Weathering vs. Erosion?

1. Weathering vs. Erosion? • Many people think of weather and erosion as the same thing. • Weathering – is the break down of rock into smaller particles. • Erosion – is the removal (transportation) of the weathered sediments.

2. 2 Types of Weathering • There are 2 types of Weathering. • Mechanical Weathering – sometimes called “Physical Weathering,” and Chemical Weathering.

3. Mechanical Weathering • Mechanical Weathering – breaks down rocks “physically” – without changing the rock’s chemical composition. • Agents of Mechanical Weathering include tree roots, frost wedging, or wind abrasion.

4. What type of Climate? • What type of climate would Physical Weathering thrive in? • Dry, Cold Climate • A desert, although very hot during the day, gets cold at night. • This promotes ice wedging. • Also, Wind Abrasion – through sand blasting – weathers rocks in desert climates.

5. Do You Know? • What caused this rock formation? • a. water • b. gravity • c. ice • d. wind

6. Do You Know? • What caused the Grand Canyon to form? • a. wind • b. ice (glaciers from the last ice age) • c. water • d. gravity

7. The Power of Water!

8. Chemical Weathering • Chemical Weathering – weathers rocks by breaking them down by chemical reactions • Agents of Chemical Weathering are – water, oxygen, “acid rain” (carbonic acid)

9. Agents of Chemical Weathering • Agents of Chemical Weathering are: • Oxidation • Acid Precipitation • Hydrolysis

10. Oxidation • Oxidation – is the chemical breaking down of rock through the chemical reaction of oxygen, water, and some type of metal in the rock. • Many times the metal is iron (Fe) or copper (Cu).

11. Effects of Chemical Weathering

12. Effects of Chemical Weathering

13. Chemical Weathering • Caves are caused by chemical weathering. • Chemical weathering thrives in a warm, moist climate.

14. What affects weathering? • There are 4 factors affecting the rate at which weathering occurs: • Climate • Rock type and composition • Surface Area • Topography

15. What is Erosion? • Erosion is the removal of weathered sediment by natural processes. • What are the 4 Agents of Erosion? • Wind • Water • Ice (Glaciers) • Gravity

16. Deposition • Deposition occurs when the erosional force has lost its ability to carry or transport the weathering sediment.

17. Depositional Features • What type of depositional feature is shown in the picture? • a. water deposit • b. glacial deposit • c. wind deposit

18. Depositional Features • What type of depositional feature is shown in the picture? • a. water deposit • b. glacial deposit • c. wind deposit

19. Depositional Features • What type of depositional feature is shown in the picture? • a. water deposit • b. glacial deposit • c. wind deposit

20. Mechanical Weathering Review

21. Chemical Weathering Review

22. The formation of Soil! • When rocks weather they are broken down into smaller fragments (sediments). • The formation of soil is the result. • Soil – is the mixture of rock fragments, mineral fragments, and organic matter overlying the bedrock of Earth’s surface.

23. Organic Matter • In order for sediments to be considered to be soil, there must be the appearance of organic matter. • Humus – is the dark decaying organic matter composed of dead leaves, twigs, and/or dead animal remains.

24. Soil Development • The type of soil that forms is determined by: CORPT • Climate – type of climate • Organic matter – how much is available • Relief– how the slope of the land is. • Parent material – type of bedrock being weathered. • Time – how long has the soil been developing.

25. Stages of Soil Development

26. Soil Profile • Scientists divide every soil into 4 horizons (layers). • A Horizon • B Horizon • C Horizon • D Horizon (Bedrock)

27. A Horizon • A Horizon is sometimes called the “topsoil.” • It is characterized by being dark due to it being loaded with humus. • It is the most developed horizon.

28. B-D Horizons A Horizon “Topsoil” B Horizon “Subsoil” some organic matter leached from A C Horizon – Parent Material Partially weathered rock. BEDROCK – this is the parent rock that has been weathered.

