The Rock Cycle

What is a rock?

Answer

• A naturally occurring solid mixture of 1 or more minerals/organic matter

• Rocks are always changing• New rocks form from old rocks = ROCK CYCLE

How can rocks help Humans?

HMMMMMMM…

Human Usage of Rocks

• Used for tools– Hammers, knives, arrowheads, spear points,

scrapers• Roads + monuments– Pyramids, capitol buildings

Weathering

• IS H2O, wind, ice, and heat break down rock• Breaks rocks down into fragments• These fragments will become part of

sedimentary rocks

Erosion

• Sediment is removed from its source• This is caused by H2O, wind, ice, + gravity

Deposition

• Process in which sediment moved by erosion is dropped and comes to rest is this.

• Sediment is deposited in bodies of water or areas of low-lying land

• Sediment will be pressed and cemented together to form sedimentary rock

Example of this

• Bryce Canyon is an example of weathering, erosion, and deposition

Heat and Pressure

• Sedimentary rock can also form when sediment is buried and squeezed by weight

• IF add heat to the process then the sediment rock can change to metamorphic rock

• If HOT enough to melt then will create magma when MAGMA cools then have igneous rock

Uplift

• Buried rock will eventually be exposed to Earth due to uplift and erosion

• Uplift is movement within the Earth that causes rocks inside the Earth to be moved to the surface

• Uplifted rocks will then go through weathering, erosion, and deposition

Rock cycle steps/paths

1. sedimentary rock-grains of sand and other sediments erode from hills

and Mts—wash into rivers—oceans—form the ocean floor—compacted together to form this

2. Metamorphic rock-Earth’s crust collide (tectonic plates) some rock is

forced downward—get intense heat + pressure= m. Rock

3. Magma-Hot Liquid forms when rock is melted

4. Igneous Rock-Magma rises (is less dense), cools= I. rock

5. Sediment -Uplift and Erosion expose the Igneous Rock—weathers, wears back into Sedimentary rock

Rocks changing

• So rocks are continually changing what time they’re due to the Earth’s process– Igneous –Sedimentary-Metamorphic

• The location of the rock is a huge factor is what the rock will change into– Surface- have weathering, erosion, deposition– Deep down- heat and pressure

Rock Classification

• Rocks are first divided into igneous, metamorphic, and sedimentary by how they form

• But then will divided them down even farther– Ex. Igneous- if cooled on Earth’s surface or below

• 2 main items scientist use is the composition and texture of rock to identify them

Composition

• Minerals that make up the rock• Look @ pg. 95

Texture

• The size, shape, and position of the grains that make up the rock = texture of it– Sedimentary= fine-medium, or coarse- depends on

size of grains– Igneous= fine to coarse-depends on how time

magma has to cool– Metamorphic = fine or coarse- depends on

temperature and pressure rock gets– Texture can also tell how rock was formed-look on

pg. 96

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