteristics and behavior of this large scale landslide combined with debris flow disasters are analyzed and Investigated to rule out the interaction of factors concerned above and identify the disaster extent of rainfall induced landslide during the period of this study. In order to reduce the disaster risk of large scale landslide and debris flow, the adaption strategy of hazard mitigation system should be set up as soon as possible and taken into consideration of slope land conservation, landslide control countermeasure planning, disaster database establishment, environment impact analysis and disaster risk assessment respectively. As a result, this 3-year research has been focused on the field investigation by using GPS/GIS/RS integration, mechanism and behavior study regarding to the rainfall induced landslide occurrence, disaster database and hazard mitigation system establishment. In fact, this project has become an important issue which was seriously concerned by the government and people live in Taiwan. Hopefully, all results come from this research can be used as a guidance for the disaster prevention and

  20. Physical Controls on Delta Formation and Carbon Storage in Mountain Lakes

    NASA Astrophysics Data System (ADS)

    Scott, D.; Wohl, E.

    2014-12-01

    Carbon acts as a component in greenhouse gases that regulate global climate. It is imperative to understand the transport and storage of carbon in order to understand and manage climate change. We examine terrestrial carbon storage in mountain lake deltas as a way of furthering our understanding of the terrestrial carbon sink, which is a poorly understood but significant contributor to the global carbon cycle. We examined subalpine lake deltas in the Washington Cascade Range and Colorado Front Range to test the following hypotheses: 1) The size of the deltaic carbon sink is strongly correlated with incision at the outlet of the lake and the topography of the basin. 2) Areas of high exhumation rates will have smaller and fewer deltas because a high exhumation rate should lead to more confined basins and more colluvium available to dam lake outlets, preventing lake level drop and corresponding delta formation. 3) High-energy deltas will transport more carbon to lakes, avoiding the deltaic carbon sink. At 27 lakes, we surveyed mountain lake deltas and took sediment samples, surveyed lake outlets in the field, and measured lake valley confinement in GIS to test hypotheses 1 and 3. Across the Snoqualmie and Skykomish watersheds in the Washington Cascades and the Colorado Front Range, we took a census of the number of natural lakes and the proportion of those lakes with deltas to test hypothesis 2. Preliminary results indicate that the Washington Cascades (high exhumation rate) have a higher density of lakes, but fewer deltas, than the Colorado Front Range (low exhumation rate). We also suspect that deltas in the Washington Cascades will have a lower carbon content than the Colorado Front Range due to generally higher energy levels on deltas. Finally, we found a substantial difference in the geomorphology and sediment type between beaver-affected and non-beaver-affected lakes in the Colorado Front Range.

  1. Landslide Geohazard Monitoring, Early Warning and Stabilization Control Methods

    NASA Astrophysics Data System (ADS)

    Bednarczyk, Zbigniew

    2014-03-01

    This paper is a presentation of landslide monitoring, early warning and remediation methods recommended for the Polish Carpathians. Instrumentation included standard and automatic on-line measurements with the real-time transfer of data to an Internet web server. The research was funded through EU Innovative Economy Programme and also by the SOPO Landslide Counteraction Project. The landslides investigated were characterized by relatively low rates of the displacements. These ranged from a few millimetres to several centimetres per year. Colluviums of clayey flysch deposits were of a soil-rock type with a very high plasticity and moisture content. The instrumentation consisted of 23 standard inclinometers set to depths of 5-21 m. The starting point of monitoring measurements was in January 2006. These were performed every 1-2 months over the period of 8 years. The measurements taken detected displacements from several millimetres to 40 cm set at a depth of 1-17 m. The modern, on-line monitoring and early warning system was installed in May 2010. The system is the first of its kind in Poland and only one of several such real-time systems in the world. The installation was working with the Local Road Authority in Gorlice. It contained three automatic field stations for investigation of landslide parameters to depths of 12-16 m and weather station. In-place tilt transducers and innovative 3D continuous inclinometer systems with sensors located every 0.5 m were used. It has the possibility of measuring a much greater range of movements compared to standard systems. The conventional and real-time data obtained provided a better recognition of the triggering parameters and the control of geohazard stabilizations. The monitoring methods chosen supplemented by numerical modelling could lead to more reliable forecasting of such landslides and could thus provide better control and landslide remediation possibilities also to stabilization works which prevent landslides.

  2. Geologic Map of the San Luis Quadrangle, Costilla County, Colorado

    USGS Publications Warehouse

    Machette, Michael N.; Thompson, Ren A.; Drenth, Benjamin J.

    2008-01-01

    The map area includes San Luis and the primarily rural surrounding area. San Luis, the county seat of Costilla County, is the oldest surviving settlement in Colorado (1851). West of the town are San Pedro and San Luis mesas (basalt-covered tablelands), which are horsts with the San Luis fault zone to the east and the southern Sangre de Cristo fault zone to the west. The map also includes the Sanchez graben (part of the larger Culebra graben), a deep structural basin that lies between the San Luis fault zone (on the west) and the central Sangre de Cristo fault zone (on the east). The oldest rocks exposed in the map area are the Pliocene to upper Oligocene basin-fill sediments of the Santa Fe Group, and Pliocene Servilleta Basalt, a regional series of 3.7?4.8 Ma old flood basalts. Landslide deposits and colluvium that rest on sediments of the Santa Fe Group cover the steep margins of the mesas. Rare exposures of the sediment are comprised of siltstones, sandstones, and minor fluvial conglomerates. Most of the low ground surrounding the mesas and in the graben is covered by surficial deposits of Quaternary age. The alluvial deposits are subdivided into three Pleistocene-age units and three Holocene-age units. The oldest Pleistocene gravel (unit Qao) forms extensive coalesced alluvial fan and piedmont surfaces, the largest of which is known as the Costilla Plain. This surface extends west from San Pedro Mesa to the Rio Grande. The primary geologic hazards in the map area are from earthquakes, landslides, and localized flooding. There are three major fault zones in the area (as discussed above), and they all show evidence for late Pleistocene to possible Holocene movement. The landslides may have seismogenic origins; that is, they may be stimulated by strong ground shaking during large earthquakes. Machette and Thompson based this geologic map entirely on new mapping, whereas Drenth supplied geophysical data and interpretations.

  3. Maps of the Bonsall area of the San Luis Rey River valley, San Diego County, California, showing geology, hydrology, and ground-water quality

    USGS Publications Warehouse

    Izbicki, John A.

    1985-01-01

    In November 1984, 84 wells and 1 spring in the Bonsall area of the San Luis Rey River valley were inventoried by U.S. Geological Survey personnel. Depth to water in 38 wells ranged from 1.3 to 38 ft and 23 wells had depths to water less than 10 feet. Dissolved solids concentration of water from 29 wells and 1 spring sampled in autumn 1983 and spring 1984 ranged from 574 to 2,370 mgs/L. Groundwater with a dissolved solids concentration less than 1,000 mgs/L was generally restricted to the eastern part of the aquifer. The total volume of alluvial fill in the Bonsall area is 113,000 acre-feet; the amount of groundwater storage available in the alluvial aquifer is 18,000 acre-feet. The alluvial aquifer is, in part, surrounded and underlain by colluvium and weathered crystalline rock that add some additional groundwater storage capacity to the system. Data in this report are presented on five maps showing well locations , thickness of alluvial fill, water level contours in November 1983 and hydrographs of selected wells, groundwater quality in spring 1960 and graphs showing changes in dissolved solids concentrations of water from selected wells with time, and groundwater quality in spring 1984. This report is part of a larger cooperative project between the Rainbow Municipal Irrigation District and the U.S. Geological Survey. The purpose of the larger project is to develop an appropriate groundwater management plan for the Bonsall area of the San Luis Rey River valley. (USGS)

  4. Instrumental record of debris flow initiation during natural rainfall: Implications for modeling slope stability

    USGS Publications Warehouse

    Montgomery, D.R.; Schmidt, K.M.; Dietrich, W.E.; McKean, J.

    2009-01-01

    The middle of a hillslope hollow in the Oregon Coast Range failed and mobilized as a debris flow during heavy rainfall in November 1996. Automated pressure transducers recorded high spatial variability of pore water pressure within the area that mobilized as a debris flow, which initiated where local upward flow from bedrock developed into overlying colluvium. Postfailure observations of the bedrock surface exposed in the debris flow scar reveal a strong spatial correspondence between elevated piezometric response and water discharging from bedrock fractures. Measurements of apparent root cohesion on the basal (Cb) and lateral (Cl) scarp demonstrate substantial local variability, with areally weighted values of Cb = 0.1 and Cl = 4.6 kPa. Using measured soil properties and basal root strength, the widely used infinite slope model, employed assuming slope parallel groundwater flow, provides a poor prediction of hydrologie conditions at failure. In contrast, a model including lateral root strength (but neglecting lateral frictional strength) gave a predicted critical value of relative soil saturation that fell within the range defined by the arithmetic and geometric mean values at the time of failure. The 3-D slope stability model CLARA-W, used with locally observed pore water pressure, predicted small areas with lower factors of safety within the overall slide mass at sites consistent with field observations of where the failure initiated. This highly variable and localized nature of small areas of high pore pressure that can trigger slope failure means, however, that substantial uncertainty appears inevitable for estimating hydrologie conditions within incipient debris flows under natural conditions. Copyright 2009 by the American Geophysical Union.

  5. Sediment characterization, stocks and erodible relief quantification in alpine context using sloping local base level, from single watersheds to large-scale source-to-sink systems

    NASA Astrophysics Data System (ADS)

    Rudaz, Benjamin; Gavillet, Lauren; Jaboyedoff, Michel

    2014-05-01

    Erosion rates in alpine context since the last glacial maximum are classically calculated from accumulated sediments in glacial overdeepenings. Such erosion rates omit stored sediments in lateral valleys and secondary glacial troughs that have yet to get transported to the final sink. Their potential availability to the dominant mass wasting processes, such as landslides and debris-flows, is also important to assess, since sediment production and availability is a major driver of those hazardous phenomenon. In this study, a methodology to characterize sediment stocks and estimate their volume is applied to several watersheds, ranging from single torrential systems up to whole lateral valleys, and finally the complete source-to-sink system of the alpine Rhône river. First, areas occupied by colluvium, Holocene processes deposits and slope instabilities are mapped, using geological maps and HR-DEM hillshade. Each area is identified by its dominant formation process, and its situation in regard to glacially shaped valley geometry. For instance, glacial troughs are treated differently from valley walls and glacial cirques. The volume of sediments is given by subtracting a bedrock surface estimated with the SLBL methodology, with rock outcrops as fixed points, from the current topography. Where available, coring and geophysical data are used to constrain the geometry of the bedrock surface. Secondly, erodible relief is identified by considering the upper reaches of hydrologic networks as base levels. The volumes are constrained at the base with a slope angle derived from rock mechanics literature, thus changing with lithology, to emulate future potential slope movements towards the river network. The estimated stocks are then analyzed by process, age, and situation in the sediment cascade. The erodible relief allows localisation of future mass wasting potential, including the remobilization of existing stocks and future input from the still intact rock mass. The

  6. Dip-slope and Dip-slope Failures in Taiwan - a Review

    NASA Astrophysics Data System (ADS)

    Lee, C.

    2011-12-01

    Taiwan is famous for dip-slope and dip-slope slides. Dip-slopes exist at many places in the fold-and-thrust belt of Taiwan. Under active cutting of stream channels and man-made excavations, a dip-slope may become unstable and susceptible for mass sliding. Daylight of a bedding parallel clay seam is the most dangerous type for dip-slope sliding. Buckling or shear-off features may also happen at toe of a long dip-slope. Besides, a dip-slope is also dangerous for shallow debris slides, if the slope angle is between 25 to 45 degrees and the debris (colluvium or slope wash) is thick (>1m). These unstable slopes may slide during a triggering event, earthquake or typhoon storm; or even slide without a triggering event, like the 2010 Tapu case. Initial buckling feature had been found in the dip-slope of the Feitsui arch dam abutment after detailed explorations. Shear-off feature have also been found in dip-slope located in right bank of the Nahua reservoir after field investigation and drilling. The Chiufengerhshan slide may also be shear-off type. On the other hand, the Tapu, the Tsaoling slides and others are of direct slide type. The Neihoo Bishan slide is a shallow debris slide on dip-slope. All these cases demonstrate the four different types of dip-slope slide. The hazard of a dip-slope should be investigated to cover these possible types of failure. The existence of bedding parallel clay seams is critical for the stability of a dip-slope, either for direct slide or buckling or shear-off type of failure, and is a hot point during investigation. Because, the stability of a dip-slope is changing with time, therefore, detailed explorations to including weathering and erosion rates are also very necessary to ensure the long-term stability of a dip-slope.

  7. Widespread Expansion of Boreal Shrublands in the Siberian Low Arctic Is Linked to Cryogenic Disturbance and Geomorphology

    NASA Astrophysics Data System (ADS)

    Frost, G. V.; Epstein, H. E.; Walker, D. A.

    2012-12-01

    Declassified imagery from the KH-4B "Corona" and KH-7 "Gambit" Cold War satellite surveillance systems (1963-1972) are a unique, high-resolution dataset that establishes a baseline for landcover-change studies in the Russian Arctic spanning 6 decades. We co-registered Corona/Gambit and modern high-resolution imagery for seven ~65 km2 Low Arctic sites in northwest Siberia and Chukotka and quantified changes in the extent of tall shrublands dominated by Siberian alder (Alnus fruticosa) using a point-intercept sampling approach. We made ground observations at two sites to identify important geomorphic processes and physiographic units associated with shrub expansion. Alder shrubland cover increased at all sites; relative to the 1960s extent, shrubland extent increased by 5-31% at the northwest Siberian sites and by 9% at both Chukotkan sites,. In northwest Siberia, alder expansion was closely linked to cryogenic disturbances related to patterned-ground and active-layer detachments. At the Chukotkan sites, most alder expansion occurred on hillslope colluvium and floodplains; we also observed modest increases in Siberian dwarf pine (Pinus pumila). The close correspondence between expanding shrub patches and disturbance processes indicates that sparsely-vegetated, mineral-rich seedbeds strongly facilitate alder recruitment, and that the spatio-temporal attributes of disturbance mechanisms are a key determinant of landscape susceptibility to shrub expansion. Shrub expansion, in turn, initiates a cascade of effects on permafrost thermal regime and disturbance, promoting the accumulation of biomass and potentially buffering permafrost from climate warming.; Recently-established alder shrubs growing on non-sorted circles in patterned ground near Obskaya, northwest Siberia.

  8. Pedogenesis and Stability of Two Late Cenozoic Paleosols Developed on Alluvium in East-Central Pennsylvania

    NASA Astrophysics Data System (ADS)

    Cummins, K. T.; Peters, S.; Pazzaglia, F. J.

    2014-12-01

    The ridge and valley province of central Pennsylvania is named for the resistant ridges of sandstone and quartzite adjacent to more easily eroded valleys of limestone and shale. Colluvium and alluvium have accumulated against the base of the ridges, enabling pedogenic processes to develop and preserve a rich history of paleoenvironmental conditions in buried soils. Our group builds on the legacy of existing scholarship on these paleosols by deciphering the timing of the initiation of pedogenesis, and characterizing the most likely paleoenvironmental conditions of soil formation. In this work, we report on our first efforts to study two paleosols developed through alluvium deposited on the north-facing slope of South Mountain adjacent to the Cumberland and Lehigh Valleys. The first is a periglacial kame deposit near Emmaus, Pennsylvania that hosts a 4 meter thick soil, and the second deposit is a series of alluvial fan sequences near Mainsville, Pennsylvania that host a 10 meter thick soil. Common features observed in both these soils include a deeply rubified color and horizons with abundant iron and manganese oxides. In some localities, these iron oxides were abundant enough to be a source of iron ore during in the late 1800s. The relative proportion of amorphous iron oxides, as calculated from the ratio of oxalate extractable iron to dithionite extractable iron can be used to coarsely estimate an age for these soils. Ratios in the shallow modern brown-colored soils range from 0.21 to 0.35, and then evolve towards values of 0.088 to 0.143 in the rubified paleosols as the amorphous iron is converted to crystalline iron minerals. Evolution of iron crystallinity from comparable profiles reported in the literature takes between 1e5 and 1e6 years, suggesting a fairly long period of stability in these hillslopes.

  9. Gravity and magnetic data in the vicinity of Virgin Valley, southern Nevada

    USGS Publications Warehouse

    Morin, Robert L.

    2006-01-01

    This report contains 10 interpretive cross sections and an integrated text describing the geology of parts of the Colorado, White River, and Death Valley regional ground-water flow systems, Nevada, Utah, and Arizona. The primary purpose of the report is to provide geologic framework data for input into a numerical ground-water model. Therefore, the stratigraphic and structural summaries are written in a hydrogeologic context. The oldest rocks (basement) are Early Proterozoic metamorphic and intrusive crystalline rocks that are considered confining units because of their low permeability. Late Proterozoic to Lower Cambrian clastic units overlie the crystalline rocks and are also considered confining units within the regional flow systems. Above the clastic units are Middle Cambrian to Lower Permian carbonate rocks that are the primary aquifers in the flow systems. The Middle Cambrian to Lower Permian carbonate rocks are overlain by a sequence of mainly clastic rocks of late Paleozoic to Mesozoic age that are mostly considered confining units, but they may be permeable where faulted. Tertiary volcanic and plutonic rocks are exposed in the northern and southern parts of the study area. In the Clover and Delamar Mountains, these rocks are highly deformed by north- and northwest-striking normal and strike-slip faults that are probably important conduits in transmitting ground water from the basins in the northern Colorado and White River flow systems to basins in the southern part of the flow systems. The youngest rocks in the region are Tertiary to Quaternary basin-fill deposits. These rocks consist of middle to late Tertiary sediments consisting of limestone, conglomerate, sandstone, tuff, and gypsum, and younger Quaternary surficial units consisting of alluvium, colluvium, playa deposits, and eolian deposits. Basin-fill deposits are both aquifers and aquitards.

  10. Geomorphological, pedological and dendrochronological signatures of a relict landslide terrain, Mt Garbatka (Kamienne Mts), SW Poland

    NASA Astrophysics Data System (ADS)

    Migoń, Piotr; Kacprzak, Andrzej; Malik, Ireneusz; Kasprzak, Marek; Owczarek, Piotr; Wistuba, Małgorzata; Pánek, Tomaš

    2014-08-01

    In the Kamienne Mountains the largest concentration of apparently relict landslides in the Sudetes range occurs. On the northern slopes of Mt Garbatka mass movements re-shaped two adjacent slope hollows and a wide depositional area is located down the valley. The main landslide body is nearly 1 km long and 200-300 m wide. Its flattened surface morphology and the occurrence of large dispersed allochtonous boulders in the distal part suggests a flow-like movement, initiated by shallow translational slides in the upper slopes. The thickness of colluvium, determined by an ERT survey, may reach 10 m. Geomorphic signatures of mass movement are subdued, suggesting that considerable time has elapsed since the origin of the landslide and that large-scale mass movements are likely pre-Holocene in age. This is consistent with the results of an extensive soil survey within the landslide body and on the surrounding slopes. Similarity of soil properties and well-developed horizonation of profiles both within the landslide and outside it shows that no major disturbance has taken place during the soil formation period. Dendrogeomorphological research, in turn, yielded evidence of numerous growth disturbances recorded in tree rings of Norway spruce growing on the landslide body. These signals are interpreted that the slope surface is not entirely stable under current environmental conditions. Flow or creep of landslide material is not very likely, given the characteristics of cover materials, and it is hypothesized that dendrochronological signals develop in response to ground deformation through piping and throughflow. Landslide hazard in the valley below Mt Garbatka appears low at present but to claim complete stability would be premature.

  11. Trends of grain sizes on gravel bars in the Rio Chagres, Panama

    NASA Astrophysics Data System (ADS)

    Rengers, Francis; Wohl, Ellen

    2007-01-01

    We examined the trends of grain sizes along the upper 414 km 2 of the mountainous Rio Chagres drainage basin in Panama. Gravel bars were sampled along 40 km of the Rio Chagres and five major tributary streams using a transect pebble count of median diameter, lithology, and clast rounding. Although previous investigators have found that downstream fining can be obscured by inputs of colluvial sediment and other local controls in mountain drainages, we decided to examine the trends of grain sizes along a tropical mountain river where rapid weathering and high capability of transport might be capable of overriding the input effects of colluvium. Specifically, we tested the hypotheses that downstream fining would be present as a result of selective sorting, and that weak felsic particles would decrease in size preferentially to strong mafic particles because of abrasion. Statistical analyses reveal a weak downstream decrease of sediment size on gravel bars along the study reach of the Rio Chagres, with a Sternberg diminution coefficient ( α) for felsic and mafic grains of - 0.013 and - 0.017, respectively. Felsic clasts have thicker weathering rinds and become rounded downstream faster than mafic particles, but tumbling-mill tests of abrasion show no significant differences in rate of mass loss in relation to lithology, and downstream decreases in grain size are similar between lithologies. Dividing the study reach into six sub-reaches bounded by major tributary junctions, we further tested the hypothesis that downstream trends in fining might be obscured at the basin scale by sediment input from tributaries, but that trends in grain sizes might be more visible at the reach scale between tributaries. We did not find any consistent trends in grain size between tributaries. Stream width appears to assert a local control on grain size; coarse particles are associated with narrow channel reaches, whereas smaller particles are associated with wide channel reaches.

  12. A spatial database of bedding attitudes to accompany Geologic Map of Boulder-Fort Collins-Greeley Area, Colorado

    USGS Publications Warehouse

    Colton, Roger B.; Brandt, Theodore R.; Moore, David W.; Murray, Kyle E.

