Earth science including physical geology and geophysics; the history of the earth, stratigraphy, and paleontology; and engineering, mining, and petroleum geology.
From Greek γη- (ge-, "the earth") and λογος (logos, "word", "reason") is the science and study of the solid matter of the earth, its composition, structure, physical properties, history and the processes.
Geology plays a large role in the movement of groundwater and the quality thereof.
Source: www.decadevolcano.net