Silurian Ripogenus Formation

Silurian Ripogenus Formation
State Maine
Name Silurian Ripogenus Formation
Geologic age Silurian
Lithologic constituents
Sedimentary > Clastic > Sandstone (Calcareous)W - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite; GS - Greenschist facies; Protolith L - Calcareous quartz sandstone
Comments In western sequence of central Maine trough, divided into a main body, lower member near Woodstock (schist and granofels probably equivalent to member B), upper member near Woodstock (schist and granofels probably equivalent to member C), member A (in turn divided into gray shale and massive sandstone facies, massive sandstone facies, and polymict conglomerate facies), member B (in turn divided into quartz-rich, polymictic conglomerate facies and gray shale and sandstone facies), and member C (in turn divided into quartz conglomerate, sandstone, and gray shale; impure limestone and quartz conglomerate lenses; and upper gray shale and sandstone). (ME004) Unit description from USGS GEOLEX website (ME078). GS - Greenschist facies; AB - Medium rank amphibolite facies; AC - High rank amphibolite facies; Protolith Q - Interbedded pelite and sandstone.

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., Griscom, A., and Allingham, J.W., 1964, Geologic and aeromagnetic map of northern Maine: U.S. Geol. Surv., Map GP-312.

Griscom, A., 1976, Bedrock geology of the Harrington Lake area, Maine: Ph.D. dissert., Harvard Univ., Cambridge, 373 p.

Willard, B., 1945, Silurian fossils from Ripogenus dam, Maine: Jour. Paleontology, v. 19, p. 64-68.

NGMDB product
Counties Piscataquis