Named as the upper formation of the Wapsipinicon Group (rank raised) for exposures--the type locality--at Pinicon Ridge Park, northwest Linn Co, IA on the Iowa shelf. Recognized in northern and east-central IA. Overlies Spillville Formation of Wapsipinicon Group. Disconformably underlies Solon or Bassett Member of Little Cedar Formation (new) of the Cedar Valley Group. Divided into (ascending): Kenwood, Spring Grove, and Davenport Members, all previously named members of Wapsipinicon Formation. Dominated by carbonate rock (thin-bedded, nonfossiliferous, argillaceous to shaly dolomite, thin- to medium-bedded dolomite, and dense limestone). Has some gypsum and anhydrite. Ranges between 20 to 40 m thick. Its stratigraphic position suggests late Eifelian and early Givetian or Middle Devonian age. Is nonfossiliferous. Widespread subtidal deposition in a restricted seaway suggested for some parts of formation. Other parts of formation deposited in intertidal, supratidal, sabkha, and lagoonal environment. Graphic lithologic sections. Nomenclature charts.

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