Sedimentary Rocks

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Sedimentary Rocks

• Bits and Pieces

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Sedimentary rocks form as sediment
is lDeposited lBuried lCompacted lCemented
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Sedimentary rocks fall into 3 groups

• Clastic/inorganic
• Organic
• Chemical

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Physical Weathering

• Clastic sediments are produced when rock
  physically weathers, which means it breaks apart.
  
• Big rocks break into smaller rocks.
• Weathering is an extremely slow process.

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There are 6 sizes of clastic sediments.

• Boulders
• Cobbles
• Pebbles
• Sand
• Silt
• Clay

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Particles are collected and transported by
running water.
http//www.youtube.com/watch?vfATA1SOLICo
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Abrasion

• Sediments become smoothed and rounded as they
  bounce along the bottom of the stream and hit
  against each other.

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Deposition and Sorting

• A stream loses velocity when entering quiet
  waters so its ability to transport sediment
  decreases. Particles drop to the bottom. This is
  deposition.
• Large particles settle first. Other particles
  settle according to size. Smallest particles
  last. This is sorting.

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Burial and Compaction

• As more sediments accumulate, the bottom ones are
  buried.
• This increased weight of the top sediments
  physically squeezes the lower sediments together
  which compacts them.

Heavy Weight OUCH!
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Cementation

• All the waters of the Earth contain dissolved
  minerals. These dissolved minerals and sometimes
  clay fill up spaces between the rock fragments
  and bind them together. This is cementation.

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Stratification

• Sedimentary rocks often form in horizontal layers
  called strata.

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Fossils

• These layers or strata often contain fossils.
• Only sedimentary rocks contain fossils.

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Fossil Structures

• Mud cracks and ripple marks give evidence of
  environment at formation.

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Organic(Bioclastic)Sediments

• The remains of plants and animals. The two most
  common are shells and plant material.

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Chemical Sediments

• Chemical sediments form when water evaporates and
  the materials dissolved in the water precipitate
  (settle).

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Bonneville Salt Flats

• Home of the land speed record.

Thrust SSC 763 mph
http//www.youtube.com/watch?vLKQ-xj5C2m8
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Yucca Mountain

• Nuclear waste depository

http//www.youtube.com/watch?vtbq9a2oyMAo
http//www.youtube.com/watch?vQ41vzLjwZqM
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Characteristics of Sedimentary Rocks

• Sedimentary rocks are the most common type of
  rocks on Earths surface.
• Sedimentary rocks usually form underwater.
• Sedimentary rocks may contain fossils.
• Sedimentary rocks often form in layers or strata.
• Sedimentary rocks are our keys to the past.

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Natures Palette

• Antelope Canyon

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Bryce Canyon
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Mexican Hat
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Clastic Sedimentary Rocks

• Breccia angular
• Conglomerate - rounded

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Clastic Sedimentary Rocks

• Sandstone can be various size grains.

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Clastic Sedimentary Rocks

• Siltstone

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Clastic Sedimentary Rocks

• Shale breaks along bedded planes.

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Bioclastic Sedimentary Rocks

• Bituminous coal plant remains carbon

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Bioclastic Sedimentary Rocks

• Limestone cemented shell fragments or
  precipitates of biologic origin calcite

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Chemical Sedimentary Rocks

• Rock salt - Crystalline texture composed of
  halite.

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Chemical Sedimentary Rocks

• Dolostone Crystalline texture composed of
  dolomite.

Fossil
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Chemical Sedimentary Rocks

• Rock Gypsum Crystalline texture composed of
  gypsum.