Geologists, Geophysicists and Hydrogeologists study the composition, structure and other physical attributes of the earth, locate and advise on the extraction of minerals, petroleum and ground water, and detect, monitor and forecast seismic, magnetic, electrical, thermal and oceanographic activity. Geographers are not included here, they are included in Social Professionals.
You need a bachelor degree in a related science field to work as a Geologist, Geophysicist or Hydrogeologist. It is also common to complete postgraduate studies.