Devonian-Missisippian undivided (GADMu;2)

State	Georgia
Name	Devonian-Missisippian undivided
Geologic age	Devonian-Mississippian
Original map label	DMu
Comments	Ridge and Valley sedimentary rocks Secondary unit descriptions from USGS Geologic Names lexicon (ref. GA003): The Fort Payne consists of limestones that are commonly cherty, biostromal, crinoidal, or siliceous. It also contains cherty dolostones and calcareous, cherty siltstones. Age is Early Mississippian. Named Chattanooga black shale. Thickness is 0 to 35 ft. In northwestern GA, underlain by the Rockwood formation and overlain by the Fort Payne chert. Armuchee chert described in northwestern GA as rusty, sandy, bedded chert, at places grading into ferruginous sandstone. Thickness 0 to 50 ft. Underlies Chattanooga shale and overlies Rockwood formation on north side of Coosa Valley, northwest of Coosa fault. Probably contemporary with Frog Mountain sandstone of Oriskany age, which is present only in the southwest corner of Rome quad.
Primary rock type	shale
Secondary rock type	chert
Other rock types
Lithologic constituents	Major Sedimentary > Chemical > Chert Sedimentary > Clastic > Mudstone > Shale > Black-shale
Map references	Lawton, D.E., and others, 1976, Geologic Map of Georgia: Georgia Geological Survey, scale = 1:500,000.
Unit references	Lawton, D.E., and others, 1976, Geologic Map of Georgia: Georgia Geological Survey, scale = 1:500,000.
Geographic coverage	Catoosa - Chattooga - Dade - Floyd - Gordon - Walker - Whitfield