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Theresa Formation

Theresa Formation - dolostone, sandstone (Chateauguay in Quebec).
State New York
Name Theresa Formation
Geologic age Cambrian - Lower Ordovician
Comments part of Beekmantown Group, Potsdam Sandstone, and Vermont Valley Sequence up to 2500 ft. (760 m). Secondary unit description from USGS Geologic Names lexicon (ref. NY046): Named Theresa formation in central and eastern NY. Consists of somewhat calcareous, sandy dolomites with interbedded weak sandstones, especially near base. Thickness is 20 to 70 feet. Very closely related to underlying Potsdam sandstone and formerly included in Potsdam but here separated as distinct formation. Base drawn at base of first dolomite layer. Unconformably underlies the Pamelia limestone (of Chazy age) in Theresa and Alexander Bay quadrangles, Jefferson County. The Theresa is of Late Cambrian age.
Primary rock type dolostone (dolomite)
Secondary rock type sandstone
Other rock types
Lithologic constituents
Major
Sedimentary > Carbonate > Dolostone
Minor
Sedimentary > Clastic > Sandstone
Map references
NYS Museum, NYS Geological Survey, NYS Museum Technology Center, 1999, 1:250,000 Bedrock geology of NYS, data is distributed in ARC/INFOr EXPORT format (with ".e00" extension) in 5 seperate files based on printed map sheets, http://www.nysm.nysed.gov/gis.html.
Unit references
D. W. Fisher; Y. W. Isachsen, L. V. Rickard, 1970, Geologic Map of New York State, consisting of 5 sheets: Niagara, Finger Lakes, Hudson-Mohawk, Adirondack, and Lower Hudson, New York State Museum and Science Service, Map and Chart Series No. 15, scale 1:250000.
USGS Geologic Names Lexicon (GEOLEX)
Counties Clinton - Franklin - Jefferson - Lewis - Saint Lawrence