Joachim Dolomite

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.^[4]

Joachim Dolomite
Stratigraphic range: Ordovician
Joachim Dolomite over St. Peter Sandstone (Pacific, Missouri)
Type	Formation
Unit of	Ancell Group
Underlies	Pecatonica Formation and Plattin Limestone
Overlies	St. Peter Sandstone
Thickness	0 to 100+ feet in Arkansas[1]
Lithology
Primary	dolomite
Location
Region	Arkansas, Illinois, Missouri
Country	United States
Type section
Named for	Joachim Creek, Jefferson County, Missouri
Named by	Arthur Winslow[2]

See also

• Paleontology portal

• List of fossiliferous stratigraphic units in Arkansas
• Paleontology in Arkansas