Devonian Trout Valley Formation

Devonian Trout Valley Formation
State Maine
Name Devonian Trout Valley Formation
Geologic age Devonian
Lithologic constituents
Major
Sedimentary > Clastic > ConglomerateU- unmetamorphosed; W - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite; Protolith H - Lithic sandstone and conglomerate
Sedimentary > Clastic > SandstoneU- unmetamorphosed; W - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite; Protolith H - Lithic sandstone and conglomerate
Sedimentary > Clastic > Mixed-clasticU- unmetamorphosed; W - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite; Protolith H - Lithic sandstone and conglomerate
Comments Revised as a member of the Tomhegan formation (new). Consists of blue-gray, bone-white-weathering, massive, conchoidally fracturing felsite with quartz and feldspar phenocrysts; blue-gray, greenish-white-weathering, irregularly fracturing felsite with garnet and white feldspar phenocrysts; dark-blue-gray, greenish-white to light-gray-weathering tuff; blue-gray, chalky-white-weathering tuff containing felsite and pumice fragments and fine-grained volcanic debris (devitrified shards); rhyolitic felsite pebble conglomerate; and flow breccia resembling the felsite but containing numerous irregular felsite fragments in a matrix of same material. Thickness ranges from 0 to 4,000 ft. Underlies main part of Tomhegan formation; overlies Tarratine formation. Report includes geologic map and correlation chart. (ME003) Revised to include rocks previously mapped as both Heald Mountain Rhyolite and Kineo Volcanic Member of Boucot and Heath (1969). Exposed in Long Pond and Pierce Pond 15-min quads. Consists of weakly metamorphosed rhyolite ash-flow tuff, flows, domes, volcanic breccia, grit, and conglomerate as well as associated hypabyssal, garnet-bearing felsic intrusive rocks. Separately mapped intrusive garnet rhyolite in Tomhegan Formation, previously mapped as both unnamed garnet rhyolite and garnet rhyolite of the Kineo Volcanic Member by Boucot and Heath (1969), is now considered to be equivalent to Kineo. (ME004) Unit description from USGS GEOLEX website (ME078). W - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite; Protolith T - Rhyolitic volcanic rocks.
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.

Dorf, Erling and Rankin, D.W., 1962, Early Devonian plants from the Traveler Mountain area, Maine: Journal of Paleontology, v. 36, no. 5, p. 999-1004.

Andrews, H.N., and Kasper, A.E., 1970, Plant fossils of the Trout Valley Formation: Maine Geol. Surv., Bull. 23, p. 3-16.

Andrews, H.N., Kasper, A.E., Forbes, W.H., Gensel, P.G., and Chaloner, W.G., 1977, Early Devonian flora of the Trout Valley Formation of northern Maine: Rev. Paleobot. Palynol., v. 23, p. 255-285.

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

NGMDB product
Counties Piscataquis