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Ordovician - Precambrian Z Columbia Falls Formation

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Ordovician - Precambrian Z Columbia Falls Formation
State Maine
Name Ordovician - Precambrian Z Columbia Falls Formation
Geologic age Ordovician - Precambrian Z
Lithologic constituents
Major
Igneous > Volcanic > Felsic-volcanicGS - Greenschist facies; Protolith X - Undetermined volcanic rocks
Igneous > Volcanic > Mafic-volcanicGS - Greenschist facies; Protolith X - Undetermined volcanic rocks
Comments Named for development at Cape Elizabeth, Cumberland Co., southwestern ME. Named as a formation in Casco Bay group. Consists of an assemblage of mostly thin-bedded, light-gray, siliceous and sericitic slates; and heavier beds of graywacke slate, schist, and quartzite containing, at short intervals, thin layers or laminae of black, micaceous phyllite and light-bluish calcareous schist or slate. Thickness about 600 ft. Underlies Spring Point greenstone; overlies Kittery quartzite. (ME062) Unit description from USGS GEOLEX website (ME078). GS - Greenschist facies; E - Epidote-amphibolite facies; AA - Low rank amphibolite facies; AB - Medium rank amphibolite facies; AC - High rank amphibolite facies; Protolith Q - Interbedded pelite and sandstone.
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.
NGMDB product
Counties Washington