Pinicon Ridge Formation of Wapsipinicon Group (IL,IA,MN,MO)
(alphabetical): Davenport Member (IA), Kenwood Member (IL,IA), Spring Grove Member (IA).
Middle Devonian (late Eifelian to early Givetian)
At Pinicon Ridge, northwest Linn Co., IA (Witzke and others, 1988).
Iowa shelf
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