Subject
Petrology
764
Geology
245
Geology, Stratigraphic
179
Mineralogy
85
Igneous rocks
80
Paleontology
52
Mines and mineral resources
45
Sedimentary rocks
38
Geochemistry
34
Ore deposits
31
Powder River Basin (Wyo. and Mont.)
26
Metamorphic rocks
22
Geology, Structural
21
Rocks Analysis
21
Intrusions (Geology)
19
Borings
16
Volcanic ash, tuff, etc
16
Uranium ores
14
Sandstone
13
Carbonate rocks
12
Crystalline rocks
12
Pegmatites
12
Granite
10
Melanges (Petrology)
10
Petroleum Geology
10
Sedimentation and deposition
10
Batholiths
9
Lunar petrology
9
Basalt
8
Geology, Economic
8
Paleogeography
8
Physical geography
8
Colorado
7
Metamorphism (Geology)
7
Petroleum
7
Water quality
7
California
6
Earthquakes
6
Formations (Geology)
6
Geophysical well logging
6
Gold ores
6
Igneous rocks Analysis
6
Montana
6
Paleobotany
6
Sedimentary rocks Analysis
6
Shale
6
Ultrabasic rocks
6
Volcanoes
6
Crystallography
5
Groundwater
5
more ...