Name LeClaire limestone introduced for gray or whitish gray magnesian, semi-crystalline, very porous and vesicular limestone overlying the Niagara limestone in Scott Co, east-central IA. Contains some brecciated beds in upper, middle, and lower parts. Thickness ranges from 100 to 540 ft. Fossils are distinct from those found in the Niagara. Underlies Onondaga Salt group. Age is Silurian.

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

LeClaire facies of previous workers is given formal status in this report. Includes both mounded and flat-lying dolomite sequence in Scott Co., IA. Primary reference section designated along Bud Creek, 3 mi north of LeClaire where unit is 45 ft thick. Strata elsewhere included by previous workers in LeClaire facies are now assigned to underlying Scotch Grove Formation or Brady Member of Gower. Recognized in Caroll Co., IL. Authors suggest that Racine Formation in IL be replaced with Anamosa and LeClaire Members of Gower.

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

One of author's 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 Gower is over 150 ft thick in the Quad Cities area. The dominant facies is the Anamosa Member, which is characterized by flat-lying laminated dolomite. The eastward extent of the Anamosa strata in IL is not known with certainty, but the study area is probably the eastern limit. Laminated Anamosa strata interbed complexly with the LeClaire Member in the Quad Cities area. The LeClaire represents a complex carbonate mound and bank facies. The name LeClaire has been used in the area since 1858 and has clear stratigraphic precedence over any subsequent term applied to equivalent strata in the area, including the Port Byron and Racine Formations. The Gower unconformably underlies the Middle Devonian Wapsipinicon Group or Pennsylvanian shale or sandstone. The Gower is approximately mid-Wenlockian in age at its base, and may be Ludlovian in its upper part.

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