Silurian Smalls Falls Formation

Silurian Smalls Falls Formation
State Maine
Name Silurian Smalls Falls Formation
Geologic age Silurian
Lithologic constituents
Major
Sedimentary > Clastic > Mudstone > ShaleAC - High rank amphibolite facies; Protolith C - Sulfidic/carbonaceous pelite
Sedimentary > Clastic > SandstoneAC - High rank amphibolite facies; Protolith C - Sulfidic/carbonaceous pelite
Minor
Metamorphic > Metasedimentary > Calc-silicate-rock (Amphibolite)AC - High rank amphibolite facies; Protolith C - Sulfidic/carbonaceous pelite
Comments Named the Penobscot formation for Penobscot Bay, central-south ME. Consists of metamorphosed shaly sediments (slates, schists, quartzites) typically developed along nearly whole length of western shore of Penobscot Bay. Color varies from light gray through steel gray and purplish gray to black, the darker grays being predominant. Locally injected and metamorphosed by granite and diorite. Weathered surfaces usually rusty. In a few places only the rock exhibits a very perfect slaty cleavage, highly inclined to bedding planes. Conformably overlies Battie quartzite. (ME025) Unit description from USGS GEOLEX website (ME078). AA - Low rank amphibolite facies; AB - Medium rank amphibolite facies; AC - High rank amphibolite facies; E - Epidote-amphibolite facies; GS - Greenschist facies; Protolith C - Sulfidic/carbonaceous pelite
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.

Moench, R.H. and Pankiwskyj, K.A., 1988, Geologic map of western interior Maine: U.S. Geological Survey Miscellaneous Investigations Series Map, I-1692, 21 p., 1 sheet, scale 1:250,000.

https://pubs.er.usgs.gov/publication/i1692

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

NGMDB product
Counties Franklin - Kennebec - Oxford - Penobscot - Piscataquis - Somerset