The Rock Cycle The rock cycle is an

The Rock Cycle

• The rock cycle is an ongoing process, beginning as rocks are pushed up by tectonic forces, and eroded by wind and rain. The eroded rocks travel by wind or moving water until they are deposited, settling into layers. • Additional eroded rocks may bury these layers until heat and pressure change the underlying layers to metamorphic rock. • More eroded rocks may squeeze and press the layers into sedimentary rocks. • Buried rocks may also melt and recrystalize into igneous rocks. • Metamorphic, sedimentary, and igneous rocks may then be pushed up by tectonic forces, starting the rock cycle again.

Three Types of Rocks • Igneous Rock • Metamorphic Rock • Sedimentary Rock

Igneous Rocks • Igneous rock is rock formed by the hardening and crystallization of molten material that originates deep within the earth. • The rocks of the Canadian Shield are made of igneous rock.

• The two best-known igneous rock types are basalt and granite • Basalt makes up most of the world’s oceanic crust.

• Igneous Basalt is dark, fine-grained rock from lava flows and magma intrusions. Its dark minerals are rich in magnesium and iron

• Igneous Columnar basalt in Eugene, Oregon

• Igneous Sometimes the iron-rich minerals in Basalt cause it to weather into reddish stains. California

Igneous Granite is light, coarse-grained rock formed at great depth under the earth’s surface and exposed after deep erosion. It is rich in quartz.

Igneous Granite

Igneous Granite Canadian Shield Granite.

Igneous Granite Glacial shaped Canadian Shield granite

Sedimentary Rocks • Sedimentary forms near the Earth's surface, wherever sediments can pile up and be gradually buried. • Whereas igneous rocks are born hot, sedimentary rocks are born cool. • Sedimentary rocks usually form under water. • They usually consist of layers.

Sedimentary

Sedimentary • Sedimentary rock eroded by wind and water. • Gabriola Island, British Columbia, Canada.

Sedimentary

Sedimentary Limestone Coal

Sedimentary Sandstone Shale

Sedimentary Fossilized Rocks

Metamorphic Rocks • Metamorphic rocks are the most complex rock class, forming by the compression and chemical alteration of other rocks, both sedimentary and igneous. • The four main agents that metamorphose rocks are heat, pressure, fluids and strain.

Metamorphic Slate (formerly sedimentary shale)

Metamorphic Schist (formed from clay minerals)

Metamorphic Gneiss • Gneiss is like schist but less strongly layered. • It is usually tougher. • It may derive from a rock with less clay.

Metamorphic Gneiss

Metamorphic Quartzite (formerly sandstone) Marble (formerly limestone)

The End