Rocks•A solid material made up of 1 or more minerals, or other things – including the remains of once-living things.
Classify Rocks• Color: color of rock depends on
the minerals that make it up.
• Texture: size, shape, arrangement of the grains
Large grains – coarse texture
Small grains – fine texture
• Composition: The minerals the rock is made up of –Easier to ID course grained rocks
• How/where rocks are formed -
http://www.fi.edu/fellows/payton/rocks/create/igneous.htm
Igneous Rock
Intrusive Igneous Rock
• Cools and hardens beneath the surface.
• Coarse grained. Larger mineral crystals.
• Forms much Continental Crust.
• Ex: Granite, diorite, pegmatite
Extrusive Igneous Rock• Forms from Lava on the
surface of the Earth.• Fine-grained. Small Crystals
Cool quickly – Basalt most common Makes up the oceanic crust.
• Ex: Obsidian, pumice, andesite
Sedimentary Rock
http://www.fi.edu/fellows/payton/rocks/create/sediment.htm
Sedimentary Rock• Form in places where there was
once water
• Form from sediment that is compacted and cemented together
• Takes millions of years to form
Sediments
• Particles of rock, minerals or organic material.
• Sand, gravel, seashells, leaves, dead plants & animals.
• Weathering - The chemical and physical processes that break down rock at Earth’s surface.
• 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 minerals behind which glue the sediments together
3 Types of Sedimentary Rock
Clastic Rock: Made up of particles of pre-existing rock
Can form from igneous, metamorphic or other sedimentary rocks
Ex: sandstone, conglomerate
Chemical Sedimentary Rock
• Form due to chemical reaction –Evaporites http://geology.campus.ad.csulb.edu/people/bperry/Sedimentary%20Rocks%20Tour/
chemical_sedimentary_rocks.htm
• Can occur in oceans, lakes, caves and hot springs.
• Ex: limestone, halite, calcite
Organic SedimentaryRock
• Form when organic material – sea shells, dead animals and plant material – is compacted and cemented together
• Ex: coquina, coal, anthacite
Metamorphic Rock• Meta – Change
• Morph - form
• Original rock – igneous, sedimentary, metamorphic – is changed by intense heat and pressure causing physical or chemical changes
Metamorphic Rock
• Can form when: –rock is deep within earth’s surface –
subjected to high temps and pressure of layers above
–Tectonic processes – continental plates colliding
–Rock is heated by molten magma nearby
Metamorphic Rock
• One type of rock is changed into another type of rock
• Igneous granite is changed into metamorphic gneiss
• Sedimentary rock sandstone changes into quartzite
Metamorphic Rock
• 2 Types: foliated and non-foliated
–Foliated- banded
•Examples - Gneiss, schist, slate
–Non-foliated – not banded
•Examples – marble, quartzite
• 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