UCMP Glossary: Geology
gabbro Highly mafic igneous plutonic rock, typically dark in color; rough plutonic equivalent of basalt. gastroliths n. Fossilized gizzard stones, usually only applicable in the study of fossil reptiles. geologic maps Maps that show the types and ages of rock of an area. These maps are used by paleontologists to find areas that are likely to contain fossils they are interested in.