Geology 705
Mines and mineral resources 278
Montana 276
Geology, Stratigraphic 201
Land use, Rural 150
Groundwater 92
Coal 60
Water quality 49
Ore deposits 43
Stream measurements 43
Water-supply 42
Forest management 41
Uranium ores 39
Geology, Structural 37
Paleontology 37
Glacier National Park (Mont.) 35
Montana History 34
Petrology 34
Coal mines and mining 33
Streamflow 33
Geomagnetism 32
Hydrology 30
Mineral industries 30
Outdoor recreation 30
Public lands 30
Igneous rocks 28
Petroleum 28
Aquifers 27
Frontier and pioneer life 27
Land use 26
Water rights 26
Wildlife refuges 26
Natural gas 25
Coal mines and mining Environmental aspects 23
Hydrogeology 22
Land titles Registration and transfer 22
Conservation of natural resources 21
Forest reserves 20
Gold mines and mining 20
Indians of North America Legal status, laws, etc 20
Montana Description and travel 20
National parks and reserves 20
Flood forecasting 19
Forests and forestry 19
Chromite 18
Geochemistry 18
Geology, Economic 18
Water Pollution 18
Charles M. Russell National Wildlife Refuge (Mont.) 17
Historic sites 17
Land use Planning 17
Lolo National Forest (Mont.) 17
Phosphate rock 17
Public lands Management 17
Wilderness areas 17
Groundwater Quality 16
Mineralogy 16
Paleobotany 16
Water resources development 16
Lignite 15
Little Bighorn, Battle of the, Mont., 1876 15
Petroleum Geology 15
Stratigraphic correlation 15
Wilderness areas Law and legislation 15
Geology Research 14
Groundwater Pollution 14
Wildlife conservation 14
Environmental impact analysis 13
Acid mine drainage 12
Clay 12
Federally recognized Indian tribes 12
Formations (Geology) 12
Geochemical prospecting 12
Grant-Kohrs Ranch National Historic Site (Mont.) 12
Idaho 12
Iron ores 12
Lee Metcalf National Wildlife Refuge (Mont.) 12
Mines and mineral resources Environmental aspects 12
Motor vehicles Recreational use 12
Roads 12
Strip mining Environmental aspects 12
Water quality Measurement 12
Benton Lake National Wildlife Refuge (Mont.) 11
Coal Geology 11
Earthquakes 11
Intrusions (Geology) 11
Management 11
Natural resources Management 11
Thorium ores 11
Thrust faults (Geology) 11
Water Law and legislation 11
Water quality management 11
Geophysics Research 10
Gravity anomalies 10
Indians of North America 10
Invasive plants 10
Mineral rights 10
Public lands Recreational use 10
Reservoir sedimentation 10
Timber 10