geologist
scientist who studies geology
mineralogist
person studying minerals
speleologist
person who specializes in speleology (caves)
petrologist
person specializing in petrology
petroleum geologist
occupation in the field of petroleum geology
volcanologist
person who studies the formation of volcanoes
geophysicist
person who studies the Earth's physical properties and the physical processes acting upon, above, and within the Earth
paleontologist
scientist specialising in paleontology
engineering geologist
profession