Maps

The geologic map of the San Antonio Mountain area in northern New Mexico and southern Colorado is located along the west-central part of the San Luis Valley. The San Luis Valley is the geomorphic expression of the San Luis Basin, an extensional basin associated with the northern Rio Grande rift. Deposits within the map area record volcanic, sedimentary, and tectonic processes over the last ~33 mil

This map summarizes the geology of the U.S. Geological Survey Osage SW 7.5-minute quadrangle in the Ozark Plateaus region of northern Arkansas. Physiographically, the Osage SW quadrangle is located within a transitional area between the Boston Mountains to the south, and the Springfield Plateau to the north. Geologically, the area is on the southern flank of the Ozark dome; an uplift with the olde

The Fort Morgan 7.5′ quadrangle is located on the semiarid plains of northeastern Colorado, along the South Platte River corridor where the river has incised into Upper Cretaceous Pierre Shale. The Pierre Shale is largely covered by surficial deposits that formed from alluvial, eolian, and hillslope processes operating in concert with environmental changes from the late Pliocene to the present. Th

The Leadville North 7.5’ quadrangle lies at the northern end of the Upper Arkansas Valley, where the Continental Divide at Tennessee Pass creates a low drainage divide between the Colorado and Arkansas River watersheds. In the eastern half of the quadrangle, the Paleozoic sedimentary section dips generally 20–30 degrees east. At Tennessee Pass and Missouri Hill, the core of the Sawatch anticlinori

The Weldona 7.5′ quadrangle is located on the semiarid plains of northeastern Colorado, along the South Platte River corridor where the river has incised into Upper Cretaceous Pierre Shale. The Pierre Shale is largely covered by surficial deposits that formed from alluvial, eolian, and hillslope processes operating in concert with environmental changes from the Pleistocene to the present. The Sout

The surficial geologic map of Berrien County, southwestern Michigan (sheet 1), shows the distribution of glacial and postglacial deposits at the land surface and in the adjacent offshore area of Lake Michigan. The geologic map differentiates surficial materials of Quaternary age on the basis of their lithologic characteristics, stratigraphic relationships, and age. Drill-hole information correlate

The Edwards and Trinity aquifers are major sources of water in south-central Texas and are both classified as major aquifers by the State of Texas. The population in Hays and Comal Counties is rapidly growing, increasing demands on the area’s water resources. To help effectively manage the water resources in the area, refined maps and descriptions of the geologic structures and hydrostratigraphic

IntroductionThe northern White Hills map area lies within the Kingman Uplift, a regional structural high in which Tertiary rocks lie directly on Proterozoic rocks as a result of Cretaceous orogenic uplift and erosional stripping of Paleozoic and Mesozoic strata. The Miocene Salt Spring Fault forms the major structural boundary in the map area. This low-angle normal fault separates a footwall (lowe

The 7.5′ Strawberry Butte quadrangle in Meagher County, Montana near the southwest margin of the Little Belt Mountains, encompasses two sharply different geologic terranes.  The northern three-quarters of the quadrangle are underlain mainly by Paleoproterozoic granite gneiss, across which Middle Cambrian sedimentary rocks rest unconformably.  An ancestral valley of probable late Eocene age, eroded

This 1:24,000-scale geologic map includes new geologic mapping as well as compilation and revision of previous geologic maps in the area. Field investigations were carried out during 2009–2011 that included mapping and investigations of the geology and hydrology of the Chickasaw National Recreation Area, Oklahoma, west of the map area.The Fittstown quadrangle is in Pontotoc and Johnston Counties i

This 1:50,000-scale U.S. Geological Survey geologic map represents a compilation of the most recent geologic studies of the upper Arkansas River valley between Leadville and Salida, Colorado. The valley is structurally controlled by an extensional fault system that forms part of the prominent northern Rio Grande rift, an intra-continental region of crustal extension. This report also incorporates

This report presents the geologic framework, hydro­stratigraphy, and ichnology of the Trinity and Edwards Groups in the Blanco, Payton, and Rough Hollow 7.5-minute quad­rangles in Blanco, Comal, Hays, and Kendall Counties, Texas. Rocks exposed in the study area are of the Lower Cretaceous Trinity Group and lower part of the Fort Terrett Formation of the Lower Cretaceous Edwards Group. The mapped u