Hydrology-groundwater
Geophysics-structure of the subsurface
Seismology-earthquakes
Petrology-rock types
Sedimentology/Stratigraphy-layering, deposition
Structure-faults and folds
Minerology-minerals
Paleontology-ancient life
Geomorphology-landforms
Glaciology-glaciers
Geodynamics-inner workings/physics of the earth
Economic-mining
Petroleum-oil, natural gas etc.
Enviornmental-groundwater cleanup