Region
- IrelandDublin2
- Maryland2
- MassachusettsCape Cod2
- Mississippi River2
- Patapsco Aquifer2
- Pierre Shale2
- San Bernardino County (Calif.)2
- Snake River Plain (Idaho and Or.)2
- South DakotaEllsworth Air Force Base2
- Southern States2
- United States2
- Venezuela2
- Alabama1
- Alaska1
- Aquia Formation1
- Arizona1
- ArkansasMississippi County1
- Ashumet Pond (Mass.)1
- Atlantic Ocean1
- AustraliaDarwin (N.T.)1