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Published byKelly Harrington Modified over 9 years ago
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Igneous rocks Crystallize from a molten rock: magma
Magma: liquid rock beneath earth’s surface Lava: liquid rock above earth’s surface Igneous rocks classified on Mineral size composition
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Igneous rocks Intrusive igneous rocks Extrusive igneous rocks
Cool below ground (slowly) All minerals visible w/out microscope Extrusive igneous rocks Cool above ground (fast) Most minerals too small to see w/out microscope
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Igneous rocks Intrusive igneous rocks Extrusive igneous rocks
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Intrusive or extrusive?
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Slow or fast cooling?
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Intrusive or extrusive?
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Slow or fast cooling?
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Light colored igneous rocks
Granite and rhyolite
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Intermediate igneous rocks
Andesite
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Dark colored igneous rocks
Gabbro and basalt
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Aphanitic Texture – Rapid Cooling Small Crystals
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Phaneritic Texture – Slow Cooling Large Crystals
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Glassy Texture - Very Rapid Cooling - No Crystal Structure
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Where do igneous rocks form?
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What is left behind when igneous rocks cool?
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Rock Cycle Igneous rocks can become what other kind of rocks?
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Metamorphic rocks Formed by transformation of other rocks
Heat and pressure do this transforming! End up with New minerals And/or texture changes
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Metamorphic textures Foliated: alignment of minerals
Rock looks banded/layered Nonfoliated: random orientation of minerals
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Foliated or nonfoliated?
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Foliated metamorphic rocks
Smallest minerals Slate Clue: like shale/mudstone but harder
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Foliated metamorphic rocks
Schist Shiny with bigger minerals
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Foliated metamorphic rocks
Gneiss Big minerals Looks like a granite with bands of color
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Nonfoliated met. rocks Marble Made of calcite Best way to ID?
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Nonfoliated met. rocks Quartzite
Can look like marble, but no fizz with acid Hand out met rocks to ID
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Nonfoliated met. rocks Greenstone Clue: green basalt
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Rock Cycle
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Sedimentary rocks Clastic sed rock: made of solid particles once part of other rocks Classified by grain size Chemical sed rock: made from dissolved material in water Classified by chemical composition Biochemical sed rock: made of dead plants and animals
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Biochemical, chemical, or detrital?
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Clastic sed rocks Big particles Conglomerate Sand size Sandstone
Small particles Mudstone (shale)
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Clastic sed rocks Conglomerate
Clue: Particles of lots of different sizes
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Clastic sed rocks Sandstone Clue: feels sandy
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Clastic sed rocks Mudstone (shale) Clue: very small particles
No grit when you taste it
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Chemical sed rocks Limestone Made of calcite Clues: fizzes with acid
Often contains fossils
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Chemical sed rocks Rock salt/halite Gypsum Clue: tastes salty
Clue: easily scratched, not salty
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Biochemical sed rocks Category of chemical sed rocks Coal
Limestone if with fossils
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Importance of sed rocks
Key to interpreting Earth’s history
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Homework Go to website and complete the relative age assignment.
Other website for checking to see if you are on the right track! Websites are on our class page
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