Just found this at http://education-portal.com/geologist.html:
Education Requirements for Geologists
Most geologist positions require a master's degree; however, entry-level positions are available for graduates with a bachelor's degree. Upper-level supervisory positions, research assignments and teaching positions at a university require a doctorate degree. Geology programs include the study of mineralogy, petrology, paleontology, stratigraphy and structural geology, as well as physics, chemistry, biology, mathematics and engineering. Geologists who offer their services directly to the public may need to be licensed in their state. Requirements vary but generally include a minimum level of education and experience, as well as the passing of an exam.