Geologic maps show the distribution of bedrock and unconsolidated sediments using colors, lines, and symbols. These maps contain an explanation that describes the composition, texture, and age of the rocks. Geologic maps may be accompanied by one or more geologic cross-sections, showing the bedrock relationships in the subsurface. The locations of important features such as folds and faults are also shown on geologic maps.
Schematic of the Mapping process
Geologic maps provide basic information for land development and conservation projects. Large projects (dams, roads, bridges, and buildings) require detailed geological analysis because of monetary, health, and safety concerns. Smaller projects, such as waste disposal systems and water wells also benefit from an understanding of the local geology. Geologic maps are also used for:
- Evaluation of geologic hazards (landslides, earthquakes, land subsidence)
- Planning transportation and utility routes
- Site selection for public facilities (landfills, waste-treatment facilities, waste-disposal sites, schools)
- Land-use planning and evaluation of land-use proposals
- Regulatory decisions
- Environmental assessment and protection planning (underground storage tanks, landfills, aquifer contamination)
- Development and protection of groundwater
- Natural-resource assessment, exploration, development, and management
- Basic earth-science research
DGMR has a team of geologists working on geologic mapping in Virginia. The maps we produce will enhance Virginia's ability to develop and conserve natural resources in a safe and environmentally sound manner to support a more productive economy. Each year we have map deliverables showing our progress. Final map products are published and available for free download or purchase.
A map-based index to publications is available as a layer in our map viewer :
The National Geologic Map Database has a searchable database of geologic maps, including those found in Virginia:
The National Geologic Mapping Act of 1992 established the National Cooperative Geologic Mapping Program to implement and coordinate an expanded geologic mapping effort by the U.S. Geological Survey, the state geological surveys, and universities. The primary goal of the STATEMAP program is to collect, process, analyze, translate, and disseminate earth-science information through geologic maps. In Virginia, priorities for the program are cooperatively developed through a Geologic Mapping Advisory Committee.
DMME completes geologic mapping in accordance with a STATEMAP proposal that is developed each year with input from an advisory committee. The Virginia STATEMAP proposal details the work DGMR plans to complete in the upcoming year.
What are some of the tools we use for geologic mapping?
Our mapping geologists use LiDAR to accurately map geologic landforms like river terraces and sand dunes. LiDAR, which stands for Light Detection and Ranging, is a method of remote sensing that uses lasers to measure the distance between two objects. Precise, three-dimensional models of the Earth’s surface can be generated from these measurements. LiDAR allows DGMR geologists to examine and map both natural and manmade features in fine detail.
Find out more about how DMME geologists turn field work into a map here »