1. Weathering and Erosion

2. Weathering
The breakdown do the materials of Earth’s crust into smaller pieces called Sediment.

3. Mechanical Weathering
Process by which rocks are broken down into smaller pieces by external conditions.
Types of Mechanical weathering
Frost heaving and Frost wedging
Plant roots
Friction and impact
Burrowing of animals
Temperature changes

4. Frost Wedging

5. Frost Heaving

6. Plant Roots

7. Friction and Repeated Impact

8. Burrowing of Animals

9. Temperature Changes

10. Chemical Weathering
The process that breaks down rock through chemical changes.
The agents of chemical weathering
Water
Oxygen
Carbon dioxide
Living organisms
Acid rain

11. Water
Water weathers rock by dissolving it

12. Oxygen
Iron combines with oxygen in the presence of water in a processes called oxidation
The product of oxidation is rust

13. Carbon Dioxide CO2 dissolves in rain water and creates carbonic acid
Carbonic acid easily weathers limestone and marble

14. Living Organisms
Lichens that grow on rocks produce weak acids that chemically weather rock

15. Acid Rain
Compounds from burning coal, oil and gas react chemically with water forming acids.
Acid rain causes very rapid chemical weathering

16. Karst Topography
A type of landscape in rainy regions where there is limestone near the surface, characterized by caves, sinkholes, and disappearing streams.
Created by chemical weathering of limestone

17. Features of Karst: Sinkholes

18. Features of Karst: Caves

19. Features of Karst: Disappearing Streams

20. Soil Soil is the product of weathering rocks and dying living things.
Mixture of sediment and organic matter
Plants, as well as Fungi, Bacteria, and Invertebrates mix soil to form different layers.

21. Soil Profile
A cross section of soil that shows the different layers, called horizons.
There are 3 different horizons characterized by how much organic matter is present.

23. A Horizon The top layer of soil, often referred to as topsoil.
Dark in color because it has the most organic matter.
Also contains roots and animals.
The most evolved layer.

24. B Horizon Middle layer of soil.
Much lighter because it has little to no organic matter.
Some plant roots reach this layer.
Minerals from topsoil’s organic matter is leeched into this layer.

25. C Horizon First layer of soil above the bed rock.
Contains no Organic matter, only weathered rock.
Also contains little to no nutrients.

26. Soil Profiles (cont)
Soil profiles differ based on the climate in the area.
Thickness of the various layers depends on the climate type as well as the plant/animal activity above.

28. Erosion
The process by which water, ice, wind or gravity moves fragments of rock and soil.

29. Water Erosion
Rivers, streams, and runoff

30. Rills and Gullies
Rill and Gully Erosion occur when water moves over steep areas, carving out channels.
Rills are formed by small streams.
Gullies are formed as rills become broader and deeper due to more water.
The fast moving water removes sediment.

33. Sheet Erosion
Sheet erosion occurs in flat areas where the water slows down.
Because the water has less energy, it drops much of its sediment, covering the area like a sheet.

35. Ice Erosion
Glaciers

36. Glaciers Valley Glaciers - small glaciers that exist between mountains
Leave a small U-shaped valley.
Continental Glaciers - large glaciers that cover vast areas.
Currently cover 10% of earth

38. Erosion and Deposition
Glaciers erode as they move.
They can pick up sediment and move it great distances - Plucking
They can also scrape the surface rock resulting in striations
Glaciers drop their sediment as they melt.
Moraines - pile of sediment perpendicular to movement
Eskers - pile of sediment parallel to movement
Glacial Erratic - single large rock dropped by glacier

40. Wind Erosion

41. Wind Erosion Acts as a sand blaster.
Wind carries small pieces of sediment and smashes them into rock or other hard surfaces - Abrasion
When the wind slows it deposits this material in thick layers of fine sediment - Loess
Deposition occurs on a small scale behind objects

42. Gravity Erosion (Mass Movements)
Slumps, Creeps, Rockslides and Mudslides

43. Slumps
Occurs on a steep slope when loose materials slide down the slope in one large mass.
Layers under the soil are weakened due to erosion or earthquakes.
Leaves curved scar in soil

45. Creep Slow mass movement down a less steep slope.
Often caused by repeated thaw melt cycles.
Causes tree and fence-posts to lean downhill.

47. Rockslides
Rockslides occur when large piece of rock break loose from a steep slope and roll quickly downhill.
Occur often after earthquakes or heavy rains.
Piles of broken rocks at the bottom of a slope is good evidence of a rockslide.

49. Mudflow Occur as mixtures of water and sediment flow down a slope.
Occur after heavy rains in areas of thick dry sediment.
Water and sediment forms a thick paste that has lots of momentum, and causes lots of damage.