3 Main Types of Rocks

http://www.fi.edu/fellows/payton/rocks/create/igneous.htm

Igneous Rock

“Fire Formed”

Volcano Rock

Igneous Rock• Forms when magma or lava cools and hardens

• Some above E, some below.

• Ex: Granite, Basalt, Pumice, Obsidian,

2 main types of Igneous Rock

Grouped by where they cool down.

Intrusive Igneous Rock

Extrusive Igneous Rock

Intrusive Igneous Rock

• Cools and hardens beneath the surface.

• Coarse grained. Larger grains.

• Forms much Continental Crust.

• Ex: Granite,

Dorite Pegmatite

http://geology.com/rocks/igneous-rocks.shtml

Extrusive Igneous Rock• Forms from Lava on the surface of the Earth.

• Fine-grained. Small. Cool quickly – Basalt most common. Oceanic Crust.

• Ex: Obsidian, pumice,

Obsidian Scoria

http://geology.com/rocks/obsidian.shtml

http://geology.com/rocks/igneous-rocks.shtml

• What type of rock do I have• http://www.minsocam.org/MSA/K12/rkcycle/typeofrock.html• Rock cycle real pix and describe steps• http://www.open2.net/geologytoolkit/rockcycle_embedded.html• Good click and drag animation• http://www.kscience.co.uk/animations/rock_cycle.htm

• Pictures of Different Rocks – Rock Picture Gallery• http://geology.about.com/library/bl/images/blrockindex.htm

3 Main Types of Rocks

http://www.fi.edu/fellows/payton/rocks/create/metamorph.htm

Metamorphic Rock

Metamorphic Rock• Formed by Heat & Pressure deep beneath the E’s surface.

• Some heat from nearby volcano.

• Happens beneath the Earth’s crust

• Any rock can change to Metamorphic – all you need is Heat & Pressure!

• Chemical reaction can change the minerals in the rock.

• Chemical reaction changes the rock from Sedimentary & Igneous to Metamorphic

Heat & pressure changes the texture (grain size)

• Granite (Igneous w/ large grains) changes to Gneiss (crystals are flattened).

Laxfordian felsic gneiss, Lewisian Complex, Loch LaxfordThis is the typical appearance of the gneiss on the north side of Loch Laxford. The main feature of the gneiss at this scale is the banding of grey and white layers. This banding is also folded. The white bands are coarser grained and very poor in mafic minerals. The grey bands contain mafic minerals, principally biotite mica. Some of the sheets of white material look as if they have been intruded after the formation of the banding, as they cut across it. At the right hand side there is also a small sheet of pink granite. Gneissic rocks in Precambrian terrains are often as complex as this.

http://www.earth.ox.ac.uk/~oesis/nws/nws-a98-9.html

• What type of rock do I have• http://www.minsocam.org/MSA/K12/rkcycle/typeofrock.html• Rock cycle real pix and describe steps• http://www.open2.net/geologytoolkit/rockcycle_embedded.html• Good click and drag animation• http://www.kscience.co.uk/animations/rock_cycle.htm

• Pictures of Different Rocks – Rock Picture Gallery• http://geology.about.com/library/bl/images/blrockindex.htm

3 Main Types of Rocks

Sedimentary Rock

http://www.fi.edu/fellows/payton/rocks/create/sediment.htm

Sedimentary Rock• Particles of rock and other materials are pressed and stuck together

• Erosion & deposition

• Compaction & Cementation

Sediments

• Particles of rock or organic material.

• Sand, gravel, seashells, leaves, dead plants & animals.

• Become Sedimentary Rock over time.

• Erosion: wind, water, gravity carries sediments to a new place.

• Deposition: when the water stops moving and “drops off” the sediments.

Compaction: slowly the layers of sediment press down on top of other layers.

Cementation: when the layers are “stuck” together.

Water evaporates, leaving the sediments glued to each other.

1) Flood erodes and carries new sediments downstream.

2) Sediments are deposited in riverbanks and on the ocean floor.

3) More sediments are compacted on top of other ones.

4) Over time, layers are cemented together and hardened.

5) Result – Sedimentary Rock

3 Types of Sedimentary

Sedimentary: Clastic Rock:

*Can see pieces of other rock

• can see grains of sand cemented together.

• Can see layers of sand.

Sandstone

Sedimentary, Clastic RockSandstone

Conglomerate

Sedimentary, Clastic RockConglomerate

Sedimentary: Organic Rock

• From organic remains: dead plants & animals

• Limestone – from shells & skeletons in oceans

• Coal – plants & animals in swamps millions of years.

Limestone forming Coral Reefs off the coast of China

Limestone found in Arizona – Once part of a reef under water

Limestone in Guadelupe Mnts in West Texas – 280 million years ago

was under water now 8,000 ft above sea level.

Sedimentary: Chemical Rock

• Dissolved minerals form crystals.

• Once under water.• Water dissolved minerals, then evaporated, leaving crystals behind.

Sedimentary, Chemical RockHalite

• What type of rock do I have• http://www.minsocam.org/MSA/K12/rkcycle/typeofrock.html• Rock cycle real pix and describe steps• http://www.open2.net/geologytoolkit/rockcycle_embedded.html• Good click and drag animation• http://www.kscience.co.uk/animations/rock_cycle.htm

• Pictures of Different Rocks – Rock Picture Gallery• http://geology.about.com/library/bl/images/blrockindex.htm