Types of Rocks

1. Explain how rocks can be formed?

2. What is the rock cycle?

Warm-Up:

Warm-Up:

Describe the texture and composition of the two igneous rocks.

A B

How to Classify a RockHow to Classify a RockRock - A naturally occurring, solid, mixture of one or more minerals or organic matter

3 Groups (based on formation): igneous, sedimentary, and metamorphic

Texture and composition give clues as to how rocks are formed, and are used to classify rocks

Composition – the type of material a rock contains

Texture – the size, shape and arrangement of the minerals/particles that make up a rock.

Rocks are always changing form in a cycle called the Rock Cycle

Web Links (also found on my website)

Rock Cycle Interactivehttp://www.learner.org/interactives/rockcycle/index.html

Rock Cycle Animations

http://www.classzone.com/books/earth_science/terc/content/investigations/es0602/es0602page02.cfm

Igneous RocksExtrusive rocks- formed by cooling lava

Texture:• glassy (obsidian)• porous (pumice)• fine-grained (basalt)

Intrusive rocks- formed by cooling magma

Texture: • coarse-grained (granite)

Formation of Extrusive Igneous Rock

Extrusive Igneous Rock

Formation of Intrusive Igneous Rock

Intrusive Igneous Rock

Yosemite N.P.

Obsidian…

Basalt…

Granite…

Course Grained Texture

Pumice…

Porous Texture

Sedimentary Rocks Formed by:

Weathering (breaking down of rock)

Examples of WeatheringMechanical Weathering

Root Action

Frost Action

Moss

Examples of Weathering

Chemical Weathering: Oxidation (rock exterior)

Sedimentary Rocks Formed by:

Weathering (breaking down of rock)

Erosion (movement of sediments)

Five Agents of Erosion

Gravity (Mass wasting)

Gravity (Mass Wasting)

Slumping

Soil creep

Five Agents of Erosion

Gravity (Mass wasting)Wind

Wind

Five Agents of Erosion

Gravity (Mass wasting)WindRunning water

Running Water

Yellowstone Canyon & River

Niagara Falls

Five Agents of Erosion

Gravity (Mass wasting)WindRunning waterGlaciers

Glaciers

Five Agents of Erosion

Gravity (Mass wasting)WindRunning waterGlaciersWaves

Waves

Australia

Five Agents of Erosion

Gravity (Mass wasting)WindRunning waterGlaciersWaves

Sedimentary Rocks Formed by:

Weathering (breaking down of rock)

Erosion (movement of sediments)

Deposition (collection of sediments)

Examples of Deposition

Lateral moraine

Cape Cod (spit)

Nile River Delta

Sedimentary Rocks Formed by:

Weathering (breaking down of rock)

Erosion (movement of sediments)

Deposition (collection of sediments)

Compaction & Cementation

Compaction & Cementation

Sedimentary Rocks (categorized by composition)

Clastic Rocks (rock fragments) • Conglomerates (pebbles) • Sandstones (sand) • Shales (mud & clay)

Organic Rocks (once living) • Ex: limestone(coral and shells), coal (plants)

Chemical Rocks (evaporation)• Ex: rock salt, limestone, geodes, gypsum

Clastic Sedimentary Rock…Conglomerate

Shale

Sandstone

Organic Sedimentary Rocks…

Coal (plant mateiral) Limestone (shell & coral)

Chemical Sedimentary Rocks…

Limestone

Gypsum rock

Geode

Metamorphic Rocks Formed by tremendous heat & pressure, and chemical reactions inside the crust.

Formed from all three rock types.

Types of Metamorphic Rock

Foliated (bands or layers) Ex: schist, slate, gneiss

Gneiss

Slate

Foliated texture

Unfoliated (no bands or layers) Ex: marble and quartzite

Types of Metamorphic Rock

Quartzite

Sedimentary Rocks

Metamorphic Rocks

Igneous Rocks

Sediments

Magma & Lava

Heat Pressure

Compaction &Cementation

W.E.D.

W.E.D.

W.E.D.

Melting

Heat Pressure

Cooling

W.E.D. = Weathering, Erosion, & Deposition

Closure:

Describe the texture and composition of the two igneous rocks.

A B

Warm-up / Closure:

1. In igneous rocks how is cooling rate and crystal size related?

2. Which rock type would you have the best chance of finding a fossil? Why?