Skip to main content

Cambrian Grand Pitch Formation

Cambrian Grand Pitch Formation
State Maine
Name Cambrian Grand Pitch Formation
Geologic age Cambrian
Comments Named for Grand Pitch of East Branch of Penobscot River. Penobscot Co., northeastern ME. Name replaces Grand Falls Formation of Ruedemann and Smith (1935); name was preoccupied. Continuous exposure lines riverbanks for 1000 ft in vicinity of Grand Pitch. At type section, consists of light-greenish-gray, fine-grained quartzite in massive beds interbedded with thinner layers of light-greenish-gray and medium gray slate; and red slate containing OLDHAMIA SMITHI Ruedemann. Proportions of slate increase both upstream and downstream. (ME073) Unit description from USGS GEOLEX website (ME078). W - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite; Protolith Q - Interbedded pelite and sandstone Also GS - Greenschist facies; Protolith Q - Interbedded pelite and sandstone
Primary rock type mudstone
Secondary rock type sandstone
Other rock types
Lithologic constituents
Major
Sedimentary > Clastic > SandstoneProtolith Q - Interbedded pelite and sandstone W - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite; Also GS - Greenschist facies
Sedimentary > Clastic > Mudstone (Greenschist)Protolith Q - Interbedded pelite and sandstone W - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite; Also GS - Greenschist facies
Map references
Digital bedrock data downloaded from Maine Office of GIS in September 2005 from http://apollo.ogis.state.me.us/catalog/catalog.asp?state=2&extent=cover#bedrock Bedrock units table (publication date 11/15/2002) downloaded from same site. Permission to redistribute these data granted by Dr. Robert Marvinney, State Geologist of Maine, in September 2006.
Unit references
Osberg, P. H., Hussey, A.M., and Boone, G. M., 1985, Bedrock geologic map of Maine: Maine Geological Survey, Dept. of Conserv., scale 1:500,000.
Neuman, R.B., 1967, Bedrock geology of the Shin Pond and Stacyville quadrangles, Penobscot County, Maine, IN Shorter contributions to general geology, 1965: U.S. Geological Survey Professional Paper, 524-I, p. I1-I39.
Neuman, R.B., 1962, The Grand Pitch Formation; new name for the Grand Falls Formation (Cambrian?) in northeastern Maine: American Journal of Science, v. 260, no. 10, p. 794-797.
Rankin, D.W., 1994, Continental margin of the eastern United States; past and present, IN Speed, R.C., ed., Phanerozoic evolution of North American continent-ocean transitions: Geological Society of America, The Decade of North American Geology (DNAG), Continent-Ocean Transect Series, p. 129-218.
USGS Geologic Names Lexicon (GEOLEX)
Counties Aroostook - Penobscot