    2003-01-01

    This digital map shows bedding attitude data displayed over the geographic extent of rock stratigraphic units (formations) as compiled by Colton in 1976 (U.S.Geological Survey Map I-855-G) under the Front Range Urban Corridor Geology Program. Colton used his own mapping and published geologic maps having varied map unit schemes to compile one map with a uniform classification of geologic units. The resulting published color paper map was intended for planning for use of land in the Front Range Urban Corridor. In 1997-1999, under the USGS Front Range Infrastructure Resources Project, Colton's map was digitized to provide data at 1:100,000 scale to address urban growth issues(see cross-reference). In general, the west part of the map shows a variety of Precambrian igneous and metamorphic rocks, major faults and brecciated zones along an eastern strip (5-20 km wide) of the Front Range. The eastern and central part of the map (Colorado Piedmont) depicts a mantle of Quaternary unconsolidated deposits and interspersed Cretaceous or Tertiary-Cretaceous sedimentary rock outcrops. The Quaternary mantle is comprised of eolian deposits (quartz sand and silt), alluvium (gravel, sand, and silt of variable composition), colluvium, and few landslides. At the mountain front, north-trending, dipping Paleozoic and Mesozoic sandstone and shale formations (and sparse limestone) form hogbacks, intervening valleys, and in range-front folds, anticlines, and fault blocks. Localized dikes and sills of Tertiary rhyodacite and basalt intrude rocks near the range front, mostly in the Boulder area.

  13. A spatial database of bedding attitudes to accompany Geologic map of the greater Denver area, Front Range Urban Corridor, Colorado

    USGS Publications Warehouse

    Trimble, Donald E.; Machette, Michael N.; Brandt, Theodore R.; Moore, David W.; Murray, Kyle E.

    2003-01-01

    This digital map shows bedding attitude symbols display over the geographic extent of surficial deposits and rock stratigraphic units (formations) as compiled by Trimble and Machette 1973-1977 and published in 1979 (U.S. Geological Survey Map I-856-H) under the Front Range Urban Corridor Geology Program. Trimble and Machette compiled their geologic map from published geologic maps and unpublished geologic mapping having varied map unit schemes. A convenient feature of the compiled map is its uniform classification of geologic units that mostly matches those of companion maps to the north (USGS I-855-G) and to the south (USGS I-857-F). Published as a color paper map, the Trimble and Machette map was intended for land-use planning in the Front Range Urban Corridor. This map recently (1997-1999), was digitized under the USGS Front Range Infrastructure Resources Project (see cross-reference). In general, the mountainous areas in the west part of the map exhibit various igneous and metamorphic bedrock units of Precambrian age, major faults, and fault brecciation zones at the east margin (5-20 km wide) of the Front Range. The eastern and central parts of the map (Colorado Piedmont) depict a mantle of unconsolidated deposits of Quaternary age and interspersed outcroppings of Cretaceous or Tertiary-Cretaceous sedimentary bedrock. The Quaternary mantle is comprised of eolian deposits (quartz sand and silt), alluvium (gravel, sand, and silt of variable composition), colluvium, and few landslides. At the mountain front, north-trending, dipping Paleozoic and Mesozoic sandstone, shale, and limestone bedrock formations form hogbacks and intervening valleys.

  14. Multi-stage evolution process of large scale landslides at the Patanpunas stream, Taiwan

    NASA Astrophysics Data System (ADS)

    Lin, Ming-Lang; Lee, Kuo-Chen; Lo, Chia-Ming; Weng, Meng-Chia; Lee, Shun-Min

    2016-04-01

    This study used multi-temporal terrain and remote sensing images to investigate the geomorphological evolution of the Putanpunas stream caused by large-scale landslides over the last decade. We conducted an analysis of the landslides evolution process within the study area, which included a multi-temporal terrain analysis, remote sensing interpretation, surface displacement analysis, and mechanism investigation. By integrating the results from these analyses, we provided explanations for the topographic and geomorphologic action processes of the deep-seated landslides as well as the development of the potential collapsing mechanisms within the study area. Then, discrete element method was used to simulate the process of landslide movement and deposition. The results show that the evolution process of large-scale landslides in the Putanpunas stream can be divided into four stages, namely downcutting of the stream gully and decompression of the river gully in the early stage, creep and deformation of the rock slope, sliding surface development of the deformed bands in the rock strata, and movement of the sliding mass. The results of terrain analysis and interpretation show topographical changes in the alluvial fan downstream and the deposits in the midstream and downstream segments of the Putanpunas Stream between 2005 and 2009. In 2009, torrential rainfall induced large-scale landslides that greatly altered the terrain of the Putanpunas Stream and the alluvial fan. There still exists 7.2 × 107 m3 of unstable colluvium accumulated at the slope surface and stream gully within the upstream and midstream areas. In 2012, further large-scale landslides turned the colluvial layer into debris flows that cut across the Ryukyu Terraces downstream to the downstream segment of the Laonong Stream to the southwest. This greatly changed later debris flows and alluvial fan deposits. Key Words: large-scale landslides, multi-temporal terrain, remote sensing, discrete element method

  15. Geophysical exploration in the Lautertal at the Combat Maneuver Training Center, Hohenfels, Germany

    SciTech Connect

    Heigold, P.C.; Thompson, M.D.; Borden, H.M.

    1994-10-01

    Geophysical exploration was conducted in the Lautertal at the Combat Maneuver Training Center, Hohenfels, Germany, to determine the shallow geological framework of a typical dry valley in this karstic environment. The complementary methods of electromagnetic surveying, vertical electrical soundings, and seismic refraction profiling were successful in determining the depth and configuration of the bedrock surface, the character of the unconsolidated deposits resting on the bedrock surface, and the nature of the bedrock surface. Channels and other depressions in the bedrock surface are aligned with structurally induced fractures in the bedrock. The unconsolidated deposits consist of coarse alluvium and colluvium, which are confined to these channels and other depressions, and fine-grained loam and loess, which cover most of the Lautertal. Wide ranges in the electrical and elastic parameters of the bedrock surface are indicative of carbonate rock that is highly fractured and dissolved at some locations and competent at others. Most local groundwater recharge occurs in the uplands where the Middle Kimmeridge (Delta) Member of the Maim Formation (Jurassic) is widely exposed. These carbonate rocks are known to be susceptible to dissolution along the fractures and joints; thus, they offer meteoric waters ready access to the main shallow aquifers lower in the Malm Formation. These same rocks also form the bedrock surface below many of the dry valleys, but in the Lautertal, the infiltration of meteoric waters into the subsurface is generally impeded by the surficial layer of fine-grained loam and loess, which have low hydraulic conductivity. Further, the rocks of the Middle Kimmeridge Member appear to be closely associated with the localized occurrence of turbidity in such perennial streams as the Lauterach.

  16. Erosion processes, fluvial sediment transport, and reservoir sedimentation in a part of the Newell and Zayante Creek basins, Santa Cruz County, California

    USGS Publications Warehouse

    Brown, W. M., III

    1973-01-01

    The drainage basins upstream from Loch Lomond, a water-supply reservoir on Newell Creek, and a proposed reservoir site on Zayante Creek were investigated for their characteristics with respect to the erosion, transportation, and deposition of sediment. The study area is underlain predominantly by sandstone, siltstone, and shale of Tertiary age that decompose readily into moderately deep soils, friable colluvium, and easily transported sediment particles. The Rices Mudstone and Twobar, Shale Members of the San Lorenzo Formation of Brabb (1964) underlie steep dip slopes in the study area, and probably are the most highly erodible of the several geologic units present there. However, nearly all of the geologic units have shown a propensity for accelerated erosion accompanying the disturbance of the land surface by the roadbuilding practices that predominate over other types of sediment-producing land-use activities in the study area. Sediment transport in the study area was estimated from (1) a reservoir survey of Loch Lomond in 1971 that was compared with a preconstruction survey of 1960, and (2) sampling of sediment transported in suspension by Zayante Creek during the 1970 and 1971 water years. At least 46 acre-feet of sediment accumulated in Loch Lomond in a 10-year period, and an unmeasured quantity of very fine sediment in the form of a thin layer over much of the reservoir bottom was observed. The measured quantity of deposited sediment in a 10-year period represented a sediment yield of about 1,100 tons annually per square mile of drainage basin upstream from the reservoir arms where the major deposition occurred. This sediment occupied less than i percent of the original capacity of Loch Lomond, but the volume of measured sediment deposition is probably conservative in view of the unmeasured deposits observed and a reservoir trap efficiency of about 95 percent. Sediment sampling on Zayante Creek indicated suspended-sediment yields of about 4,570 and 570 tons

  17. Geologic Map of the Shenandoah National Park Region, Virginia

    USGS Publications Warehouse

    Southworth, Scott; Aleinikoff, John N.; Bailey, Christopher M.; Burton, William C.; Crider, E.A.; Hackley, Paul C.; Smoot, Joseph P.; Tollo, Richard P.

    2009-01-01

    ridges from 800 to 400 meters in altitude. The Page Valley is underlain by Cambrian and Ordovician carbonate rocks. Siliciclastic rocks are mostly west of the South Fork of the Shenandoah River and underlie Massanutten Mountain. Surficial deposits in the highlands include colluvium and debris fans. The lowlands have broad alluvial fans, alluvial plains, and fluvial terraces. Ridges underlain by siliciclastic rocks have abundant boulder fields. Numerous sinkholes and caves are due to the dissolution of the carbonate bedrock.

  18. Sediment Budgets the 'Old Fashioned' way for two Subbasins of the Rio Puerco, Central New Mexico

    NASA Astrophysics Data System (ADS)

    Pavich, M. J.; Gellis, A. C.; Clark, I.; Ellwein, A. L.; Aby, S.

    2005-12-01

    A sediment budget was constructed for two subbasins of the Rio Puerco watershed, Volcano Hill Wash (9.30 km2) and Arroyo Chavez (2.28 km2), using data collected from 1995 through 1998. The subbasins were selected based on differences in land use. Arroyo Chavez was considered more degraded than Volcano Hill Wash, the latter of which received a grazing management award. The grazing density in the Arroyo Chavez watershed was higher (7.3 animals per 100 hectares) than in the Volcano Hill Wash watershed (1.0 animals per 100 hectares). A gas pipeline and numerous dirt roads are located within the Arroyo Chavez subbasin; neither are present within the Volcano Hill Wash subbasin. The 'old fashioned' sediment budget refers to the approach that was used--determining the total sediment leaving a basin and accounting for that sediment with a variety of field-based, labor intensive techniques. A sediment station with an automatic suspended-sediment sampler was installed at the mouth of each stream to quantify the amount of sediment leaving the subbasins. Upland erosion was measured using erosion pins and sediment traps. Channel erosion was measured using surveyed channel cross sections, bank pins, and scour chains. Aeolian dust deposition was measured with dust traps. Each subbasin was divided into geomorphic surfaces using aerial photographs and field descriptions of soils, slopes, and vegetation cover. In Volcano Hill Wash subbasin, five geomorphic surfaces were delineated: mesa, steep colluvial slopes, alluvium/ colluvium, eolian/alluvium, and the alluvial valley floor. In the Arroyo Chavez subbasin, seven geomorphic surfaces were delineated: mesa, steep colluvial slopes, moderate sloping hillslopes, gently sloping hillslopes, alluvial fans, well-vegetated alluvial valley floor, and a sparsely vegetated alluvial valley floor. Upland erosion and channel erosion rates were summed for each geomorphic surface using a geographical information system (GIS). Results indicate that

  19. Whole watershed quantification of net carbon fluxes by erosion and deposition within the Christina River Basin Critical Zone Observatory

    NASA Astrophysics Data System (ADS)

    Aufdenkampe, A. K.; Karwan, D. L.; Aalto, R. E.; Marquard, J.; Yoo, K.; Wenell, B.; Chen, C.

    2012-12-01

    We have proposed that the rate at which fresh, carbon-free minerals are delivered to and mix with fresh organic matter determines the rate of carbon preservation at a watershed scale (Aufdenkampe et al. 2011). Although many studies have examined the role of erosion in carbon balances, none consider that fresh carbon and fresh minerals interact. We believe that this mechanism may be a dominant sequestration process in watersheds with strong anthropogenic impacts. Our hypothesis - that the rate of mixing fresh carbon with fresh, carbon-free minerals is a primary control on watershed-scale carbon sequestration - is central to our Christina River Basin Critical Zone Observatory project (CRB-CZO, http://www.udel.edu/czo/). The Christina River Basin spans 1440 km2 from piedmont to Atlantic coastal plain physiographic provinces in the states of Pennsylvania and Delaware, and experienced intensive deforestation and land use beginning in the colonial period of the USA. Here we present a synthesis of multi-disciplinary data from the CRB-CZO on materials as they are transported from sapprolite to topsoils to colluvium to suspended solids to floodplains, wetlands and eventually to the Delaware Bay estuary. At the heart of our analysis is a spatially-integrated, flux-weighted comparison of the organic carbon to mineral surface area ratio (OC/SA) of erosion source materials versus transported and deposited materials. Because source end-members - such as forest topsoils, farmed topsoils, gullied subsoils and stream banks - represent a wide distribution of initial, pre-erosion OC/SA, we quantify source contributions using geochemical sediment fingerprinting approaches (Walling 2005). Analytes used for sediment fingerprinting include: total mineral elemental composition (including rare earth elements), fallout radioisotope activity for common erosion tracers (beryllium-7, beryllium-10, lead-210, cesium-137), particle size distribution and mineral specific surface area, in addition

  20. Whole Watershed Quantification of Net Carbon Fluxes by Erosion and Deposition within the Christina River Basin Critical Zone Observatory

    NASA Astrophysics Data System (ADS)

    Aufdenkampe, A. K.; Karwan, D. L.; Aalto, R. E.; Marquard, J.; Yoo, K.; Wenell, B.; Chen, C.

    2013-12-01

    We have proposed that the rate at which fresh, carbon-free minerals are delivered to and mix with fresh organic matter determines the rate of carbon preservation at a watershed scale (Aufdenkampe et al. 2011). Although many studies have examined the role of erosion in carbon balances, none consider that fresh carbon and fresh minerals interact. We believe that this mechanism may be a dominant sequestration process in watersheds with strong anthropogenic impacts. Our hypothesis - that the rate of mixing fresh carbon with fresh, carbon-free minerals is a primary control on watershed-scale carbon sequestration - is central to our Christina River Basin Critical Zone Observatory project (CRB-CZO, http://www.udel.edu/czo/). The Christina River Basin spans 1440 km2 from piedmont to Atlantic coastal plain physiographic provinces in the states of Pennsylvania and Delaware, and experienced intensive deforestation and land use beginning in the colonial period of the USA. Here we present a synthesis of multi-disciplinary data from the CRB-CZO on materials as they are transported from sapprolite to topsoils to colluvium to suspended solids to floodplains, wetlands and eventually to the Delaware Bay estuary. At the heart of our analysis is a spatially-integrated, flux-weighted comparison of the organic carbon to mineral surface area ratio (OC/SA) of erosion source materials versus transported and deposited materials. Because source end-members - such as forest topsoils, farmed topsoils, gullied subsoils and stream banks - represent a wide distribution of initial, pre-erosion OC/SA, we quantify source contributions using geochemical sediment fingerprinting approaches (Walling 2005). Analytes used for sediment fingerprinting include: total mineral elemental composition (including rare earth elements), fallout radioisotope activity for common erosion tracers (beryllium-7, beryllium-10, lead-210, cesium-137), particle size distribution and mineral specific surface area, in addition

  1. Gully Development in Tributaries to Caspar Creek, Northern California Coast Range

    NASA Astrophysics Data System (ADS)

    Dewey, N. J.; Lisle, T. E.; Reid, L. M.

    2002-12-01

    1970's. Though some gullies cut into colluvium and fill from roads and skid trails, some cut into saprolite and down to bedrock.

  2. Sudden Morphometric Changes Induced by Diffuse Mass Wasting Processes

    NASA Astrophysics Data System (ADS)

    Moretti, S.; Casagli, N.; Catani, F.; Battistini, A.; Raspini, F.

    2010-12-01

    On October 1st, 2009, an exceptionally intense and prolonged rainfall event, preceded by two similar storms on 16 and 23-24 September, triggered a large number of shallow landslides in the province of Messina (Sicily), causing human losses and extensive damages. In a follow-up study a detailed geomorphological survey was carried out as well as a LIDAR digital elevation model. In this paper we present an attempt at using such data to model and understand the mass wasting processes and their consequences in terms of slope morphometry changes in one of the affected watersheds, the Briga creek. Here, the event was characterized by a sudden triggering of many similar shallow soil failures, generating in turn a sediment flow that moved along the main directions of drainage with high velocities and modalities ranging from debris flow to mud flow. The main damages were registered at the channel junctions and at the watershed outlet, where the major mass concentration was reached. Starting from the landslide inventory mapping carried out a few days after the event, we performed an analisys of mobilized volumes, using a method that numerically compares the pre-event and the post-event DEMs. Afterwards, we generated a very accurate, morphology-based reconstruction of flow directions for the entire watershed, in order to understand which were the main avenues of mass flow over the area and where most of the mobilized sediment was deposited. Finally, combining the extensive data connected with landslide scars with a statistical model for the prediction of regolith thickness, we propose a distributed model of colluvium depth for the Briga watershed. The use of this dataset together with present-day topography as derived from LIDAR data allows for the definition of topographic and bedrock gradient maps which, in turn, constitute an important step towards the definition of the actual boundary conditions for slope stability analysis. We believe that this will be a fundamental

  3. Structural analysis of the Cordillera Blanca detachment: Geometry, kinematics and fault rocks

    NASA Astrophysics Data System (ADS)

    Shaw, C. A.; Jessup, M. J.; Hughes, C. A.; Newell, D. L.

    2015-12-01

    The Cordillera Banca Detachment (CBD) in the north-central Peruvian Andes is recognized as a rare example of active extension parallel to the direction of shortening within a convergent orogenic setting. Despite longstanding interest in the geodynamic significance of the CBD relatively little work has been done to characterize the basic geometry, kinematics and evolution of the detachment or the petrology and distribution of brittle and ductile tectonites within the fault zone. This contribution presents preliminary results of a basic structural analysis of the CBD based on field observations, laboratory results, and GIS analysis. Basic structural observations of fault geometry and kinematics are needed to constrain the regional geodynamic role of the CBD. The NNW topographic trace of the CBD is defined by faceted ridges up to 2000 m in height. The lower slopes of the facets are locally cut by steep fault scarps that offset quaternary glacial moraines, debris fans and colluvium. The shear zone comprises both brittle and ductile tectonites including mylonite series rocks, pseudotachylyte, and breccia - often highly silicified. Highly polished mirrored surfaces are observed locally. Deformation mechanisms show a consistent progression from plastic in structurally lower positions to brittle in structurally higher positions. Evidence for overprinting deformation mechanisms is preserved in many samples. The shear zone ranges up to about 200 m thick. The average orientation of mylonitic foliation and fault slip surfaces (strike/dip = 140/30) and lineations/slickenlines (plunge-trend = 35-235) is quite consistent along the ~200 km detachment, but some systematic variation along strike may be related to concave fault segments or corrugations. Slip indicators are nearly down-dip with a minor left-lateral or right-lateral component in some locations. Offsets in marker horizons constrain total offset between about 4500 m near the central section of the fault to near zero

  4. Cold Climate Related Structural Sinks Accommodate Unusual Soil Constituents, Pinelands National Reserve, New Jersey, USA

    NASA Astrophysics Data System (ADS)

    Demitroff, M.; Lecompte, M. A.; Rock, B. N.

    2009-12-01

    Firestone and others proposed an extraterrestrial (ET) impact upon the Laurentide Ice Sheet 12,900 years ago led to abrupt climate change and left behind a distinct suite of microscopic soil markers. If so, then soil memory of such an extreme event should be apparent across a wide swath of ice-marginal North America. New Jersey’s Pine Barrens has a remarkably well-preserved record of Late Pleistocene soil structures that provide snapshots of rigorous climatic episodes, the youngest of which are potential reservoirs for ET markers. Cryogenic macrostructures are fissures related to episodic temperature and moisture extremes providing excellent chronostratigraphic control - unlike soil horizons that are often affected by denudation and pedogenic modification. Three distinct ground structures were sampled for evidence of infill-related ET markers: 1) two ground (soil) wedges (early Holocene?); 2) a younger sand-wedge cast (late-Wisconsinan?); and 3) an older sand-wedge cast (early-Wisconsinan?). Attendant host sediment and capping colluvium coversand samples were also collected for evidence of ET markers to detect potential source sinks. Our pedocomplex contained elements ranging from Miocene Cohansey Formation basement sands to early-Holocene fluvioeolian coversands. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive x-ray analysis (EDX) are being used to characterize soil constituents of interest. Carbon and luminescence dating are underway to provide geomorphic events timing associated with specific soil constituent trap formation. Fly ash collected from a coal-fired electrical plant 13-km distant was also examined. Several soil constituents atypical to the local petrology as currently understood were found. Infill from two ground (soil) wedges contained ~100,000 to ~500,000 magnetic spherules/kg, 25 to 50 translucent amber-colored spherules/kg, 250 to 500 carbon spherules/kg, charcoal, and pieces of glass-like carbon

  5. Multiple-Event Deformation on the West Tahoe Fault from Lidar and Trenching: Reconciling On and Offshore Paleoseismology

    NASA Astrophysics Data System (ADS)

    Seitz, G. G.; Mareschal, M.

