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The Raton basin is a large asymmetric syncline (2500 mi2 area) that extends from Huerfano Park, Colorado to Cimarron, New Mexico. As used here, the basin is defined by the limits of the outcrop of the Trinidad Sandstone. The Cretaceous and Tertiary rocks are sharply flexed to form hogbacks along the western margin of the basin on the east flank of the Sangre de Cristo Mountains. These rocks assume more gentle dips along the other margins of the Raton basin and are highly dissected. The Late Cretaceous in the Raton basin was a period of emergence of land and retreat of the Cretaceous epeiric sea. The coastline advanced eastward across New Mexico, as broad prograding deltaic and barrier coastal plains were formed...
The geologic map of the Hogback Mountain quadrangle, scale 1:24,000, was made as part of the Montana Investigations Project to provide new information on the stratigraphy, structure, and geologic history of an area in the geologically complex southern part of the Montana disturbed belt. In the Hogback Mountain area, rocks ranging in age from Middle Proterozoic through Cretaceous are strongly folded within and under thrust plates of equivalent rocks. Continental rocks of successive thrust plates have been telescoped eastward over a buttress of the stable continent. Erosional remnants of Oligocene andesitic basalt lie on highest surfaces eroded across the strongly deformed older rocks; younger erosion has dissected...
The Palisade 1:24,000 quadrangle is in Mesa County in westernColorado. Because the map area is dominated by various surficialdeposits, the map depicts 22 different Quaternary units. Twoprominent river terraces are present in the quadrangle containinggravels deposited by the Colorado River. The map area containsmany mass movement deposits. Extensive landslide deposits arepresent along the eastern part of the quadrangle. These massivelandslides originate on the flanks of Grand Mesa, in the GreenRiver and Wasatch Formations, and flow west onto the Palisadequadrangle. In addition, large areas of the eastern and southernparts of the map are covered by extensive pediment surfaces.These pediment surfaces are underlain...
This digital geologic map compilation presents new polygon(i.e., geologic map unit contacts), line (i.e., fault, foldaxis, and structure contour), and point (i.e., structuralattitude, contact elevations) vector data for the Jasper 7 1/2'quadrangle in northern Arkansas. The map database, which is at1:24,000-scale resolution, provides geologic coverage of anarea of current hydrogeologic, tectonic, and stratigraphicinterest. The Jasper quadrangle is located in northern Newtonand southern Boone Counties about 20 km south of the town ofHarrison. The map area is underlain by sedimentary rocks ofOrdovician, Mississippian, and Pennsylvanian age that weremildly deformed by a series of normal and strike-slip faults andfolds....
New 1:24,000-scale geologic mapping along the Interstate-70urban corridor in western Colorado, in support of the State/USGS Cooperative Geologic Mapping Project, is contributing to amore complete understanding of the stratigraphy, structure,tectonic evolution, and hazard potential of this rapidlydeveloping region. The 1:24,000-scale Vail East quadranglestraddles the Gore fault system, the western structuralboundary of the Gore Range. The Gore fault system is acontractional structure that has been recurrently active sinceat least the early Paleozoic and marks the approximate easternboundary of the Central Colorado trough, a thick late Paleozoicdepocenter into which thousands of meters of clastic sedimentwere deposited...
The Quaternary Geologic Map of the Lake Erie 4� x 6� Quadranglewas mapped as part of the Quaternary Geologic Atlas of the United States.The atlas was begun as an effort to depict the areal distribution ofsurficial geologic deposits and other materials that accumulated orformed during the past 2+ million years, the period that includes allactivities of the human species. These materials are at the surface ofthe earth. They make up the "ground" on which we walk, the "dirt" inwhich we dig foundations, and the "soil" in which we grow crops. Mostof our human activity is related in one way or another to these surfacematerials that are referred to collectively by many geologists asregolith, the mantle of fragmental and...
