|Name||Silurian - Ordovician unnamed pelite|
|Geologic age||Silurian - Ordovician|
Sedimentary > Clastic > MudstoneW - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite; GS - Greenschist facies; AA - Low rank amphibolite facies; AB - Medium rank amphibolite facies; Protolith A - Pelite
|Comments||Volcanic rocks of the Canada Falls Member of the Frontenac Formation crop out in three northeast-trending lens-shaped bodies in southwestern ME. Estimated thickness of the largest is 1000 to 2000 m. Predominantly green basalt, which weathers light green. Exposures are of two types: well-pillowed and poorly cleaved and poorly pillowed and well-cleaved. Pillows range in diameter from 10 cm to 2 m. A thin pyroclastic layer of volcanic bombs and tuff is located near base of unit. Also contains minor beds of intercalated siltstone and mudstone slate that generally drape over the pillow basalt and are only a few meters thick. Author considers Frontenac to be no older than Silurian or latest Ordovician. (ME011) Unit description from USGS GEOLEX website (ME078). W - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite; GS - Greenschist facies; Protolith V - Basaltic volcanic rocks|
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.
|Counties||Aroostook - Franklin - Kennebec - Waldo|