    2014-12-01

    The West Tahoe Fault has a mapped length of 45 km, and its vertical slip rate is estimated at 0.6-1.0 mm/yr (Dingler et al., 2009). It is the range bounding, east dipping normal fault along the west margin of the basin, and the highest slip rate section is located along the western base of Lake Tahoe at a water depth of 400-500 m. In the lake, the fault has clearly defined scarps that displace submarine fans, lake-bottom sediments, and the ~50 ka age (Kent et al., 2005; Smith et al, 2013) McKinney Bay slide. Onshore the fault displaces tree-covered glacial and fluvial landforms. In October 2013 we conducted the first trenching study of the geomorphically well-defined West Tahoe Fault. Using Lidar, we selected a site with fine-grained surface sediments, as opposed to the boulder-rich moraine sediments that cover most of the onshore fault. The site is located ~3.5 km from the southern end of the mapped fault, adjacent to Osgood Swamp. In the excavation, we observed an east-dipping, normal fault juxtaposing glacial deposits against datable peat-bearing and charcoal-rich younger alluvial sediments. The glacial deposits and peat layers can be matched across the fault. Clear evidence for two earthquakes was based on scarp-derived colluvium, fissures, faulted scarp-related alluvium, liquefaction, and upward terminations of faults. Retrodeformation of the sediments results in nearly equal vertical displacements of about 1.7 m/event. Results from multiple C-14 analysis place the most recent event at ~5.3 ka and the penultimate event at ~7.4 ka. The fault scarp at the trench is 3.5 m high; at the bottom of the lake at a depth of 400 m a postulated same-age fan as the trench site post-glacial deposits, has a vertical scarp of 10-12 m. As expected the slip rate decreases towards the southern end of the fault. However, if the same number of events resulted in the underwater scarp then events must average about 5-6 m vertical displacement per event. This has serious implications

  6. A 3000-year record of ground-rupturing earthquakes along the central North Anatolian fault near Lake Ladik, Turkey

    USGS Publications Warehouse

    Fraser, J.; Pigati, J.S.; Hubert-Ferrari, A.; Vanneste, K.; Avsar, U.; Altinok, S.

    2009-01-01

    The North Anatolian fault (NAF) is a ???1500 km long, arcuate, dextral strike-slip fault zone in northern Turkey that extends from the Karliova triple junction to the Aegean Sea. East of Bolu, the fault zone exhibits evidence of a sequence of large (Mw >7) earthquakes that occurred during the twentieth century that displayed a migrating earthquake sequence from east to west. Prolonged human occupation in this region provides an extensive, but not exhaustive, historical record of large earthquakes prior to the twentieth century that covers much of the last 2000 yr. In this study, we extend our knowledge of rupture events in the region by evaluating the stratigraphy and chronology of sediments exposed in a paleoseismic trench across a splay of the NAF at Destek, ???6:5 km east of Lake Ladik (40.868?? N, 36.121?? E). The trenched fault strand forms an uphill-facing scarp and associated sediment trap below a small catchment area. The trench exposed a narrow fault zone that has juxtaposed a sequence of weakly defined paleosols interbedded with colluvium against highly fractured bedrock. We mapped magnetic susceptibility variations on the trench walls and found evidence for multiple visually unrecognized colluvial wedges. This technique was also used to constrain a predominantly dip-slip style of displacement on this fault splay. Sediments exposed in the trench were dated using both charcoal and terrestrial gastropod shells to constrain the timing of the earthquake events. While the gastropod shells consistently yielded 14 C ages that were too old (by ???900 yr), we obtained highly reliable 14 C ages from the charcoal by dating multiple components of the sample material. Our radiocarbon chronology constrains the timing of seven large earthquakes over the past 3000 yr prior to the 1943 Tosya earthquake, including event ages of (2?? error): A.D. 1437-1788, A.D. 1034-1321, A.D. 549-719, A.D. 17-585 (1-3 events), 35 B.C.-A.D. 28, 700-392 B.C., 912-596 B.C. Our results

  7. A probable martian analogue in muttom in southern india

    NASA Astrophysics Data System (ADS)

    Wankhede, Tushar; Rajesh, V. J.; Charri, Abhishek

    2012-07-01

    beach and dune environment, or as similar to colluvium (formed by mass wasting and fluvial processes). Comparative studies between the red sand beds formations on Martian surface and southern Tamil Nadu can provide valuable insights on the origin, weathering pattern, tectonics and depositional environment of red sand beds in Mars.

  8. Drainage Area-Dependent Knickpoint Generation Mechanisms, Smith River, northern California

    NASA Astrophysics Data System (ADS)

    Caldwell, D. J.; Kelsey, H. M.

    2011-12-01

    , that knickpoints in upper drainage area positions (less than about 250 km2) are a response to hillslope instabilities that catastrophically deposit colluvium in channels creating a stationary knickpoint on geologic timescales.

  9. Fault-scarp morphology and amount of surface offset on late-Quaternary surficial deposits, eastern escarpment of the central Sierra Nevada, CA

    SciTech Connect

    Berry, M.E. . Dept. of Geology)

    1992-01-01

    Faults scarps, formed on glacial deposits and an alluvial fan near the east-central Sierra Nevada mountain front by late-Quaternary movement on the Hilton Creek (HCF), Wheeler Crest (WCFZ) and Coyote Warp (CWFZ) fault zones, were profiled to determine the amount and to estimate the recency of fault offset. Areas studied include McGee (N--near Lake Crowley), Pine, Mount Tom, Basin Mountain, McGee (S--near Bishop), and Bishop Creek drainages. The profile data indicate that movement of the range-front faults (HCF and WCFZ), which is characterized by normal slip, has offset Tioga-age deposits 6.5-26 m. Offset of Tahoe-age moraines cannot be measured directly because the landforms are buried at the mountain-front by moraines from later glaciations. However, the amount of offset is estimated at 52--130 m, based on crest-height differences between Tahoe and Tioga moraines. The rates of slip are highest on the northern end of the HCF, at McGee (N) Creek; the higher slip rates in this latter area may be related to its close proximity to the Long Valley caldera, where tectonic processes are complex and considered closely related to ongoing magmatic activity. The preservation of bevels on the fault scarps in both HCF and WCFZ, combined with the amounts of surface offset on the late-Pleistocene moraines, and AMS C-14 dates for charcoal found in fault-scarp colluvium, indicate that large ground-rupturing events have occurred on these faults during the Holocene. In contrast to the mountain-front faults, faults in the CWFZ, on a broad warp that separates the WCFZ from range-front faults to the south of Bishop, do not cross Tioga moraines, implying that surface rupture has not occurred in the CWFZ for at least 15,000-25,000 years. The degraded morphology of the fault scarps on adjacent Tahoe and pre-Tahoe moraines, which have been offset between 10.5 and 30 m, attests to the lack of late-Pleistocene and Holocene fault activity in this latter area.

  10. Using Logistic Regression and Random Forests multivariate statistical methods for landslide spatial probability assessment in North-Est Sicily, Italy

    NASA Astrophysics Data System (ADS)

    Trigila, Alessandro; Iadanza, Carla; Esposito, Carlo; Scarascia-Mugnozza, Gabriele

    2015-04-01

    North-East Sicily is strongly exposed to shallow landslide events. On October, 1st 2009 a severe rainstorm (225.5 mm of cumulative rainfall in 9 hours) caused flash floods and more than 1000 landslides, which struck several small villages as Giampilieri, Altolia, Molino, Pezzolo, Scaletta Zanclea, Itala, with 31 fatalities, 6 missing persons and damage to buildings and transportation infrastructures. Landslides, mainly consisting in earth and debris translational slides evolving into debris flows, triggered on steep slopes involving colluvium and regolith materials which cover the underlying metamorphic bedrock of Peloritani Mountains. In this area catchments are small (about 10 square kilometres), elongated, with steep slopes, low order streams, short time of concentration, and discharge directly into the sea. In the past, landslides occurred at Altolia in 1613 and 2000, at Molino in 1750, 1805 and 2000, at Giampilieri in 1791, 1918, 1929, 1932, 2000 and on October 25, 2007. The aim of this work is to define susceptibility models for shallow landslides using multivariate statistical analyses in the Giampilieri area (25 square kilometres). A detailed landslide inventory map has been produced, as the first step, through field surveys coupled with the observation of high resolution aerial colour orthophoto taken immediately after the event. 1,490 initiation zones have been identified; most of them have planimetric dimensions ranging between tens to few hundreds of square metres. The spatial hazard assessment has been focused on the detachment areas. Susceptibility models, performed in a GIS environment, took into account several parameters. The morphometric and hydrologic parameters has been derived from a detailed LiDAR 1×1 m. Square grid cells of 4×4 m were adopted as mapping units, on the basis of the area-frequency distribution of the detachment zones, and the optimal representation of the local morphometric conditions (e.g. slope angle, plan curvature). A

  11. Preferential flow paths in paraglacial catchments: first order controls on the long-term stability of 'biodiversity hotspots' in a changing climate

    NASA Astrophysics Data System (ADS)

    Grocott, Michael; Kettridge, Nick; Bradley, Chris; Milner, Alexander

    2016-04-01

    PFPs are a fundamental first order control upon the occurrence of 'biodiversity hotspots' within paraglacial floodplains, and highlights their role as an important conduit for hillslope-floodplain connectivity. Given the expected changes in the hydrological dynamics of paraglacial catchments this research raises questions about the long-term stability of GW-fed streams, and whether the increasing relative importance of groundwater sources (e.g. from colluvium) can sustain flow of GW-fed streams. In addition glacial retreat and associated long-term declines in sediment yields could have negative implications for the development and renewal of PFPs across paraglacial floodplains, which would be detrimental to the persistence of 'biodiversity hotspots'.

  12. Piezometric response in shallow bedrock at CB1: Implications for runoff generation and landsliding

    NASA Astrophysics Data System (ADS)

    Montgomery, David R.; Dietrich, William E.; Heffner, John T.

    2002-12-01

    Experimental observations comparing two steep unchanneled valleys in the Oregon Coast Range, one intensively instrumented (CB1) and the other monitored for runoff but which produced a debris flow (CB2), shed light on the mechanisms of shallow flow in bedrock, its interaction with the vadose zone, and its role in generating landslides. Previous work at CB1 led to the proposal that during storms pulses of rainfall transmit pressure waves through the vadose zone and down to the saturated zone to create rapid pore pressure response and runoff [, 1998]. Here, we document the associated rapid pore pressure response in the shallow fractured bedrock that underlies these colluvium-mantled sites and examine its influence on the generation of storm flow, seasonal variations in base flow, and slope stability in the overlying colluvial soil. Our observations document rapid piezometric response in the shallow bedrock and a substantial contribution of shallow fracture flow to both storm flow and seasonal variations in base flow. Saturated hydraulic conductivity in the colluvial soil decreases with depth below the ground surface, but the conductivity of the near-surface bedrock displays no depth dependence and varies over five orders of magnitude. Analysis of runoff intensity and duration in a series of storms that did and did not trigger debris flows in the surrounding area shows that the landslide inducing storms had the greatest intensity over durations similar to those predicted by a simple model of piezometric response. During a monitored storm in February 1992, the channel head at the base of the neighboring CB2 site failed as a debris flow. Automated piezometric measurements document that the CB2 debris flow initiated several hours after peak discharge, coincident with localized development of upward spikes of pressure head from near-surface bedrock into the overlying colluvial soil in CB1. Artesian flow observed exfiltrating from bedrock fractures on the failure surfaces

  13. Deriving earthquake history of the Knidos Fault Zone, SW Turkey, using cosmogenic 36Cl surface exposure dating of the fault scarp.

    NASA Astrophysics Data System (ADS)

    Yildirim, Cengiz; Ersen Aksoy, Murat; Akif Sarikaya, Mehmet; Tuysuz, Okan; Genc, S. Can; Ertekin Doksanalti, Mustafa; Sahin, Sefa; Benedetti, Lucilla; Tesson, Jim; Aster Team

    2016-04-01

    Formation of bedrock fault scarps in extensional provinces is a result of large and successive earthquakes that ruptured the surface several times. Extraction of seismic history of such faults is critical to understand the recurrence intervals and the magnitude of paleo-earthquakes and to better constrain the regional seismic hazard. Knidos on the Datca Peninsula (SW Turkey) is one of the largest cities of the antique times and sits on a terraced hill slope formed by en-echelon W-SW oriented normal faults. The Datça Peninsula constitutes the southern boundary of the Gulf of Gökova, one of the largest grabens developed on the southernmost part of the Western Anatolian Extensional Province. Our investigation relies on cosmogenic 36Cl surface exposure dating of limestone faults scarps. This method is a powerful tool to reconstruct the seismic history of normal faults (e.g. Schlagenhauf et al 2010, Benedetti et al. 2013). We focus on one of the most prominent fault scarp (hereinafter Mezarlık Fault) of the Knidos fault zone cutting through the antique Knidos city. We collected 128 pieces of tablet size (10x20cm) 3-cm thick samples along the fault dip and opened 4 conventional paleoseismic trenches at the base of the fault scarp. Our 36Cl concentration profile indicates that 3 to 4 seismic events ruptured the Mezarlık Fault since Last Glacial Maximum (LGM). The results from the paleoseismic trenching are also compatible with 36Cl results, indicating 3 or 4 seismic events that disturbed the colluvium deposited at the base of the scarp. Here we will present implications for the seismic history and the derived slip-rate of the Mezarlık Fault based on those results. This project is supported by The Scientific and Technological Research Council of Turkey (TUBITAK, Grant number: 113Y436) and it was conducted with the Decision of the Council of Ministers with No. 2013/5387 on the date 30.09.2013 and was done with the permission of Knidos Presidency of excavation in

  14. Laboratory Study of Quaternary Sediment Resistivity Related to Groundwater Contamination at Mae-Hia Landfill, Mueang District, Chiang Mai Province

    NASA Astrophysics Data System (ADS)

    Sichan, N.

    2007-12-01

    This study was aimed to understand the nature of the resistivity value of the sediment when it is contaminated, in order to use the information solving the obscure interpretation in the field. The pilot laboratory experiments were designed to simulate various degree of contamination and degree of saturation then observe the resulting changes in resistivity. The study was expected to get a better understanding of how various physical parameters effect the resistivity values in term of mathematic function. And also expected to apply those obtained function to a practical quantitatively interpretation. The sediment underlying the Mae-Hia Landfill consists of clay-rich material, with interfingerings of colluvium and sandy alluvium. A systematic study identified four kinds of sediment, sand, clayey sand, sandy clay, and clay. Representative sediment and leachate samples were taken from the field and returned to the laboratory. Both the physical and chemical properties of the sediments and leachate were analyzed to delineate the necessary parameters that could be used in Archie's equation. Sediment samples were mixed with various concentration of leachate solutions. Then the resistivity values were measured at various controlled steps in the saturation degree in a well- calibrated six-electrode model resistivity box. The measured resistivity values for sand, clayey sand, sandy clay when fully and partly saturated were collected, then plotted and fitted to Archie's equation, to obtain a mathematical relationship between bulk resistivity, porosity, saturation degree and resistivity of pore fluid. The results fit well to Archie's equation, and it was possible to determine all the unknown parameters representative of the sediment samples. For sand, clayey sand, sandy clay, and clay, the formation resistivity factors (F) are 2.90, 5.77, 7.85, and 7.85 with the products of cementation factor (m) and the pore geometry factors (a) (in term of -am) are 1.49, -1.63, -1.92, -2

  15. Near-Channel Sources and Sinks along a Mountainous Stream: Establishing the Controls and Time Scales of the Lateral Transfer of Sediment and Carbon

    NASA Astrophysics Data System (ADS)

    Gartner, J. D.; Renshaw, C. E.

    2015-12-01

    River channels exchange sediment, carbon, and other matter with hillslopes and floodplains. An ongoing challenge is to quantify the time and length scales of these lateral interactions, and to establish physical controls on direction of transfer. Here we investigate whether downstream changes in stream power (Ω) can predict near-channel sources or sinks of matter on decadal time scales in a case study of Mink Brook, a 50 km2 watershed in New Hampshire, USA. Building on the Exner equation, we hypothesize that reaches with downstream increases in stream power (Ω↑) exhibit near-channel deposition and accumulation of organic matter, and reaches of downstream decreases in stream power (Ω↓) exhibit near-channel erosion and stripping of organic matter. We measured 210Pbex inventory (an indicator of erosion versus deposition), organic matter inventory, grain size, and depth of alluvium/colluvium in 29 soil pits at 6 cross sections along the brook. Sites had equivalent total Ω for a given storm event. However, 3 cross sections exhibited Ω↑, and 3 exhibited Ω↓. All cross sections showed a general trend of stripping of organic matter and fine sediment particles in the channel, paired with loading of matter at the ~2-year flood elevation. From the ~2- to ~25-year flood elevation, a marked difference appeared between sites. The Ω↑ cross sections exhibited several locations of erosion and stripping of organic matter, as evidenced by low 210Pbex inventories (70 to 1,000 bq m-2), low organic matter inventories (17 to 219 kg m-2), and thin alluvial cover (average 23 cm). The low 210Pbex inventories, below the characteristic 6,000 bq m-2 of stable soil profiles in this region, suggest no areas had consistent deposition over the last century. In contrast, the Ω↓ cross sections exhibited deposition of fine particles and organic matter from the ~2- to ~25-year flood elevation, as evidenced by elevated 210Pbex inventories (up to 9,100 bq m-2), elevated organic matter

  16. Late Quaternary erosion events in lowland and mid-altitude Tasmania in relation to climate change and first human arrival

    NASA Astrophysics Data System (ADS)

    McIntosh, P. D.; Price, D. M.; Eberhard, R.; Slee, A. J.

    2009-05-01

    The establishment of a chronology of landscape-forming events in lowland and mid-altitude Tasmania, essential for assessing the relative importance of climatic and human influences on erosion, and for assessing present erosion risk, has been limited by the small number of ages obtained and limitations of dating methods. In this paper we critically assess previous Tasmanian studies, list published radiocarbon ages considered to be dependable, present new radiocarbon and thermoluminescence (TL) ages for 25 sites around Tasmania, and consider the evidence for the hypotheses that erosion processes at low and mid altitudes have been: (1) purely climatically controlled; and (2) influenced both by climatic and anthropogenic (increased fire frequency) effects. A total of 94 dependable finite ages (calibrated for radiocarbon and 'as measured' for TL and optically stimulated luminescence (OSL) determinations) are listed for deposits comprising dunes, colluvium, alluvium and loess-like aeolian deposits. Two fall in the >100 ka period, 15 fall in the period 65-35 ka, and 77 fall in the period 35-0.3 ka. There was a sustained increase in erosion recorded in the period 35-15 ka, as reflected by a greater number of dated aeolian deposits during this period. We considered three possible biases that may have affected the age distribution obtained: the limitations of radiocarbon dating, sampling bias, and preservation bias. Sampling bias may have favoured more recent dune strata, but radiocarbon dating and preservation biases are unlikely to have significantly distorted the age distribution obtained. Long but intermittent aeolian deposition is recorded at two sites (Southwood B; c. 59-28 ka and Dunlin Dune; c. 29-14 ka) but there is no evidence of regional loess deposits such as found in New Zealand. The timing of increased erosion in Tasmania between 35 and 30 ka approximately coincides with the intermittent ten-fold increase of dust accumulation between 33 and 30 ka in the

  17. Pedology around a 6700 year old Neolithic ring ditch system in Germany

    NASA Astrophysics Data System (ADS)

    Leopold, Matthias; Völkel, Jörg; Schmotz, Karl; Huerkamp, Kerstin

    2010-05-01

    The cultural landscape in Europe is the product of many different human and natural activities and processes. Settlement, clearing and farming over thousands of years are constantly transforming the landscape and the according bio- and geo-components like flora and fauna, relief, hydrology, soils and others. As Geoarchaeology tries to reconstruct certain stages of this cultural landscape development, the existence of geoarchives of the respective time period are a crucial precondition. Soil science often works with colluvium as geoarchives but that presupposes the original soil to be destroyed by erosion. Therefore there is a lack of in situ soils of certain time periods throughout Europe. During archaeological excavations conducted by the Kreisarchäologie Deggendorf in eastern Bavaria late 2008 a new Neolithic ring ditch system was discovered which dates back to 4700 BC. Beside its enormous archaeological relevance the study site offers unique possibilities for pedological studies. Situated in the loess belt of eastern Bavaria calcic luvisols form the native soils of the region. However, black soils from older floodplains, the so-called Tschernitza, are described some hundred meters beside the excavation area. In addition black sediments which fill the pits of a Neolithic settlement close to the ring ditch system have been detected. The black backfill sediments are correlated with anthropogenic settlement activities. Interestingly, the backfills of the contemporaneous ring ditch system differ. The 2 m wide and 2.5 m deep ditch functioned as an ideal trap for naturally eroded sediments. The backfills of the ditch indicate different phases of sedimentation and artificial reformation of the ditch. Furthermore, the analysis of thin sections and laboratory data (such as RFA, RDA, pedogenic oxides , magn. suszept., etc.) together with geophysical measurements point to the existence of a fully developed calcic luvisol around 6700 years ago. At the same time within some

  18. PROFILE: Management of Sedimentation in Tropical Watersheds.

    PubMed

    NAGLE; FAHEY; LASSOIE

    1999-05-01

    / The sedimentation of reservoirs is a serious problem throughout the tropics, yet most attempts to control sedimentation in large river basins have not been very successful. Reliable information on erosion rates and sources of sediments has been lacking. In regions where geologically unstable terrain combines with high rainfall, natural erosion rates might be so high that the effects of human activity are limited. Estimates of natural erosion in these situations often have been poor because of the episodic nature of most erosion during large storms and because mass-wasting may supply much of the sediment. The predominance of mass-wasting in some watersheds can result in an unexpectedly high ratio of bedload to suspended load, shifting sedimentation to "live" rather than "dead" storage within reservoirs. Furthermore, the inappropriate use of the Universal Soil Loss Equation to assess the effectiveness of erosion control measures has led to inaccurate estimates of the sediment reduction benefits that could accrue to watershed treatment efforts. Although reducing erosion from cultivated areas is desirable for other reasons, efforts aimed at reducing reservoir sedimentation by controlling agricultural sources of erosion may have limited benefits if the principal sources are of natural origin or are associated with construction of the dams and reservoirs and with rural roads and trails. Finally, the most appropriate locations for watershed rehabilitation depend on the magnitude of temporary storage of colluvium and alluvium within the river basin: Where storage volume is large and residence time of sediment very long, reducing agricultural erosion may have limited impacts on sedimentation within the expected life of a reservoir. Systematic development and analysis of sediment budgets for representative watersheds is needed to address these limitations and thereby improve both the planning of river basin development schemes and the allocation of resources towards

  19. Influence of successive phases of volcanic construction and erosion on Mayotte Island's hydrogeological functioning as determined from a helicopter-borne resistivity survey correlated with borehole geological and permeability data

    NASA Astrophysics Data System (ADS)

    Vittecoq, B.; Deparis, J.; Violette, S.; Jaouën, T.; Lacquement, F.

