Tioga Bentonites

Tioga Ash Beds
Stratigraphic range: Lochkovian-Eifelian ~417.6–390.0 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Unit of	Helderberg Group, Onondaga Limestone and Marcellus Shale
Sub-units	Bald Hill, Sprout Brook, Tioga Middle Course Zone, and Tioga A-G
Lithology
Primary	Tuff
Location
Region	Indiana,  Illinois,  Maryland,  Michigan,  New York,  Ohio,  Pennsylvania,  Tennessee,  Virginia and  West Virginia
Country	United States
Extent	Appalachian Basin, Illinois Basin and Michigan Basin of eastern North America
Type section
Named for	Tioga Gas Fields
Named by	Ebright, Fettke, and Ingham

The Tioga Bentonites are a series of ash bed layers occurring in three Sedimentary basins in the eastern and midwestern United States. The primary basin they are found in is the Appalachian Basin, as well as the Illinois Basin and the Michigan Basin. Due to an unconformity these ash beds are not present in the southern Appalachians.^[1]