Devonian Tomhegan Formation (MEDto;0)

State	Maine
Name	Devonian Tomhegan Formation
Geologic age	Devonian
Lithologic constituents	Major Sedimentary > Clastic > SandstoneProtolith E - Feldspathic sandstone; W - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite; GS - Greenschist facies. Minor Metamorphic > Metasedimentary > Metaclastic > Quartzite (Greenschist, Zeolitic (prehnite-pumpellyite))Protolith E - Feldspathic sandstone; W - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite; GS - Greenschist facies. Metamorphic > Metasedimentary > Metaclastic > Slate (Greenschist, Zeolitic (prehnite-pumpellyite))Protolith E - Feldspathic sandstone; W - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite; GS - Greenschist facies.
Comments	Named as a member in Tarratine formation (new) for Misery Ridge in the Brassua Lake 15-min quad. Type section is at northwest end of railroad cut through Misery Ridge east of Tarratine in Brassua Lake 15-min quad. Occurs in northern Somerset Co., ME. Where present, it divides Tarratine formation into an upper and lower part. Consists mainly of light-gray, fine- to medium-grained quartzite; sandstone, siltstone, and slate interbedded in the member are similar to that of the main part of the Tarratine. Thickness ranges from 4 to 500 ft. Grades into main part of the Tarratine above and below. Report includes geologic map and correlation chart. (ME003) Unit description from USGS GEOLEX website (ME078). W - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyit; GS - Greenschist faciese; Protolith F - Quartz sandstone.
Stratigraphic units	Moose River Group
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. Boucot, A.J., 1961, Stratigraphy of the Moose River synclinorium, IN Contributions to general geology, 1959: U.S. Geological Survey Bulletin, 1111-E, p. E153-E188. https://pubs.er.usgs.gov/publication/b1111E Moench, R.H., Boone, G.M., Bothner, W.A., Boudette, E.L., Hatch, N.L., Jr., Hussey, A.M., III, Marvinney, R.G. and Aleinikoff, J.N., 1995, Geologic map of the Sherbrooke-Lewiston area, Maine, New Hampshire, and Vermont, United States, and Quebec, Canada: U.S. Geological Survey Miscellaneous Investigations Series Map, I-1898-D, 56 p., 2 sheets, scale 1:250,000, Prepared in cooperation with the Maine Geological Survey and the New Hampshire Geological Survey. https://pubs.er.usgs.gov/publication/i1898D Boucot, A.J., 1969, Geology of the Moose River and Roach River synclinoria, northwestern Maine: Maine Geol. Surv., Bull. 21, 123 p. US Geological Survey, 2005, National Geologic Map Database, Geologic Names Lexicon "GEOLEX", http://ngmdb.usgs.gov/Geolex/.
NGMDB product	NGMDB product page for 16547
Counties	Piscataquis - Somerset

State

Name

Devonian Tomhegan Formation

Geologic age

Devonian

Lithologic constituents

Major

Sedimentary > Clastic > SandstoneProtolith E - Feldspathic sandstone; W - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite; GS - Greenschist facies.

Minor

Metamorphic > Metasedimentary > Metaclastic > Quartzite (Greenschist, Zeolitic (prehnite-pumpellyite))Protolith E - Feldspathic sandstone; W - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite; GS - Greenschist facies.

Metamorphic > Metasedimentary > Metaclastic > Slate (Greenschist, Zeolitic (prehnite-pumpellyite))Protolith E - Feldspathic sandstone; W - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite; GS - Greenschist facies.

Comments

Named as a member in Tarratine formation (new) for Misery Ridge in the Brassua Lake 15-min quad. Type section is at northwest end of railroad cut through Misery Ridge east of Tarratine in Brassua Lake 15-min quad. Occurs in northern Somerset Co., ME. Where present, it divides Tarratine formation into an upper and lower part. Consists mainly of light-gray, fine- to medium-grained quartzite; sandstone, siltstone, and slate interbedded in the member are similar to that of the main part of the Tarratine. Thickness ranges from 4 to 500 ft. Grades into main part of the Tarratine above and below. Report includes geologic map and correlation chart. (ME003) Unit description from USGS GEOLEX website (ME078). W - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyit; GS - Greenschist faciese; Protolith F - Quartz sandstone.

Stratigraphic units

Moose River Group

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.

Boucot, A.J., 1961, Stratigraphy of the Moose River synclinorium, IN Contributions to general geology, 1959: U.S. Geological Survey Bulletin, 1111-E, p. E153-E188.

https://pubs.er.usgs.gov/publication/b1111E

Moench, R.H., Boone, G.M., Bothner, W.A., Boudette, E.L., Hatch, N.L., Jr., Hussey, A.M., III, Marvinney, R.G. and Aleinikoff, J.N., 1995, Geologic map of the Sherbrooke-Lewiston area, Maine, New Hampshire, and Vermont, United States, and Quebec, Canada: U.S. Geological Survey Miscellaneous Investigations Series Map, I-1898-D, 56 p., 2 sheets, scale 1:250,000, Prepared in cooperation with the Maine Geological Survey and the New Hampshire Geological Survey.

https://pubs.er.usgs.gov/publication/i1898D

Boucot, A.J., 1969, Geology of the Moose River and Roach River synclinoria, northwestern Maine: Maine Geol. Surv., Bull. 21, 123 p.

US Geological Survey, 2005, National Geologic Map Database, Geologic Names Lexicon "GEOLEX", http://ngmdb.usgs.gov/Geolex/.

NGMDB product

NGMDB product page for 16547

Counties

Piscataquis - Somerset