    2014-02-01

    The purpose of this study is to show how a multidisciplinary approach that combines geophysics, geology and hydrogeology has made it possible to: (a) significantly improve our understanding of the hydrogeological regime of the volcanic island of Mayotte, and (b) provide a new set of geophysical measurement calibration data. In 2010 a helicopter-borne geophysical survey (SkyTEM) was flown over the entire island (374 km2) with a measurement density hitherto unheard of in a volcanic environment. In addition, a database was compiled containing the geological logs of 55 boreholes. 52 of these boreholes have hydrogeological information like aquifer position and piezometric level. 21 of the boreholes have transmissivity values. Correlations were made between the inverted resistivities as obtained from the helicopter-borne TDEM profiles and the nature, age and hydrodynamic properties of the formations as obtained from the borehole data. Five hydrogeological units were mapped. These are characterized by an alternation between phases of dominant volcanic construction, with the emplacement of basaltic lavas, phonolite massifs and pyroclastic deposits, and phases of dominant erosion with the deposition of volcaniclastic material (colluvium, breccias, basaltic lavas and phonolite blocks and all materials resulting from slope slides) along the slopes and in the topographic depressions. It has also been possible to assign resistivity and permeability ranges to four of these units. Ranges that are also dependent on the age of the deposits: the younger the formation is, the greater its resistivity and the higher its permeability. The hydrogeological regime is marked by the phases of volcanic construction and erosion that succeeded one another during the geological history of Mayotte over the last 10 Ma. A conceptual model adapted to the specific geological context of this island, and differing from the Canarian and Hawaiian models, is also put forward. This model is marked by the

  20. Late Quaternary landscape evolution in the Great Karoo, South Africa: Processes and drivers.

    NASA Astrophysics Data System (ADS)

    Oldknow, Chris; Hooke, Janet; Lang, Andreas

    2016-04-01

    The Great Karoo spans the north-central part of South Africa at a major climatic boundary. The characteristics, sequences, spatial patterns and drivers of river response to Late Quaternary climate changes in this region remain unclear due to the fragmentary alluvial/colluvial stratigraphic record and the lack of dated palaeoclimatic archives. Dendritic gully networks incised into deep deposits (up to 6 m) of colluvium and alluvium in the upper Sundays River catchment expose a legacy of "cut and fill" features. In 1st order tributaries, these are predominantly discontinuous palaeochannels and flood-outs with localised palaeosols, whereas in 2nd & 3rd order tributaries there are: 1) incised palaeo-geomorphic surfaces, 2) semi-continuous inset terrace sequences, 3) buried palaeo-gully topography. Using a combination of field mapping, logging of sediment outcrops, soil micromorphological and grain size analysis, mineral magnetic measurements and radiometric dating (OSL & 14C), we derive a stratigraphic evolution model which demonstrates a) the number of phases of incision, aggradation and pedogenesis, b) the spatial and temporal extent of each phase and c) the drivers of alluviation and associated feedbacks. Our reconstruction of regional valley alluviation indicates four distinct terrace units of contrasting depositional age. The base of the succession reflects slow aggradation under periglacial conditions associated with the Last Glacial Maximum. Subsequent channel entrenchment, causing terrace abandonment (T1) occurred in the deglacial period when vegetation and rainfall were in anti-phase. Re-instatement of connectivity with deep upland colluvial stores resulted in the injection of a pulse of sediment to valley floors, triggering compartmentalised backfilling (aggradation of T2) which propagated upstream as far as the second order drainage lines. This backfilling restructured the local hydrology, which, in concert with enhanced summer-rainfall, contributed to a

  1. Weathering processes as predisposing factors of the landscape evolution along plutono-metamorphic profiles of the Sila Massif, Calabria, southern Italy

    NASA Astrophysics Data System (ADS)

    Perri, Francesco; Borrelli, Luigi; Muto, Francesco; Gullà, Giovanni; Critelli, Salvatore; Conforti, Massimo; Filomena, Luciana; Rago, Valeria

    2013-04-01

    This work is aimed to join interdisciplinary research topics of weathering profile stages on plutonic (granitoid) and metamorphic (gneissic) rocks related to tectonic and landscape evolution of the western Sila Grande Massif (southern Italy). The grain-size of the studied samples is related to the parent rocks in response to physical and chemical weathering processes. Weathering processes produce an unconsolidated rock characterized by sand-gravel grain-size fraction for the granitoid rocks and by sand-silt grain-size fraction for the gneissic rocks. Chemical and mineralogical analyses confirm the granulometric observations. The difference between granitoid and gneissic rocks are mainly related to a higher content of quartz and feldspars for the first one rock type, whereas the second rock type shows higher content of neoformed clay minerals as well expandable phases. The main mineralogical changes concern the partial transformation of biotite and the partial destruction of feldspars, associated with the neoformation of secondary minerals (clay minerals and Fe-oxides) during the most advanced weathering stage; these processes also produce a substitution of the original rock fabric. All these petrological, chemical and mineralogical observations associated to microfractures and morphological variations occur on both plutonic and metamorphic original rocks and, thereby, affect the surrounding landscape processes. Generally, the granitoid profiles are regular and simple, characterized by gradual variation in the degree of weathering from bottom to top; where granitoid rocks show strong morphologies characterized by high relief energy and steep slopes, earth and debris slides, soil slips and earth flow can occur especially when fresher granitoids is near the surface and is covered by organic debris, colluvium, or soil. The gneissic profiles are characterized by structural complexity may be related to several factors such as presence of faults, high state of fracturing

  2. Detrital shocked minerals: microstructural provenance indicators of impact craters

    NASA Astrophysics Data System (ADS)

    Cavosie, A. J.

    2014-12-01

    The study of detrital shocked minerals (DSMs) merges planetary science, sedimentology, mineralogy/crystallography, accessory mineral geochemistry, and geochronology, with the goal of identifying and determining provenance of shock metamorphosed sand grains. Diagnostic high-pressure impact-generated microstructures (planar fractures, planar deformation features) are readily identified on external grain surfaces using standard SEM imaging methods (BSE), and when found, unambiguously confirm an impact origin for a given sand grain. DSMs, including quartz, zircon, monazite, and apatite, have thus far been documented at the Vredefort Dome [1,2,3], Sudbury [4], Rock Elm [5], and Santa Fe [6,7] impact structures. DSMs have been identified in alluvium, colluvium, beach sand, and glacial deposits. Two main processes are recognized that imply the global siliciclastic record contains DSMs: they survive extreme distal transport, and they survive 'deep time' lithification. Distal transport: In South Africa, shocked minerals are preserved in alluvium from the Vaal River >750 km downstream from the Vredefort impact; SHRIMP U-Pb geochronology has confirmed the origin of detrital shocked zircon and monazite from shocked Vredefort bedrock [2]. Vredefort-derived shocked zircons have also been found at the mouth of the Orange River on the Atlantic coast, having travelled ~2000 km downriver from Vredefort [8]. Deep time preservation: Vredefort-derived shocked zircon and quartz has been documented in glacial diamictite from the 300 Myr-old Dwyka Group in South Africa. Shocked minerals were thus entrained and transported in Paleozoic ice sheets that passed over Vredefort [9]. An impact crater can thus be viewed as a unique 'point source', in some cases for billions of years [2,4]; DSMs thus have applications in studying eroded impact craters, sedimentary provenance, landscape evolution, and long-term sediment transport processes throughout the geologic record. This work was supported by

  3. Sensitivity of long-term bare soil infiltration simulations to hydraulic properties in an arid environment

    NASA Astrophysics Data System (ADS)

    Stothoff, Stuart A.

    1997-04-01

    The suitability of Yucca Mountain, Nevada, for emplacement of a high-level nuclear waste geologic repository is currently being evaluated. Assessments of the repository performance suggest that the uncertainty in infiltration rates strongly affects predicted repository performance. Most of the ground surface over the potential repository footprint is characterized by shallow to deep colluvium/alluvium overlying densely fractured, welded tuffs. In order to identify characteristic behavior of infiltration that might be expected at the site, two idealizations of this situation are examined: an effectively semi-infinite column of alluvium and a two-layer column of alluvium over a fractured impermeable matrix. For each idealization the impact of hydraulic properties is assessed. Examining the sensitivity of bare soil simulator predictions for an effectively semi-infinite column, it is found that decreasing the air entry pressure while holding all other parameters at a fixed level tends to increase both the long-term average moisture content and the long-term average net infiltration flux for homogeneous media. In contrast, increasing the van Genuchten scale parameter (m=1 - 17sol;n) or decreasing the porosity tends to decrease the average soil moisture but increase the infiltration. Most interestingly, three regimes are found for permeability. For relatively high permeabilities, there is a trend toward increasing average infiltration and increasing average moisture content with decreasing permeability. For relatively low permeabilities, vapor transport dominates over liquid transport, runoff and evaporation overwhelm infiltration, and the soil becomes very dry with essentially no infiltration flux. Between the extreme cases of high and low permeability, there is a zone where decreasing permeability results in decreased infiltration but increased moisture content, which is explained by the capacity of more permeable media to maintain surface wetness for longer periods of

  4. Field and Laboratory Data From an Earthquake History Study of Scarps of the Lake Creek-Boundary Creek Fault Between the Elwha River and Siebert Creek, Clallam County, Washington

    USGS Publications Warehouse

    Nelson, Alan R.; Personius, Stephen F.; Buck, Jason; Bradley, Lee-Ann; Wells, Ray E.; Schermer, Elizabeth R.

    2007-01-01

    Fault scarps recently discovered on Airborne Laser Swath Mapping (ALSM; also known as LiDAR) imagery show Holocene movement on the Lake Creek-Boundary Creek fault on the north flank of the Olympic Mountains of northwestern Washington State. Such recent movement suggests the fault is a potential source of large earthquakes. As part of the effort to assess seismic hazard in the Puget Sound region, we map scarps on ALSM imagery and show primary field and laboratory data from backhoe trenches across scarps that are being used to develop a latest Pleistocene and Holocene history of large earthquakes on the fault. Although some scarp segments 0.5-2 km long along the fault are remarkably straight and distinct on shaded ASLM imagery, most scarps displace the ground surface <1 m, and, therefore, are difficult to locate in dense brush and forest. We are confident of a surface-faulting or folding origin and a latest Pleistocene to Holocene age only for scarps between Lake Aldwell and the easternmost fork of Siebert Creek, a distance of 22 km. Stratigraphy in five trenches at four sites help determine the history of surface-deforming earthquakes since glacier recession and alluvial deposition 11-17 ka. Although the trend and plunge of indicators of fault slip were measured only in the weathered basalt exposed in one trench, upward-splaying fault patterns and inconsistent displacement of successive beds along faults in three of the five trenches suggest significant lateral as well as vertical slip during the surface-faulting or folding earthquakes that produced the scarps. Radiocarbon ages on fragments of wood charcoal from two wedges of scarp-derived colluvium in a graben-fault trench suggest two surface-faulting earthquakes between 2,000 and 700 years ago. The three youngest of nine radiocarbon ages on charcoal fragments from probable scarp-derived colluvum in a fold-scarp trench 1.2 km to the west suggest a possible earlier surface-faulting earthquake less than 5,000 years

  5. Violent Explosive Eruptions in the Ararat Valley, Armenia and Associated Volcanic Hazards

    NASA Astrophysics Data System (ADS)

    Meliksetian, Khachatur; Savov, Ivan; Connor, Charles; Gevorgyan, Hripsime; Connor, Laura; Navasardyan, Gevorg; Manucharyan, Davit; Jrbashyan, Ruben; Ghukasyan, Yura

    2016-04-01

    The Anatolian-Armenian-Iranian volcanically active orogenic plateau is located in the collision zone between the Arabian and Eurasian plates. The majority of regional geodynamic and petrologic models of collision-related magmatism use the model proposed by Keskin (2003), where volcanism is driven by Neo-Tethyan slab break-off, however an updated model by Neill et al. (2015) and Skolbeltsyn et al.(2014) comprise break-off of two slabs. One of the significant (and understudied) features of the regionally extensive collision zone volcanism is the diversity of eruption styles and also the presence of large number of highly explosive (Plinian) eruptions with VEI≥5 during the Middle-Upper Pleistocene. Geological records of the Ararat depression include several generations of thick low aspect ratio Quaternary ignimbrites erupted from Aragats volcano, as well as up to 3 m thick ash and pumice fall deposit from the Holocene-historically active Ararat volcano. The Ararat tephra fall deposit is studied at 12 newly discovered outcrops covering an area ˜1000 km2. It is noteworthy, that the Ararat tephra deposits are loose and unwelded and observed only in cross-sections in small depressions or in areas where they were rapidly covered by younger, colluvium deposits, presumably of Holocene age. Therefore, the spatial extent of the explosive deposits of Ararat is much bigger but not well preserved due to rapid erosion. Whole rock elemental, isotope (Sr, Nd) and mineral chemistry data demonstrate significant difference in the magma sources of the large Aragats and Ararat stratovolcanoes. Lavas and pyroclastic products of Aragats are high K calc-alkaline, and nearly always deprived from H2O rich phases such as amphibole. In contrasts lavas and pyroclastic products from Ararat are medium K calc-alkaline and volatile-rich (>4.6 wt% H2O and amphibole bearing) magmas. Here we shall attempt to reveal possible geochemical triggers of explosive eruptions in these volcanoes and assess

  6. Flashy Water and Sediment Delivery to Fluvial Megafan andFan Delta Systems on Opposing Shorelines of an Early Eocene Lake

    NASA Astrophysics Data System (ADS)

    Jones, E. R.; Plink-Bjorklund, P.

    2015-12-01

    Flashy delivery of water and sediment had distinct effects on the process of deposition in coeval fluvial megafan and fan delta deposits on opposing shorelines of a paleolake that occupied the Uinta Basin throughout the Eocene. The Tertiary Uinta Basin was an asymmetric continental interior basin with a steep northern margin, adjacent to the block uplift controlling basin subsidence, and a low gradient southern margin. A ~140 km wide fluvial megafan with catchments as far as ~750 km away occupied the southern margin of the lacustrine basin. Within this megafan system, fluvial deposits contain within-channel continental bioturbation and paleosol development on bar accretion surfaces that are evidence of prolonged periods of groundwater flow or channel abandonment. These are punctuated by channel fills exhibiting a suite of both high-deposition rate and upper flow regime sedimentary structures that were deposited by very rapid suspension-fallout during seasonal to episodic river flooding events. A series of small (~8 km wide) and proximally sourced fan deltas fed sediment into the steeper northern margin of the lacustrine basin. 35-50% of the deposits in the delta plain environment of these fan deltas are very sandy debris flows with as low as 5% clay and silt sized material. Detrital zircon geochronology shows that these fan deltas were tapping catchments where mostly unconsolidated Cretaceous sedimentary cover and thick Jurassic eolianites were being eroded. A combination of flashy precipitation, arid climate, catchments mantled by abundant loose sand-sized colluvium, and steep depositional gradients promoted generation of abundant very sandy (5-10% clay and silt sized material) debris flows. In this way, the Wasatch and Green River Formations in the Uinta Basin, Utah, U.S.A. gives us two very different examples of how routing flashy water and sediment delivery (associated with pulses of hyperthermal climate change during the Early Eocene) through different

  7. Structural and Geomorphic Controls on Dryland Salinity and Regolith Distribution in the Critical Zone, North-east Tasmania, Australia.

    NASA Astrophysics Data System (ADS)

    Sweeney, M. E.; Moore, C. L.

    2015-12-01

    Salinity occurs in the drier and flatter Australian landscapes because there is insufficient rain to flush salts from critical zone. Changes in land use due to agriculture and urbanisation can accelerate salinity effects, leading to soil and water degradation and threatening infrastructure and ecosystems. The dominant lithology in the salt affected regions of North-east Tasmania is dolerite. The geochemistry of dolerite regolith has been examined in order to understand the association between salinity and weathered dolerite. The electrical conductivity of 1:5 soil-waters is higher in the more weathered material (maximum 4.9 dS/m). This confirms field observations that highly weathered dolerite can serve as a significant store for salt in the landscape. However, the clay content and salinity varies, depending on the local geomorphic context. Dolerite weathering on well-drained slopes has favoured the formation of 1:1 kaolinite clays, and sometimes bauxite formation. Kaolinite-bearing regolith can store salt via matrix diffusion processes. However, there are fault-bounded pockets of colluvium and highly-weathered in situmaterial, where the supply of cations has not been diminished and 2:1 montmorillonite clays dominate. These regions have the capacity to store large volumes of salts. The geomorphology also affects the volume of rain and flux of salt from windblown dust and oceanic aerosols. The chemistry of rainwater from an array of bulk deposition collectors was studied from Spring 2013 to Winter 2014. The average salt flux was 79± 10 kg/ha/yr in the study region, ranging from 170± 12 kg/ha/yr in the north to 42 ± 6 kg/ha/yr inland. To assist in understanding why salt is found in certain parts of the landscape but not in others, it is essential to model how water moves through the critical zone and geological structures. By exploring the complex interactions of geomorphology and other biophysical parameters the study area has been divided into Hydrogeological

  8. Revised Geologic Map of the Fort Garland Quadrangle, Costilla County, Colorado

    USGS Publications Warehouse

    Wallace, Alan R.; Machette, Michael N.

    2008-01-01

    The map area includes Fort Garland, Colo., and the surrounding area, which is primarily rural. Fort Garland was established in 1858 to protect settlers in the San Luis Valley, then part of the Territory of New Mexico. East of the town are the Garland mesas (basalt-covered tablelands), which are uplifted as horsts with the Central Sangre de Cristo fault zone. The map also includes the northern part of the Culebra graben, a deep structural basin that extends from south of San Luis (as the Sanchez graben) to near Blanca, about 8 km west of Fort Garland. The oldest rocks exposed in the map area are early Proterozic basement rocks (granites in Ikes Creek block) that occupy an intermediate structural position between the strongly uplifted Blanca Peak block and the Culebra graben. The basement rocks are overlain by Oligocene volcanic and volcaniclastic rocks of unknown origin. The volcanic rocks were buried by a thick sequence of basin-fill deposits of the Santa Fe Group as the Rio Grande rift formed about 25 million years ago. The Servilleta Basalt, a regional series of 3.7?4.8 Ma old flood basalts, was deposited within sediment, and locally provides a basis for dividing the group into upper and lower parts. Landslide deposits and colluvium that rest on sediments of the Santa Fe Group cover the steep margins of the mesas. Exposures of the sediment beneath the basalt and within the low foothills east of the Central Sangre de Cristo fault zone are comprised of siltstones, sandstones, and minor fluvial conglomerates. Most of the low ground surrounding the mesas and in the graben is covered by surficial deposits of Quaternary age. The alluvial deposits are subdivided into three Pleistocene-age units and three Holocene-age units. The oldest Pleistocene gravel (unit Qao) is preserved as isolated remnants that cap high surfaces north and east of Fort Garland. The primary geologic hazards in the map area are from earthquakes, landslides, and localized flooding. The Central

  9. Multi-proxy record of land use change derived from colluvial soils of the western Pyrenees Mountains, France

    NASA Astrophysics Data System (ADS)

    Leigh, David S.; Gragson, Theodore L.; Coughlan, Michael R.

    2016-04-01

    Archaeological evidence and paleoenvironmental proxies from wetland bogs (e.g. charcoal, pastoral pollen, fungal spores of sheep dung) clearly outline the regional chronology of Holocene pastoral activity in the Pyrenees. We increase the spatial and temporal resolution of this chronology through a place-based, millennial-scale investigation of land use activities within individual fields in the commune of Larrau, Pyrénées Atlantiques, France. We have identified several stratigraphic records of slopewash colluvium that span the entire Holocene that occur at the outlets of zero-order watersheds, each draining several hectares. To examine forest-to-pasture transformation, two to three meter long auger holes were sampled in contiguous five centimeter intervals. These samples were analyzed for charcoal content, radiocarbon age, magnetic susceptibility, particle size, organic matter, and n-alkane concentrations. Results indicate that intentional burning and clearing were initiated by the Late Neolithic (ca. 5000-6000 cal. BP), but more intense burning, clearing, and pronounced soil erosion occurred later during the Bronze Age and Iron Age. Charcoal concentrations and low frequency magnetic susceptibility provide evidence of initial burning and subsequent variation in the intensity of fire use. Radiocarbon chronologies exhibit order-of-magnitude spikes in sedimentation rates (1-10 mm/yr) during the Bronze Age and Iron Age that are asynchronous between sites. Asynchronous records suggest anthropic, rather than climatic, drivers and imply that land use varied in intensity across the landscape, unlike the uniform intensity of pasture use typical of the modern landscape. Sedimentation rates, and presumably erosion rates, returned to very near pre-pastoral background levels (<1mm/yr) during the last 1500 years. A pristine-degraded-recovery cycle is thus indicated for the span of the Holocene illustrating that not all pastures around the world persist with stereotypical

  10. Can the flow dynamics of debris flows be identified from seismic data?

    NASA Astrophysics Data System (ADS)

    Kean, J. W.; Coe, J. A.; Smith, J. B.; Coviello, V.; McCoy, S. W.

