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During 2009, the Alaska Division of Geological & Geophysical Surveys continued a program, begun in 2006, of reconnaissance mapping of surficial geology in the proposed natural-gas pipeline corridor through the upper Tanana River valley. The study area is a 12-mi-wide (19.3-km-wide) area that straddles the Alaska Highway from the western boundaries of the Tanacross B-3 and A-3 quadrangles near Tetlin Junction eastward to the eastern boundaries of the Nabesna D-1 and C-1 quadrangles along the Canada border. Mapping during 2008-2009 in the Tanacross and Nabesna quadrangles linked with the mapping completed in the Tanacross, Big Delta and Mt. Hayes quadrangles in 2006-2008. Surficial geology was initially mapped in...
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This map illustrates extents and types of unconsolidated deposits and bedrock in the Big Delta A-4 Quadrangle, Alaska. This map is based on field observations begun by P�w� in 1949 and by Reger in 1976. Unit characteristics and extents were determined during field visits and by interpreting 1:40,000-scale black-and-white aerial photographs taken in August 1949 and 1:63,360-scale, false-color infrared aerial photographs taken in July 1978, August 1980, and August 1981.
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Temporal and spatial sources of silica for chert remain poorly constrained. Modern sources to the worlds oceans include silica in rivers > aeolian (dust) deposition > sea floor vents and submarine weathering. However, changes in aridity and dust flux during the Phanerozoic may explain variations in the ocean silica cycle and times and places of chert formation. The chemistry of fine quartz dust (FQD) provides a chemical mechanism for the transformation of FQD to polymorphs of silica in chert; FQD is readily dissolved, then reprecipitated as Opal-A by either biotic or abiotic processes. An unequivocal relation between increases in dust flux and biogenic opal-A in the western Pacific Ocean during the past 200 kyr...
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The surficial geologic map of the Eastern and Central United Statesdepicts the areal distribution of surficial geologic deposits and othermaterials that accumulated or formed during the past 2+ million years,the period that includes all activities of the human species. Thesematerials are at the surface of the earth. They make up the "ground"on which we walk, the "dirt" in which we dig foundations, and the �soil�in which we grow crops. Most of our human activity is related in oneway or another to these surface materials that are referred tocollectively by many geologists as regolith, the mantle of fragmentaland generally unconsolidated material that overlies the bedrockfoundation of the continent. The map is based...
Tags: Lake Erie quadrangle, West Virginia, Grus, Till, Marl, All tags...
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This digital database is the product of collaboration between the U.S. Geological Survey, the Alfred Wegener Institute for Polar and Marine Research Potsdam, Foothill College GeoSpatial Technology Certificate Program, and the Geophysical Institute at the University of Alaska. The primary goal for creating this digital database is to enhance current estimates of organic carbon stored in deep permafrost, in particular Late Pleistocene syngenetic ice-rich loess permafrost deposits, called Yedoma. This deposit is vulnerable to thermokarst and erosion due to natural and anthropogenic disturbances. The original paper maps were issued by the Department of Natural Resources of the Russian Federation or its predecessor the...
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Thirty-nine types of surficial geologic deposits and residualmaterials of Quaternary age are described and mapped in the greaterDenver area, in part of the Front Range, and in the piedmont andplains east of Denver, Boulder, and Castle Rock. Descriptionsappear in the pamphlet that accompanies the map. Landslidedeposits, colluvium, residuum, alluvium, and other deposits ormaterials are described in terms of predominant grain size, mineralor rock composition (e.g., gypsiferous, calcareous, granitic,andesitic), thickness of deposits, and other physicalcharacteristics. Origins and ages of the deposits and geologichazards related to them are noted. Many lines between geologicunits on our map were placed by generalizing...
Tags: gravel, Watkins, 08031 = Denver, 08049 = Grand, 08059 = Jefferson, All tags...
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Thin loess deposits on the uplands of the southeastern Colorado Plateau have previously not been well studied. We sampled deposits and soils from trenches on Hatch Point mesa near Canyonlands National Park, Utah, and from two outcrops in Mesa Verde National Park, Colorado. At Hatch Point, the oldest buried unit yielded two OSL ages of 10,370 and 7,555 yr; the middle unit yielded 10 OSL ages from 6220 to 1385 yr; and the youngest unit has a single age of 1740 yr. At Mesa Verde, three loess units are preserved in the two outcrops we examined; six OSL ages range from 51 to 17 ka. At least one buried soil is present between two units with ages of about 50 and 40 ka. The ages of the loess units in both study areas correspond...


map background search result map search result map Surficial deposits and materials in the eastern and central UnitedStates (east of 102 degrees west longitude) Generalized Surficial Geologic Map of the Denver 1�x2� Quadrangle, Colorado Geologic map of the Saint Joseph area, Missouri and Kansas Digital Database and Maps of Quaternary Deposits in East and Central Siberia Data release for Late Quaternary loess and soils on uplands in the Canyonlands and Mesa Verde areas, Utah and Colorado Engineering-geologic map of the Alaska Highway corridor, Tetlin Junction to Canada border, Alaska Surficial geology of the Dalton Highway (Itkillik-Sagavanirktok rivers) area, southern Arctic foothills, Alaska Geologic map of the Big Delta A-4 Quadrangle, Alaska The chemistry of eolian quartz dust and the origin of chert Data release for Late Quaternary loess and soils on uplands in the Canyonlands and Mesa Verde areas, Utah and Colorado Geologic map of the Big Delta A-4 Quadrangle, Alaska Geologic map of the Saint Joseph area, Missouri and Kansas Surficial geology of the Dalton Highway (Itkillik-Sagavanirktok rivers) area, southern Arctic foothills, Alaska Generalized Surficial Geologic Map of the Denver 1�x2� Quadrangle, Colorado Engineering-geologic map of the Alaska Highway corridor, Tetlin Junction to Canada border, Alaska Surficial deposits and materials in the eastern and central UnitedStates (east of 102 degrees west longitude) Digital Database and Maps of Quaternary Deposits in East and Central Siberia The chemistry of eolian quartz dust and the origin of chert