Post on 16-Dec-2015
SedimentaryRocks
SedimentaryRocksCH 3 Prentice Hall
p. 82-86CH 3 Prentice Hall
p. 82-86
Weathering
• Weathering: break down rocks on the surface into sediments.– Sediments : pieces of material that come
from rocks or living things.
Weathering
Mechanical (pg 213)
Chemical (pg 215)
• Freezing & thawing• Growth of plants• Animal actions• Abrasion -
sediments wear down exposed rock
• Water (solution)• Oxygen (rust)• Carbon Dioxide• Acid Rain -
pollutants in the air make water vapor acidic.
Which is a form of Chemical weathering?
A
•Abrasion
B
•Plants
C
•Freezing & Thawing
D
•Oxygen
Erosion
• Running water or wind carries away loose sediments.
Deposition
• When sediments are “dropped off” by the water or wind carrying it.
When sediment is carried away by wind or water.
A
•Compaction
B
•Erosion
C
•Deposition
D
•Weathering
Compaction
• Pressing rocks together due to gravity and the weight of overlying layers.
– Layers build up over time
– As layers form on top, press down and compact layers below
– Creates visible layers
Cementation
• When dissolved minerals crystallize and glue sediment together.• Occurs during compaction• Dissolved minerals fill in the spaces
between sediments.
When layers of sediment are pressed together by gravity.
A
•Compaction
B
•Cementation
C
•Deposition
D
•Weathering
Sedimentary rocks are formed by…
A
•Human interactions
B
•Cooling of molten material
C
•Physical and chemical processes
D
•Metamorphism
What to Work On
• Take a Pink Letter Packet, a Sedimentary Rock, kit and a tray.
• With your partner, organize your rocks.• Write down the numbers of the rocks in
each group you make.
• Sedimentary rock from rock fragments that are squeezed together.
Clastic Rocks
Shale Sandstone Conglomerate
• (Breccia)
Clastic Rocks
Shale• Common rock that
forms from clay• Thin, flat layers that
split easily• Smooth
Clastic Rocks
Sandstone
• Forms from sand that is compacted and cemented
• Mostly made of quartz
• Somewhat porous
Clastic Rocks
Conglomerate / Breccia
• Mixture of grain sizes• Conglomerate has
more rounded grains• Breccia has sharp-
edged grains
Which process forms Sedimentary rock after it is deposited?
A
•Mechanical Weathering
B
•Erosion
C
•Compaction
D
•Chemical Weathering
• The remains of plants and animals deposited in thick layers.
Organic Rocks
Coal
• From plants buried in swamps
• Compacted over millions of years
Limestone
• From shells of aquatic animals (Calcite)
• Some shells are compacted, some dissolve
• Dissolved calcite cements it together.
Chemical Rocks
• Forms when dissolved minerals crystallize.
Rock Salt
• Forms from evaporation.
• Made of halite.
Gypsum
• Forms from evaporation.
Limestone
• Forms from dissolved calcite.
Which of these is an Organic rock?
A
•Shale
B
•Sandstone
C
•Conglomerate
D
•Limestone
Which of these is a Chemical rock?
A
•Shale
B
•Sandstone
C
•Conglomerate
D
•Limestone
Uses of Sed. Rocks
• Sandstone and Limestone are commonly used as building material
• Easily cut into slabs
• Limestone is used in cement.
What to Work On
• Look at the groups you made and reorganize them by the 3 types–Clastic, Organic, Chemical
• How did your groups change?• Note the different textures. How do they
compare to the Igneous rocks?
Which of these does NOT describe how Sedimentary rocks are
classified?
A
•What it’s made of
B
•Size of grains
C
•If it was compacted
D
•If it crystallized