Tymochtee and Greenfield Formations, Undivided (OHStg;0)

State	Ohio
Name	Tymochtee and Greenfield Formations, Undivided
Geologic age	Silurian
Original map label	Stg
Comments	Secondary unit description from USGS Lexicon website (ref. OH017) and OH005:Rock units forming the bedrock in the Maumee, Lucas Co., OH, and that crop out in the walls of a quarry are the Lockport Dolomite and the Greenfield Dolomite. The two form a thick reef complex roughly 600 m in diameter and about 68 m thick. The Lockport contains multistory stromatolite, thrombolite, and coral-microbialite reefs that were probably formed in a subtidal setting within a hypersaline lagoon. Lockport may be Wenlockian or Llandoverian to Ludlovian. In contrast to the mostly massive Lockport, the Greenfield at Maumee quarry is well bedded. It is Wenlockian, according to Shaver (1991), but fig. 16 of this report (after Howell, 1993) depicts the Greenfield as Llandoverian with a significant hiatus between deposition of the two units (Kahle, 1994).
Primary rock type	dolostone (dolomite)
Secondary rock type	shale
Other rock types
Lithologic constituents	Major Sedimentary > Carbonate > Dolostone (Bed)olive-gray to yellowish- brown, thin to massive bedded, upper two-thirds commonly contains brownish-black to gray shale laminae; locally developed brecciated zones in lower one third. Minor Sedimentary > Clastic > Mudstone > Shale (Bed)upper two-thirds commonly contains brownish-black to gray shale laminae.
Map references	Digital Ohio map from CD produced as a result of a contract between the U.S. Geological Survey and the Ohio Geological Survey. Released with permission of the Ohio Geological Survey, June 2005.
Unit references	Digital Ohio map from CD produced as a result of a contract between the U.S. Geological Survey and the Ohio Geological Survey. Released with permission of the Ohio Geological Survey, June 2005. File of unit descriptions received from Ohio Geological Survey. Kahle, C.F., 1994, Facies and evolution of a Silurian coral-microbialite reef complex, Maumee, Ohio, USA: Journal of Sedimentary Research, v. A6, no. 4, p. 711-725. USGS Geologic Names Lexicon (GEOLEX) [http://ngmdb.usgs.gov/Geolex/]
Geographic coverage	Allen - Auglaize - Champaign - Clark - Clinton - Fayette - Franklin - Greene - Hancock - Hardin - Highland - Logan - Lucas - Madison - Marion - Mercer - Ottawa - Pickaway - Putnam - Ross - Sandusky - Seneca - Shelby - Union - Van Wert - Wood - Wyandot