RocksRockspg 84pg 84

Pumice

Scoria

Pegmatite

coquina

Schist

Gneiss

RocksRocks

A rock is a naturally A rock is a naturally occurring solid that is occurring solid that is usually made up of one usually made up of one or more types of or more types of minerals. minerals.

How are rock How are rock classified?classified?

Rocks are classified by how they are Rocks are classified by how they are formed, their composition, and formed, their composition, and texture. There are three main texture. There are three main categories of rock: igneous, categories of rock: igneous, sedimentary and metamorphic. sedimentary and metamorphic.

Rock CycleRock Cycle Rocks change over time through Rocks change over time through

the rock cycle. The rock cycle is the rock cycle. The rock cycle is the set of natural processes that the set of natural processes that form, change, break down and form, change, break down and re-form rocks. It is a continuous re-form rocks. It is a continuous process; therefore it has no process; therefore it has no beginning and no end. beginning and no end.

Gabbro

limestone

Few rock types do not contain any Few rock types do not contain any minerals at all. minerals at all.

Ex. Obsidian which is made of natural Ex. Obsidian which is made of natural glass, which is not a mineral because it glass, which is not a mineral because it doesn’t have a crystal structure.doesn’t have a crystal structure.

Ex. Coal is made up of the remains of Ex. Coal is made up of the remains of ancient plants that have been buried and ancient plants that have been buried and pressed into rock.pressed into rock.

coal

Obsidian

Rock TypesRock Types

Rocks are classified by how they Rocks are classified by how they form.form.

The 3 types of rocks are:The 3 types of rocks are: Igneous rocksIgneous rocks Sedimentary rocksSedimentary rocks Metamorphic rocksMetamorphic rocks

Igneous RocksIgneous RocksPage 86Page 86

Igneous RocksIgneous Rocks

Igneous rocks are formed from melted Igneous rocks are formed from melted minerals that have cooled and hardened.minerals that have cooled and hardened.

The term “igneous” means born of fireThe term “igneous” means born of fire

There are two types of igneous rocks: There are two types of igneous rocks: intrusive and extrusive intrusive and extrusive

Intrusive Igneous RocksIntrusive Igneous Rocks

Intrusive igneous rocks are formed Intrusive igneous rocks are formed underground from cooled magma. underground from cooled magma. They have large crystals because They have large crystals because magma deep below the surface cools magma deep below the surface cools slowly.slowly.

Most common Intrusive Igneous= Most common Intrusive Igneous= GraniteGranite

GraniteGranite

Extrusive Igneous RocksExtrusive Igneous Rocks Extrusive Igneous rock is formed from Extrusive Igneous rock is formed from

cooled lava on the Earth’s surface. cooled lava on the Earth’s surface. They have small crystals because lava They have small crystals because lava cools too quickly for larger crystals to cools too quickly for larger crystals to form.form.

Most common Extrusive Igneous rock= Most common Extrusive Igneous rock= Basalt (The Hawaiian Islands are made Basalt (The Hawaiian Islands are made of Basalt, resulting from volcanic of Basalt, resulting from volcanic eruptions.)eruptions.)

BasaltBasalt

Extrusive Igneous RocksExtrusive Igneous Rocks

If lava cools so quickly that no If lava cools so quickly that no crystals form you end up with a rock crystals form you end up with a rock called obsidian, which is glassy and called obsidian, which is glassy and smooth.smooth.

Variety of color & transparency

Sedimentary RocksSedimentary RocksPage 88Page 88

Sedimentary RocksSedimentary Rocks Sedimentary rocks are formed by Sedimentary rocks are formed by

weathered (breaking a rock down) and weathered (breaking a rock down) and eroded (moving the broken pieces) bits of eroded (moving the broken pieces) bits of sediments like sand, soil, pebbles, and sediments like sand, soil, pebbles, and the remains of dead plants and animals the remains of dead plants and animals are deposited(where they land). As the are deposited(where they land). As the layers settle on top of each other they layers settle on top of each other they get compacted and cemented (pressed get compacted and cemented (pressed and hardened) together to make a and hardened) together to make a Sedimentary Rock.Sedimentary Rock.

Three types of Sedimentary Three types of Sedimentary Rocks:Rocks:

ClasticClastic ChemicaChemica

ll OrganicOrganic

Clastic RocksClastic Rocks

Clastic – form from fragments of Clastic – form from fragments of other rocks. These are the most other rocks. These are the most common types of Sedimentary Rockscommon types of Sedimentary Rocks Examples: Shale, Conglomerate, Examples: Shale, Conglomerate,

SandstoneSandstone

Examples are: Shale, Conglomerate, Examples are: Shale, Conglomerate, SandstoneSandstone

Chemical RocksChemical Rocks

Chemical – form from chemicals Chemical – form from chemicals dissolved in water. dissolved in water. Example: Limestone, Rock Salt, GypsumExample: Limestone, Rock Salt, Gypsum

Organic RocksOrganic Rocks Organic – form from the remains of Organic – form from the remains of

living things.living things. Example: Limestone is made from shells of Example: Limestone is made from shells of

clams and mussels that pile up on the clams and mussels that pile up on the oceanflooroceanfloor

Did you know? Limestone makes chalk!Did you know? Limestone makes chalk!

Metamorphic RocksMetamorphic RocksPage 90Page 90

Metamorphic RocksMetamorphic Rocks

Metamorphic rocks are formed by Metamorphic rocks are formed by heat and pressure from deep inside heat and pressure from deep inside the Earth. This heat and pressure the Earth. This heat and pressure squeezes, bends or bands, and twists squeezes, bends or bands, and twists rock from all sides. Hot fluids move rock from all sides. Hot fluids move through the rock. The heat, pressure, through the rock. The heat, pressure, and liquids can change the texture and liquids can change the texture and look of the rock.and look of the rock.

Foliated Metamorphic RockFoliated Metamorphic Rock

Foliated metamorphic rocks have Foliated metamorphic rocks have visible bands. You see the layers visible bands. You see the layers within the rocks.within the rocks.

Examples are: Slate, Gneiss and Examples are: Slate, Gneiss and SchistSchist

Non-Foliated Metamorphic Non-Foliated Metamorphic RockRock

Non-foliated are metamorphic rock Non-foliated are metamorphic rock that do NOT have visible bends or that do NOT have visible bends or bands.bands.

Example: MarbleExample: Marble

Metamorphic Rock LabMetamorphic Rock Lab  

  Materials:

3 Different Colored Starburst

Procedures:Unwrap the starburst.Stack the starburst on top of each other in the open palms of your hands.Push your palms together slowly. (Do Not Twist!)Hold the candy for 3 minute.Open your hands.Observe the candy.

Analysis:1.Why did each student receive 3 different colored starburst? What does it represent?2.What forces are being added to the candy? ____ and ____ 3. What did you observe after completing the experiment? 4. Is this an example of a foliated or nonfoliated metamorphic rock?  5. Explain how a metamorphic rock is formed.

How do they all fit together in How do they all fit together in the rock cycle?the rock cycle?