1. Weathering, Erosion, and Deposition
Review 4
Weathering, Erosion, and Deposition

2. Weathering- Breakdown of rocks into particles called Sediment
Weathering occurs when rocks are exposed to:
1. Atmosphere 2. Hydrosphere 3. Living things

3. TYPES OF WEATHERING
1. Physical - Breakdown of rock into smaller pieces without chemical change.
EXAMPLES:
a) Root Action: Plant roots grow through cracks and break the rock.

4. b) Frost Action water freezes and expands in cracks
b) Frost Action water freezes and expands in cracks. As this happens over and over again the rock breaks.
c) Exfoliation: surface of the rock “peels” off.

5. d) Abrasion: When rocks or sediments rub against another rock
ex: sandblasting

6. 2. Chemical - Breakdown of rock by chemical action that results in a change in mineral composition
EXAMPLES:
a) Oxidation - When elements in the rock react with O2 (oxygen)
Fe (iron) + O2 (oxygen) = | Fe2O2 (iron oxide or rust)

7. b) HYDRATION- When elements in
the rock react with H2O (water- the “universal dissolver”)
Feldspar (common mineral) H2O = Clay
Clay = fine particles that are usually wet

8. c) CARBONATION- When elements are dissolved by acid rain.
Carbon Dioxide + Water = Carbonic Acid or
Sulfur Dioxide + Water = Sulfuric acid
Example: Marble grave stone dissolved by acid rain

9. PRODUCTS OF WEATHERING
Weathering results in four types of sediment:
1. Solid sediment - sand and pebbles.
2. Colloids clay sized particles (small sediment)
3. Ions - Particles dissolved in water (salty oceans)
4. Soil - a mixture of sediment and organic matter

10. O=dark organic layer
 A= topsoil, highly weathered rock mixed   with organically rich material
B=Subsoil, less organic material and  weathered rock
C-weathered rock and parent material
D- Bedrock base.

11. Deposition
I. Deposition is the process by which sediments are RELEASED, SETTLED FROM, or DROPPED from an erosional system.

12. II. Factors that Affect Rate of D
A. Size
1. Larger sediments will settle FASTER. [Think of the ESRT! Bigger sediments are harder to carry.]

13. What happens to particle size?
Why?

14. the movement of weathered material
EROSION
What is erosion?
the movement of weathered material

15. Greatest
FORCE
Greatest
AGENT
water
gravity

16. carving out V-shaped valleys?
What agent of erosion
is responsible for
carving out V-shaped valleys?
Figure A steep mountain stream eroded a V-shaped valley into soft shale in the Canadian Rockies.
running water

17. carving out U-shaped valleys?
What agent of erosion
is responsible for
carving out U-shaped valleys?
glaciers

18. Meandering Streams

19. Where is
erosion
greatest?
Outside of Curve

20. Where does
the river flow
fastest?
Center
down from
surface