Cheshire Quartzite and Dalton Formation (NYCAcd;2)

State	New York
Name	Cheshire Quartzite and Dalton Formation
Geologic age	Cambrian
Original map label	Ccd
Comments	part of Beekmantown and Stockbridge Groups, Potsdam Sandstone, and Vermont Valley Sequence up to 3500 ft. (1100 m) Secondary description of Dalton Formation from USGS Geolex (ref. NY046): Early Cambrian Dalton Formation unconformably overlies Beckett gneiss and grades into overlying Cheshire quartzite; thickness 600-700 ft; basal conglomerate grading into light-colored gneiss or schist. Dalton phyllite of Emerson's unpublished Hawley, MA, map (1892) is revised as Dalton formation. Occurs in western MA from Hinsdale into Washington. Best exposed at site of former Dalton clubhouse, on the high hill south of Dalton Station, in the open pasture farther south, and on the southeast to the new lookout tower. Consists of basal conglomerate grading into light-colored gneiss or schist in which muscovite is sericitized. Conglomerate consists of quartz (black, blue, and white), and some feldspar and gneiss pebbles between 5 and 100 mm long. Thickness ranges from 600 to 700 ft. Grades into overlying Cheshire quartzite; unconformably overlies Becket gneiss. Age is Early Cambrian.
Primary rock type	quartzite
Secondary rock type	gneiss
Other rock types	schist; conglomerate
Lithologic constituents	Major Metamorphic > Metasedimentary > Metaclastic > QuartziteCheshire Quartzite Minor Metamorphic > Schistlight-colored gneiss or schist (Dalton Formation). Metamorphic > Gneisslight-colored gneiss or schist (Dalton Formation). Incidental Sedimentary > Clastic > Conglomeratebasal conglomerate grading into light-colored gneiss or schist (Dalton Formation).
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. [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) [http://ngmdb.usgs.gov/Geolex/]
Geographic coverage	Columbia