The informal Waubeek facies of Witzke (1981: Geological Society of Iowa, Guidebook 35, 38 p.) is here formally named the Waubeek Member of the Scotch Grove Formation (new name) in eastern IA. Consists of dense to vuggy, chert-free, sparsely fossiliferous, finely crystalline to microcrystalline dolomite. Fossil molds are locally common in some beds. Overlies the Buck Creek Quarry Member (new), reassigned from the revised Hopkinton Formation, or the Fawn Creek Member (new), both of Scotch Grove in the western portion of the study area. Unit is replaced laterally by the Buck Creek Quarry, Fawn Creek, and Palisades-Kepler (new) Members. Sharply underlies the Anamosa Member of the Gower Formation. Thickness averages 40 ft but attains a maximum of 56 ft. Age is Early Silurian (early and middle Wenlockian).

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

According to author, one of his primary aims in this report is to strongly encourage adoption of IA nomenclature in adjacent IL. The only major change is the incorporation of the Sweeney and Marcus as members within the Hopkinton and replacement of the Racine with upper members of the Hopkinton, the Scotch Grove Formation, and the Gower Formation. The Scotch Grove occurs entirely in the subsurface in the Quad Cities area. Members of the Scotch Grove recognized in the eastern IA and western IL Quad Cities area are the basal Johns Creek Quarry Member, the Welton Member (which composes the bulk of the formation), and the Waubeek Member. Though the Welton extends to the top of the Scotch Grove locally, for the most part, the Waubeek occupies the upper 25 to 40 ft of the formation and is composed of denser, less fossiliferous dolomite than the Welton. The flat-lying Waubeek is a lateral equivalent of the Palisades-Kepler mounds, which are exposed to the northwest.

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