Region
Colorado
8
Colorado Plateau
8
Chinle Formation
7
Nevada
7
Utah
7
North America
6
Alaska
3
Arizona
3
China
3
New Mexico
3
Texas
3
Wyoming
3
California
2
Dockum Group
2
Texas Panhandle
2
United States
2
Virginia
2
West (U.S.)
2
Barboursville Basin
1
Bristol Region
1
British Columbia
1
Butte County
1
Chugwater Group (Wyo.)
1
Connecticut
1
Connecticut River Valley
1
Culpeper Basin (Va. and Md.)
1
Cutler Formation
1
Danville Basin
1
Durango Region
1
Durham Region
1
Eagle County
1
Emery County
1
Gondwana (Continent)
1
Guadalupe County
1
Humboldt Range
1
Inyo Mountains
1
Lisbon Valley
1
Moffat County
1
Mohawk Canyon
1
Monument Valley (Ariz. and Utah)
1
Navajo Indian Reservation
1
New Jersey
1
North Carolina
1
North Dakota
1
Paradox Basin
1
Pershing County
1
Petrified Forest National Park
1
Petrified National Park
1
Pitkin County
1
Powder River Basin (Wyo. and Mont.)
1
more ...