Geophysics focuses on the physical properties of Earth at all scales, from atomic to global. At Princeton, we study the physical properties of minerals in Earth's deep interior with high pressure experiments, we develop images of Earth's 3D structure using seismic tomography, we study the physics of earthquakes and the laws of friction, we model wave propagation using vast parallel computers, and we study subtle changes in Earth's gravity to model processes as diverse as plate tectonics and the growth and decay of ice sheets.<br><br>The Department of Geosciences, together with its affiliated interdepartmental programs and institutes, serves as Princeton's central focus for the earth, atmospheric, oceanographic and environmental sciences. As such, the department encompasses a rich diversity of scientific expertise and initiatives that strive to understand Earth's deep structure, climate, biosphere, atmosphere and oceans, landscapes, and how these systems interact and evolve over all timescales. The Department of Geosciences covers a wide range of fields and actively promotes interdisciplinary study and research. Students with interest in tectonics and geophysics, seismology, Earth history, geochemistry, geochronology, petrology, mineral physics, biological oceanography, biogeochemistry, paleontology, paleoceanography and paleoclimate and environmental geology will find most of their research and educational needs accommodated within the laboratories of Guyot Hall. Graduate education within the department, in general, is strongly focused on research, as well as on developing a keen sense for the interdisciplinary nature of the geosciences. As a consequence, Princeton has been extraordinarily successful in mentoring students to move on to tenure-track positions in academia as well as leading research positions in industry or government laboratories. The department offers only a Doctor of Philosophy (Ph.D.) program, for which students with and without master's degrees may apply. The target time to graduation is five years.