Rocks, Rocks, and more Rocks - Sedimentary

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Rocks, Rocks, and more Rocks - Sedimentary

• Sedimentary rocks are classified by the types of
  sediments that make up the rock

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What are sediments?

• Definition
• Small, solid pieces of material that come from
  rocks or living things like bones, leaves, stems,
  etc

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Sizes of Sediments
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Sediments will layer up over time, forming
layered rocks
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There are 4 main processes needed to form
sedimentary rock

• Step 1 EROSION (wash away)
• Forces of running water, wind, or ice that loosen
  carry away fragments of rock

Can you see the sediment moving in the
water? Have you ever seen sediments being moved
during a hard rain?
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There are 4 main processes needed to form
sedimentary rock

• Step 2 DEPOSITION (drop down)
• Sediments settle out of the water or wind
  carrying them settle to the bottom of a lake or
  ocean.

Sediments move down the sloped land settle at
the bottom. Over time these sediments layer up.
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There are 4 main processes needed to form
sedimentary rock

• Step 3
• COMPACTION
• (smashed together)
• Process that presses sediments together. Thick
  layers of sediment build up over time weigh
  down the layers compacting them.

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Those smashed sediments can form into layers like
the ones shown above.
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There are 4 main processes needed to form
sedimentary rock

• Step 4
• CEMENTATION
• (glued together)
• Dissolved minerals seep into spaces between
  particles (sediments) then crystallize as they
  harden.

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Examples of cementation
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3 Types of Sedimentary Rocks

• Clastic Sedimentary Rock
• Made from fragments that are squeezed together

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Comparing 2 Clastic Sedimentary Rocks

• Shale
• Forms from mud - tiny clay particles, quartz
  calcite

• Sandstone
• Forms from sand on beaches, ocean floor, river
  beds, etc

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Comparing 2 more

• Conglomerate
• From rounded sediments

• Breccia
• From larger, sharp fragments

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3 Types of Sedimentary Rocks

• 2. Organic Sedimentary Rock
• Forms where the remains of plants animals are
  deposited in thick layers

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Comparing 2 Organic Sedimentary Rocks

• Limestone
• Forms from hard shells w/calcite from seashells,
  coral, clams, oysters or skeletons that pile up
  on the ocean floor for millions of years slowly
  changing the sediment to limestone

• Coal
• From swamp plants buried in water for millions of
  years (plants ? peat ? coal)

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Use for coal a location of limestone

• Coal

• Limestone

Plant Bowen is a power plant that uses coal. Has
anyone seen this before? Its not too far away!
Limestone in England where there was once H2O
covering the land.
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3 Types of Sedimentary Rock

• 3. Chemical Sedimentary Rock
• Forms when minerals that have been dissolved in a
  solution with water, crystallize

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Examples of Chemical Sedimentary Rock

• Limestone
• Another form of limestone forms from calcite in
  seas, lakes underground caves forms caverns
  sinkholes in the ground when it is eroded by
  ground water

• Rock Salt
• Forms from halite when evaporation leaves salt
  behind

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Comparing 2 Chemical Sedimentary Rocks

• Rock Salt

• Limestone

600 million year old rock salt being mined in the
Himalayan Crystal Rock Mine.
Ruby Falls cave is made of limestone! How did the
cave form?
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Uses What things have been made from
Sedimentary Rock?

• Flint Arrowheads
• Sandstone THE WHITE HOUSE
• Limestone Blocks slabs for building, making
  cement steel, flooring

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Possibly the coolest thing about Sedimentary Rock

• FOSSILS are always found in Sedimentary Rock
  ONLY!
• Why???

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Fossils are the signs of the plants animals
that have lived on Earth for millions of
yearssometimes we see the whole creature or
actual parts of the plantsometimes we see
evidence that a creature lived
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One type of Fossil Body Fossil
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Another type of FossilTrace Fossil
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Law of Superpositionstates that new sediment
layers are added on top of older rock layers on
the bottom
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What is the correct order of the layers from
OLDEST to YOUNGEST?
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Oldest FNext EWhat happened with layer
D?Then C, B, AWhat is happening over on
top of layer A?
Law of Superposition states that older rock
layers are at the bottom. If there is tectonic
plate movement or if an Igneous rock intrusion
breaks through the rock layers, then the order is
disrupted.
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How can fossils help us determine the relative
age of rocks?
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Some great resources for Sedimentary Rocks
moreAdditional resources can be found on my
webpage. You can also use the internet to search
the topic you are interest in. Lots of great
stuff out there!

• Geology
• http//www.kidsgeo.com/geology-for-kids/0027-sedim
  entary-rocks.php
• More Geology
• http//www.rocksforkids.com/RFK/howrocks.html
• Science Articles
• http//www.buzzle.com/articles/rocks-and-minerals-
  for-kids.html
• Sedimentary Rocks
• http//www.rocksforkids.com/RM/sedimentary.htm