New 1:24,000-scale geologic mapping along the Interstate-70 urban corridor in western Colorado, in support of the USGS Central Region State/USGS Cooperative Geologic Mapping Project, is contributing to a more complete understanding of the stratigraphy, structure, tectonic evolution, and hazard potential of this rapidly developing region. The 1:24,000-scale Frisco quadrangle is near the headwaters of the Blue River and straddles features of the Blue River graben (Kellogg, K.S., 1999, Neogene basins of the northern Rio Grande rift�partitioning and asymmetry inherited from Laramide and older uplifts: Tectonophysics, v. 305, p. 141-152.), part of the northernmost reaches of the Rio Grande rift, a major late Oligocene...
The Sawmill Mountain quadrangle is located in the western Transverse Ranges of California, about 10 km west of Frazier Park. It includes Mt. Pinos, Mt. Abel (Cerro Noroeste), a part of the southern San Emigdio Mountains, and straddles an eleven-kilometer reach of the nearly east-west striking "Big Bend" section of the San Andreas Fault.South of the San Andreas Fault, the oldest rocks include undated amphibolite-grade biotite and hornblende-biotite gneiss that is probably early or middle Proterozoic in age. The older gneiss is intruded by strongly deformed and foliated biotite orthogneiss that has an age on biotite of 67.2+0.5 Ma (Late Cretaceous). Several other weakly foliated to massive Late Cretaceous granitic...
This digital geologic map compilation presents new polygon (i.e., geologic map unit contacts), line (i.e., fault, fold axis, dike, and caldera wall), and point (i.e., structural attitude) vector data for the Thirsty Canyon NW 7 1/2' quadrangle in southern Nevada. The map database, which is at 1:24,000-scale resolution, provides geologic coverage of an area of current hydrogeologic and tectonic interest. The Thirsty Canyon NW quadrangle is located in southern Nye County about 20 km west of the Nevada Test Site (NTS) and 30 km north of the town of Beatty. The map area is underlain by extensive layers of Neogene (about 14 to 4.5 million years old [Ma]) mafic and silicic volcanic rocks that are temporally and spatially...
The Eagle quadrangle covers an area that straddles the Eagle River and Interstate 70 (I-70) and it includes the town of Eagle, Colo., which is located in the southwestern part of the quadrangle, just south of I-70 and the Eagle River, about 37 km west of Vail, Colo. The map area is part of the I-70 urban corridor, which is experiencing rapid and escalating urban growth. Geologic mapping along this corridor is needed for ongoing land-use planning. A variety of rocks and deposits characterize the map area and areas nearby. Sedimentary rocks present in the map area range in age from Pennsylvanian rocks, which were deposited in the ancestral Eagle basin during the formation of the ancestral Rocky Mountains, to Late...
1:24,000-scale geologic mapping in the Clifton 7.5' quadrangle, insupport of the USGS Colorado River/I-70 Corridor Cooperative GeologicMapping Project, provides interpretations of the Quaternarystratigraphy and geologic hazards in this area of the Grand Valley.The Clifton 1:24,000 quadrangle is in Mesa County in westernColorado. Because the map area is dominated by various surficialdeposits, the map depicts 16 different Quaternary units. Fiveprominent river terraces are present in the quadrangle containinggravels deposited by the Colorado River. The map area contains alarge landslide deposit on the southern slopes of Mount Garfield.The landslide developed in the Mancos Shale and contains large blocksof the overlying...
This quadrangle lies 6.4 km (4 mi) northeast of Bozeman, Mont., insouthwestern Montana. Metamorphic, sedimentary, and volcanic rocksof Precambrian to Tertiary age are exposed in the Bridger Range andsouthwestern margin of the Crazy Mountains Basin in a crustal crosssection and a structural triangle zone. Surface geology recordsPrecambrian extension, Late Paleocene east-vergent contraction,including backthrusts, and Holocene basin-range extension.
