Petrology Petrology Petrology (from the Greek πέτρος, "pétros", "rock" and λόγος, "lógos", "subject matter", see -logy) is the branch of geology that studies rocks and the conditions under which they form. Petrology has three subdivisions: igneous, metamorphic, and sedimentary petrology. Igneous and metamorphic petrology are commonly taught together because they both contain heavy use of chemistry, chemical methods, and phase diagrams. Sedimentary petrology is, on the other hand, commonly taught together with stratigraphy because it deals with the processes that form sedimentary rock. Lithology was once approximately synonymous with petrography, but in current usage, lithology focuses on macroscopic hand-sample or outcrop-scale
What Is This? following week. The group decided to change their name to the Red Hot Chili Peppers, played several more shows at various L.A. clubs and musical venues, and eventually recorded a demo tape, all while Slovak and Irons were still playing with What Is This?. A few months later, What Is This received a record deal with MCA Records and the Red Hot Chili Peppers received a joint deal with EMI America and Enigma Records. Hillel Slovak and Jack Irons decided to leave the Red Hot Chili Peppers and stay with What Is This? as the latter was their primary musical