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