Sedimentary Rocks

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Sedimentary Rocks
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Origin

• Comprise 75 of the Earths surface
• Formed when sediments become compacted and
  cemented together
• Usually has layers called strata

The highest layer has the least pressure.
The lowest layer has the most pressure.
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Compaction

• What does compaction mean?
• Layer upon layer of sediment builds up and the
  pressure from the upper layers pushes down on the
  lower layers.
• Only SMALL sediments will stick together to form
  rock

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Cementation

• What does it mean?
• Water soaks through soil and rock. The water
  dissolves minerals in soil and rock.
• The solution of minerals and water moves between
  the sediments.
• The sediments stick together when the minerals
  crystallize.
• Common with LARGE sediments

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Classification

• Sedimentary rocks are classified in 3 ways
• 1. Clastic Sedimentary Rocks
• 2. Chemical Sedimentary Rocks
• 3. Organic Sedimentary Rocks

WHAT?
Its by the way they are formed!!!
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Clastic Sedimentary Rock

• Made from broken fragments of other rocks.
• Conglomerate large/round fragments
• Breccia large/sharp fragments

Breccia Conglomerate
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Chemical Sedimentary Rock

• Formed from minerals crystallizing out of a
  solution
• The solution is made of minerals and water.

Halite (Rock Salt)
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Organic Sedimentary Rock

• Rocks formed from once-living (organic!) things.

Ocean animals called coral create huge deposits
of limestone. As they die, their skeletons
collect on the ocean floor.
Organic Limestone
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Stratification

• The process in which sedimentary rocks are
  arranged in layers.

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Stratification