|Name||Beekmantown Group (in part)|
Sedimentary > Carbonate > Dolostone
Metamorphic > Metasedimentary > Metaclastic > QuartziteDanby Formation-sandstone, quartzite, dolostone.
Sedimentary > Carbonate > Limestone (Reef)Whitehall Formation-limestone (with Cryptozoon reefs)
Sedimentary > Clastic > Sandstone
|Comments||part of Beekmantown Group, Potsdam Sandstone, and Vermont Valley Sequence up to 2500 ft. (760 m). Secondary unit descriptions from USGS Lexicon website (ref. NY046) and references NY037 and NY038. The Beekmantown Group in east-central NY includes the (ascending) Potsdam Sandstone, Ticonderoga Formation, Whitehall Formation, Great Meadows Formation, Fort Ann Formation, and Fort Cassin Formation. The Cambrian-Ordovician boundary is within the Whitehall Formation, and therefore, the Beekmantown Group is of Late Cambrian to Early Ordovician age (Croixian to Canadian). Unit overlies the Lake George Group and underlies the Black River Group (Fisher, 1984). Paleozoic cover sequence adjacent to Adirondack massif in western part of Glens Falls quad consists of (ascending): Late Cambrian Potsdam Sandstone, Late Cambrian Ticonderoga Formation, Late Cambrian and Early Ordovician Beekmantown Group (with Whitehall Formation at base), early Middle Ordovician Chazy Group, Middle Ordovician Black River and Trenton Groups, and Mohawk Valley shales (Canajoharie Shale and Snake Hill Formation). Potsdam and Ticonderoga are partly correlative with Danby Formation of Middlebury synclinorium in VT. Beekmantown and part of Chazy correlate directly with limestones and dolomites above Danby. Paleozoic cover sequence is interpreted as a platform sequence. [Text states Beekmantown "as used by Fisher (1984)", but this appears to be an error because Fisher (1984) included Potsdam and Ticonderoga in his Beekmantown. Fisher (1977) abandoned Canajoharie but USGS still recognizes it.] (Thompson, 1990).|
Fisher, D.W., Isachsen, Y.W., and Rickard, L.V., 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 1:250,000.
Fisher, D.W., 1984, Bedrock geology of the Glens Falls-Whitehall region, New York: New York State Museum Map and Chart Series, 35, 60 p., 1 sheet, scale 1:48,000.
Thompson, J.B., Jr., 1990, An introduction to the geology and Paleozoic history of the Glens Falls 1 degrees x 2 degrees quadrangle, New York, Vermont, and New Hampshire, IN Slack, J.F., ed., Summary results of the Glens Falls CUSMAP project, New York, Vermont, and New Hampshire: U.S. Geological Survey Bulletin, 1887-A, p. A1-A13.
USGS Geologic Names lexicon found at: http://ngmdb.usgs.gov/Geolex/
|Counties||Essex - Warren - Washington|