Earth’s Structure and Materials – Course 2
Table of Contents
3-5 Sedimentary Rocks
Ms. De Los Rios
Sedimentary Rocks 3-5
How Do Sedimentary Rocks Form?
What Are the Three Major Types of Sedimentary Rocks?
How Are Sedimentary Rocks Formed?
Vocabulary 3.5
Sediment- Small, solid pieces of material that come from rocks or living things.
Weathering- the effects of freezing, thawing, plant roots, acid and
other forces on rock that break down the rock into fragments.
Erosion –process by which running water, wind, or ice carry away the fragments
of broken-up rock.
Deposition- the process by which sediment settles out of the water or wind
carrying it.
Compaction- the process that presses sediments together
Clastic Rock- a sedimentary rock formed when rock fragments are squeezed
together.
Organic Rock- a sedimentary rock formed with the remains of plants and animals
are deposited in layers.
Chemical Rock- a sedimentary rock that forms when minerals dissolved in a water
solution crystallize.
How Do Sedimentary Rocks Form? Pg. 120
Sediment is small, solid pieces of material that come from
rocks or living things.
How do sedimentary rocks form?
Sedimentary rocks form when sediment is deposited by water and wind.
Most sedimentary rocks are formed through a sequence of
processes:
1. weathering
2. erosion
3. deposition
4. compaction
5.cementation
Sedimentary Rocks
WEDCC
How Sedimentary Rock Forms
Sedimentary rocks form through a
series of processes over millions of
years.
How Do Sedimentary Rocks Form? Pg. 121
Rock on Earth’s surface is constantly broken up by
weathering—the effects of freezing and thawing, plant
roots, acid, and other forces on rock.
After the rock is broken up, the fragments are carried
away as a result of erosion—the process by which running
water, wind, or ice carry away bits of broken-up rock.
Deposition is the process by which sediment settles out of
the water or wind carrying it.
The process that presses sediments together is compaction.
Cementation is the process in which dissolved minerals
crystallize and glue particles of sediment together.
What Are The Three Major Types Of Sedimentary Rocks?
Geologists classify sedimentary rocks according to the type of sediments that
make up the rock.
The 3 major groups of sedimentary rocks are:
Clastic rocks
Chemical rocks
Organic rocks
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Clastic Sedimentary Rocks – pg 122
Clastic Rock
•A sedimentary rock formed when rock fragments are squeezed together.
•The fragments size vary from clay particles that are too small to see without
a microscope to large heavy boulders.
How are Clastic rocks classified?
by the size of the rock particles that make them up.
SOME COMMON CLASTIC ROCKS ARE:
 SHALE -Which forms from tiny particles of clay which water deposits in
thin flat layers
SANDSTONE-Which forms from sand on beaches, the ocean floor,
riverbeds and sand dunes
 CONGLOMERATE- forms from rock fragments that have rounded edges
BRECCIA- Forms from rock fragments that have sharp edges
Organic Sedimentary Rocks pg. 123
Organic rock
•A sedimentary rock that forms where the remains of plants and animals
are deposited in layers.
•Organic means substances that were once living or that were made by
living things.
SOME COMMON ORGANIC ROCKS ARE:
COAL -which is made from the remains of swamp plants buried in water.
As layers build up, the weight squeezes the decaying plants together. Over
millions of years they slowly change into coal.
LIMESTONE- Which forms in the ocean, where coral, clams, and oysters
have hard shells or skeletons made of the mineral calcite. When they die,
their shells pile up and over millions of years, compaction and cementation
change the thick sediment into limestone.
Sedimentary Rocks pg. 123
Organic Rocks
How do coal and limestone form?
Chemical Sedimentary Rocks pg. 124
Chemical rock forms when minerals dissolved
in a water solution crystallize.
SOME COMMON CHEMICAL ROCKS ARE:
LIMESTONE-forms when calcite that is dissolved in lakes,
seas, or underground water comes out of a solution and
creates crystals.
ROCK SALT- made from the mineral halite
which forms by evaporation.
Apply It! Pg. 124
These rock “towers” in Mono Lake, California, are made of tufa, a form of
limestone. Tufa forms from water solutions that contain dissolved materials.
The towers formed under water. They became exposed when the water level
in the lake dropped as a result of water needs for the city of Los Angeles.
1. Classify Tufa is a (clastic, organic, chemical) sedimentary rock.
2. Infer What mineral was dissolved in the waters of Mono Lake and
later crystallized to form the rock towers?
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3. Challenge When acid comes into contact with calcite, the acid
bubbles. How can geologists use acid to confirm that the rock towers
are made of limestone?
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How Are Sedimentary Rocks Used? Pg. 125
People have used sedimentary rocks throughout
history for many different purposes, such as tools and
building materials.
Guess what Material is the White House made of?
The White House is made out of sandstone!!!
Chert and flint were used to make
spearheads and arrowheads.
Sandstone and limestone are used as
building materials because they are both soft
enough to be cut easily into blocks or slabs.
Limestone and sandstone are used on
monuments and buildings.
Limestone is also used to make cement and
steel.
Figure 4 Hurricane Monument (Islamorada, FL)
Evaluate the design
Do the benefits of constructing
monuments out of limestone outweigh
the damage acid rain causes them?
Explain._____________________________
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