Igneous and Sedimentary Igneous and Sedimentary RocksRocks

SWBAT explain how extrusive and SWBAT explain how extrusive and intrusive igneous rocks are different; intrusive igneous rocks are different;

describe how different types of describe how different types of sedimentary rocks are formedsedimentary rocks are formed

What are the three types of rocks?What are the three types of rocks?

• Igneous

• Sedimentary

• Metamorphic

Igneous RocksIgneous Rocks

• Igneous rocks – form when melted rock material from inside

Earth cools.

• Extrusive – igneous rocks that cool on Earth’s surface.

• Intrusive – igneous rocks that cool under Earth’s surface.

Chemical CompositionChemical Composition

• What determines the color of a rock?– Color in rocks is determined by the chemical

materials in it.

• If a rock has a high percentage of silica and little iron, magnesium, or calcium, what color will it be and what is it called?– It will be light in color– It is called granitic– They are generally intrusive rocks

Chemical CompositionChemical Composition

• If a rock has a low percentage of silica and contains more iron, magnesium, or calcium, what color will it be and what do we call it?– It is darker in color– It is called basaltic– They are generally extrusive

Rocks from LavaRocks from Lava

• Extrusive rocks – have small crystals because of the quick

cooling time. They are formed from lava.

• Fissure – A large crack in earth’s surface that magma

can come up through

Rocks from MagmaRocks from Magma

• Intrusive rocks – have large crystals because of the extended

cooling time. They are formed from magma.

Sedimentary RocksSedimentary Rocks

• Sediments – pieces of broken rock, shells, mineral grains,

and other materials.

• Sedimentary rocks – when sediments collect in layers to form

rocks.

3 types of sedimentary rocks3 types of sedimentary rocks

• Detrital rocks – made of grains of minerals or other rocks that

have moved and been deposited in layers by water, wind, gravity, or ice.

– They are cemented together by minerals dissolved in water.

– The weight of the layers above squeezes or compacts them into rock.

3 types of sedimentary rocks3 types of sedimentary rocks

• Chemical rocks – form when seawater, loaded with dissolved

materials, evaporates and layers of minerals are left behind.

• Organic rocks – form when living matter dies, piles up, and

then is compressed into rock