|Name||Devonian - Silurian undifferentiated sedimentary rocks in areas of extreme migmatization|
|Geologic age||Devonian - Silurian|
Metamorphic > Migmatite (Amphibolite)AC - High rank amphibolite facies; Protolith Q - Interbedded pelite and sandstone
|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.|
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.