Subject
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Gravity
41
Nebraska
41
Hidalgo County (Tex.)
40
Michigan
40
Tamaulipas (Mexico : State)
40
Continental shelf
38
Hidalgo County (N.M.)
37
Historical geography
37
National monuments
37
New York (State)
37
Hunting
36
Kenedy County (Tex.)
36
Blue Ridge Parkway (N.C. and Va.)
35
Coast changes
35
High Plains Aquifer
35
Iowa
35
Maine
35
Digital mapping
34
Dolores County (Colo.)
34
Geomorphology
34
Kentucky
34
Land use Planning
34
North Dakota
34
Oklahoma
34
Venus (Planet) Geology
34
Coal mines and mining
33
Dane County (Wis.)
33
Flood forecasting
33
Garfield County (Colo.)
33
Gas fields
33
Geothermal resources
33
Glaciers
32
Groundwater Pollution
32
South Dakota
32
Fishing
31
Groundwater flow
31
Mesa County (Colo.)
31
Starr County (Tex.)
31
Topographical surveying
31
Volcanic ash, tuff, etc
31
Wallowa-Whitman National Forest (Or.)
31
Boats and boating
30
Grant County (Wis.)
30
Moon
30
Biotic communities
29
Pima County (Ariz.)
29
Sullivan County (N.Y.)
29
Ulster County (N.Y.)
29
Umatilla National Forest (Or. and Wash.)
29
Waterfowl
29
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