Pg. 60-61, 228. Defiance Member of Joachim Dolomite of Ancell Group (new). Name proposed for member of Joachim Dolomite [also called Joachim Formation in text]. Mostly silty, partly argillaceous, thick-bedded dolomite that has smooth, white, weathered face. Contains several beds of gray-green shale in type area, including one 18- to 24-inch bed about 2 feet below top. In Ancell type section, Defiance Member consists of silty dolomite and limestone interbedded with pure limestone. Thickness 20.5 feet in type section; as much as 50 feet in well near Grand Tower, Illinois. Overlies Boles Member (new); underlies Matson Member (new). Age is Middle Ordovician (Champlainian).
Type section: quarry in bluffs on north side of Missouri River, 1 mi southwest of Matson, northeast corner of SE/4 NE/4 SW/4 sec. 4, T. 44 N., R. 2 E., Augusta quadrangle [Labadie 7.5-min quadrangle], St. Charles Co., eastern MO. Named from village of Defiance, St. Charles Co., 3 mi east of type section.

Source: US geologic names lexicon (USGS Bull. 1350, p. 200-201); supplemental information from GNU records (USGS DDS-6; Reston GNULEX).

Pg. 53 (fig. O-4), 61 (fig. O-15), 67. Defiance Member of Joachim Dolomite of Ancell Group. Exposed in southern Illinois only in Mississippi River bluffs at West Point Landing, Calhoun County. Consists of silty dolomite, 20 to 40 feet thick. Contains numerous algal domes and beds of limestone are common in southern part of outcrop area. Similar in lithology to Augusta Member. Lies below Matson Member and above Boles Member; both of Joachim. Age is Middle Ordovician (Champlainian, Blackriveran).

Source: Publication.

Pg. 81. Defiance Member of Joachim Dolomite. The Defiance and Boles Members are often difficult to distinguish. If chert is present, it is in the Boles (by definition; Templeton and Willman, 1963). Here, the term "middle Joachim Dolomite" can be especially useful, for the shaly Boles-Defiance package usually can readily be distinguished from the overlying massively-bedded Matson Member and the slabby-bedded, sandy Augusta Member below. Age is [Late] Ordovician (Mohawkian).

Source: Publication.