An ever changing Earth Rock Cycle

Magma A body of molten rock found at depth. (2000 °F)

SiO 2 is the most abundant compound in magma.

Magma cools more slowly since it is insulated inside the earth – large grains form inside the rock.

When magma reaches the earth’s surface, it is called lava.

Lava cools more quickly since it is exposed to air or water – small grains form inside the rock.

Rock A solid mixture of two or more minerals.

Rock Cycle A model that shows the origin of the three rock types & processes that change them.

James Hutton, the founder of modern geology, authored the concept of the rock cycle.

Metamorphic Sediment Igneous Sedimentary Magma melting cooling weathering compacting/ cementation Heat & Pressure Breaking down heat & pressure

Three Types of Rock

Rocks formed from the solidification, or cooling, of molten rock.

Igneous rocks are the most common in the earth’s crust.

Types of Igneous Rock

Igneous rock that formed below the earth’s surface. (granite)

Rock formed from igneous activity that occurred at the earth’s surface. (rhyolite)

Texture In igneous rocks, texture relates to the size of the mineral grains.

Glassy An igneous texture which occurs when cooling is so rapid that there is no mineral growth & the resulting solid is glass.

Igneous Rock Examples Granite Basalt Gabbro Rhyolite

Rock formed from the weathered products of pre-existing rocks that have been transported, deposited, and hardened.

About 75% of the earth’s land surface is covered by sedimentary rocks.

Fossiliferous A sedimentary rock which contains a large portion of fossils.

Sediments are pieces of solid material that have been deposited by wind, water, ice, gravity, or chemical precipitation.

Grain size represents how far the sediment traveled. Larger grains traveled short distances and smaller grains traveled great distances.

Rounded Any sediment with smooth edges.

Usually indicates abrasion by moving water or wind.

Occurs when sediments are laid down on the ground or sink to the bottom of water.

As chemicals come out of water, they eventually dry up & become hard – they cement the sediment grains together.

A type of lithification in which the weight of overlying material compresses more deeply buried sediment.

The primary feature of sedimentary rocks is horizontal layering called

Bedding in which the particle sizes become progressively heavier & coarser towards the bottom layers is called

is formed as inclined layers of sediment move forward across a horizontal surface.

Found in sedimentary rocks: Oil Uranium Natural Gas Coal

Sedimentary Rock Examples Shale Coal Limestone Chert Bauxite

During metamorphism, a rock changes form while remaining solid.

Rock formed by the changing of pre-existing rock deep within the earth by heat, pressure, and/or chemically active fluids.

Occurs when molten rock comes in contact with solid rock. (intrusion)

Zone of contact metamorphism

Occurs when high temperature & pressure affect large areas of the earth’s crust.

Regional metamorphism is common around mountain building zones.

Occurs when very hot water reacts with rock & changes its composition.

Hydrothermal metamorphism is common around active volcanoes.

Wavy layers & bands of minerals in metamorphic rocks. Gneiss is a foliated metamorphic rock.

Metamorphic rocks that do not have bands or layers. Marble is a nonfoliated metamorphic rock.

Metamorphic Changes Marble is metamorphosed limestone Slate is metamorphosed shale Gneiss is metamorphosed granite

Metamorphic Rock Examples Marble Slate Gneiss Schist

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