Devonian - Silurian Madrid Formation (MEDSmd;0)

State	Maine
Name	Devonian - Silurian Madrid Formation
Geologic age	Devonian - Silurian
Original map label	DSm
Comments	Probably named for Madrid, ME. Consists of calcareous quartzite with lime-silicate minerals in middle-grade metamorphic zones. Contains minor amounts of argillaceous rocks and calcareous beds. Sulfides absent or inconspicuous. Quartzite grades upward into Dyer Hill member (new). Age is younger than Parmachenee formation (new). (ME031) Unit description from USGS GEOLEX website (ME078). AA - Low rank amphibolite facies; Protolith M - Calcareous sandstone; interbedded sandstone and impure limestone To avoid digital confusion with Dsm, the map symbol for this unit (DSm) has been changed to DSmd in this file and on the digital map.
Primary rock type	quartzite
Secondary rock type	calc-silicate rock
Other rock types
Lithologic constituents	Major Metamorphic > Metasedimentary > Calc-silicate-rockAA - Low rank amphibolite facies; Protolith M - Calcareous sandstone; interbedded sandstone and impure limestone Metamorphic > Metasedimentary > Metaclastic > QuartziteAA - Low rank amphibolite facies; Protolith M - Calcareous sandstone; interbedded sandstone and impure limestone
Map references	Digital bedrock data downloaded from Maine Office of GIS in September 2005 from http://apollo.ogis.state.me.us/catalog/catalog.asp?state=2&extent=cover#bedrock Bedrock units table (publication date 11/15/2002) downloaded from same site. Permission to redistribute these data granted by Dr. Robert Marvinney, State Geologist of Maine, in September 2006. [http://apollo.ogis.state.me.us/catalog/catalog.asp?state=2&extent=cover#bedrock]
Unit 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. Cariani, A.R., 1959, The geology of the Anson quadrangle, Maine: Dissertation Abstracts, v. 19, no. 10, p. 2577. USGS Geologic Names Lexicon (GEOLEX) [http://ngmdb.usgs.gov/Geolex/]
Geographic coverage	Aroostook - Franklin - Kennebec - Oxford - Penobscot - Piscataquis - Somerset