Subject
Geology
50
Geology, Stratigraphic
10
South Dakota
10
Uranium ores
5
Paleontology
4
Hydrology
3
Pegmatites
3
Groundwater
2
Moraines
2
Sediments (Geology)
2
Boring
1
Carnotite
1
Clay
1
Dakota Aquifer
1
Faults (Geology)
1
Glacial epoch
1
Gold ores
1
Homestake Mine (S.D.)
1
Iron ores
1
Lake sediments
1
Middle West Discovery and exploration
1
Mineralogy
1
Missouri River Valley
1
Natural history
1
Nebraska
1
Nebraska Description and travel
1
Petroleum Geology
1
Petrology
1
Phosphates
1
Pottery
1
Rapid Creek Valley (S.D.)
1
Roads
1
Rocks
1
Sandstone
1
Sedimentary rocks
1
Sedimentation and deposition
1
Shale
1
South Dakota Description and travel
1
Vertebrates, Fossil
1
Water-supply
1
Wyoming
1