The Raton basin is a large asymmetric syncline (2500 mi2 area) that extends from Huerfano Park, Colorado to Cimarron, New Mexico. As used here, the basin is defined by the limits of the outcrop of the Trinidad Sandstone. The Cretaceous and Tertiary rocks are sharply flexed to form hogbacks along the western margin of the basin on the east flank of the Sangre de Cristo Mountains. These rocks assume more gentle dips along the other margins of the Raton basin and are highly dissected. The Late Cretaceous in the Raton basin was a period of emergence of land and retreat of the Cretaceous epeiric sea. The coastline advanced eastward across New Mexico, as broad prograding deltaic and barrier coastal plains were formed...
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...
New 1:24,000-scale geologic mapping in the Colorado National Monument Quadrangle and adjacent areas, in support of the USGS Western Colorado I-70 Corridor Cooperative Geologic Mapping Project, provides new interpretations of and data for the stratigraphy, structure, geologic hazards in the area from the Colorado River in Grand Valley onto the Uncompahgre Plateau. The plateau drops abruptly along northwest-trending structures toward the northeast 800 m to the Redlands area and the Colorado River in Grand Valley.In addition to common alluvial and colluvial deposits, surficial deposits include Holocene and late Pleistocene charcoal-bearing valley-fill deposits, late to middle Pleistocene river-gravel terrace deposits,...
This dataset represents geology compiled for the upper AnimasRiver Watershed near Silverton, Colorado. The source data usedare derived from 1:24,000, 1:20,000, 1:48,000 and 1:250,000-scalegeologic maps by geologists who have worked in this area sincethe early 1960's.
The Bernalillo NW quadrangle is located in the northern part of theAlbuquerque basin, which is the largest basin or graben within theRio Grande rift. The quadrangle is underlain by poorly consolidatedsedimentary rocks of the Santa Fe Group. These rocks are best exposedin the southwestern part of the quadrangle in the Rincones de Zia, abadland topography cut by northward-flowing tributary arroyos of theJemez River. The Jemez River flows through the northern half of thequadrangle; extensive fluvial and eolian deposits cover bedrock unitsalong the river. The structural fabric of the quadrangle is dominatedby dozens of generally north striking, east and west-dipping normalfaults and minor folds associated with the Neogene...
During the late Wisconsin glaciation (circa 26,000-13,000 carbon-14 yrBP) the Cordilleran glacier complex formed vast ice fields and largeglaciers along the crest of the Coast Mountains. As these glaciersflowed west to the Pacific Ocean, they were joined by local glaciersoriginating on the higher reaches of the Alexander Archipelago (Mannand Hamiltion, 1995). This extensive volume of ice was channeled intodeep troughs (present-day fiords) that formed major outlet glaciers,such as the glaciers that occupied Chatham Strait and Dixon Entrance.In several places along the coast, deep glacially scoured submarinetroughs indicate that glaciers reached to the edge of the continentalshelf. For instance, the glacier that extended...
This new 1:24,000-scale geologic map of the Vail West 7.5' quadrangle, as part of the USGS Western Colorado I-70 Corridor Cooperative Geologic Mapping Project, provides new interpretations of the stratigraphy, structure, and geologic hazards in the area on the southwest flank of the Gore Range.Bedrock strata include Miocene tuffaceous sedimentary rocks, Mesozoic and upper Paleozoic sedimentary rocks, and undivided Early(?) Proterozoic metasedimentary and igneous rocks. Tuffaceous rocks are found in fault-tilted blocks. Only small outliers of the Dakota Sandstone, Morrison Formation, Entrada Sandstone, and Chinle Formation exist above the redbeds of the Permian-Pennsylvanian Maroon Formation and Pennsylvanian Minturn...
The locations of principal faults and structural zones that may influence ground-water flow were compiled in support of a three-dimensional ground-water model for the Death Valley regional flow system (DVRFS), which covers 80,000 square km in southwestern Nevada and southeastern California. Faults include Neogene extensional and strike-slip faults and pre-Tertiary thrust faults. Emphasis was given to characteristics of faults and deformed zones that may have a high potential for influencing hydraulic conductivity. These include: (1) faulting that results in the juxtaposition of stratigraphic units with contrasting hydrologic properties, which may cause ground-water discharge and other perturbations in the flow system;...
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