Sedimentary ROCKS

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Sedimentary ROCKS

• Most of the earth is covered with sediments

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Weathering

• Weathering the break down into sediments

• Chemical weathering is a change in the chemical
  formula example burning or rusting
• Physical weathering is just an appearance
  change example breaking or eroding

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Erosion

• Erosion the moving of sediment from one place
  to another
• There are four major agents of erosion
• Water, Wind, Ice, Gravity

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Deposition

• Deposition the drop down
• Sediments (clasts) are deposited according to
  size.
• The smaller the sediment (clast) the further it
  travels.

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How to make a sedimentary rock

• Lithification process of turning sediment into
  sedimentary ROCK
• - Compaction - squeezes out the water and
  compacts sediments through the force of gravity
  (caused by the weight of the sediments)
• - Cementation - dissolved minerals are deposited
  in the tiny spaces (PORES) among the sediments
  its like glue because it holds the sediments
  together

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Porosity

• Porosity refers to the of space between
  sediments
• Water, oil, natural gas may be stored in these
  pores

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3 types of Sedimentary Rocks

• 1. Clastic made of weathered bits of
• pre-existing rock grouped according to the
  size of the particles they contain.

• Gravel-sized contained in breccias
  conglomerates
• Sand-sized contained in sandstones
• Silt-sized contained in siltstones
• Clay-sized contained in the shale which is the
  most
• common clastic sedimentary rock

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Conglomerate Breccia

• Conglomerate has rounded pebbles worn down in a
  water environment
• Breccia has more jagged pebbles broken in a dry
  environment

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Sandstone Shale

• Sandstone is made of sand-sized grains cemented
  together
• Shale contains the smallest clast or particle
  size which are clay-sized particles.

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• 2. Chemical
• If the air is dry, water will evaporate leaving
  behind minerals/sediments
• If the water is saturated (holding all it
  can)then minerals will precipitate out of the
  water.

Limestone Rocksalt Gypsum
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• 3. Organic made from once living material

Coal Coquina

• Coal made from decayed and compressed plant
  material

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The Story of Limestone

• Once upon a time.there were these Seashells
  (calcite)
• When the shells dissolved in ocean water over
  time they precipitated to the bottom and produce
  limestone chemically
• BUT, if the shells themselves cemented together
  or fossilized organic

Shell Limestone
Limestone
Coquina
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Sedimentary Rock Features
Ripple marks indicate that the rock formed along
a beach or stream bed.
Mud cracks formed when wet mud or clay dried and
shrank, leaving cracks that filled in with other
sediments and solidified into rock.
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Sedimentary rocks are good for fossils

• Sediments settle gently over deceased
  plants/animals/tracks bury them to preserve the
  fossil