The Rock CycleWhat 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 &…

arrowheads

knives

chertobsidian

Rocks were not only used to make tools…Rocks were also used to make

buildings, 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 & deposition

influence 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 & PressureSediment that is buried, can be squeezed by weight of

layers on top of 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

Metamorphic Rock

Sedimentary Rock

Magma

melting

melting

Weathering

cooling

Weathering

sediment

Heat & pressure

Heat & pressure

Weathering

Compaction & cementation

Round & round the cycle goesBuried 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

Calcite95%

Aragonite5%

Mineral Composition of Limestone

Calcite

Quartz35%

Biotite mica10%

Feldspar55%

Mineral Composition

of Granite

Rock Textures can VarySedimentary 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. Rock Type Fine Grained Medium

GrainedCoarse Grained

Sedimentary X X XIgneous X X

Metamorphic X X

Why do we care to look @ the texture anyway?!

• For clues to tell us where & how the rock was formed

Sandstone

Basalt

Let’s see what we’ve learned!

Fill in the Blank:1. The minerals that a rock is made of

determine the __________ of that rock.

2. ______ 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) depositionb) erosion

c) upliftd) weathering

Describe 2 ways that rocks have been used by humans.

Explain the difference between composition & texture

Look @ the table below to answer the questionTexture Particle Size

Coarse grained > 2mmMedium grained 0.06 – 2 mm

Fine grained <0.06 mm

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?

Power Point Presentation made by

Ms. Luck