Geology 683
Arizona 308
Mines and mineral resources 231
Groundwater 167
Geology, Stratigraphic 160
Land use, Rural 97
Land titles Registration and transfer 83
Forest management 77
Water-supply 74
Water quality 67
Copper mines and mining 63
Uranium ores 61
Ore deposits 56
Hydrogeology 50
Outdoor recreation 50
Floods 46
Copper ores 43
Hydrology 43
National parks and reserves 41
Water rights 41
Forest reserves 40
Public lands 38
Arizona History 37
Wilderness areas 37
Coconino National Forest (Ariz.) 36
Conservation of natural resources 36
Grand Canyon National Park (Ariz.) 33
Indians of North America 32
Land use 32
Stream measurements 32
Geomagnetism 31
Kaibab National Forest (Ariz.) 31
Groundwater flow 30
Streamflow 30
Geology, Structural 29
Public lands Management 29
Arizona Description and travel 28
Frontier and pioneer life 27
Aquifers 26
Environmental impact statements 25
Groundwater Quality 25
Glen Canyon Dam (Ariz.) 24
Grand Canyon (Ariz.) 24
Arizona Antiquities 23
Manganese ores 23
Petrology 23
Trails 23
Geochemical prospecting 22
Colorado River (Colo.-Mexico) 20
Indian land transfers 20
Indians of North America Antiquities 20
Indians of North America Legal status, laws, etc 20
Real property, Exchange of 20
Sediment transport 20
Sedimentation and deposition 20
Water chemistry 20
Geochemistry 19
Groundwater Pollution 19
National monuments 19
Prescott National Forest (Ariz.) 19
Forest restoration 18
Forests and forestry 18
National parks and reserves Law and legislation 18
New Mexico 18
Plants 18
Volcanic ash, tuff, etc 18
Breccia 17
Igneous rocks 17
Apache National Forest (Ariz. and N.M.) 16
Environmental monitoring 16
Indians of North America Land tenure 16
Land use Planning 16
Paleontology 16
Soils 16
Chiricahua National Monument (Ariz.) 15
Environmental impact analysis 15
Geomorphology 15
Gold mines and mining 15
Public lands Recreational use 15
Riparian ecology 15
Silver mines and mining 15
Sitgreaves National Forest (Ariz.) 15
Soil surveys 15
Subsidences (Earth movements) 15
Water quality management 15
Arizona Geology 14
Historic sites 14
Indians of North America Government relations 14
Tonto National Forest (Ariz.) 14
Wild and scenic rivers 14
Breccia pipes 13
Fossil Creek (Ariz.) Environmental conditions 13
National parks and reserves Management 13
Natural resources 13
Ponderosa pine 13
River sediments 13
Saguaro National Park (Ariz.) 13
Sonora (Mexico : State) 13
Streamflow velocity 13
Ecosystem management 12