Subject
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
more ...