UNIT 2
Sedimentary Rocks
And the geologic
History of your
Community
Think About It
Page #
How does sediment
“turn into”
sedimentary rock?
1
Part A
Making Models
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Directions: Draw the table below in your notebook. In the boxes
under “Ingredients”, write down the different ingredients that
each rock is composed of (made up of). Leave the top boxes
open for now.
Mudstone
Rock Salt
Sandstone
Conglomerate
Ingredients
(composition)
Ingredients
(composition)
Ingredients
(composition)
Ingredients
(composition)
 silt
 water
 salt
 water
 sand
 glue
(cemented)
 water




sand
gravel
silt
glue
(cemented
 water
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Part B
Identify
Rocks
(15 minutes)
Rock
Description
1
Fragments of
rocks and
minerals
Sedimentary
Type
Clastic
Name
Conglomerate
2
3
4
a
b
c
d
e
f
g
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Digging Deeper
Sedimentary Rocks
In the Earth’s Crust
Page U8- U12
Date:
Page #
Bedrock
A solid rock that is connected continuously
down into the Earth’s crust, rather than
existing as separate pieces or masses
surrounded by loose materials.
Sedimentary
rock
a rock, usually layered, that results
from the consolidation or lithification of
sediment.
http://www.classzone.com/books/earth_science/terc/content/visu
alizations/es0605/es0605page01.cfm?chapter_no=visualization
Example: - sandstone (clastic rock)
- rock salt (chemical rock)
- coal (organic rock)
form layers; usually means that those areas
were below sea level at certain times in the
past.
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Middle of
Continent?
the presence of sedimentary layers
generally means it might have been
topographically low relative to nearby
mountain ranges or covered by a shallow
sea.
Clastic Sedimentary Rocks
Clastic
Sedimentary
Rock
a sedimentary rock made up mostly of
fragments derived (sourced / taken) from
pre-existing rocks and transported
mechanically (wind, water (rivers, glacier),
rock slides) to their places of deposition
Clastic sedimentary rocks are made of
fragments called clasts.
Clasts
an individual fragment of sediment
produced by the physical disintegration of a
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larger rock mass.
Examples
Conglomerate
Sandstone
Siltstone
Mudstone
Claystone
Shale
Clay
small clasts
Silt
clasts sizes between clay and sand
Shale
flat chips broken off from claystone or
mudstone
Particle names are determined by their size
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Chemical
sedimentary
rock
Chemical Sedimentary Rocks
a sedimentary rock formed by
direct chemical precipitation of
minerals from a solution (liquid).
Limestone
is the most common chemical sedimentary
rock which precipitated (came from) out of
sea water, and some of it is precipitated by
marine animals to make their shells.
Dolomite
another common chemical sedimentary
rock.
Areas
areas where intense evaporation is most
likely to happen are those with arid (dry)
climate.
Organic Sedimentary Rocks
Organic
sedimentary
rock
a sedimentary rock consisting mainly
of the remains of organisms.
Example:
coal forms when plants in
swamps with rich vegetation die and are
buried by the remains of later plants. Over
time, the plant material is compacted so
much by the weight of overlying sediment
that it is turned into rock.
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Lignite
brown coal
Bituminous coal
soft coal
Anthracite
hard coal
Sedimentary Environments
Limestone
deposited in a shallow ocean.
Sandstone
deposited in a shallow ocean, but it can also
form in a beach environment, a desert
environment, or a river environment.
Coal
formed in swamps
Sedimentary Rocks and Climate
Sandstone
was deposited as desert sand dunes; records
a time when the area was dry and lacking
protective vegetation (plant roots lock down
soil)
Limestone
deposition in warm shallow ocean
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Coal
forms in tropical to subtropical climates
Ancient coal
found in Antarctica suggests that climate has
changed over time in the Antarctic.
How Sediment Becomes Rock
Explain the process
& use the terms “compaction” and “cementation”
In many places where sediment deposition
continues for a long time, the sediments
become buried deep below the Earth’s
surface (COMPACTION)
The pressure on the sediment increases,
causing the particles to be pressed together.
Water solutions filtering up through the pore
spaces of the sediment from deeper in the
Earth tend to precipitate cementing material
around the sediment particles
(CEMENTATION).
http://www.learner.org/interactives/rockcycle/change3.html
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Sedimentary Rocks
Check Your Understanding
page U12
________________________
1. What does the
presence of sedimentary
rock layers reveal
about sea level or past
topography in a region?
2. Why is gravel more
likely to be found on
a river bottom than
on a lake bottom?
3. The top of Mt.
Everest is made of
Limestone. What does
this suggest about how
the topography of
that area has changed
through time?
4. Rock salt is mined
throughout the Great
Lakes region. What
does this suggest about
the past climate of this
area?
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Sedimentary Rocks
Understanding and Applying
Due Date:
page U12
_______________________
1. Explain how the
three main types
of sedimentary
rock form
2. Label True (T) or
False (F) and explain
your reasoning.
a. ( T ) coal and peat form from
the same material.
Explain:
b. ( T ) Limestone indicates that a
shallow sea once covered an area.
Explain:
c. ( F ) The presence of sandstone
indicates that the area was once a
shoreline.
Explain:
d. ( T ) Rock salt indicates that a
region once had an arid climate.
Explain:
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REVIEW Question(s)
1. How do sedimentary rocks form?
2. What are the different types of sedimentary rock?
3.
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