1. Weathering and Erosion

2. Weathering
The process that breaks down rocks and other materials of Earth’s crust into smaller pieces.

3. Erosion
The removal of rock particles by wind, water, ice, or gravity.

4. Weathering and erosion work together to wear down and carry away rocks on Earth’s surface

5. Avalon
Wildwood

6. Weathering

7. Weathering can happen two different ways - Physical and Chemical

8. Physical Weathering
Rock is physically broken down into smaller pieces

9. There are five types of physical weathering

10. 1. Freezing and thawing

11. Frost Wedging

12. Frost Heaving

13. 2. Plant Growth

15. 3. Animal Actions

16. Burrowing of Animals

17. 4. Friction and impact
River rocks are rounded and smoothed due to the repeated tumbling along the river bed as they roll downstream

18. 5. Temperature Changes
Rocks expand (get bigger) when they are hot, and contract (get smaller) when they are cold.

19. This brick wall has expanded and there is a visible crack

21. Chemical Weathering
The process that breaks down rock through chemical changes.

22. There are five types of chemical weathering

23. 1. Water
Water weathers rock by dissolving it

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

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

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

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

29. All this weathering can create interesting landforms

30. Formation of Devil’s Tower, Wyoming

31. Karst Topography
A type of landscape in rainy regions where there is limestone near the surface
Created by chemical weathering of limestone

32. Features of Karst: Sinkholes

33. Features of Karst: Caves

34. Features of Karst: Disappearing Streams

35. Erosion

36. Erosion moves rock particles using four different methods

37. 1. Water Erosion Rivers, streams, and runoff

38. 2. Ice Erosion
Glaciers

39. 3. Wind Erosion

40. 4. Gravity Landslides, mudslides, slump and creep

41. Summary Weathering breaks down rocks Erosion moves the rocks
It can be physical (ice, plants, animals, friction, temperature change) or chemical (water, oxidation, acid rain, carbon dioxide, living organisms)
Erosion moves the rocks
Together they produce soil

42. Soil
Soil is made from rocks, minerals (mostly sand and clay), and organic materials
Soil forms layers of different characteristics called horizons

43. What is soil? Soil is a material that forms the crust of the earth.
It comes from the weathering of rocks and decomposition of organisms.
It is formed very slowly.

44. What’s in soil?
Minerals
Organic matter
Air and water
Living organisms

45. Soil is found in layers called horizons

46. Soil

47. O horizon (green) O = Organic
The top, organic layer made up mostly of leaf litter and humus.
Humus is decomposed organic matter.

48. A horizon (dark brown) A = Topsoil. Dark colored
Where seeds germinate and roots grow. This is generally the most productive layer of soil.

49. B horizon (light brown)
B = Subsoil
Lighter colored
Contains clay and mineral deposits (iron, aluminum, etc)

50. C horizon (tan)
C = Parent Material
Layer of large unbroken rocks

51. R horizon (black)
R = Bedrock.
The solid rock that is under the soil

53. Areas with a lot of humus and topsoil are great for growing plants.

54. Mosaic
of closely
packed
pebbles,
boulders
Alkaline,
dark,
and rich
in humus
Weak humus-
mineral mixture
Dry, brown to
reddish-brown, with
variable accumulations
of clay, calcium
carbonate, and
soluble salts
Clay,
calcium
compounds
Desert Soil
(hot, dry climate)
Grassland Soil
(semiarid climate)

55. Forest litter
leaf mold
Acid litter
and humus
Acidic
light-
colored
humus
Humus-mineral
mixture
Light-colored
and acidic
Light, grayish-
brown, silt loam
Iron and
aluminum
compounds
mixed with
clay
Dark brown
firm clay
Humus and
iron and
aluminum
compounds
Tropical Rain Forest Soil
(humid, tropical climate)
Deciduous Forest Soil
(humid, mild climate)
Coniferous Forest Soil
(humid, cold climate)

56. Soil lab online
Tomorrow you will meet in the computer lab (229) and compare rainfall amounts to topsoil depths.
You will learn how rainfall affects topsoil depth.