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GMEG - Geology and Geophysics


Geologic Mapping

and Three-Dimensional Modeling of Geologic Framework

A geologic map is a representation of natural earth materials exposed on the landscape and shows the geometry of geologic structures in the subsurface using colors, lines, and symbols. Understanding geologic map requires basic knowledge of geologic time, earth materials, earth processes, and fundamental principals of geology. Click here to learn more about geologic maps and their numerous applications.

Geologic mapping and associated research are primary activities of the Geology & Geophysics (G & G) staff. Geologic mapping is a fundamental component of nearly all geologic research conducted by the USGS. G & G geologic mapping and research are supported by the National Cooperative Geologic Mapping Program (NCGMP). The NCGMP is a collaboration of Federal, State, and academic organization that are collectively working to provide geologic map coverage for the nation.

Current G & G research involves integration of geologic mapping databases with applications in the fields of biology and ecosystem science, water science, urban development, natural-hazard studies, and much more. The USGS conducts geologic mapping in collaboration with other Federal agencies including the National Park Service, Bureau of Land Management, Bureau of Indian Affairs, US military, public utilities, and State, cities, and other organizations responsible for land trust and resource management.

Geologic map of part of the Grand Canyon
Geologic cross section of a portion of the Grand Canyon
Example of a geologic map and cross section in the vicinity of the South Rim of the Grand Canyon. Click on images for a larger view.
Three-dimensional modeling of geologic framework: Mapping of the subsurface geologic structure below the landscape is conducted using deep geophysical investigation techniques involving seismic, gravity, natural magnetic, electrical properties of rocks, well information, and other data. When combined with traditional surface geologic mapping, these geophysical models can help delineate three-dimensional (3D) interpretations of the rock units and features in the subsurface, such as the extent and shape of fault systems, volcanic intrusive bodies, the volume and extent of sedimentary basins (and the water they may contain).
3D map of the Santa Clara Valley around San Jose, California
3D geologic model of the Santa Clara Valley around San Jose, California.

See examples of geologic maps, surficial geologic maps, geophysical maps, three-dimensional (3D) geologic maps, geologic mapping applications to fault hazard studies and ecological studies.

See selected references for recent G & G research on Geologic mapping, three-dimensional modeling of geologic framework studies, western tectonics research and mapping, 3D modeling, geophysical studies, gravity mapping, magnetism and paleomagnetism, groundwater and geothermal resource studies, buried mineral deposit assessments


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