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Igneous Rock. Chapter 2 section2. Origins of Igneous Rock. Begins as magma Magma can form When rock is heated Pressure is released Rock changes composition When magma cools it solidified or becomes hard Magma has many different minerals with different melting points.
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Igneous Rock Chapter 2 section2
Origins of Igneous Rock • Begins as magma • Magma can form • When rock is heated • Pressure is released • Rock changes composition • When magma cools it solidified or becomes hard • Magma has many different minerals with different melting points
Composition and Texture of Igneous Rock • Light colored rocks are less dense, rich in elements such as aluminum, potassium, silicon, and sodium and are called felsic rocks • Dark colored rock are more dense rich in calcium, iron and magnesium and are called mafic rocks • Fast cooling magma causes fine grained rock and slowing cooling magma causes course grained rock
Igneous Rock Formation • Igneous rock forms above and below the earths • Intrusive Igneous Rock –forms below the earth surface and usually had course grained rock • Common intrusions • Plutons large and irregular bodies and • Batholiths are the largest • Stocks exposed over smaller areas • Dike sheet like and cut across previous rock • Sills sheet like that are parallel to previous rock
Extrusive Rock • Extrusive Igneous Rock forms from magma that erupts or extrudes onto the earths surface • Cools quickly and has small crystals • Lava flows form from an eruption • Fissures are long cracks in earths crust where lava flows • Lava Plateaus are large amounts of lava that form a plain