Unit 2 – Weathering and Erosion

1. Unit 2 – Weathering and Erosion Unit Essential Question (EQ) : How do Earth’s processes and human activities change the surface of the Earth?

2. By the end of Unit 2, students will understand that… • Weathering is the process that breaks down rock and other substances at Earth’s surface. • Erosion is the movement of rock particles by water and wind. • Deposition occurs where the agents (forces) of erosion lay down sediment. • Weathering and erosion wear down, and deposition fills in the Earth’s surface.

3. Students will also understand that… • Although weathered rock is the basic component of soil, the composition and texture of soil and its fertility and resistance to erosion are greatly influenced by plants and other organisms. • Human activities, such as reducing forest cover and intensive farming have changed the Earth’s surface.

4. Concept #1: - Weathering, Erosion, and Deposition Lesson Essential Questions (LEQs): How does weathering affect Earth’s surface? How does erosion and deposition affect Earth’s surface?

5. Weathering, Erosion, and Deposition – Lesson vocabulary Weathering Erosion Mechanical Weathering Abrasion Biological Weathering Oxidation Chemical weathering Slump Landslides

6. Weathering • What is weathering? • What are the two types of weathering? How are they different? • What affects the rate (how fast or slow) at which weathering occurs? • What examples have you seen of each type of weathering around the school, your home, or community?

7. Weathering: is the process that breaks down rock and other substances at Earth’s surface. These pieces do not move to a new location. They simply break down but remain next to one another.

8. Weathering White lichens cover a blue granite gravestone like snow near Lake Champlain, New York. Lichens, symbiotic organisms that combine fungi and algae, can be powerful weathering agents, secreting chemicals called chelates that work to break down rock.

9. Erosion: is the movement of rock particles by water and wind. Lesson Essential Question (LEQ): How does erosion and deposition affect Earth’s surface?

10. Erosion by Gravity • A landslides happen when lots of materials are carried down a steep hill by gravity. • A mudslide is when water makes the side of a hill heavy, and carries it downward. • Slumps occur when a large amount of rock or dirt, or other sediments, fall. All the material in a slump always comes down at once, where a landslide can have many rocks tumbling down at different times. • When the earth moves slowly, it's called a creep.

11. Erosion by Gravity Slumps are landslides in which the moving material moves in a block.

12. Erosion by Gravity Creep is the gradual movement of soil down a slope in response to gravity. This eventually results in a mass downward movement of soil on the slope. Evidence of soil creep includes the formation of step-like ridges along the hillside, leaning walls and telegraph poles, and trees that grow in a curve to counteract progressive leaning.

13. Erosion by Gravity Landslides may involve rock, debris (mixed rock and soil) or earth (fine-grained material). • This slide cleared a long path across route 121 and down a forested hillside in Wooden Valley, California.

14. Erosion by Gravity A mudslide is when water makes the side of a hill heavy, and carries it downward.

15. Review Question: The wearing away of soil and rock is called __________. A) runoff B) Drainage C) Erosion D) infiltration

16. Water and Wind Erosion • This is an example of how water and wind can erode or wear down the Earth’s surface. • Poor farming practices allowed soil erosion to happen here very quickly. Picture taken in Providence Canyon State Park, which is located 7 miles west of Lumpkin on Ga. Hwy. 39C.

17. Water Erosion Moving water is among the most powerful of nature's landscape-altering tools.

18. Wind Erosion Winds sweeping through the Grand Canyon have eroded this sandstone outcrop into an anvil shape. Wind shapes these fantastical forms by eroding less dense rock, like sandstone, faster than surrounding rock. Desert winds sculpted these gentle swirls out of the limestone hills in Black Gap Wildlife Management Area, Texas.

19. Wind Erosion Wind erosion makes these layered sandstone hills swirl in Paria Canyon-Vermilion Cliffs Wilderness Area.

20. Glacial Erosion The Bernard Glacier in Alaska's Saint Elias Mountains looks like a huge alpine highway. Glaciers are slow but highly effective shapers of the land, essentially carrying away anything in their path—from soil and rocks to hills and even the sides of mountains.

21. Deposition: is when sediment, and broken down substances are deposited, or dropped off somewhere.

22. Deposition • This can happen in a river when the water slows and creates a new bank, or delta. • The Mekong Delta ( “Nine Dragon river delta”) is the region in southwestern Vietnam where the Mekong River approaches and empties into the sea through a network of distributaries.

23. Deposition • When wind slows down it can also drop sediment.

24. Concept #2 – Formation/Composition of Soil Lesson Essential Question (LEQ): How does the formation of soil relate to the processes of weathering and erosion?

25. Formation/Composition of Soil – Lesson vocabulary Soil Fertility Soil profile Topsoil Soil horizon Subsoil Bedrock Litter Decomposer Humus

26. How does the formation of soil relate to the processes of weathering and erosion? • What is soil? • Soil is the loose weathered material on Earth’s surface on which plants can grow. • Makeup of soil includes rock particles, minerals, decayed organic matter, water, and air. • Where did soil come from? • One of the main ingredients of soil is bedrock. • Bedrock is a solid layer is rock beneath the soil. • How does bedrock become soil????

27. How does the formation of soil relate to the processes of weathering and erosion? • As we learned in the earlier part of this lesson and in Unit 1, weathering and erosion both help to break down rocks into smaller and smaller pieces. • Weathering and erosion work together continuously to wear down and carry away rocks at Earth’s surface. • The bedrock will become exposed at the surface where weathering will turn into sediment that helps create soil.

28. How does the formation of soil relate to the processes of weathering and erosion? • Soil is constantly being formed where bedrock is exposed. • Soil continues to form as rock is broken down by weathering. • These rock particles mix with other materials on the surface and the soil continues to develop. • Soil takes a very long time to form.

29. How does the formation of soil relate to the processes of weathering and erosion? • You can see the different transitions or stages of soil layers if you dig about half a meter deep. • These different layers showing the gradual development or changes in the soil are called a soil horizon. • A soil horizon is a layer of soil that differs in color and texture from the layers above or below it. Go to www.phschool.com “Soil layers activity” - web code cfp-2022

30. Soil Profile

31. How does the formation of soil relate to the processes of weathering and erosion? • What factors affect the rate at which soil forms? • The same things that affect the rate of weathering also determine how fast or how slow soil forms! • Climate • Since weathering takes place faster in warm, rainy climates, soil will develop faster in this environment also. • Rock type • Some rocks weather faster than others. Rocks that contain minerals that dissolve in water or that are permeable, which means it has a lot of tiny, connected air spaces in them, weather faster. limestone

32. Concept #3 – Conservation Lesson Essential Questions (LEQs): How does human activity affect the eroding of Earth’s surface? How can humans conserve water, soil, and air?

33. Conservation – Lesson vocabulary Soil conservation Dust Bowl Contour plowing Wind breaks Ground cover Terracing Renewable Natural resources Nonrenewable Natural resources

34. How does human activity affect the eroding of Earth’s surface? • Human activities that have helped contribute to soil erosion include: • Poor farming practices • Construction • Timber Industry

35. How does human activity affect the eroding of Earth’s surface? • These are photographs from the Dust Bowl of the 1930’s. • Poor farming practices, which helped increase soil erosion, was a major cause that led to this devastating event.

36. Examples of Soil Conservation Techniques – Contour Plowing and Terracing • Alternating strips of alfalfa with corn on the contour protects this crop field in northeast Iowa from soil erosion.

37. How does human activity affect the eroding of Earth’s surface?