Unit 4: Earth’s CrustUnit 4: Earth’s Crust

Ch 7, 8, 9Ch 7, 8, 9

Chapter 7Chapter 7

7.3 Families of Rocks

VocabularyVocabulary

• Magma• Igneous rock• Intrusive• Lava• Extrusive• Sediment• Sedimentary rock• Metamorphic rock

• Geologists classify rocks into 3 families based on how they are formed:

1. Igneous

2. Sedimentary

3. metamorphic

1.1. Igneous RocksIgneous Rocks• Hot molten rock escapes to cracks in Earth’s

crust = magma

• Hardened magma = igneous rock

• If magma gets to Earth’s surface = lava

There are 2 types of Igneous There are 2 types of Igneous rock which depend on how rock which depend on how

fast the magma or lava coolsfast the magma or lava cools

If hardens slowly underground If hardens slowly underground (magma) = intrusive igneous rock (magma) = intrusive igneous rock

(granite/large crystals)(granite/large crystals)

If hardens quickly above ground If hardens quickly above ground (lava) = extrusive igneous rock (lava) = extrusive igneous rock

(basalt/ obsidian/pumice)(basalt/ obsidian/pumice)

2. Sedimentary2. Sedimentary

• Sediment = rock particles, clay, mud, sand, gravel and boulders

• Sediment forms layers, pressure builds, deposits compact/cement together = sedimentary rock (fossils!)

Sandstone (sand), shale (clay, silt), Sandstone (sand), shale (clay, silt), conglomerates (pebbles/ small conglomerates (pebbles/ small

stones)stones)

3. Metamorphic3. Metamorphic

• Buried igneous or sedimentary rock= high temperature and pressure

• Causes the rocks properties to change

The Rock video’sThe Rock video’s

• Rock song

• http://www.youtube.com/watch?v=i81eVDgvKas

• Tim and Moby

• http://www.youtube.com/watch?v=OxMz441UiaY&feature=related