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