Plattin_Formation
The Plattin Limestone is a Middle Ordovician geologic formation in Arkansas, Illinois, and Missouri.[1] The name was first introduced in 1904 by Edward Oscar Ulrich in his study of the geology of Missouri.[2] A type locality was designated at the mouth of the Plattin Creek in Jefferson County, Missouri, however a stratotype was not assigned. As of 2017, a reference section has not been designated. The name was introduced into Arkansas in 1927, replacing part of the, now abandoned, Izard Limestone.[3]