<p> How Do Rocks Form Anyway?</p><p>Igneous Rocks (Rocks from Fire)</p><p> Rocks formed from the cooling of hot, molten rock (magma or lava)</p><p> Two Types o Intrusive . Cooling of magma deep beneath the surface . Magma contained in batholiths (large), dikes (angled), sills (horizontal) . Magma intrudes (advances by burning its way into existing rock) . Cool very slowly - form large crystals . Examples: Granite, Gabbro, Diorite</p><p> o Extrusive . Cooling of magma (near surface) or lava (at surface) . Cool quickly - form small crystals . Examples: Basalt, Rhyolite, Andesite, Obsidian, Pumice, Scoria</p><p>Sedimentary Rocks (Rocks from the Surface)</p><p> Rocks formed from the lithification (compaction and cementation) of sediment</p><p> Sediment o Broken up pieces of rock and/or organic materials o Mostly sand, silt, and clay o Made from weathering and erosion of rocks</p><p> Compaction o As sediments are deposited and buried by layer upon layer o Force from above pushes sediment together</p><p> Cementation o Water carries dissolved minerals thru sediment o Compaction forces water and air out and minerals are left behind as the cement</p><p> Three Types o Clastic . Rock fragments (any combo of size and shape) are compacted and cemented together (ex. conglomerate, breccia, sandstone) . Can be formed from pressure only (ex. shale)</p><p> o Chemical . Minerals that were once dissolved in water . Evaporation - water leaves minerals behind (ex. rock salt is left behind by water) . Precipitation - minerals fall out of water due to temperature change in the water (ex. chert, compact limestone)</p><p> Organic o Remains of once living things . Ex. Coal from plants . Ex. Fossiliferous limestone, coquina, and chalk from the shells of tiny marine animals Metamorphic Rocks (Rocks from Heat and Pressure)</p><p> Metamorphosis - changing of one rock into another by heat, pressure, and/or chemical processes</p><p> Minerals in rock change in size & shape and may form parallel bands or layers</p><p> Two types o Contact . Metamorphism due to rock coming into direct contact with magma o Regional . Heat and pressure due to tectonic activity . Most met. rocks are formed by regional metamorphism</p>