GLG 111 Lecture Notes - Lecture 4: Diorite, Oceanic Crust, Continental Crust
Document Summary
Igneous rocks formed by cooling and solidification of molten rock (magma or lava) Material can melt and re-cool and it will still be an igneous rock. Cooling and solidification of molten material it cools and begins to crystalize forming the rock. What is the difference between magma and lava. Magma molten liquid below the earths surface. Lava molten liquid rock once it reaches the earths surface. Extrusive (volcanic) igneous rocks formed when lava solidifies at the earths surface extruded onto the earths surface . Rapid cooling generates small crystals slow cooling generates large crystals. Igneous rocks w/ large crystals (phaneritic) are generally intrusive rocks composition: Oceanic crust basalt (top/surface) and gabbro (bottom/below) commonly make up oceanic crust. Continental crust rhyolite (top) and granite (bottom) commonly make up the continental crust. Both contain low % of ferromagnesian minerals = less dense; more buoyant. Peridotite is an ultramafic igneous rock that makes up the earths mantle.