The Joachim Dolomite is a Middle Ordovician geologic formation in Arkansas, Illinois, and Missouri.

[1] The name was first introduced in 1894 by Arthur Winslow in his study of the geology of Missouri.

[2] Winslow designated a stratotype along Plattin Creek, which was misidentified as Joachim Creek, in Jefferson County.

[3] The name was introduced into Arkansas in 1911, replacing part of the, now abandoned, Izard Limestone.

This article about a specific stratigraphic formation in the United States is a stub.