    2014-12-01

    There is growing interest in the use of seismic and acoustic data to interpret a variety of geomorphic processes including landslides and debris flows. This measurement technique is attractive because a broad area can be monitored from a safe distance, unlike more direct methods of instrumentation, which are restricted to known flow paths and are vulnerable to damage by the flow. Previous work has shown that measurements of ground vibrations are capable of detecting the timing, speed, and location of landslides and debris flows. A remaining question is whether or not additional flow properties, such as basal stress, impact force, or flow magnitude can be inferred reliably from seismic data. This question has been difficult to answer, because detailed, independent measurements of flow dynamics are lacking. Here, we explore characteristics of debris-flow induced ground vibrations using new data from the Chalk Cliffs monitoring site in central Colorado. Monitoring included a heavily instrumented cross-section consisting of two tri-axial geophones to record ground vibrations (at 333 Hz), a small, 225 cm2 force plate to record basal impact forces (at 333 Hz), a laser distance meter to record flow stage over the plate (at 10 Hz), and a high definition camera to record flow dynamics (at 24 Hz). One geophone (A) was mounted on a boulder partially buried in colluvium; the other (B) was mounted directly to weathered bedrock typical of the site. This combination of instrumentation allowed us to compare the spectral response of different geophone installations to independently measured flow depth and basal impact force. We also compared the response of the geophones to surges that flowed over a sediment-covered bed (40-cm thick) to surges that flowed over a bare bedrock channel. Preliminary results showed that site conditions have a large effect on recorded debris-flow vibrations. The seismic signature of debris flow was very different between the geophones, with geophone B

  11. Holocene earthquakes and right-lateral slip on the left-lateral Darrington-Devils Mountain fault zone, northern Puget Sound, Washington

    USGS Publications Warehouse

    Personius, Stephen F.; Briggs, Richard W.; Nelson, Alan R.; Schermer, Elizabeth R; Maharrey, J. Zebulon; Sherrod, Brian; Spaulding, Sarah A.; Bradley, Lee-Ann

    2014-01-01

    Sources of seismic hazard in the Puget Sound region of northwestern Washington include deep earthquakes associated with the Cascadia subduction zone, and shallow earthquakes associated with some of the numerous crustal (upper-plate) faults that crisscross the region. Our paleoseismic investigations on one of the more prominent crustal faults, the Darrington–Devils Mountain fault zone, included trenching of fault scarps developed on latest Pleistocene glacial sediments and analysis of cores from an adjacent wetland near Lake Creek, 14 km southeast of Mount Vernon, Washington. Trench excavations revealed evidence of a single earthquake, radiocarbon dated to ca. 2 ka, but extensive burrowing and root mixing of sediments within 50–100 cm of the ground surface may have destroyed evidence of other earthquakes. Cores in a small wetland adjacent to our trench site provided stratigraphic evidence (formation of a laterally extensive, prograding wedge of hillslope colluvium) of an earthquake ca. 2 ka, which we interpret to be the same earthquake documented in the trenches. A similar colluvial wedge lower in the wetland section provides possible evidence for a second earthquake dated to ca. 8 ka. Three-dimensional trenching techniques revealed evidence for 2.2 ± 1.1 m of right-lateral offset of a glacial outwash channel margin, and 45–70 cm of north-side-up vertical separation across the fault zone. These offsets indicate a net slip vector of 2.3 ± 1.1 m, plunging 14° west on a 286°-striking, 90°-dipping fault plane. The dominant right-lateral sense of slip is supported by the presence of numerous Riedel R shears preserved in two of our trenches, and probable right-lateral offset of a distinctive bedrock fault zone in a third trench. Holocene north-side-up, right-lateral oblique slip is opposite the south-side-up, left-lateral oblique sense of slip inferred from geologic mapping of Eocene and older rocks along the fault zone. The cause of this slip reversal is

  12. Woodland clearance alters geomorphic, hydrologic, and pedogenic drivers of ecosystem services: examples from the southern Blue Ridge (USA) and the French western Pyrenees Mountains

    NASA Astrophysics Data System (ADS)

    Leigh, David

    2016-04-01

    The southern Blue Ridge (USA) and French western Pyrenees both are humid-temperate mountains where native woodlands have been cleared on soils formed in residuum and colluvium on hillslopes. Forest removal increased rates of erosion and sediment yield that drove both negative and positive ecosystem services. For example, the supportive ecosystem service of soil formation was diminished on eroded hillslopes, but may have been enhanced by accumulation of sediment on bottomlands far downstream from the highland source areas. Negative effects on provisional ecosystem services (e.g. water supply) resulted in aggraded bottomlands by increasing the depth to the water table. Legacy effects linger on hillslopes that reforested (diminished soil properties), and ongoing alteration of pedogenic and hydrologic processes affect pastures that persisted from cleared woodlands. Beyond those general similarities, pastures of the two regions exhibit very different pedogenic pathways and ecosystem service outcomes. Soils of the Blue Ridge pastures adhere to a typical degradation scenario of erosion, compaction, and reduced infiltration capacities, whereas Pyrenees pastures exhibit soil qualities trending in the opposite direction and arguably now are better quality soils than their forested predecessors. Major differences in temporal duration and management styles apparently have led to such contrasts in soil quality. The Blue Ridge pastures are only tens to hundreds of years old, whereas Pyrenees pastures are thousands of years old. Blue Ridge pastures are maintained by mowing with tractors and year-round grazing primarily with beef cattle, whereas Pyrenees pastures (outfields) lack tractors and are only grazed seasonally (summer), primarily with sheep. Fire is rarely used as a management tool in the Blue Ridge, while Pyrenees pastures frequently are burned. Such management practices, and their influence on pedogenic and hydrologic processes, generally have resulted in negative

  13. Applying Terzaghi's method of slope characterization to the recognition of Holocene land slippage

    NASA Astrophysics Data System (ADS)

    Rogers, J. David; Chung, Jae-won

    2016-07-01

    During site investigations, engineering geologists are expected to recognize landslides, both active and dormant. Those without substantial experience evaluating the evolution of geomorphic features associated with localized mass wasting often mischaracterize site conditions. Karl Terzaghi suggested seven steps in characterizing natural hillslopes, including (1) a literature review, (2) site reconnaissance, (3) a program of subsurface exploration, (4) preparation of sketches and diagrams illustrating the essential features, (5) preparation of a preliminary geology report, (6) observation and mapping of geologic structures exposed during excavation for construction, and (7) development of contingency plans for anticipated variations in old landslide features. Based on our interpretation of Terzaghi's original principles, we review some of the most common interpretive problems with nomenclature of landslide features, describe common mistakes in characterizing old landslides, and present technical approaches that often aid in the recognition of old landslide features. A wide variance in geological terms exists for describing landslides, and various terms have been applied to the same features by workers in different areas, which often leads to confusion. Some of these terms include nomenclature such as slip surfaces, alluvial fans, colluvium, and slope creep. Active surficial landslides are relatively easy to recognize when they are well exposed. Although these features tend to become obscured with time, anomalous, hummocky topography often provide key recognition features of a slope's geomorphic evolution. Deeper-seated bedrock landslides can be more difficult to recognize because their features become increasingly mollified with time. These features can often be identified by anomalous geomorphic features, such as isolated saddles or anomalous/discontinuous benches. These features are some of the best locations to excavate borings or exploratory trenches. Well

  14. Environmental impacts of oil production on soil, bedrock, and vegetation at the U.S. Geological Survey Osage-Skiatook Petroleum Environmental Research site A, Osage County, Oklahoma

    USGS Publications Warehouse

    Otton, J.K.; Zielinski, R.A.; Smith, B.D.; Abbott, M.M.; Keeland, B.D.

    2005-01-01

    The U.S. Geological Survey is investigating the impacts of oil and gas production on soils, groundwater, surface water, and ecosystems in the United States. Two sites in northeastern Oklahoma (sites A and B) are presently being investigated under the Osage-Skiatook Petroleum Environmental Research project. Oil wells on the lease surrounding site A in Osage County, Oklahoma, produced about 100,000 bbl of oil between 1913 ard 1981. Prominent production features on the 1.5-ha (3.7-ac) site A include a tank battery, an oil-filled trench, pipelines, storage pits for both produced water and oil, and an old power unit. Site activities and historic releases have left open areas in the local oak forest adjacent to these features and a deeply eroded salt scar downslope from the pits that extends to nearby Skiatook Lake. The site is underlain by surficial sediments comprised of very fine-grained eolian sand and colluvium as much as 1.4 m (4.6 ft) thick, which, in turn, overlie flat-lying, fractured bedrock comprised of sandstone, clayey sandstone, mudstone, and shale. A geophysical survey of ground conductance and concentration measurements of aqueous extracts (1:1 by weight) of core samples taken in the salt scar and adjacent areas indicate that unusual concentrations of NaCl-rich salt are present at depths to at least 8 m (26 ft) in the bedrock; however, little salt occurs in the eolian sand. Historic aerial photographs, anecdotal reports from oil-lease operators, and tree-ring records indicate that the surrounding oak forest was largely established after 1935 and thus postdates the majority of surface damage at the site. Blackjack oaks adjacent to the salt scar have anomalously elevated chloride (>400 ppm) in their leaves and record the presence of NaCl-rich salt or salty water in the shallow subsurface. The geophysical measurements also indicate moderately elevated conductance beneath the oak forest adjoining the salt scar. Copyright ?? 2005. The American Association of

  15. Alpine debris flows triggered by a 28 July 1999 thunderstorm in the central Front Range, Colorado

    USGS Publications Warehouse

    Godt, J.W.; Coe, J.A.

    2007-01-01

    On 28 July 1999, about 480 alpine debris flows were triggered by an afternoon thunderstorm along the Continental Divide in Clear Creek and Summit counties in the central Front Range of Colorado. The thunderstorm produced about 43??mm of rain in 4??h, 35??mm of which fell in the first 2??h. Several debris flows triggered by the storm impacted Interstate Highway 70, U.S. Highway 6, and the Arapahoe Basin ski area. We mapped the debris flows from color aerial photography and inspected many of them in the field. Three processes initiated debris flows. The first process initiated 11% of the debris flows and involved the mobilization of shallow landslides in thick, often well vegetated, colluvium. The second process, which was responsible for 79% of the flows, was the transport of material eroded from steep unvegetated hillslopes via a system of coalescing rills. The third, which has been termed the "firehose effect," initiated 10% of the debris flows and occurred where overland flow became concentrated in steep bedrock channels and scoured debris from talus deposits and the heads of debris fans. These three processes initiated high on steep hillsides (> 30??) in catchments with small contributing areas (< 8000??m2), however, shallow landslides occurred on slopes that were significantly less steep than either overland flow process. Based on field observations and examination of soils mapping of the northern part of the study area, we identified a relation between the degree of soil development and the process type that generated debris flows. In general, areas with greater soil development were less likely to generate runoff and therefore less likely to generate debris flows by the firehose effect or by rilling. The character of the surficial cover and the spatially variable hydrologic response to intense rainfall, rather than a threshold of contributing area and topographic slope, appears to control the initiation process in the high alpine of the Front Range. Because

  16. Geology of the Western Part of Los Alamos National Laboratory (TA-3 to TA-16), Rio Grande Rift, New Mexico

    SciTech Connect

    C.J.Lewis; A.Lavine; S.L.Reneau; J.N.Gardner; R.Channell; C.W.Criswell

    2002-12-01

    We present data that elucidate the stratigraphy, geomorphology, and structure in the western part of Los Alamos National Laboratory between Technical Areas 3 and 16 (TA-3 and TA-16). Data include those gathered by geologic mapping of surficial, post-Bandelier Tuff strata, conventional and high-precision geologic mapping and geochemical analysis of cooling units within the Bandelier Tuff, logging of boreholes and a gas pipeline trench, and structural analysis using profiles, cross sections, structure contour maps, and stereographic projections. This work contributes to an improved understanding of the paleoseismic and geomorphic history of the area, which will aid in future seismic hazard evaluations and other investigations. The study area lies at the base of the main, 120-m (400-ft) high escarpment formed by the Pajarito fault, an active fault of the Rio Grande rift that bounds Los Alamos National Laboratory on the west. Subsidiary fracturing, faulting, and folding associated with the Pajarito fault zone extends at least 1,500 m (5,000 ft) to the east of the main Pajarito fault escarpment. Stratigraphic units in the study area include upper units of the Tshirege Member of the early Pleistocene Bandelier Tuff, early Pleistocene alluvial fan deposits that predate incision of canyons on this part of the Pajarito Plateau, and younger Pleistocene and Holocene alluvium and colluvium that postdate drainage incision. We discriminate four sets of structures in the area between TA-3 and TA-16: (a) north-striking faults and folds that mark the main zone of deformation, including a graben in the central part of the study area; (b) north-northwest-striking fractures and rare faults that bound the eastern side of the principal zone of deformation and may be the surface expression of deep-seated faulting; (c) rare northeast-striking structures near the northern limit of the area associated with the southern end of the Rendija Canyon fault; and (d) several small east

  17. Reach-Scale Channel Adjustments to Channel Network Geometry in Mountain Bedrock Streams

    NASA Astrophysics Data System (ADS)

    Plitzuweit, S. J.; Springer, G. S.

    2008-12-01

    surveys in order to analyze whether stream power and shear stress are adjusted to reflect CNG at the reach- scale. These models are compared to those with discharges calculated using drainage area and precipitation totals alone. We conclude that gradients in bedrock mountain streams may reflect basin-scale hydrology (CNG) and not simply local geological or geomorphic factors. This challenges the conclusions of others who ascribe local channel adjustments to: i) lithology and structure alone, or ii) local colluvium grain sizes.

  18. Geologic map of the Kings Mountain and Grover quadrangles, Cleveland and Gaston Counties, North Carolina, and Cherokee and York Counties, South Carolina

    USGS Publications Warehouse

    Horton, J. Wright, Jr.

    2006-01-01

    show a westward decrease from upper amphibolite facies (sillimanite zone) near the High Shoals Granite on the east side of the map to greenschist (epidote-amphibolite) facies in the south-central part of the area near the Kings Mountain shear zone. Amphibolite-facies mineral assemblages in the Inner Piedmont terrane increase in grade from the kyanite zone near the Kings Mountain shear zone to the sillimanite zone in the northwest part of the map. Surficial deposits include alluvium in the stream valleys and colluvium along ridges and steep slopes. These quadrangles are unusual in their richness and variety of mineral deposits, which include spodumene (lithium), cassiterite (tin), mica, feldspar, silica, clay, marble, kyanite and sillimanite, barite, manganese, sand and gravel, gold, pyrite, and iron. (Abstract from pamphlet.)

  19. Geologic Map of the Kings Mountain and Grover Quadrangles, Cleveland and Gaston Counties, North Carolina, and Cherokee and York Counties, South Carolina

    USGS Publications Warehouse

    Horton, J. Wright, Jr.

    2008-01-01

    sequence show a westward decrease from upper amphibolite facies (sillimanite zone) near the High Shoals Granite in the eastern side of the map area to upper greenschist (epidote-amphibolite) facies in the south-central part of the area near the Kings Mountain shear zone. Amphibolite-facies mineral assemblages in the Inner Piedmont terrane increase in grade from the kyanite zone near the Kings Mountain shear zone to the sillimanite zone in the northwestern part of the map area. Surficial deposits include alluvium in the stream valleys and colluvium along ridges and steep slopes. These quadrangles are unusual in the richness and variety of the mineral deposits that they contain, which include spodumene (lithium), cassiterite (tin), mica, feldspar, silica, clay, marble, kyanite and sillimanite, barite, manganese, sand and gravel, gold, pyrite, and iron.

  20. A comparison of soil properties under four vegetation units from six metalliferous hills in Katanga

    NASA Astrophysics Data System (ADS)

    Kaya, Donato; Gregory, Mahy; Michel, Ngongo; Gilles, Colinet

    2013-04-01

    In Katanga (Democratic Republic of Congo), numerous metalliferous hills are distributed along what is called the copperhill belt from Kolwezi to Lubumbashi. Very specific vegetation developed on these hills within the miombo forest in response to very specific soil conditions, among which the copper content. Previous studies have already shown the existence of gradients of copper from the mineralized rocks outcropping at the top of the hills to the foot slopes on colluviums. After a characterization of the vertical variability of soil properties in pits distributed along the main slopes, we investigated the soil-vegetation relationships in six hills located between the towns of Tenke and Fungurume. Observation 1-square meter plots were installed in four vegetation units and sixty of them were selected according to their relative importance on the six hills. The soil from the top 10cm was sampled and analyzed for pH, Total Organic Carbon, available P, K, Mg, Ca, Cu, Co and Mn and soluble Cu and Co. Analysis of variance was performed in order to assess whether the effects of the "Hill" and of the "Vegetation Unit" were significant to explain soil chemical variability. Additionally, short transects were sampled at the boundaries from adjacent vegetation units in order to evaluate the gradual or rough nature of change in soil properties under these units. The results indicate that the six hills can not be considered as different for pH and available nutrients, excepted K, nor for the available Cu and Mn. Only TOC and Co contents were differing, mainly from one hill compared to the other five. The vegetation effect is significant for almost every studied soil characteristics, to the exception of Ca and Mn. Soluble Cu and Co significantly correlate to available Cu and Co, respectively. The pH variations however explain local departures from linear regression. The ANOVA models take into account 30 to 60% of the variations of soil properties. The study of the boundaries

  1. Late Quaternary mass-wasting records and formation of alluvial terraces in the actively uplifting Lao-nong catchment, southwestern Taiwan

    NASA Astrophysics Data System (ADS)

    Tsui, H. K.; Hsieh, M. L.; Li, W. L.; Hsiao, Y. T.

    2014-12-01

    , and frequency of the events. Our field observation suggests that at least some of the large Holocene tributary-fan terraces were sourced from pre-Holocene colluviums.

  2. Erosion of an ancient mountain range, the Great Smoky Mountains, North Carolina and Tennessee

    USGS Publications Warehouse

    Matmon, A.; Bierman, P.R.; Larsen, J.; Southworth, S.; Pavich, M.; Finkel, R.; Caffee, M.

    2003-01-01

    Analysis of 10Be and 26Al in bedrock (n=10), colluvium (n=5 including grain size splits), and alluvial sediments (n=59 including grain size splits), coupled with field observations and GIS analysis, suggest that erosion rates in the Great Smoky Mountains are controlled by subsurface bedrock erosion and diffusive slope processes. The results indicate rapid alluvial transport, minimal alluvial storage, and suggest that most of the cosmogenic nuclide inventory in sediments is accumulated while they are eroding from bedrock and traveling down hill slopes. Spatially homogeneous erosion rates of 25 - 30 mm Ky-1 are calculated throughout the Great Smoky Mountains using measured concentrations of cosmogenic 10Be and 26Al in quartz separated from alluvial sediment. 10Be and 26Al concentrations in sediments collected from headwater tributaries that have no upstream samples (n=18) are consistent with an average erosion rate of 28 ?? 8 mm Ky-1, similar to that of the outlet rivers (n=16, 24 ?? 6 mm Ky-1), which carry most of the sediment out of the mountain range. Grain-size-specific analysis of 6 alluvial sediment samples shows higher nuclide concentrations in smaller grain sizes than in larger ones. The difference in concentrations arises from the large elevation distribution of the source of the smaller grains compared with the narrow and relatively low source elevation of the large grains. Large sandstone clasts disaggregate into sand-size grains rapidly during weathering and downslope transport; thus, only clasts from the lower parts of slopes reach the streams. 26Al/10Be ratios do not suggest significant burial periods for our samples. However, alluvial samples have lower 26Al/10Be ratios than bedrock and colluvial samples, a trend consistent with a longer integrated cosmic ray exposure history that includes periods of burial during down-slope transport. The results confirm some of the basic ideas embedded in Davis' geographic cycle model, such as the reduction of relief

  3. Characterizing Controls of Riparian Width for Mountain Streams in the Colorado Front Range

    NASA Astrophysics Data System (ADS)

    Polvi, L. E.; Wohl, E. E.

    2007-12-01

    High variability of mountain streams causes riparian width to vary greatly from changes in drainage, valley and channel characteristics. GIS- based models for predicting flood-prone width, valley bottoms, or riparian zones may not accurately reflect processes at the reach scale, therefore field verification and reach-specific studies are needed. Management of riparian areas often designates a generalized width, which may under- or over-estimate the true riparian width. This study examines correlations between potential control variables and riparian zone width in the Colorado Front Range. Results from this study will be used to predict the riparian zone as a proxy for flood-prone width in the semi-arid Colorado Front Range. We hypothesize that local controls interact with large- scale controls to determine floodplain processes. Large-scale controls identified are elevation, which reflects hydroclimatology and glacial history, gradient and drainage area. Local controls are entrenchment, the ratio of the valley width to channel width, connectedness, defined as the distance from the channel to valley edge, presence of colluvium, and vegetation type, affecting roughness during flooding and bank stability. We chose twenty reaches based on elevation, connectedness, gradient and drainage area using a GIS base map in anthropogenically undisturbed areas of the Colorado Front Range, which included the Cache la Poudre and North St. Vrain drainages. Riparian width was defined using a three-tiered approach: evidence of fluvial processes and presence of riparian vegetation, compared with the Q100 stage. A longitudinal and two valley and channel cross-section surveys were completed at each stream reach to determine valley and channel geometry and bed gradient. Preliminary results show significant positive correlations between drainage area, entrenchment, and connectedness and riparian width, and negative correlations between gradient and riparian width, supporting the hypothesis

  4. Baltic Sea coastal erosion; a case study from the Jastrzębia Góra region

    NASA Astrophysics Data System (ADS)

    Uścinowicz, Grzegorz; Kramarska, Regina; Kaulbarsz, Dorota; Jurys, Leszek; Frydel, Jerzy; Przezdziecki, Piotr; Jegliński, Wojciech

    2014-12-01

    The coastline in the Jastrzębia Góra area can be divided into three major zones of general importance: a beach and barrier section, a cliff section, and a section protected by a heavy hydrotechnical construction. These areas are characterised by a diverse geology and origin, and hence different vulnerability to erosion. In addition, observations have demonstrated a different pace of erosion within each zone. Based on the results obtained by remote sensing methods (analysis of aerial photographs and maps), it has been determined that the coastline in the barrier area, i.e., to the west of Jastrzębia Góra, moved landwards by about 130 m, in a period of 100 years, and 80 m over about 50 years. A smaller displacement of the shoreline could be observed within the cliff. Between the middle of the twentieth and the start of the twenty-first centuries the shore retreated by about 25 m. However, in recent years, an active landslide has led to the displacement of the uppermost part of the cliff locally up to 25 m. Another issue is, functioning since 2000, a heavy hydrotechnical construction which has been built in order to protect the most active part of the cliff. The construction is not stable and its western part, over a distance of 50 m, has moved almost 2 m vertically downwards and c. 2.5 m horizontally towards the sea in the past two years. This illustrates that the erosional factor does not comprise only marine abrasion, but also involves land-based processes determined by geology and hydrogeology. Changes in the shoreline at the beach and barrier part are constantly conditioned by rising sea levels, the slightly sloping profile of the sea floor and low elevation values of the backshore and dune areas. Cliffs are destroyed by mass wasting and repetitive storm surges that are responsible for the removal of the colluvium which protects the coast from adverse wave effects. Presumably, mass movements combined with groundwater outflow from the cliff, plus sea abrasion

  5. Paleoseismologic evidence for late Holocene earthquakes on the Southern Panamint Valley fault zone: Implications for earthquake clustering in the Eastern California Shear Zone north of the Garlock fault

    NASA Astrophysics Data System (ADS)

    McAuliffe, L. J.; Dolan, J. F.; Kirby, E.; Haravitch, B.; Alm, S.

