Igneous Rock How do these form??

Answer Hot, liquid rock, or magma cools + solidifies The type of I. rock depends on the composition of magma and the amount of time it takes to cool

Origins of I. Rock 3 ways I. rock forms Rock is heated Pressure is released Rock changes composition

Magma cools is solidifies = I. rock This happens the same way H2O freezes Magma can be made up off different minerals and each of their own melting point Results some minerals are melting why others are still in the hard stage

Composition + Texture of I. Rock Look @ pg. 99 Light colored = less dense so cooled fast Minerals = Aluminum, Potassium, Silicon, Sodium Called felsic rock Dark colored = more dense- cooled slower Minerals = Calcium, iron, magnesium, a little silicon Called mafic rock

The longer the magma has to cool the bigger the crystals will be = coarser texture of I. rock Less time –smaller crystals = finer texture of I. rock

Igneous Rock Formation Happens above and below Earth’s surface Above= volcanoes

Intrusive Igneous Rock This is magma that intrudes/pushes, into surrounding rock below Earth’s surface and cools Has coarse-grained texture (large crystals)

Plutons-large, irregular shaped intrusive bodies Batholiths- large igneous intrusive-under round Stocks-intrusive areas that are over smaller underground areas Dikes- cut across other rocks –can be above ground Sills-sheet-like intrusions that run parallel-underground

Extrusive Igneous Rock Forms when magma erupts or extrudes onto Earth’s surface Usually around volcanoes Lava flow forms when magma is released

Cools quickly-very small to no crystals-fine texture Fissures are long cracks that magma can come out off Can be found on ocean floor-where plates come together Can create a lava plateau