A new bedrock geologic map of the state was unveiled in a ceremony at the Vermont State House today, bringing a critical tool to land managers involved in natural resource planning and environmental assessment (from a USGS news release, April 11, 2012).
The map was a joint project of the Vermont Agency of Natural Resources, the U.S. Geological Survey, and the University of Vermont. The state’s last map of this kind was produced in 1961, with the first geologic map of the state being produced 150 years ago.
“Vermont’s new map shows an uncommon level of detail for state geologic maps. Mapped rock units are based on lithology, or rock type, rather than traditional rock formations that may include multiple rock types. This map identifies more than 486 different types of rock throughout the state of Vermont, a design feature intended to facilitate use by multiple disciplines. During the project, scientists also discovered many fault lines, advancing understanding about how and where water travels through the underground rock formations and providing clues about where underground aquifers — an important source for potable fresh water — may be located.
“Vermont’s new geologic map substantially builds upon the state’s previous geologic map – created in 1961– by incorporating the theory of plate tectonics, which had not yet been developed 50 years ago. The Green Mountains form the backbone of Vermont. Their geologic history, spanning more than 1.4 billion years, attests to a complex series of plate tectonic events including the formation of corals reefs, ocean basins and volcanic arcs punctuated by periods of Appalachian mountain building.”
Reference: Ratcliffe, N.M., Stanley, R.S, Gale, M.H., Thompson, P.J., and Walsh, G.J., 2011, Bedrock Geologic Map of Vermont: U.S. Geological Survey Scientific Investigations Map 3184, 3 sheets, scale 1:100,000
Digital files, including a GIS database, can be downloaded from the USGS web site. The digital files are offered in several formats:
- AdobeTM Acrobat PDF
- ESRITM shapefile (ZIP file with base or ZIP file without base)
- Google EarthTM KMZ
- Map images in TIFF and JPEG formats
More links and historic maps:
- USGS Newsroom. “New Geologic Map of Vermont Unveiled,” April 11, 2012
- 2011 Bedrock Geologic Map of Vermont (also read the fascinating “Inside Story,” with major findings and a comparison of the 1861, 1961, and 2011 maps)
- 1961 Centennial Geologic Map of Vermont
- 1861 Geological Map of Vermont
- 1877 Geological Map of New Hampshire and Vermont (C. H. Hitchcock)