The Rock Cycle n Once igneous metamorphic and

The Rock Cycle

n Once igneous, metamorphic, and sedimentary rocks are formed, do they stay in the same form forever?

No, rocks can change over time Igneous rock can change into sedimentary rock or into metamorphic rock. n Sedimentary rock can change into metamorphic rock or into igneous rock. n Metamorphic rock can change into igneous or sedimentary rock. n

In other words… n Any rock can become any other kind of rock. n What causes these changes to happen?

Two major processes cause rocks to change: 1. Plate Tectonics 2. Weathering & Erosion

Plate Tectonics Review n According to Plate Tectonic Theory, the surface of the Earth is broken into large plates.

n n The position of tectonic plates changes over time. Plates are in constant motion. The edges of these plates, where they move against each other, are sites of intense geological activity, such as n Earthquakes & volcanoes n Subduction (as rocks move deeper they undergo heat and pressure) n Uplift (such as mountain building)

n Erosion is another major process that modifies the earth’s surface.

n n n What causes erosion? n Wind, Water, and Gravity With time, erosion breaks down all the rock material at the earth’s surface and redistributes it, carrying it to other places. The eroded rock pieces, called sediments, drop from the wind or water to make a layer. This is called deposition because the sediments have been “deposited” on the bottom of a river or on the ocean floor or on land.

Compaction and Cementation n When the deposited layers gets buried under other layers of sediment, they go through compaction and cementation (also known as “lithification”) becoming sedimentary rock.

Sedimentary Rock Layers Grand Canyon National Park

Sedimentary Rock Sandstone, Lower Antelope Canyon, Arizona

IGNEOUS ROCK n n Igneous rock forms when magma cools and makes crystals. Magma is a hot liquid made of melted minerals. When it pours out on Earth's surface, magma is called lava. The minerals can form crystals when they cool. Igneous rock can form underground, where the magma cools slowly. This forms intrusive igneous rocks. Or, igneous rock can form above ground, where the magma cools quickly. This forms extrusive igneous rocks.

Intrusive Igneous Rocks Gabbro Granite

Extrusive Igneous Rocks Obsidian Pumice Rhyolite

METAMORPHIC ROCK Metamorphic rocks are formed by heat and pressure. n Heat “bakes” the rock. The rock does not melt, but it does change. It forms crystals, and if it has crystals already, it forms larger crystals. n Because this rock changes, it is called metamorphic. n Metamorphosis can occur in rocks when they are heated to 300 to 700 degrees Celsius. n

Metamorphic Rocks Marble Migmatite Gneiss pronounced “nice”

THE ROCK CYCLE n Landforms made of metamorphic rocks and igneous rocks can be broken up and washed away by streams through erosion. n New sediments from these landforms can make new sedimentary rock. n The rock cycle never stops.

Color-Code your Diagram n Color the product ovals (what the rock becomes) YELLOW n Circle the 3 main types of rock in RED n Underline the processes (what happens to the rock) in GREEN

DIAGRAM QUESTIONS Examine your Rock Cycle diagram. With your partner, answer the following questions on a sheet of lined paper. 1. List the 3 processes that igneous rock can experience (follow the arrows). 2. List the 3 processes that metamorphic rock can experience. 3. List the 3 processes that sedimentary rock can experience. 4. What type of rock does magma become? 5. What types of rock can become sediment? 6. Describe a path that sedimentary rock can follow to become igneous rock? Use arrows.

Refer to your diagram to answer the following questions: 7. Metamorphic Rock goes through __________ to become Magma. 8. Magma undergoes _______________ and _____________ to become Igneous Rock. 9. Igneous Rock experiences ____________ to become Sediment. 10. Sediment goes through the processes of ________ and _________to become Sedimentary Rock. 11. Sedimentary Rock undergoes ____________ to become Metamorphic Rock. 12. Write down two DIFFERENT paths that an igneous rock could take to become an igneous rock in the future. Include the names of all the steps it goes through in each path.

Resources http: //www. cotf. edu/ete/modules/msese/ea rthsysflr/rock. html