What is petrology and what does a petrologist do?
Petrology is the scientific study of rocks. A petrologist is a scientist who examines rocks to determine their origin, composition, and geologic history. By studying rocks, one can learn about past climates and geography, the past and present composition of the Earth, and conditions within the interior of the Earth. Sources: Hamilton, William R. The Henry Holt Guide to Minerals, Rocks, and Fossils, p. 146; McGraw-Hill Dictionary of Earth Science, p. 274.