Map Releases

The Catahoula aquifer is an important source of fresh groundwater in central Louisiana. In 2010, about 3.96 million gallons per day (Mgal/d) were withdrawn from the Catahoula aquifer in Louisiana. In 2012, the U.S. Geological Survey in cooperation with the Louisiana Department of Natural Resources began a study to document current water levels in selected aquifers in Louisiana. This...

Geologic cross section I‒I’ is the fourth in a series of cross sections constructed by the U.S. Geological Survey to document and improve understanding of the geologic framework and petroleum systems of the Appalachian basin. Cross section I‒I’ provides a regional view of the structural and stratigraphic framework of the Appalachian basin from the eastern margin of the Illinois basin in...

The U.S. Geological Survey (USGS), in cooperation with the National Oceanic and Atmospheric Administration's National Marine Sanctuary Program, has conducted seabed mapping and related research in the Stellwagen Bank National Marine Sanctuary (SBNMS) region since 1993. The area is approximately 3,700 square kilometers (km2) and is subdivided into 18 quadrangles. Seven maps, at a scale of...

Introduction Chambers Lake is a manmade reservoir on Birch Run, a tributary to West Branch Brandywine Creek in Chester County, Pennsylvania. The lake was created in 1994 after the completion of Multi-Purpose Dam PA-436F (Hibernia Dam), which was built under the Watershed Protection & Flood Control Prevention Act (U.S. Soil Conservation Service, 1991). Hibernia dam is 1,700 feet upstream...

The Alamosa 30'× 60' quadrangle is located in the central San Luis Basin of southern Colorado and is bisected by the Rio Grande. The Rio Grande has headwaters in the San Juan Mountains of Colorado and ultimately discharges into the Gulf of Mexico 3,000 kilometers (km) downstream. Alluvial floodplains and associated deposits of the Rio Grande and east-draining tributaries, La Jara Creek...

Digital flood-inundation maps for a 5.3-mile reach of South Fork Peachtree Creek that extends from about 500 feet above the Brockett Road bridge to the Willivee Drive bridge were developed by the U.S. Geological Survey (USGS) in cooperation with DeKalb County, Georgia. The flood-inundation maps, which can be accessed through the USGS Flood Inundation Mapping Science Web site at http:/...

The bedrock geology of the 7.5-minute Worcester South quadrangle, Massachusetts, consists of deformed Neoproterozoic to Paleozoic crystalline metamorphic and intrusive igneous rocks in three fault-bounded terranes (zones), including the Avalon, Nashoba, and Merrimack zones (Zen and others, 1983). This quadrangle spans the easternmost occurrence of Ganderian margin arc-related rocks...

This map and accompanying digital files are the result of the interpretation of aerial photographs from the 1950s as well as more modern imagery. The area, long considered a part of Alaska that was largely not glaciated (see Karlstrom, 1964; Coulter and others, 1965; or Péwé, 1975), actually has a long history reflecting local and more distant glaciations. An unpublished photogeologic...

The Masters 7.5' quadrangle is located along the South Platte River corridor on the semiarid plains of eastern Colorado and contains surficial deposits that record alluvial, eolian, and hillslope processes that have operated in concert with environmental changes from Pleistocene to present time. The South Platte River, originating high in the Colorado Front Range, has played a major role...

Digital flood-inundation maps for a 12.4-mile reach of Big Creek that extends from 260 feet above the McGinnis Ferry Road bridge to the U.S. Geological Survey (USGS) streamgage at Big Creek below Hog Wallow Creek at Roswell, Georgia (02335757), were developed by the USGS in cooperation with the cities of Alpharetta and Roswell, Georgia. The inundation maps, which can be accessed through...

This map updates the geology of Baranof Island based on fieldwork, petrographic analyses, paleontologic ages, and isotopic ages. These new data provide constraints on depositional and metamorphic ages of lithostratigraphic rock units and the timing of structures that separate them. Kinematic analyses and thermobarometric calculations provide insights on the regional tectonic processes...

Coastal zone managers and researchers often require detailed information regarding emergent marsh vegetation types (that is, fresh, intermediate, brackish, and saline) for modeling habitat capacities and needs of marsh dependent taxa (such as waterfowl and alligator). Detailed information on the extent and distribution of emergent marsh vegetation types throughout the northern Gulf of...