29. Leaching occurs when nutrients (organic matter) is washed from one horizon to another. Leaching generally occurs when nutrients are washed from the A horizon to the B horizon. This is why tropical soils are considered to be not fertile due to the constant leaching of nutrients. If this is true, how can tropical rainforests maintain mass diversity of different species? What is Leaching?

30. Tropical Rainforest

31. Desert Soils • Desert Soils – receive low levels of precipitation. • This causes them to accumulate a high level of salt. • The lack of rainfall causes desert soils to have a very thin A horizon & little organic matter.

32. Temperate Soils • Temperate Soils generally have horizons A – D and can support diverse environments such as forests, grasslands, and prairies. • Virginia has a temperate soil.

33. Polar Soils • Polar soils – occur in high latitudes and high elevations. • They generally have good drainage and no distinct horizons. • They are very thin.

34. Soil Texture Particles of soil are classified according to size as being sand, silt, or clay, with sand being the largest and clay being the smallest. The texture of a soil affects its capacity to retain moisture and therefore its ability to support plant growth. Soil Fertility Soil fertility is the measure of how well a soil can support the growth of plants. Factors affecting it are: availability of minerals and nutrients, amount of organic matter present, amount of precipitation, topography, & level of acidity. Soil Texture & Fertility

35. What would cause soil to erode? • Soil erosion occurs when the agents of erosion come in contact when bare soil. • Factors Affecting Soil Erosion: • Slope • Agricultural Practices

36. The Dust Bowl

37. About The Dust Bowl • For Eight Years Dust Bowl blew on the Southern plains. • It came in yellowish- Brown haze from the South an in rolling walls of black From the North. • The Simplest acts of life-breathing, eating, taking a walk-were no longer simple. • Children wore dust masks to and from school, women hung wet sheets or windows in a futile attempt to stop the dirt, farmers watched helplessly as their crops blew away.

38. 1930 The Dust Bowls Begins! • AS John Steinbeck wrote 1939 Novel The Grapes of wrath: The Dust Bowl caused people to get out by the carload. • Homeless migrated through the mountains. • Thousands and thousands went through the mountains hungry and restless.

39. Causes of the Dust Bowl • Poor agriculture practices and years of sustained drought caused by the dust bowl • Plains, grasslands, had been deeply plowed and planted to wheat. • But as the drought of the early 1930s evolved, the farmers kept plowing and planting and nothing would grow. • The ground cover that held the soil in place was gone.

40. The Dust Bowl of Oklahoma • During the great storm of the 1930s in Oklahoma, the weather threw up so much dirt that, at times, there was zero visibility and everything was covered in dirt. • No matter how tightly Oklahoma sealed their homes they could not keep the dirt from entering.

41. A Family Moving West • This family from Oklahoma has packed up to head to California. • These people became known as the "Okies. Okies were people moving from ‘The Dust Bowl’ that was from Oklahoma.

42. Families Of The Dust Bowl • Here to the right is a family affected by “The Dust Bowl”. They are also “Okies” striving to get away from “The Dust Bowl”. Very many families starved to death and also died of thirst.

43. Black Sunday • By 24 [March] 1935 southeastern Colorado and western Kansas had seen twelve consecutive days of dust storms, but there was worse to come. • Near the end of March a new duster swept across the southern plains, destroying one-half the wheat crop in Kansas, one-quarter of it in Oklahoma and all of it Nebraska-5million acres blow out. • Residents of Perryton Tex, experienced 50 dust storms in 104 days.

44. What Did We Learn From The Dust Bowl? • The dust storms played an important role in soil education. • The Dust Bowl caused the formation of the U.S. Department of Soil Conservation which provides information about soil erosion. • Through this governmental agency, Farmers can learn soil conservation techniques.

45. Soil Conservation Techniques! • Techniques include: • Wind Barriers – planted near exposed fields to slow down wind velocity. • Contour Farming – planting grass along contours to slow down soil erosion by water runoff.