    2010-12-01

    New paleoseismological data from two trenches excavated across the southern end of the Panamint Valley fault (PVF), the most active of the three major faults in the eastern California shear zone (ECSZ) north of the Garlock fault, reveal the occurrence of at least two, and probably three, surface ruptures during the late Holocene. These trenches were designed to test the hypothesis that the earthquake clusters and intervening seismic lulls observed in the Mojave section of the ECSZ (Rockwell et al. 2000, Ganev et al. 2010) at 8-9.5 ka, 5-6 ka and during the past ~1-1.5 ka, also involved the fault systems of the ECSZ north of the Garlock fault. Well stratified playa sands, silts and clays exposed in the trench allowed precise identification of two event horizons; a likely third event horizon occurred during a period of soil development across the playa. Calibrated radiocarbon dates from 25 charcoal samples constrain the dates of the most recent event (MRE) to ~1450-1500 AD and the ante-penultimate event at 3.2-3.6 ka. The penultimate event occurred during a period of soil development spanning ~350-1400 AD. The presence of large blocks of soil in what appears to be scarp-derived colluvium in a large fissure opened during this event require that it occurred late during soil development, probably only a few hundred years before the MRE. The timing of the three events indicate that the southern PVF has ruptured at least once, and probably twice during the ongoing seismic cluster in the Mojave region. The PVF earthquakes also are similar in age to the 1872 Owens Valley earthquakes and the geomorphically youthful, but undated MRE in central Death Valley. Although we were unable to excavate deeply enough at this site to expose mid-to lower - Holocene playa strata, the timing of the ante-penultimate earthquake at our site shows that the PVF has ruptured at least once during the well-defined 2-5 ka seismic lull in the Mojave section of the ECSZ. Interestingly the 3.2-3.6 ka

  6. Landslides triggered by the 1946 Ancash earthquake, Peru

    NASA Astrophysics Data System (ADS)

    Kampherm, T. S.; Evans, S. G.; Valderrama Murillo, P.

    2009-04-01

    The 1946 M7.3 Ancash Earthquake triggered a large number of landslides in an epicentral area that straddled the Continental Divide of South America in the Andes of Peru. A small number of landslides were described in reconnaissance reports by E. Silgado and Arnold Heim published shortly after the earthquake, but further details of the landslides triggered by the earthquake have not been reported since. Utilising field traverses, aerial photograph interpretation and GIS, our study mapped 45 landslides inferred to have been triggered by the event. 83% were rock avalanches involving Cretaceous limestones interbedded with shales. The five largest rock/debris avalanches occurred at Rio Llama (est. vol. 37 M m3), Suytucocha (est. vol., 13.5 Mm3), Quiches (est. vol. 10.5 Mm3 ), Pelagatos (est. vol. 8 Mm3), and Shundoy (est. vol. 8 Mm3). The Suytucocha, Quiches, and Pelagatos landslides were reported by Silgado and Heim. Rock slope failure was most common on slopes with a southwest aspect, an orientation corresponding to the regional dip direction of major planar structures in the Andean foreland belt (bedding planes and thrust faults). In valleys oriented transverse to the NW-SE structural grain of the epicentral area, south-westerly dipping bedding planes combined with orthogonal joint sets to form numerous wedge failures. Many initial rock slope failures were transformed into rock/debris avalanches by the entrainment of colluvium in their path. At Acobamba, a rock avalanche that transformed into a debris avalanche (est. vol. 4.3 Mm3) overwhelmed a village resulting in the deaths of 217 people. The cumulative volume-frequency plot shows a strong power law relation below a marked rollover, similar in form to that derived for landslides triggered by the 1994 Northridge Earthquake. The total volume of the 45 landslides is approximately 93 Mm3. The data point for the Ancash Earthquake plots near the regression line calculated by Keefer (1994), and modified by Malamud et al

  7. Holocene tectonics and fault reactivation in the foothills of the north Cascade Mountains, Washington

    USGS Publications Warehouse

    Sherrod, Brian L.; Barnett, Elizabeth; Schermer, Elizabeth; Kelsey, Harvey M.; Hughes, Jonathan; Foit, Franklin F., Jr.; Weaver, Craig S.; Haugerud, Ralph; Hyatt, Tim

    2013-01-01

    We use LiDAR imagery to identify two fault scarps on latest Pleistocene glacial outwash deposits along the North Fork Nooksack River in Whatcom County, Washington (United States). Mapping and paleoseismic investigation of these previously unknown scarps provide constraints on the earthquake history and seismic hazard in the northern Puget Lowland. The Kendall scarp lies along the mapped trace of the Boulder Creek fault, a south-dipping Tertiary normal fault, and the Canyon Creek scarp lies in close proximity to the south-dipping Canyon Creek fault and the south-dipping Glacier Extensional fault. Both scarps are south-side-up, opposite the sense of displacement observed on the nearby bedrock faults. Trenches excavated across these scarps exposed folded and faulted late Quaternary glacial outwash, locally dated between ca. 12 and 13 ka, and Holocene buried soils and scarp colluvium. Reverse and oblique faulting of the soils and colluvial deposits indicates at least two late Holocene earthquakes, while folding of the glacial outwash prior to formation of the post-glacial soil suggests an earlier Holocene earthquake. Abrupt changes in bed thickness across faults in the Canyon Creek excavation suggest a lateral component of slip. Sediments in a wetland adjacent to the Kendall scarp record three pond-forming episodes during the Holocene—we infer that surface ruptures on the Boulder Creek fault during past earthquakes temporarily blocked the stream channel and created an ephemeral lake. The Boulder Creek and Canyon Creek faults formed in the early to mid-Tertiary as normal faults and likely lay dormant until reactivated as reverse faults in a new stress regime. The most recent earthquakes—each likely Mw > 6.3 and dating to ca. 8050–7250 calendar years B.P. (cal yr B.P.), 3190–2980 cal. yr B.P., and 910–740 cal. yr B.P.—demonstrate that reverse faulting in the northern Puget Lowland poses a hazard to urban areas between Seattle (Washington) and Vancouver

  8. A Lithology Based Map Unit Schema For Onegeology Regional Geologic Map Integration

    NASA Astrophysics Data System (ADS)

    Moosdorf, N.; Richard, S. M.

    2012-12-01

    A system of lithogenetic categories for a global lithological map (GLiM, http://www.ifbm.zmaw.de/index.php?id=6460&L=3) has been compiled based on analysis of lithology/genesis categories for regional geologic maps for the entire globe. The scheme is presented for discussion and comment. Analysis of units on a variety of regional geologic maps indicates that units are defined based on assemblages of rock types, as well as their genetic type. In this compilation of continental geology, outcropping surface materials are dominantly sediment/sedimentary rock; major subdivisions of the sedimentary category include clastic sediment, carbonate sedimentary rocks, clastic sedimentary rocks, mixed carbonate and clastic sedimentary rock, colluvium and residuum. Significant areas of mixed igneous and metamorphic rock are also present. A system of global categories to characterize the lithology of regional geologic units is important for Earth System models of matter fluxes to soils, ecosystems, rivers and oceans, and for regional analysis of Earth surface processes at global scale. Because different applications of the classification scheme will focus on different lithologic constituents in mixed units, an ontology-type representation of the scheme that assigns properties to the units in an analyzable manner will be pursued. The OneGeology project is promoting deployment of geologic map services at million scale for all nations. Although initial efforts are commonly simple scanned map WMS services, the intention is to move towards data-based map services that categorize map units with standard vocabularies to allow use of a common map legend for better visual integration of the maps (e.g. see OneGeology Europe, http://onegeology-europe.brgm.fr/ geoportal/ viewer.jsp). Current categorization of regional units with a single lithology from the CGI SimpleLithology (http://resource.geosciml.org/201202/ Vocab2012html/ SimpleLithology201012.html) vocabulary poorly captures the

  9. Climate impacts on groundwater storage, hydrochemistry and residence time in geologically variable, snowmelt-dominated mountain catchments, Front Range, Colorado

    NASA Astrophysics Data System (ADS)

    Zeliff, M. M.; Williams, M. W.

    2012-12-01

    Groundwater storage, hydrochemistry and residence time are all known to vary widely depending on hydrogeologic conditions. In mountainous terrain hydrogeology can vary greatly over short distances, from bedrock aquifers on ridge tops to colluvial and fluvial aquifers in valleys. Determining how climate alters groundwater in the context of variable hydrogeologic conditions is needed to understand in-stream flows and biogeochemical cycles in these climactically sensitive alpine settings. In 2005 at the Niwot LTER six piezometers were installed in surficial diamicton and colluvium at the base of a semi-permanent snowfield at the Martinelli site (3440 m). Eight piezometers were also installed at the Saddle on a ridge-top in the alpine tundra (3528 m). In 2010 12 piezometers were installed at the C1 site (3025 m) in the subalpine atop moraine deposits. Groundwater monitoring for all sites is year-round and is comprised of depth-to-water measurements by hand and pressure transducers for select wells, as well as chemistry samples for major solutes including dissolved organic matter and stable isotopes of water, δ18O and δD. Across the Niwot LTER precipitation falls predominately as snow creating a strongly snowmelt-dominated hydrograph. Groundwater response to this seasonality is reflected in both physical and hydrochemical groundwater measurements. Snowmelt leads to sharp increases in water level in all piezometers including up to 7 m of water table change at the Saddle, up to 3 m of change at Martinelli and up to 5 m of water table change at C1. Minimum water table levels are not always measureable as the water table can drop below the extent of the piezometers, however, at the Saddle there are decreasing trends in annual minimum groundwater level in 3 of the 4 deep piezometers, possibly reflecting a decrease in total aquifer storage. Hydrochemical groundwater response to snowmelt is evident in distinct harmonic trends in major solute and isotope chemistry. Time

  10. High frequency seismic monitoring of debris flows at Chalk Cliffs (CO), USA

    NASA Astrophysics Data System (ADS)

    Coviello, Velio; Kean, Jason; Smith, Joel; Coe, Jeffrey; Arattano, Massimo; McCoy, Scott

    2015-04-01

    A growing number of studies adopt passive seismic monitoring techniques to investigate slope instabilities and landslide processes. These techniques are attractive and convenient because large areas can be monitored from a safe distance. This is particularly true when the phenomena under investigation are rapid and infrequent mass movements like debris flows. Different types of devices are used to monitor debris flow processes, but among them ground vibration detectors (GVDs) present several, specific advantages that encourage their use. These advantages include: (i) the possibility to be installed outside the channel bed, (ii) the high adaptability to different and harsh field conditions, and (iii) the capability to detect the debris flow front arrival tens of seconds earlier than contact and stage sensors. Ground vibration data can provide relevant information on the dynamics of debris flows such as timing and velocity of the main surges. However, the processing of the raw seismic signal is usually needed, both to obtain a more effective representation of waveforms and to decrease the amount of data that need to be recorded and analyzed. With this objective, the methods of Amplitude and Impulses are commonly adopted to transform the raw signal to a 1-Hz signal that allows for a more useful representation of the phenomenon. In that way, peaks and other features become more visible and comparable with data obtained from other monitoring devices. In this work, we present the first debris flows seismic recordings gathered in the Chalk Cliffs instrumented basin, central Colorado, USA. In May 2014, two 4.5-Hz, three-axial geophones were installed in the upper part of the catchment. Seismic data are sampled at 333 Hz and then recorded by a standalone recording unit. One geophone is directly installed on bedrock, the other one mounted on a 1-m boulder partially buried in colluvium. This latter sensor integrates a heavily instrumented cross-section consisting of a 225 cm2

  11. Revised geologic cross sections of parts of the Colorado, White River, and Death Valley regional groundwater flow systems, Nevada, Utah, and Arizona

    USGS Publications Warehouse

    Page, William R.; Scheirer, Daniel S.; Langenheim, V.E.; Berger, Mary A.

    2006-01-01

    confining units because of their low permeability. Late Proterozoic to Lower Cambrian clastic units overlie the crystalline rocks and are also considered confining units within the regional flow systems. Above the clastic units are Middle Cambrian to Lower Permian carbonate rocks that are the primary aquifers in the flow systems. The Middle Cambrian to Lower Permian carbonate rocks are overlain by a sequence of mainly clastic rocks of late Paleozoic to Mesozoic age that are mostly considered confining units, but they may be permeable where faulted. Tertiary volcanic and plutonic rocks are exposed in the northern and southern parts of the study area. In the Clover and Delamar Mountains, these rocks are highly deformed by north- and northwest-striking normal and strike-slip faults that are probably important conduits in transmitting groundwater from the basins in the northern Colorado and White River flow systems to basins in the southern part of the flow systems. The youngest rocks in the region are Tertiary to Quaternary basin-fill deposits. These rocks consist of middle to late Tertiary sediments consisting of limestone, conglomerate, sandstone, tuff, and gypsum, and younger Quaternary surficial units consisting of alluvium, colluvium, playa deposits, and eolian deposits. Basin-fill deposits are both aquifers and aquitards. The rocks in the study area were complexly deformed by episodes of Mesozoic compression and Cenozoic extensional tectonism. Some Cretaceous thrust faults and folds of the Sevier orogenic belt form duplex zones and define areas of maximum thickness for the Paleozoic carbonate rocks. Cenozoic faults are important because they are the primary structures that control groundwater flow in the regional flow systems.

  12. Large-Scale Landslides in Rapidly Uplifted and Extremely Snowy Mountains in the Northern Japanese Alps

    NASA Astrophysics Data System (ADS)

    Kariya, Y.; Sato, G.; Arai, M.

    2006-12-01

    Mount Shirouma-dake (2932 m ASL, 36.75°N, 137.75°E) and its surrounding mountains have experienced rapid uplift and snowy climate over the late Quaternary period. The geology of this area, which comprises Paleozoic to Mesozoic ultramafic/sedimentary/metamorphic rocks and Neogene to Quaternary volcanic rocks, is very complicated. In addition, glaciers existed during MIS4 and 2 (no glaciers currently exist). Moreover, the active faults in the piedmont area are significant. This is because according to trenching studies, they have produced large earthquakes with a 1100-2400 y interval in the Holocene epoch. Therefore, it is recognized that the environment of this area is conducive to the occurrence of a landslide. Although the landforms in this area have been well described from glacial/periglacial geomorphological viewpoints, few details are available on landslides. The local sustainable tourism with geohazard mitigation requires more information on landslides because this area provides a spectacular landscape and attracts many visitors. Since the 1970s, many lodging and tourism facilities have been developed for such visitors. This area has also hosted the 1998 Winter Olympics because of its snowy climate. We performed geomorphological/geological analysis of the landslides and found that landslides and their precursors (uphill-facing scarps etc.) are common in most altitudinal zones. Many different types of landslides are observed in the bedrock slopes. Slumping is a typical mode. Mass rock creep (sagging), shallow failure, toppling, and landslide complexes are also observed. However, debris avalanche is restricted to the area in which volcanic rocks are distributed. Sometimes, the collapse of unconsolidated debris such as tills, colluvium, and alluvium occurs. In most cases, it is difficult to determine the depths of deformed zones without drilling results; however, it is assumed that a few landslides have a slip surface with a depth of 100 m. In some cases, the

  13. Soils of the coastal area of Santa Fé and Santa Cruz islands (Galápagos). Their micromorphology, mineralogy and genesis compared.

    NASA Astrophysics Data System (ADS)

    Stoops, Georges; Dumon, Mathijs; Van Ranst, Eric

    2015-04-01

    Santa Fé is a small island situated about 15 km SW of Santa Cruz and has a similar petrographic composition. The centre of Santa Cruz reaches up to 950 m a.s.l., Santa Fé is nowhere higher that 255 m. Even in the dry season the high mountain region of Santa Cruz profits therefore of an almost continuous drizzly rain (garrúa) resulting from the cooling of the rising moist air. The dry coastal zones are covered by sparse Opuntia vegetation. In the coastal soils a double to open spaced porphyric c/f related distribution pattern prevails. The micromass is greyish to yellowish brown on Santa Fé, reddish on Santa Cruz. The b-fabric is weakly granostriated, rarely calcitic crystallitic. The coarse material is restricted to fresh grains of plagioclase > iddingsite > augite > rare olivine, and some fresh basalt fragments. Remnants of illuvial clay coatings are more common on Santa Cruz. Only on Santa Fé hard, yellowish nodules (up to 700 µm) with a strongly mosaic speckled b-fabric and first order grey interference colours occur; their nature and genesis is a point of discussion. X-ray diffraction revealed the clay fraction of these soils to be comparable: poorly crystalline 2:1 phyllosilicates with broad irregular 001 reflections swelling to 1.8 nm after glycolation and collapsing to 1.0 nm after K-saturation and heating. Poorly crystalline kaolinite reflections are more prominent on Santa Cruz, whereas mica-like components (1.00 nm reflections) are restricted to Santa Fé. The presence of unweathered coarse material in an abundant micromass of alteration clay indicates a disequilibrium, and points to a transport of the fine material, in solid phase (colluvium) and/or as solution rather than an in situ weathering. Comparing the total chemical composition (corrected for LOI) of the coastal soils of Santa Cruz and Santa Fé with the average rock composition of both islands, one notes in the soils an increase in Al, Fe, Ti and K, and a loss of Mg, Ca and Na. On Santa F

  14. Bright patches on chernozems - from space to surface and soil properties

    NASA Astrophysics Data System (ADS)

    Smetanova, Anna; Burian, Libor; Holec, Juraj; Minár, Jozef

    2016-04-01

    The bright patches on chernozems can be easily visually distinguished in the aerial images, due to their bright colour contrasting with the dark colour of the surrounding chernozems. They present a typical feature of the loess hilly lands in the Danube Lowland. They reffer predominantely to the areas where (i) the soil substrate - loess is tilled, (ii) the transitional AC horizon of chernozems is tilled, (iii) or one of them, or both are mixed into the plough layer during tillage. They are usually categorized as eroded chernozems or regosols. To the lower extent, the accumulation patches might occur, if the loess material redeposited from upper part of the slope in the colluvium is tilled. This study focuses on uncovering the soil properties of bright patches, identified on different scales - spatial and temporal, combining three methods - the remote sensing, morphometric analysis and soil mapping. In the area of 31 km² (located in the Trnavska pahorkatina Hilly Land, south of Trnava), the bright patches were identified using visual analysis of georeferenced aerial images from 1949 and 2004, representing two types of landscape structure characteristic for the 20th Century. In 1949 small, in one direction elongated fields, with mean size 0.008 km2 prevailed, while in 2004 the mean size of a field was 0.28 km2. The morphometric analysis was performed based on DEM derived from topographical maps (scale 1:10 000). Soil sampling in the first phase of the project was performed in a subset of the patches in small agriculture catchment (0.28 km2), situated in one single field (in 2004). The percussion drilling or hand augering (with undisturbed structure) were used in order to describe the depth of the soil horizons and the soil properties. Together 365 bright patches covering 3.2% of the study area (31 km²) were identified in 1949; while it was twice more in 2004 (776 patches), when they covered approximately 12% of the same area. The bright patches were predominantly

  15. Seismic, magnetic, and geotechnical properties of a landslide and clinker deposits, Powder River basin, Wyoming and Montana

    USGS Publications Warehouse

    Miller, C.H.

    1979-01-01

    Exploitation of vast coal and other resources in the Powder River Basin has caused recent, rapid increases in population and in commercial and residential development and has prompted land utilization studies. Two aspects of land utilization were studied for this report: (1) the seismic and geotechnical properties of a landslide and (2) the seismic, magnetic, and geotechnical properties of clinker deposits. (1) The landslide seismic survey revealed two layers in the slide area. The upper (low-velocity) layer is a relatively weak mantle of colluvium and unconsolidated and weathered bedrock that ranges in thickness from 3.0 to 7.5 m and has an average seismic velocity of about 390 m/s. It overlies high-velocity, relatively strong sedimentary bedrock that has velocities greater than about 1330 m/s. The low-velocity layer is also present at the other eight seismic refraction sites in the basin; a similar layer has also been reported in the Soviet Union in a landslide area over similar bedrock. The buried contact of the low- and high-velocity layers is relatively smooth and is nearly parallel with the restored topographic surface. There is no indication that any of the high-velocity layer (bedrock) has been displaced or removed. The seismic data also show that the shear modulus of the low-velocity layer is only about one-tenth that of the high-velocity layer and the shear strength (at failure) is only about one-thirtieth. Much of the slide failure is clearly in the shear mode, and failure is, therefore, concluded to be confined to the low-velocity layer. The major immediate factor contributing to landslide failure is apparently the addition of moisture to the low-velocity layer. The study implies that the low-velocity layer can be defined over some of the basin by seismic surveys and that they can help predict or delineate potential slides. Preventative actions that could then be taken include avoidance, dewatering, prevention of saturation, buttressing the toe, and

  16. Fused breccia in Middle Miocene ignimbrites and other deterministic constraints on timing of faulting in Midway Valley, Nevada

    NASA Astrophysics Data System (ADS)

    Buesch, D.

