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Rocks.

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Presentation on theme: "Rocks."— Presentation transcript:

1 Rocks

2 Rocks Naturally occurring solid mixtures of one or more minerals and organic matter They can be made of two or more different minerals that have been: cemented together squeezed and heated together melted and cooled together

3 Types of Rocks Igneous Sedimentary Metamorphic

4 Igneous rocks are classified in three ways:
Most igneous rocks are produced deep underground by the cooling and hardening of magma. Igneous rocks are classified in three ways: Origin – where they are formed Composition – refers to the minerals that make up the rock Texture – the shape, size, arrangement and distribution of minerals that make up the rock

5 Origin Intrusive - Formed deep within the earth
Granite Extrusive- Formed from lava; volcanic Pumice Obsidian

6 Intrusive Igneous Rocks
Intrusive igneous rocks are formed deep within the Earth Granite is the most common (continental crust) Quartz Mica Hornblende Feldspar Intrusive masses named for their size and shape

7 Plutons are large irregularly shaped intrusions
Batholiths – largest intrusive bodies Stocks – smaller areas than batholiths Sills – sheet-like intrusions parallel to previous layers Dikes - sheet-like intrusions that cut across previous rock layers at an angle

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10 Intrusive Igneous Rocks
Pegmatite Granite Diorite Gabbro

11 Extrusive Igneous Rocks
Formed from lava; volcanic Basalt is the most common (oceanic crust) Cools quickly and contains very small, or no crystals Can erupt from fissures, which are long cracks in the Earth

12 Extrusive Igneous Rocks
Obsidian Pumice Rhyolite Andesite Basalt Scoria

13 Composition Refers to the minerals that make up the rock Felsic
light-colored rocks less dense contain elements such as aluminum, potassium, silicon, & sodium Mafic dark-colored rocks denser rich in calcium, iron and magnesium (poor in silicon)

14 The size of the crystals depends on:
Texture – refers to the shape, size, arrangement and distribution of the minerals that make up the rock Fine-grained Coarse-grained Glassy Porphyritic The size of the crystals depends on: Rapid cooling = fine-grained with small crystals Slow cooling = coarse-grained with large crystals

15 Textures Glassy Coarse-grained Granite Obsidian Fine-grained
Porphyritic Basalt Granite

16 Composition and Texture of Igneous Rock


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