Rocks and the Rock Cycle

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Rocks and the Rock Cycle

• Igneous, Sedimentary, and Metamorphic varieties

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Where do all rocks come from?

• All rocks basically come from magma (molten rock
  from the earths interior, which provides the
  parent material for igneous, sedimentary, and
  metamorphic rocks)
• The only exception are rocks composed of organic
  material ( a certain variety of sedimentary and
  metamorphic rocks)

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The Rock Cycle
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The Rock Cycle
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The Rock Cycle
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How the rock cycle works

• Relatively all rocks start out as igneous rocks.
• IGNEOUS ROCKS are formed from volcanism
• When igneous rocks are weathered, deposited
  elsewhere and then solidified, they are then
  classified as SEDIMENTARY ROCK (lithified
  sediment)
• If an Igneous rock or a Sedimentary rock somehow
  gets buried and undergoes an extensive change in
  temperature and/or pressure, the rock will then
  become metamorphosed, so classified as
  METAMORPHIC ROCK

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Igneous Rock

• Rock formed when magma cools and hardens via
  volcanism
• Two types intrusive igneous and extrusive
• Intrusive when magma doesnt quite make it to
  the surface, but crystallizes and cools below the
  surface
• Extrusive- magma that makes it to the surface,
  now lava, that crystallizes and cools above the
  surface

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Some cool intrusive sites
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Yosemite, CA
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Devils Postpile (Mammoth, CA)
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Some typical intrusive igneous rocks
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Some Cool Extrusive Igneous Sites

• Obsidian dome (Mammoth, CA)

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Not Cool extrusive
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Structures Related to Igneous Rocks

• Batholith- a large mass of intrusive igneous
  rock, sometimes called a pluton (think Sierra
  Nevada)

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A pretty cool dike
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For tomorrow

• We will talk about and look at various igneous
  compositions (Whats chemistry and viscosity got
  to do with it?)
• Also, we will start to examine Sedimentary and
  Metamorphic Rocks and Structures