Coalinga, California is located in the Great Valleys region, surrounded by oil fields. The area has diverse rock deposits from the Jurassic period 160 million years ago to present day, including sedimentary, volcanic, metamorphic, and igneous rocks. Samples from the area include andesite and basalt extrusive igneous rocks, slate metamorphic rock, quartzite metamorphic rock, and travertine sedimentary rock.