What is the rock cycle?What is the rock cycle?

The Rock CycleThe Rock Cycle

Chapter 4Chapter 4Pages 90-111Pages 90-111

What is the Rock Cycle?What is the Rock Cycle?

Process in which:1. A rock forms2. A rock changes from one type to another3. A rock forms again by processes on and

in the Earth.

Three Types of RockThree Types of Rock The three types of rock are:The three types of rock are:1.1. SedimentarySedimentary2.2. IgneousIgneous3.3. MetamorphicMetamorphic

Sedimentary RockSedimentary Rock

Formed by:• Weathering and Erosion of rocks into smaller

pieces or sediment.• Deposition• Compaction and Cementation

• Any rock (igneous, sedimentary, or metamorphic) exposed at the Earth's surface can become a sedimentary rock

Weathering and ErosionWeathering and ErosionWeathering:

BREAKDOWN of rock by water, constant heating and cooling or other natural causes, to form sediment.

Erosion: MOVEMENT of sediment

by wind and water

DepositionDeposition• Streams and rivers transport sediment to

lakes or oceans, or deposit it on nearby floodplains where it accumulates

Compaction and CementationCompaction and Cementation• Over time these deposited grains and pieces of rock

are compacted and cemented together in layers.• The compaction and cementation occurs when

sediment is squeezed by the weight of the sediment layers above it.

• Each layer may be different from the next layer depending on the type of sediment that is deposited.

• Fossils are often found in sedimentary rock.

Sedimentary RocksSedimentary Rocks

Sandstone

Shale

Breccia

Sedimentary RockSedimentary Rock

.

•The remains of plants and animals become trapped in the layers and over long periods of time and become fossils.

Igneous RockIgneous Rock• Igneous rocks (from the Greek word for fire)

form from hot molten rock (magma).• The melt originates deep within the Earth near

active plate boundaries or hot spots, then rises toward the surface.

• Igneous rocks are divided into two groups, intrusive or extrusive, depending upon where the molten rock solidifies.

• Where do you think INtrusive igneous rock forms? Where do you think EXtrusive igneous rock forms?

Extrusive Igneous RockExtrusive Igneous Rock• Extrusive igneous rock is produced when magma

exits and cools outside of, or very near the Earth's surface.

• These are the rocks that form at erupting volcanoes • The magma cools and solidifies almost instantly when

it is exposed to the cool temperature of the atmosphere. • Cooling time determines rock fromed.

•Pumice-cooled quickly •Obsidian-cooled slowly

• One of nature's rarest wonders stretches across the island of Hawaii's shores — the black-sand beach of Punalu'u. This magnificent beach formed when lava from two of the world's most active volcanoes, Mauna Loa and Kilauea, spilled into the ocean and quickly cooled, breaking into minuscule pieces that now comprise the "sand."

Black Sand Beach: Hawaii

Intrusive Igneous RockIntrusive Igneous Rock• Intrusive, or plutonic igneous rock forms when magma

is trapped deep inside the Earth. • Great globs of molten rock rise toward the surface.

Some of the magma may feed volcanoes on the Earth's surface, but most remains trapped below, where it cools very slowly over many thousands or millions of years until it solidifies.

• Intrusive igneous rock can be pushed to the surface by plate movement.

• Granite is a type of intrusive igneous rock.

Metamorphic RockMetamorphic Rock• Metamorphic rocks are rocks

that have "morphed“, or changed into another kind of rock.

• These rocks were once igneous or sedimentary rocks.

• How do sedimentary and igneous rocks change?

• When large pieces of crust collide (convergent boundary, subduction zone), rock is forced downward.

• Heat and pressure squeeze the sedimentary or igneous rock and change it into metamorphic rock.

Metamorphic RockMetamorphic Rock

•Limestone, a sedimentary rock, is changed by heat and pressure into marble. Marble is used to make statues and countertops.

•Shale, a sedimentary rock, is changed by heat and pressure into slate

S: shale M: slateS: Limestone

M: Marble

The Rock CycleThe Rock CycleTHE ROCK CYCLE

ReviewReview• Name the 3 types of rock.• This process causes rock to break down into smaller pieces called

sediment.____________________________• This action carries sediments to rivers and lakes._______________• Sedimentary rock is formed by _________________and

______________.• Igneous rock is formed from_______________________________.• Two types of igneous rock______________ and ______________.• What causes sedimentary and igneous rock to become

metamorphic rock?__________and___________• Intrusive igneous rock forms_________________________• Extrusive igneous rock forms_____________________________• Can any rock become a sedimentary rock?__________________• Which type of rock would contain fossils?_____________________