Region
Colorado
15
Wyoming
12
Alaska
4
Pakistan
4
Piceance Creek Basin
4
West Virginia
4
Powder River Basin (Wyo. and Mont.)
3
Williams Fork Formation (Colo. and Utah)
3
Almond Formation
2
Almond Formation (Wyo.)
2
Balochistān
2
Fruitland Formation (Colo. and N.M.)
2
Garfield County
2
Ghazij Formation
2
Ghazij Formation (Pakistan)
2
Mesaverde Group
2
National Petroleum Reserve
2
New Mexico
2
North Slope
2
Pennsylvania
2
Powder River Watershed (Wyo. and Mont.)
2
San Juan Basin (N.M. and Colo.)
2
Sweetwater County
2
Uinta Basin (Utah and Colo.)
2
Utah
2
Virginia
2
Wasatch Formation
2
Washington Region
2
Appalachian Region, Southern
1
Armenia (Republic)
1
Carbon County
1
China
1
Fort Union Formation
1
Green River Watershed (Wyo.-Utah)
1
Kaiparowits Plateau
1
Kentucky
1
Miānwāli District
1
Mu Us Desert (China)
1
North Carolina
1
Ordos Desert
1
Piceance Creek Watershed
1
Powder River Region (Wyo. and Mont.)
1
San Juan County
1
Sand Wash Basin
1
Shiraki Marz
1
Sindh
1
Snake River (Wyo.-Wash.)
1
Snake River Region
1
Straight Cliffs Formation (Utah)
1
Wind River Basin
1
more ...