Chapter 3, Section 3Sedimentary Rocks
Wednesday, December 9, 2009
Pages 82 -- 86
Objectives
• Describe how sedimentary rocks form.
• List and describe the three major types of sedimentary rocks.
Vocabulary Words
• Sediment• Erosion• Deposition• Compaction• Cementation• Clastic rock• Organic rock• Chemical rock
From Sediment to Rock
• Sedimentary rocks are formed from particles deposited by water and wind.– Sediments are small pieces of
material that come from rocks or living things.
– Water, wind, and ice can carry sediment and deposit in layers.
Ways Sediments are Turned to Rocks• Erosion
• Deposition
• Compaction
• Cementation
Erosion• Erosion occurs
when running water or wind loosen and carry away rock fragments.– Rock fragments
produced by forces breaking up and wearing away rocks on the Earth’s surface.
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Deposition
• This is the process by which sediment settles out of the water or wind carrying it.– Sediments include
rock particles, shells, bones, leaves, stems, and remains from other living things.
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Compaction• The process that
presses sediments together. – Each layer presses down
the the previous layer.– The weight of the layers
further compacts the sediments, squeezing them tightly together.
– Each layer remains visible.
• This process takes place over millions of years.
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Cementation• The process in
which dissolved minerals crystallize and glue particles of sediment together.
• This process takes place over millions of years.
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Types of Sedimentary Rock
• Clastic Rocks
• Organic Rocks
• Chemical Rocks
Clastic Rock• It is a sedimentary
rock that forms when rock fragments are squeezed together.
• They are grouped by size of the rock fragments by which they’re made.
• Examples include: Shale, sandstone, conglomerate, and breccia.
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conglomerate
Organic Rock
• Forms where the remains of plants and animals are deposited in thick layers.
• Examples include: Coal and limestone
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Coal
Chemical Rocks
• Forms when minerals that are dissolved in a solution crystallize.
• Can also form when mineral deposits left when seas or lakes evaporate.
• Examples include: gypsum and limestone.
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Gypsum
Homework
• Workbook 3.3 (due 12/16)
• Vocabulary quiz 3.3 (on 12/16)