GEO 303 Lecture Notes - Lecture 5: Gabbro, Oceanic Crust, Stratovolcano

• School: UT-Austin
• Department: Geological Sciences
• Course: GEO 303
• Professor: Duncan Catherine

Document Summary

Rocks: naturally occurring, solid aggregate, may be composed of: more than one mineral (ex: granite, basalt, one mineral only (ex: limestone, marble, no mineral (ex: coal, volcanic glass) Classified by the way they form: igneous rocks: crystalize from melts, sedimentary rocks: form from sediments, metamorphic rocks: form by recrystallization of igneous or sedimentary rocks. Classified according to where they cool and solidified: intrusive (plutonic): magma cools beneath earth"s surface, extrusive (volcanic): lava cools on earth"s surface. Intrusive: igneous rocks, think of how they form by cooling rate: deep subsurface cools slower, going towards surface cools faster cause less heat. Hitting surface is the fastest: cooling slowly leads to big crystals. Size of crystals can tell what type they are. Extrusive igneous rocks: form by cooling of lava at the earth"s surface: cools quickly, small or no crystals, gas vesicular (air bubbles, extreme example: quenching (cooling super fast, like when it enters water) leads to glass.