    2011-12-01

    are consistent with deposition on an irregular faulted terrain. Some post-Tmr faulting might have occurred, but it is not constrained by late Miocene events. The Miocene rocks and faults were eroded to a low-relief surface documented in 94 boreholes in Midway Valley. Based on U-Pb geochronologic techniques on pedogenic opal deposits in the post-Miocene valley-filling deposits, the minimum age of the basal colluvium and alluvium is 2.7 Ma to 1.6 Ma with an average of 1.9 Ma (Neymark and others, 2007, GSA abstracts); and parts of the basal alluvium are constrained between 7.3 Ma and 3.2 Ma (Neymark and others, 2010, GSA abstracts). These relations indicate that (1) faulting was active in the hanging wall of the Paintbrush Canyon fault during the mid-Miocene, (2) faulting ceased throughout Midway Valley by the late Pliocene to earliest Pleistocene, and (3) fault activity migrated to the block-bounding Bow Ridge and Paintbrush Canyon faults. Thus, depositional, geochemical, and geochronologic studies, combined with an understanding of mechanical processes by which rocks form and are fractured, provides deterministic bounds on the timing and locations of faulting and resolve the likelihood of future events.

  17. Earthquakes in Barcelonnette (western French Alps, 2003-2015): where are the faults?

    NASA Astrophysics Data System (ADS)

    Palis, Edouard; Larroque, Christophe; Lebourg, Thomas; Jomard, Hervé; Flamand, Aurélie; Courboulex, Françoise; Vidal, Maurin; Robert, Pierre-Louis

    2016-04-01

    surrounding summits. The slope displays creeping landforms developed during the late glacial period and the little ice age, overlying upper-cretaceous deposits (calcareous sandstone, so-called "flyschs à Helminthoides"). A 2150m-long Electrical Resistivity Tomography Profile was performed to image the first hundreds meters depth. To do so, we used 4 electrical lines of 72 electrodes (10m spacing). We did the acquisitions using 2 array types: dipole-dipole and pole-dipole. Both arrays are sensitive to vertical structures and are well suitable for faults detection at depth. Our objective is to detect if faults extends through the epicentral area and if faults scarps, possibly resulting of a postglacial activity are hidden by the recent periglacial deposits and colluviums. From a preliminary analysis, the ERT imagery of the shallow 200m help us to identify: (1) the geometry of the surficial glacial and periglacial deposits (0-20m thick), (2) the folded calcareous sandstone characterized by a shallow resistive area (100m thick) and a deep resistive area (more than 150m thick), and (3) weaker vertical structures cutting the flyschs substratum that we interpreted as a fractured zone.

  18. Historical Influence of Soil and Water Management on Carbon Erosion and Burial in the United States

    NASA Astrophysics Data System (ADS)

    Sundquist, E. T.; Visser Ackerman, K.; Stallard, R. F.; Bliss, N. B.

    2012-04-01

    The documented history of U.S. soil and water management provides a unique opportunity to examine soil and sediment carbon storage under conditions of changing management practices. Historical acceleration of erosion due to cultivation has been moderated by improved soil management. Increased construction of dams and locks has expanded areas of aquatic sedimentation in reservoirs and ponds. Enhanced historical sediment deposition rates have been documented in lakes and estuaries. All of these changes have impacts on terrestrial carbon storage and turnover. The present-day carbon budget associated with erosion and burial cannot be determined without quantifying the time-dependent changes due to past and present soil and water management. We use existing datasets with GIS and modeling techniques to estimate sediment and carbon budget trends since the year 1700 in the conterminous U.S. We begin by calculating historical sediment budget scenarios representing effects of soil- and water-management practices. Using estimates of historical cropland areas, distributions, and erosion yields, we calculate approximate "hindcast" erosion scenarios. We use systematic relationships among compiled sedimentation rates to estimate historical sedimentation for documented reservoirs, lakes, and ponds. Our analysis indicates that historical export of sediments to coastal areas is relatively insignificant, whereas substantial sediment deposition in upland areas is necessary to balance the historical sediment budget. Relatively recent rates of sedimentation in lakes and impoundments appear to match or exceed rates of upland erosion, suggesting that a fraction of recent sediment transport is derived from channel and bank erosion, including remobilization of historically deposited alluvium and colluvium. For each historical sediment budget scenario, we apply models of carbon dynamics to time-dependent accounting of carbon in erosional and depositional environments. Our carbon calculations

  19. Holocene vegetation, fire and erosional history of City of Rocks National Reserve, South-Central Idaho

    NASA Astrophysics Data System (ADS)

    Weppner, K.; Pierce, J. L.; Betancourt, J. L.

    2011-12-01

    dominant tree species at CIRO. Field observation indicates that sheetflooding is a dominant erosional process at CIRO with sheetflood deposits accounting for ~40% of total measured Holocene alluvial thickness. Only ~20% of this deposition occurred between ~7-2 ka, suggesting a prolonged period of minimal erosion. Furthermore, during this ~5 ka interval, ~60% of alluvium was deposited as sheetfloods with the remainder deposited as overbank and flood deposits, and no recorded debris flows. We hypothesize that during the drier, warmer and possibly more stable climate of the mid-Holocene, decreased vegetation density on hillslopes suppressed colluvial storage, thus limiting the supply of hillslope material for debris flow production. Hillslopes likely experienced more frequent, yet low-volume, sheetflood erosion. Between ~4-2 ka cal yr BP, cooler and wetter conditions returned, as indicated by midden records from central Idaho. After ~2.2 ka, soil horizon development suggests that increased vegetation density re-stabilized hillslopes. This accumulated colluvium supplied material for episodic, post-wildfire debris flow events.

  20. Controls of catchments` sub-storage contributions to dynamic water quality patterns in the stream network

    NASA Astrophysics Data System (ADS)

    Schuetz, Tobias; Maike Hegenauer, Anja

    2016-04-01

    Water quality is usually observed either continuously at a few stations within a catchment or with few snapshot sampling campaigns throughout the whole stream network. Although we know that the depletion of catchment sub-storages can vary throughout the stream network according to their actual water content (spatial variability of actual storage conditions can be caused amongst others by unevenly distributed rainfall, storage size or spatial differences in soil characteristics and land use), we know little about the impact of this process on spatial water quality patterns. For summer low flow recession periods, when stream water composition can be crucial for aquatic ecosystem conditions and the exceedance of water quality thresholds, knowledge on the controls of the dynamic interplay of catchment storages and stream water composition might improve water quality management and the implementation of corresponding mitigation measures. We studied this process throughout the stream network of a first-order agricultural headwater catchment in south-western Germany during two summer low flow recession periods. The underlying geology of the study area is a deep layer of aeolian loess, whilst the dominating soil is a silty calcaric regosol with gleizations in the colluvium. The land use in the catchment is dominated by viniculture (63 %) and arable crops (18 %). Due to the dense drainpipe network within the catchment we could identify 12 sub-catchments contributing during summer low flow recession periods to total stream discharge. We continuously observed discharge, electrical conductivity and water temperatures for 8 of the sub-catchments and at the catchment outlet. This data set was accomplished by 10 snapshot campaigns where we sampled for water temperatures, electrical conductivity, major ions, pH and O2 throughout the stream network. Using either discharge concentration relationships or time dependent functions, we derived continuous export rates for all measures in

  1. Surficial Geologic Mapping Using Digital Techniques Reveals Late-Phase Basin Evolution and Role of Paleoclimate, Death Valley Junction 30' × 60' Quadrangle, California and Nevada

    NASA Astrophysics Data System (ADS)

    Slate, J.; Berry, M.; Menges, C. M.

    2010-12-01

    The recently released surficial geologic map of the Death Valley Junction 30' x 60' quadrangle at 1:100,000 scale (USGS SIM 3013) was simultaneously mapped and compiled using digital photogrammetric methods. The map area covers the central part of Death Valley and adjacent mountain ranges—the Panamint Range on the west and the Funeral Mountains on the east—as well as areas east of Death Valley including some of the Amargosa Desert, the Spring Mountains, and Pahrump Valley. We mapped six alluvial units, an eolian unit, three playa or playa-related units, lacustrine beach deposits, colluvium, and marl. Interpretation of surface morphology, tone, relative height, and map pattern in air photos enabled us to differentiate among the alluvial units, which make up about 80 percent of the surficial deposits in the map area. Systematic variations in alluvial surface morphology with age permit us to map and correlate geomorphic surfaces. Surface morphology is a product of depositional and post-depositional processes. Lithologic variations across the map area influence the tone of the alluvial units. Although young alluvial units are often light-toned due to an absence or paucity of rock varnish, they may appear dark where the source rocks are dark. Lithology also influences the development of rock varnish; fine-grained or aphanitic rocks, such as quartzite or basalt, tend to become varnished more quickly than rocks such as limestone or granite. Granite commonly disaggregates to grus before becoming varnished and limestone becomes etched. Relative height (topographic position) is useful for mapping in individual drainage basins near range fronts, but basinward, especially in tectonically inactive areas, most surfaces grade to the same base level, and relative height differs little among the alluvial units. Faulting, both the magnitude and location, also affects the map pattern of alluvial units. As faulting uplifts ranges relative to the basins, streams adjust to new base

  2. Tracing the contribution of debris flow-dominated channels to gravel-bed torrential river channel: implementing pit-tags in the upper Guil River (French Alps)

    NASA Astrophysics Data System (ADS)

    Arnaud-Fassetta, Gilles; Lissak, Candide; Fort, Monique; Bétard, François; Carlier, Benoit; Cossart, Etienne; Madelin, Malika; Viel, Vincent; Charnay, Bérengère; Bletterie, Xavier

    2014-05-01

    In the upper, wider reaches of Alpine valleys, shaping of active channels is usually subject to rapid change. It mostly depends upon hydro-climatic variability, runoff concentration and sediment supply, and may result in alternating sequences of fluvial and debris-flow pulses, as recorded in alluvial fans and terraces. Our study, carried in the frame of SAMCO (ANR) project, focuses on the upper Guil River Valley (Queyras, Southern French Alps) cut into the slaty shale "schistes lustrés". Steep, lower order drains carry a contrasted solid discharge, including predominantly sandy-loam particles mixed with gravels and boulders (sandstone schists, ophiolites). Abundant sediment supply by frost shattering, snow avalanche and landslides is then reworked during snowmelt or summer storm runoff events, and may result in catastrophic, very destructive floods along the main channel, as shown by historical records. Following the RI-30 year 2000 flood, our investigations included sediment budgets, i.e. balance of erosion and deposition, and the mapping of the source, transport and storage of various sediments (talus, colluvium, torrential fans, terraces). To better assess sediment fluxes and sediment delivery into the main channel network, we implemented tracers (pit-tags) in selected sub-catchments, significantly contributing to the sediment yield of the valley bottoms during the floods and/or avalanches: Maloqueste, Combe Morel, Bouchouse and Peyronnelle catchments. The first three are direct tributaries of the Guil River whereas the Peyronnelle is a left bank tributary of the Peynin River, which joins the Guil River via an alluvial cone with high human and material stakes. The Maloqueste and the Combe Morel are two tributaries facing each other in the Guil valley, representing a double lateral constraint for the road during flood events of the Guil River. After pit-tag initialisation in laboratory, we set them up along the four tributaries: Maloqueste (20 pit-tags), Combe

  3. The landslide inventory as the basis of susceptibility and hazard assessment

    NASA Astrophysics Data System (ADS)

    Copons, Ramon; Linares, Rogelio; Cirés, Jordi; Tallada, Anna

    2010-05-01

    40km2 in Tremp (Catalan Pyrenees). The selected area is dominated by a large synclinorium and two main lythologies can be considered inside: (i) the "Garum" Formation composed by plastic clays susceptible to instability, (ii) and a calcareous rock forming rockcliffs faces from ten to hundred meters high where primary rockfalls occurs. Several types of landslides are present in Tremp: rockfalls, topples, slides, earth flows, large lateral spreads and slow earth flows in a large part of slopes. Older events dated reveal an active instability over the Pleistocene with main reactivations during the glacial periods. Nowadays, small landslides affect the superficial colluvium are present during large rainfall periods. These characteristics reveal Tremp like a complex area affected highly by landslides. Two qualified field geologists from different institutions have created two different landslide inventories at a scale 1:10.000 over the same area in Tremp. One of the inventories, which is created by an earth scientist experienced in geormorphological techniques, represents the pessimistic interpretation considering large instabilities affecting large parts of the slope. The other inventory, which is created by a professional geologist experienced in landslide mapping, considers a more optimistic interpretation of the landslides identified. Commonly, parameters considered are the morphology of terrain surface, the lithology of rock outcrops and quaternary deposits, presence of damaged vegetation, and structural patterns. Data has been obtained by using air photographs and field observations. Inventory maps have been compared in order to contrast the existing differences and to detect limitations. Usually, both inventories represent the same large events despite their boundaries can be particulars. However, smaller events mapped are sometimes different on both inventories. Results obtained allow us to contrast the use of parameters considered during the completion of

  4. Preliminary paleoseismic observations along the western Denali fault, Alaska

    NASA Astrophysics Data System (ADS)

    Koehler, R. D.; Schwartz, D. P.; Rood, D. H.; Reger, R.; Wolken, G. J.

    2013-12-01

    the fan across the main fault scarp and adjacent graben, exposed sheared debris fan parent material at its north and south ends, separated by a central zone of stacked scarp-derived colluvium and weakly developed peaty soils. Stratigraphic relations and upward fault terminations clearly record the occurrence of the past three surface-faulting earthquakes and suggest four or more such events. Results of pending 14C analyses are expected to provide new information on earthquake timing and recurrence. A Holocene slip rate for this section of the fault will be developed using back-slip models and an estimate of the age of the fan constrained by our detailed surveys of channel offsets and pending cosmogenic 10Be exposure ages for surface boulders, respectively.

  5. Debris Flows and Floods in Southeastern Arizona from Extreme Precipitation in July 2006 - Magnitude, Frequency, and Sediment Delivery

    USGS Publications Warehouse

    Webb, Robert H.; Magirl, Christopher S.; Griffiths, Peter G.; Boyer, Diane E.

    2008-01-01

    fans in the Tucson basin are extremely rare events. Although recent watershed changes - particularly the impacts of recent wildland fires - may be important locally, the record number of slope failures and debris flows were related predominantly to extreme precipitation, not other factors such as fire history. The large number of slope failures and debris flows in an area with few such occurrences historically underscores the rarity of this type of meteorological event in southeastern Arizona. Most slope failures appeared to be shallow-seated slope failures of colluvium on steep slopes that caused deep scour of chutes and substantial aggradation of channels downstream. In the southern Santa Catalina Mountains, we estimate that 1.5 million tons of sediment were released from slope failures into the channels of ten drainage basins. Thirty-six percent of this sediment (527,000 tons) is gravel-sized or smaller and is likely to be transported by streamflow out of the mountain drainages and into the drainage network of metropolitan Tucson. This sediment poses a potential flood hazard by reducing conveyance in fixed-section flood control structures along Rillito Creek and its major tributaries, although our estimates suggest that deposition may be small if it is distributed widely along the channel, which is expected. Using the stochastic debris-flow model LAHARZ, we simulated debris-flow transport from slope failures to the apices of alluvial fans flanking the southern Santa Catalina Mountains. Despite considerable uncertainty in applying coefficients developed from worldwide observations to conditions in the southern Santa Catalina Mountains, we predicted the approximate area of depositional zones for several 2006 debris flows, particularly for Soldier Canyon. Better results could be achieved in some canyons if sediment budgets could be developed to account for alternating transport and deposition zones in channels with abrupt expansions and contractions, such

  6. Slope Deposits and (Paleo)Soils as Geoarchives to Reconstruct Late Quaternary Environments of Southern Africa

    NASA Astrophysics Data System (ADS)

    Huerkamp, K.; Voelkel, J.; Heine, K.; Bens, O.

    2009-04-01

    Although it is clear that large, rapid temperature changes have occurred during the last glacial-interglacial cycle and the Holocene in southern Africa, we have only limited, and often imprecise, knowledge of how the major moisture-bearing atmospheric circulation systems have reacted to these changes. Using slope deposits and soils as palaeoclimatic geoarchives we will overcome these constraints. The role of many geoarchives in the reconstruction of the Quaternary climate in southern Africa remains controversial, since the paleoclimate data are based on evidence from marine cores, lake sediments, speleothems and spring sinter, fluvial sediments, aeolian sands and dust, colluvium, and coastal sediments. To elucidate climate controls on Quaternary landscape evolution and to use these data for palaeoclimatic reconstructions, thus far slope deposits and soils have been investigated. Climatic controls on these cycles are incompletely known. The availability of results from earlier fieldwork, micromorphology, Optical Stimulated Luminescence (OSL), 14C dating and stable carbon isotope analysis will permit a thorough assessment of slope deposits and soils in terms of their palaeoenvironmental potential. The knowledge of suitable areas and sites in different climatic zones of southern Africa where slope deposits and soils have already been found document the late Quaternary climatic history and even climatic anomalies (e.g. Younger Dryas period at Eksteenfontein, 8.2 ka event at Tsumkwe, 4 ka event in the Auob valley, Little Ice Age in the Namib Desert). The findings will show the late Quaternary history of precipitation fluctuations, of the shifting of the ITCZ (and the ABF - Agulhas-Benguela Front), of wind intensities and directions, and of extreme precipitation events. The project will employ state-of-the-art geoscience methodology to interpret the record of precipitation changes of the late Quaternary, including the shifting of the summer and winter rain belts, the

  7. Hydrogeology of, and simulation of ground-water flow in a mantled carbonate-rock system, Cumberland Valley, Pennsylvania

    USGS Publications Warehouse

    Chichester, D.C.

    1996-01-01

    The U.S. Geological Survey conducted a study in a highly productive and complex regolith-mantled carbonate valley in the northeastern part of the Cumberland Valley, Pa., as part of its Appalachian Valleys and Piedmont Regional Aquifer-system Analysis program. The study was designed to quantify the hydrogeologic characteristics and understand the ground-water flow system of a highly productive and complex thickly mantled carbonate valley. The Cumberland Valley is characterized by complexly folded and faulted carbonate bedrock in the valley bottom, by shale and graywacke to the north, and by red-sedimentary and diabase rocks in the east-southeast. Near the southern valley hillslope, the carbonate rock is overlain by wedge-shaped deposit of regolith, up to 450 feet thick, that is composed of residual material, alluvium, and colluvium. Locally, saturated regolith is greater than 200 feet thick. Seepage-run data indicate that stream reaches, near valley walls, are losing water from the stream, through the regolith, to the ground-water system. Results of hydrograph-separation analyses indicate that base flow in stream basins dominated by regolith-mantled carbonate rock, carbonate rock, and carbonate rock and shale are 81.6, 93.0, and 67.7 percent of total streamflow, respectively. The relative high percentage for the regolith-mantled carbonate-rock basin indicates that the regolith stores precipitation and slowly, steadily releases this water to the carbonate-rock aquifer and to streams as base flow. Anomalies in water-table gradients and configuration are a result of topography and differences in the character and distribution of overburden material, permeability, rock type, and geologic structure. Most ground-water flow is local, and ground water discharges to nearby springs and streams. Regional flow is northeastward to the Susquehanna River. Average-annual water budgets were calculated for the period of record from two continuous streamflow-gaging stations. Average

  8. Multi-method determination of continuous 2D velocity profiles from the surface to 1 km

    NASA Astrophysics Data System (ADS)

    Peterie, S.; Miller, R. D.; Ivanov, J.; Schwenk, J.; Bailey, B. L.; Schwarzer, J.; Markiewicz, R.

    2012-12-01

    Compressional and shear reflection data provide critical measurements of velocity and attenuation that are necessary for numerical simulations of site response from earthquake energy and seismic investigations to lithologic and pore characterizations. Imperative for accurate site response models is a seismic velocity model extending from the surface to the depth of interest that is representative of the true subsurface. In general, no seismic method can be used to characterize the shallowest (< 30 m) and deepest (30 m to 1 km) portions of the subsurface in a single pass with a consistent set of equipment and acquisition parameters. With four unique seismic surveys targeting different portions of the subsurface and different components of the seismic wavefield, we were able to build a comprehensive dataset that facilitated continuous 2D velocity profiles. The upper kilometer underlying our study site consists of Lake Bonneville lucustrine sediments and post-Bonneville alluvium and colluvium from the nearby Wasatch Front in north central Utah (Eardley, 1938; Hintze, 2005). Four unique seismic surveys were acquired along each of two 1.5 km lines located approximately 3 km apart. Data for tomography and multi-channel analysis of surface waves (MASW) were acquired with a bungee accelerated weight drop and 4.5 Hz compressional geophones. P-wave and S-wave reflection data were acquired with an IVI minivib 1 and 28 Hz compressional and 14 Hz SH geophones, respectively. P-wave and S-wave velocities from the surface to 30 m were determined using tomography and MASW, respectively. Stacking velocities of reflections on common midpoint gathers from the vibroseis data were used to determine Vp and Vs from approximately 30 m to nearly 1 km below ground surface. Each Vp and Vs dataset were merged to generate continuous interval and average velocity profiles. The sutured velocity cross-sections were produced for both P- and S-waves in a fashion not previously described in the

  9. Surficial Geologic Map of the Evansville, Indiana, and Henderson, Kentucky, Area

    USGS Publications Warehouse

    Moore, David W.; Lundstrom, Scott C.; Counts, Ronald C.; Martin, Steven L.; Andrews, William M., Jr.; Newell, Wayne L.; Murphy, Michael L.; Thompson, Mark F.; Taylor, Emily M.; Kvale, Erik P.; Brandt, Theodore R.

