New York City Geology
New York City is primarily composed of sediments that were metamorphosed during the Taconic and Acadian orogenies roughly 500 - 400 million years ago. Garnets can be found in the rocks of the Hartland Formation and Manhattan Schist (view a NYC rock sample ). It is in these hard rocks that the city skyscrapers have their foundations.
During the Pleistocene epoch (the Ice Age: about 1.8 million years ago to 8,000 years ago), large ice sheets bulldozed the landscape. Rocks within the glaciers scraped and scratched the bedrock of Central Park producing long linear striations and grooves. Long Island is composed of rubble that the glacier left behind as it melted.
The crust and part of the mantle of the Earth together form rigid plates called tectonic plates. Generally, earthquakes are located at the boundaries between plates where they collide, or grind past each other, or spread apart. New York City lies within the North American plate and the closest plate boundary is thousands of miles away in the middle of the Atlantic. Despite its intra-plate location, the city has an unusually high number of earthquakes. However, it still has fewer earthquakes than plate boundaries and most of these tremors are quite small and cannot be felt.
For links to information about New York State geology, go to the USGS Geology of New York City Region page.
NYC Geology References
- Baskerville, C.A, editor. Geology and engineering geology of the New York metropolitan area . 28th International Geological Congress Field Trip Guidebook T361, Washington: AGU, 1989.
- Baskerville, C.A. Bedrock and engineering geologic maps of New York County and parts of Kings and Queens Counties, New York, and parts of Bergen and Hudson Counties, New Jersey . USGS Misc. Invest. Series Map I-2306, 1:24,0000, 1994.
- Baskerville, C.A. Bedrock and engineering geologic maps of Bronx County and parts of New York and Queens Counties, New York . USGS Misc. Invest. Series Map I-2003, 1:24,000, 1992.
- Hanley, Thomas and M.M. Graff. Rock Trails in Central Park . New York: Greensward Foundation, Inc, 1976.
- Schuberth, Christopher. Geology of New York City and Environs . Garden City, New York: Natural History Press, 1968.
- Taterka, Bruce C. Bedrock Geology of Central Park, New York City . Contribution #61, Department of Geology and Geography, University of Massachusetts-Amherst, 1987.
- New York State Museum
Links to General Geology Sites
Dept. of Earth and Planetary Sciences, American Museum of Natural History Lamont-Doherty Earth Observatory of Columbia University United States Geological Survey Earthquakes and Volcanoes list of servers compiled by the USGS Cascades Volcano Observatory Global Maps available from the National Geophysical Data Center (NGDC) of the National Oceanic and Atmospheric Administration (NOAA) New York State Geological Survey Resources