The Rock Cycle What is the rock cycle?
What exactly is a ROCK? • A rock is a naturally occurring solid. It is a mixture of one or more minerals & organic matter. • Rocks are always changing; this process of new rocks forming from old rocks is called the Rock Cycle
Are rocks useful?! Absolutely! • What were they used for? • Uses of rocks: Hammers & other tools &… knives chert arrowheads obsidian
Rocks were not only used to make tools… Rocks were also used to makebuildings, monuments & roads. Limestone, a sedimentary rock was used to make the pyramids Washington Monument in D.C.-made of marble, granite & sandstone
What processes make & destroy rocks? Geological processes such as erosion & depositioninfluence the type of rock that is formed on Earth’s surface
Sediment:small particles (usually dirt) that was suspended in water and has settled to the bottom of water.
Erosion is the process of removing sediment from its original location. Usually carried away by water or air; (it is displaced)
Deposition is the sediment that is carried away (or displaced) by erosion, is dropped off in a new location.
Feeling the Heat & Pressure Sediment that is buried, can be squeezed by weight of layers on topof it to form sedimentary rock. When the pressure & temperature is high enough, the rock can change into metamorphic rock. If the rock gets hot enough inside the earth, the rock melts. The melted rock becomes magma; which then cools & forms igneous rock.
Igneous Rock cooling melting Weathering Magma Heat & pressure sediment melting Weathering Compaction & cementation Metamorphic Rock Weathering Heat & pressure Sedimentary Rock
Round & round the cycle goes Buried rock is brought to the Earth’s surface by erosion & uplift (movement in the Earth, that brings rocks inside the Earth to the Earth’s surface). On the Earth’s surface weathering, erosion & deposition occur.
How are rocks classified? • All rocks can be classified into 3 main classes of rock based on how it is formed: • igneous, sedimentary & metamorphic • Each rock class can be divided further; also by how they form. • Ex: Igneous rock can form beneath Earth’s surface & other igneous rock can form above Earth’s surface
What is looked @ to classify rocks? • Composition: the minerals that the rock contains • Texture: the size, shape & grain position that make up the rock
Rock Textures can Vary Sedimentary rock can be: Medium grained Fine grained Coarse grained
Varying Rock Textures Continued… Igneous Rock can be fine grained or coarse grained, depending on how much time the magma has to cool. Metamorphic rock can also be fine or coarse grained, depending on the amount of pressure & temperature the rock is exposed to.
Why do we care to look @ the texture anyway?! • For clues to tell us where & how the rock was formed Basalt Sandstone
Let’s see what we’ve learned! Fill in the Blank: • The minerals that a rock is made of determine the __________ of that rock. • ______ is a naturally occurring, solid mixture of crystals of one of more minerals.
Sediments are transported or moved from their original source by a process called: a) deposition b) erosion c) uplift d) weathering
Describe 2 ways that rocks have been used by humans. Explain the difference between composition & texture
Look @ the table below to answer the question Sandstone is a type of sedimentary rock. If you had a sample of sandstone that had an average particle size of 2 mm, what texture would your sandstone have?