    2009-01-01

    The geologic map of the Evansville, Indiana, and Henderson, Kentucky, area depicts and describes surficial deposits according to their origin and age. Unconsolidated alluvium and outwash fill the Ohio River bedrock valley and attain maximum thickness of 33-39 m under Diamond Island, Kentucky, and Griffith Slough, south of Newburgh, Indiana. The fill is chiefly unconsolidated, fine- to medium-grained, lithic quartz sand, interbedded with clay, clayey silt, silt, coarse sand, granules, and gravel. Generally, the valley fill fines upward from the buried bedrock surface: a lower part being gravelly sand to sandy gravel, a middle part mostly of sand, and a surficial veneer of silt and clay interspersed with sandy, natural levee deposits at river's edge. Beneath the unconsolidated fill are buried and discontinuous, lesser amounts of consolidated fill unconformably overlying the buried bedrock surface. Most of the glaciofluvial valley fill accumulated during the Wisconsin Episode (late Pleistocene). Other units depicted on the map include creek alluvium, slackwater lake (lacustrine) deposits, colluvium, dune sand, loess, and sparse bedrock outcrops. Creek alluvium underlies creek floodplains and consists of silt, clayey silt, and subordinate interbedded fine sand, granules, and pebbles. Lenses and beds of clay are present locally. Silty and clayey slackwater lake (lacustrine) deposits extensively underlie broad flats northeast of Evansville and around Henderson and are as thick as 28 m. Fossil wood collected from an auger hole in the lake and alluvial deposits of Little Creek, at depths of 10.6 m and 6.4 m, are dated 16,650+-50 and 11,120+-40 radiocarbon years, respectively. Fossil wood collected from lake sediment 16 m below the surface in lake sediment was dated 33,100+-590 radiocarbon years. Covering the hilly bedrock upland is loess (Qel), 3-7.5 m thick in Indiana and 9-15 m thick in Kentucky, deposited about 22,000-12,000 years before present. Most mapped surficial

  10. Geologic map of the La Mesita Negra SE Quadrangle, Bernalillo County, New Mexico

    USGS Publications Warehouse

    Shroba, Ralph R.; Thompson, Ren A.; Schmidt, Dwight L.; Personius, Stephen F.; Maldonado, Florian; Brandt, Theodore R.

    2003-01-01

    Geologic mapping, in support of the USGS Middle Rio Grande Basin Geologic Mapping Project, shows the spatial distribution of artificial-fill, alluvial, colluvial, and eolian deposits, lava flows and related sediments of the Albuquerque volcanoes, and upper Santa Fe Group sediments. These deposits are on, beneath, and along the West Mesa (Llano de Albuquerque) just west of Albuquerque, New Mexico. Artificial fill deposits are mapped chiefly beneath and near segments of Interstate 40, in an inactive landfill (or dump) north of Interstate 40 near the eastern boundary of the map area, and in the active Cerro Colorado landfill near the southwestern corner of the map area. Alluvial deposits are mapped in stream channels, beneath treads of terraces, and on hill slopes. They include alluvium in stream channels and beneath treads of low terraces, terrace alluvium, sheetwash deposits, gravelly alluvium, and old alluvium and calcic soils of the Llano de Albuquerque. Alluvial and colluvial deposits are mapped on hill slopes. They include young alluvial-slope deposits, alluvium and colluvium, undivided, and old alluvial-slope deposits. Colluvial deposits are also mapped on hill slopes. They include colluvial deposits, undivided, as well as alluvial deposits, eolian sand, and calcic soils associated with fault scarps. Eolian deposits as well as eolian and alluvial deposits mantle gently slopping surfaces on the Llano de Albuquerque. They include active eolian sand, active and inactive eolian sand and sheetwash deposits, undivided, and inactive eolian sand and sheetwash deposits, undivided. Lava flows and related sediments of the Albuquerque volcanoes were mapped near the southeast corner of the map area. They include five young lava flows, two young cinder deposits, and old lava flows. Upper Santa Fe Group sediments are well exposed and mapped in the western part of the map area. They include a gravel unit, a pebbly sand unit, and a mud and sand unit. Undivided upper Santa Fe

  11. An Alternative to Channel-Centered Views of the Landscape for Understanding Modern Streams in the Mid-Atlantic Piedmont Region, Eastern USA

    NASA Astrophysics Data System (ADS)

    Merritts, D. J.; Walter, R. C.; Rahnis, M. A.; Oberholtzer, W.

    2008-12-01

    Stream channels generally are the focus of conceptual models of valley bottom geomorphology. The channel-centered model prevalent in the tectonically inactive eastern U. S. invokes meandering stream channels migrating laterally across valley floors, eroding one bank while depositing relatively coarse sediment in point bars on the other. According to this model, overbank deposition during flooding deposits a veneer of fine sediment over the gravel substrate. Erosion is considered normal, and the net volume of sediment is relatively constant with time. A dramatic change in conditions-land-clearing during European settlement--led to widespread aggradation on valley bottoms. This historic sedimentation was incorporated in the channel-centered view by assuming that meandering streams were overwhelmed by the increased sediment load and rapidly aggraded vertically. Later, elevated stream channels cut through these deposits because of decreased sediment supply and increased stormwater runoff accompanying urbanization. This view can be traced to early ideas of stream equilibrium in which incoming sediment supply and runoff determine stream-channel form. We propose a different conceptual model. Our trenching and field work along hundreds of km of stream length in the mid-Atlantic Piedmont reveal no point bars prior to European settlement. Instead, a polygenetic valley-bottom landscape underlies the drape of historic sediment. The planar surface of this veneer gives the appearance of a broad floodplain generated by long-term meandering and overbank deposition, but the "floodplain" is a recent aggradational surface from regional base-level rise due to thousands of early American dams that spanned valley bottoms. As modern streams incise into the historic fine-grained slackwater sediment, they expose organic-rich hydric soils along original valley bottom centers; talus, colluvium, bedrock, and saprolite with forest soils along valley margins; and weathered Pleistocene (and

  12. Aquifer-test results, direction of ground-water flow, and 1984-90 annual ground-water pumpage for irrigation, lower Big Lost River Valley, Idaho

    USGS Publications Warehouse

    Bassick, M.D.; Jones, M.L.

    1992-01-01

    The study area (see index map of Idaho), part of the Big Lost River drainage basin, is at the northern side of the eastern Snake River Plain. The lower Big Lost River Valley extends from the confluence of Antelope Creek and the Big Lost River to about 4 mi south of Arco and encompasses about 145 mi2 (see map showing water-level contours). The study area is about 18 mi long and, at its narrowest, 4 mi wide. Arco, Butte City, and Moore, with populations of 1,016, 59, and 190, respectively, in 1990, are the only incorporated towns. The entire study area, except the extreme northwestern part, is in Butte City. The study area boundary is where alluvium and colluvium pinch out and abut against the White Knob Mountains (chiefly undifferentiated sedimentary rock with lesser amounts of volcanic rock) on the west and the Lost River Range (chiefly sedimentary rock) on the east. Gravel and sand in the valley fill compose the main aquifer. The southern boundary is approximately where Big Lost River valley fill intercalates with or abuts against basalt of the Snake River Group. Spring ground-water levels and flow in the Big Lost River depend primarily on temperature and the amount and timing of precipitation within the entire drainage basin. Periods of abundant water supply and water shortages are, therefore, related to the amount of annual precipitation. Surface reservoir capacity in the valley (Mackay Reservoir, about 20 mi northwest of Moore) is only 20 percent of the average annual flow of the Big Lost River (Crosthwaite and others, 1970, p. 3). Stored surface water is generally unavailable for carryover from years of abundant water supply to help relieve drought conditions in subsequent years. Many farmers have drilled irrigation wells to supplement surface-water supplies and to increase irrigated acreage. Average annual flow of the Big Lost River below Mackay Reservoir near Mackay (gaging station 13127000, not shown) in water years 1905, 1913-14, and 1920-90 was about 224

  13. Eastern Denali Fault Slip Rate and Paleoseismic History, Kluane Lake Area, Yukon Territory, Canada

    NASA Astrophysics Data System (ADS)

    Seitz, G. J.; Haeussler, P. J.; Crone, A. J.; Lipovsky, P.; Schwartz, D. P.

    2008-12-01

    expressed by an upslope southwest-facing 9-m-high scarp. In 2008 we targeted this location (61°21'54.36"N,139°07'59.34"W) with three cross-fault excavations that exposed deformed sediments. Evidence for at least 3 paleoearthquakes was recognized in fissure fills, folding, and scarp- derived colluvium. Preliminary age control is provided by the two White River volcanic ashes (1.2 ka and 1.9 ka) exposed in the trenches and by unfaulted paleo-shorelines of Alsek and Kluane Lakes, which others suggest have an age of 0.3-0.5 ka, respectively. The most recent event post-dates the 1.2 ka White River ash and occurred prior to formation of the 0.3 ka and 0.5 ka shorelines. The older events pre-date the 1.9 ka White River ash. Radiocarbon will be analyzed to further improve the chronology. Although the ages of the two older events are uncertain, trench and field relations suggest that the most recent event (MRE) occurred close in time to deposition of the 1.2 ka ash. The observations of a lower slip rate on the eastern Denali fault in the Yukon are consistent with previous regional tectonic models. The occurrence of at least three surface- rupturing paleoearthquakes in late Holocene time, and a significant elapsed time since the MRE, emphasizes the need for proper seismic design of proposed natural gas pipelines in this region.

  14. Questa Baseline and Pre-Mining Ground-Water Quality Investigation. 17. Geomorphology of the Red River Valley, Taos County, New Mexico, and Influence on Ground-Water Flow in the Shallow Alluvial Aquifer

    USGS Publications Warehouse

    Vincent, Kirk R.

    2008-01-01

    where erosion-resistant bedrock, which tends to form vertical cliffs, restricts the width of the valley bottom. Although the presence of a shallow bedrock sill, overlain by shallow alluvium, is a plausible cause of ground-water emergence, this cause was not demonstrated in the study area. The water-table gradient can locally decrease in the downstream direction because of changes in the hydraulic properties of the alluvium, and this may be a contributing cause of ground-water emergence. However, at one site (near Cabin Springs), ground-water emergence could not be explained by spatial changes in geometric or hydraulic properties of the aquifer. Furthermore, the available evidence demonstrates that ground water flowing through bedrock fractures or colluvium entered the north side of the alluvial aquifer, and is the cause of ground-water emergence. At that location the alluvial aquifer was already flowing full, causing the excess water to emerge into the stream. An indirect consequence of altered rock in the tributary watersheds is the rapid erosion rate of alteration scars combined with the hydraulic properties of sediments shed from those scars. Where alteration scars are large the debris fans at the mouths of the tributary watersheds substantially encroach into the Red River Valley. At such locations debris-fan materials dominate the width and thickness of the alluvium in the valley and reduce the rate of flow of ground water within the Red River alluvial aquifer. Most sites of groundwater emergence are located immediately upstream from or along the margins of debris fans. A substantial fraction of the ground water approaching a debris fan can emerge to become streamflow. This last observation has three implications. First, very little water can flow the entire length of the study area entirely within the alluvial aquifer because the ground water repeatedly contacts debris-fan sediments over that length. Second, it follows that emerging water containing

  15. Earthquake History of the Northern Imperial Fault, Imperial Valley, California, since the last Lake Cahuilla Highstand, circa A.D. 1680

    NASA Astrophysics Data System (ADS)

    Meltzner, A. J.; Rockwell, T. K.; Verdugo, D. M.

    2003-12-01

    has both dextral and normal slip components. On the downdropped side of the fault, a laminated clay unit (inferred to be the most recent LC clay, at ca. A.D. 1680; dating results are pending) is exposed in the trench and is overlain by nearly 2 m of younger deposits; the overlying material consists of bedded fine sands and silts (inferred to be overbank deposits from a nearby channel), which interfinger with massive silts and clays (inferred mostly to be colluvium). Unfortunately, the normal component of slip for all earthquakes in the trench was almost exclusively restricted to a single east-dipping plane or set of closely spaced planes, so that the amount of dip slip per event cannot be resolved; nonetheless, a series of fissures and flower structures adjacent to the main fault in the hangingwall block permit the distinction of individual events. There is good evidence for 4, and possibly 5 events since the last LC highstand, based on filled-in fissures and abrupt upward terminations of multiple fault strands and liquefaction cracks. The youngest of these events are inferred to be 1979 and 1940; the oldest, which produced liquefaction and ruptured to the top of the most recent lake deposits, probably occurred at or very soon after the highstand, based on the arguments that no lake deposits post-date the event, and that the ground was still saturated at the time of the earthquake. This event may have been the penultimate (ca. A.D. 1680) event seen on the central patch of the IF.

  16. Preliminary analysis of relevant parameters for debris-flow entrainment using field data and two different numerical codes in the Eastern Pyrenees.

    NASA Astrophysics Data System (ADS)

    Udia Abancó, Clá; Hürlimann, Marcel

    2010-05-01

    . 2005) that entrainment is a very complex process depending on multiple parameters. The scatter of the data makes it impossible to establish well defined empirical relationships. However, crude trends can be seen in relation to the effect of channel bed slope and peak discharge. They point out an increase of entrainment in steeper slopes, specially if an considerable colluvium layer is available. It can also be seen that in flows of greater peak discharge the entrainment ratios are higher. Results obtained by the numerical simulations of the four events using different entrainment approaches indicate that DAN can be perfectly applied for back-analyses, when post-event data of the erosion rate are available. Forward prediction, however, is more difficult since entrainment is a pre-defined variable and must be estimated by field observations. In contrast, the entrainment rate in GITS-1D strongly depends on the friction angle of the bed material and the erosion volume is very sensitive even for small changes of this parameter. References: Hungr, O., McDougall, S., Bovis, M., 2005. Entrainment of material by debris flow. In: Jakob, M., Hungr, O. (Eds.), Debris-flow Hazards and Related Phenomena. Springer, Berlin, pp. 135-158.

  17. Stability Problems at Ancient Cnidus (Datca, SW Turkey) and Its Relationship with Local Tectonics

    NASA Astrophysics Data System (ADS)

    Şengül, M. Alper

    2013-04-01

    The main scope of this work was investigating the causes of bending and collapsing in the retaining wall of Stoa at ancient Cnidus (SW Turkey) and observing its relationship with local tectonism and seismicity. As a result of datas, some solutions in order to prevent for different or more deformations that may occur on the wall in the future is presented. The observed collapse in the wall seems to be engineering problem. To be taken filling material by human factor has brought the instability in the wall. Founding of the ancient Cnidus considered many damaging natural possibilities like earthquake, landslide and rockfall and city structures designed in this way. However, these designs were insufficient to the effects of the earthquakes and active tectonism which shown on the region. The study area was located at the end of Datca Peninsula (SW Turkey). The ancient city of Cnidus and therefore Datca peninsula and Rhodes are one of the most active district in terms of seismicity in the southern Aegean sea. There are a lot of different sized earthquakes recorded both the historical and instrumental periods affecting the region. Very recently the earthquake storm in the sea maintains a sign of activity of the region. Since the establishment of the ancient Cnidus, medium and large earthquakes occurred in the area and affected by highly and experienced serious destruction. Still traces of these earthquakes can be observed on the surface and structures. These earthquakes affected structures directly and also could have made changes in ground conditions. As it is already known, because during and immediately after an earthquake, such as landslide, creep, rock fall events can be occur. The ancient Cnidus settled in an area be experienced similar problems. A part of the ancient Cnidus is located on a relatively weakly fitted colluvium material which is a cover unit on whole sloping area. The majority of structures are builded on the debris and filling material especially at

  18. Ground-water resources of Riverton irrigation project area, Wyoming

    USGS Publications Warehouse

    Morris, Donald Arthur; Hackett, O.M.; Vanlier, K.E.; Moulder, E.A.; Durum, W.H.

    1959-01-01

    The Riverton irrigation project area is in the northwestern part of the Wind River basin in west-central Wyoming. Because the annual precipitation is only about 9 inches, agriculture, which is the principal occupation in the area, is dependent upon irrigation. Irrigation by surface-water diversion was begum is 1906; water is now supplied to 77,716 acres and irrigation has been proposed for an additional 31,344 acres. This study of the geology and ground-water resources of the Riverton irrigation project, of adjacent irrigated land, and of nearby land proposed for irrigation was begun during the summer of 1948 and was completed in 1951. The purpose of the investigation was to evaluate the ground-water resources of the area and to study the factors that should be considered in the solution of drainage and erosional problems within the area. The Riverton irrigation project area is characterized by flat to gently sloping stream terraces, which are flanked by a combination of badlands, pediment slopes, and broad valleys. These features were formed by long-continued erosion in an arid climate of the essentially horizontal, poorly consolidated beds of the Wind River formation. The principal streams of the area flow south-eastward. Wind River and Fivemile Creek are perennial streams and the others are intermittent. Ground-water discharge and irrigation return flow have created a major problem in erosion control along Fivemile Creek. Similar conditions might develop along Muddy and lower Cottonwood Creeks when land in their drainage basins is irrigated. The bedrock exposed in the area ranges in age from Late Cretaceous to early Tertiary (middle Eocene). The Wind River formation of early and middle Eocene age forms the uppermost bedrock formation in the greater part of the area. Unconsolidated deposits of Quaternary age, which consist of terrace gravel, colluvium, eolian sand and silt. and alluvium, mantle the Wind River formation in much of the area. In the irrigated parts

  19. "The Great Cataract" - Effects of Late Holocene Debris Flows on Lava Falls Rapid, Grand Canyon National National Park, Arizona

    USGS Publications Warehouse

    Webb, Robert H.; Melis, Theodore S.; Wise, Thomas W.; Elliott, John G.

    1996-01-01

    Lava Falls Rapid is the most formidable reach of whitewater on the Colorado River in Grand Canyon and is one of the most famous rapids in the world. Although the rapid was once thought to be controlled by the remnants of lava dams of Pleistocene age, Lava Falls was created and is maintained by frequent debris flows from Prospect Canyon. We used 232 historical photographs, of which 121 were replicated, and 14C and 3He dating methods to reconstruct the ages and, in some cases, the magnitudes of late Holocene debris flows. We quantified the interaction between Prospect Canyon debris flows and the Colorado River using image processing of the historical photographs. The highest and oldest debris-flow deposits on the debris fan yielded a 3He date of 2.9?0.6 ka (950 BC), which indicates predominately late Holocene aggradation of one of the largest debris fans in Grand Canyon. The deposit, which has a 25-m escarpment caused by river reworking, crossed the Colorado River and raised its base level by 30 m for an indeterminate, although probably short, period. We mapped depositional surfaces of 6 debris flows that occurred after 950 BC. The most recent prehistoric debris flow occurred no more than 500 years ago (AD 1434). From April 1872 to July 1939, no debris flows occurred in Prospect Canyon. Debris flows in 1939, 1954, 1955, 1963, 1966, and 1995 constricted the Colorado River between 35 and 80 percent and completely changed the pattern of flow through the rapid. The debris flows had discharges estimated between about 290 and 1,000 m3/s and transported boulders as heavy as 30 Mg. The recurrence interval of these debris flows, calculated from the volume of the aggraded debris fan, ranged from 35 to 200 yrs. The 1939 debris flow in Prospect Canyon appears to have been the largest debris flow in Grand Canyon during the last 125 years. Debris flows in Prospect Canyon are initiated by streamflow pouring over a 325-m waterfall onto unconsolidated colluvium, a process called the

  20. Integrating Multiple Subsurface Exploration Technologies in Slope Hydrogeologic Investigation: A Case Study in Taiwan

    NASA Astrophysics Data System (ADS)

    Lo, H.-C.; Hsu, S.-M.; Jeng, D.-I.; Ku, C.-Y.

    2009-04-01

    resistivity profiles combined with rock core data, the geologic units can be primarily categorized into colluvium and weathered rock at depths of 4-23 m and 23-80 m, respectively. An approximately 20 m shear zone at depths of 45-65 m was found based on the detection outcome of low electrical resistance. Also, according to the borehole electrical logging, the layer of sandstone was identified in the interval of 48-59 m and 68.5-74 m and showed low water-bearing capacity. In addition, the electrical logging identified the layer of shale was in the interval of 59-68.5 m, which possessed a high water-bearing capacity. The velocity profile along the borehole was obtained from the flowmeter logging. A relatively high velocity zone (1.36~2.23 m/min) was measured in the interval of sandstone and relatively low velocity zone (0.12~0.78 m/min) was measured in the interval of shale, which is similar to those found in electrical logging. Moreover, 198 discontinuity planes were identified from the borehole image logging. The orientations of all discontinuities were calculated and compiled to draw a stereographic projection diagram. Judging from the discontinuity clusters on the stereographic projection diagram, a plane failure may possibly occur based on Hoek and Brown's criteria. This is a good demonstration that slope failure geometry and type can be determined by stereographic projection diagram analysis. The borehole images also clearly showed the structures of discontinuities at depth. They not only helped to characterize the results of the above investigation technologies but also provided useful indication in selecting specific geologic intervals for packer tests. The packer tests were conducted and the intervals were isolated based on the results of borehole and flowmeter logging. They indicated that the hydraulic conductivities of the shale and sandstone intervals are respectively 1.37Ã-10-8 m/sec and 2.68Ã-10-5-3.76Ã-10-5 m/sec, which are in good accordance with the hydraulic