Presentation on theme: "The Rock Cycle. THE ROCK CYCLE Rocks are constantly being formed, worn down and then formed again. This is known as the Rock Cycle It takes thousands."— Presentation transcript:
THE ROCK CYCLE Rocks are constantly being formed, worn down and then formed again. This is known as the Rock Cycle It takes thousands and million of years for rocks to change
http://www.classzone.com/books/earth_scienc e/terc/content/investigations/es0602/es0602pa ge02.cfmhttp://www.classzone.com/books/earth_scienc e/terc/content/investigations/es0602/es0602pa ge02.cfm THE ROCK CYCLE
TYPES OF ROCK Rocks are divided into 3 Types. They are classified by how they were formed: IGNEOUS SEDIMENTARY METAMORPHIC
IGNEOUS ROCK Igneous rocks form when molten rock cools and becomes solid. Molten rock is called magma when it is below the Earth’s surface and lava when it is above.Igneous rocks are divided into two groups, based on where the rock forms.
IGNEOUS ROCK Igneous rocks that form below the Earth’s surface are called intrusive igneous rocks (or plutonic). They form when magma enters an underground chamber, cools very slowly, and forms rocks full of large crystals Igneous rocks that form above the Earth’s surface are called extrusive igneous rocks. These rocks, also called volcanic rocks, form when lava cools quickly at or above the Earth’s surface.
5 KINDS OF IGNEOUS ROCK Granite Diorite Gabbro Periodotite Pegmatite
SEDIMENTARY ROCK When rocks erode, they crumble - a little bit at a time This erosion takes place because of rain, freeze/thaw cycle, wind and running water Eventually most of the broken bits of the rock end up in the streams & rivers that flow down from the mountains. These little bits of rock & sand are called sediments. When the water slows down enough, these sediments settle to the bottom of the lake or oceans they run into. Over many years, layers of different rock bits settle at the bottom of lakes and oceans.
SEDIMENTARY ROCK Over time the layers of sand and mud at the bottom of lakes & oceans turned into rocks. These are called sedimentary rocks. Fossils of ancient living things are preserved in sedimentary rocks
SEDIMENTARY ROCK There are 6 main kinds of sedimentary rocks Conglomerate Sandstone Shale Limestone Gypsum Breccia
METAMORPHIC ROCK Metamorphic rocks are rocks that have changed. Metamorphic rocks were originally igneous or sedimentary, but due to movement of the earth's crust, were changed
METAMORPHIC ROCK When the earth's crust moves, it causes rocks to get squeezed so hard that the heat causes the rock to change. Marble is an example of a sedimentary or igneous rock that has been changed into a metamorphic rock.
METAMORPHIC ROCK Rock foliation may occur. It is the result of pressure and recrystallization when rocks undergo metamorphosis. It is the layering and parallel alignment of flattened or directionally oriented mineral crystals. Slate, phyllite, schist, and gneiss are all metamorphic rocks with foliated texture.
Metamorphic rocks are igneous or sedimentary rocks that have been transformed by great heat or pressure. Slate Schist Gneiss Marble Quartzite
WEATHERING & EROSION Weathering is the mechanical and chemical hammer that breaks down and sculpts the rocks. Erosion transports the fragments away.
･ Acid Rain: chemicals in the air combine with precipitation When it rains it dissolves certain minerals sensitive to acid. ･ Leaching by ground water: water soaks into the soil, picks up chemicals This allows the water to leach or dissolve rocks it comes in contact with at bedrock. ･ Wave action at the beach: the waves tumble rocks Rocks get ground down by the sand particles already on the beach, rocks smash against each other & break. HOW WEATHERING & EROSION OCCURS
Fast moving water: rocks get picked up & carried when water runs swiftly By bouncing along a river & smashing into other rocks, the sharp edges get knocked off. ･ Glaciers: large sheets of ice pick up large rocks, scrape bedrock Rocks tumble in under-glacier rivers when glaciers melt. ･ Precipitation / Floods: heavy rain can cause floods which move & break rocks HOW WEATHERING & EROSION OCCURS
Broken glass is tumbled on the beach and worn smooth by the action of the waves Broken bits of shale tumble to the bottom of hills and river banks. Then the are washed away and tumbled by waves and water. When they are deposited at the side of rivers and on the beach, they are smooth. This is caused by erosion.
http://www.learner.org/interactives/rockcycle/diagr am.htmlhttp://www.learner.org/interactives/rockcycle/diagr am.html The Rock Cycle Diagram
Homework Assignment Complete the interactive lesson on http://www.learner.org/interactives/rockcycle/ind ex.html Begin Introduction, Types of Rocks, How Rocks Change, The Rock Cycle Diagram, Test Your Skills - read and complete the quiz of each section