Logan Formation
Stratigraphic range: Lower Carboniferous (early Osagean) PreꞒ Ꞓ O S D C P T J K Pg N
Logan Formation exposed in Wooster, Ohio.
Type	Sedimentary
Unit of	Waverly Group
Sub-units	Berne, Byer, Allenville, Vinton
Underlies	Maxville Limestone, Pottsville Group, and Rushville Shale
Overlies	Cuyahoga Formation; Black Hand Sandstone
Thickness	0 to 40 m
Lithology
Primary	sandstone, siltstone, conglomerate
Other	shale
Location
Region	Appalachian Basin
Country	United States
Extent	Ohio, West Virginia
Type section
Named for	Logan, Ohio
Named by	Andrews, 1870

The Logan Formation is the name given to a Lower Carboniferous (early Osagean) siltstone, sandstone and conglomeratic unit exposed in east-central Ohio and parts of western West Virginia, USA.

Stratigraphy and paleoenvironment

The Logan Formation was named by Andrews (1870) and originally described as a "buff-colored, fine-grained sandstone" above the Waverly Formation and below the Maxville Limestone. Bork and Malcuit (1979) concluded that the Logan Formation was deposited on a shallow marine shelf in a generally transgressing sea. The age of the Logan Formation has been established as early Osagean (Tn3) by the occurrences of brachiopods, ammonoids, conodonts and miospores (Clayton et al., 1998; Matchen and Kammer, 2006).