Region
California
3
Alameda County
2
Appalachian Basin
2
Illinois Basin
2
Michigan Basin (Mich. and Ont.)
2
San Joaquin County
2
Stanislaus County
2
Asia
1
Blake Plateau
1
Connecticut
1
Cumberland Mountains
1
Grand Banks of Newfoundland
1
Long Island Sound (N.Y. and Conn.)
1
Montana
1
North America
1
North Dakota
1
Saskatchewan
1
Southern States
1
United States
1