Pg. 62, 227-232. Metz Member of Joachim Dolomite of Ancell Group (new). Name proposed for top member of Joachim Dolomite [also called Joachim Formation in text]. Chiefly silty thin- to medium-bedded dolomite with subordinate beds of pure dolomite. Thickness commonly 15 feet; about 10 feet at type section. Overlies Matson Member (new); at type section, underlies Brickeys Member of Mifflin Formation; southward from Perry County, Missouri, and Jackson County, Illinois, underlies Pecatonica Formation. Age is Middle Ordovician (Champlainian).
Type section: quarry in east bluff of Mississippi River, and exposures in bluff north of quarry, 0.25 mi north of West Point Landing, in SE/4 NE/4 SE/4 sec. 19, T. 7 N., R. 2 E., Hardin quadrangle [Foley 7.5-min quadrangle], Calhoun Co., IL. Named from Metz Lake on floodplain of Mississippi River, Calhoun Co., IL, 5 miles north of type locality.
[Misprint (USGS Bull. 1350, p. 484): Type section in R. 2 E., not R. 2 W.]

Source: US geologic names lexicon (USGS Bull. 1350, p. 484); supplemental information from GNU records (USGS DDS-6; Reston GNULEX).

Metz Member of Joachim Dolomite is present throughout extent of Joachim. Commonly 15 feet thick, but ranges from 7 to 20 feet. Differs from underlying Matson Member, but many of the beds are lithologically similar to Defiance and Augusta Members. Dominance of dolomite differentiates it from relatively pure, lithographic limestone of unconformably overlying Platteville Group rocks. Age is Middle Ordovician (Champlainian, Blackriveran).

Source: GNU records (USGS DDS-6; Reston GNULEX).