Bell Ringer: List and explain the three types of weathering.

1. Bell Ringer: List and explain the three types of weathering. MID TERM: Monday January 14-17 with makeups on January 18th. You will get a study guide soon and you may use an index card on the midterm. GRADES CLOSE: Friday January 18 HOMEWORK: Read pg. 133-142 pg. 133 Key Concepts and vocabulary. Take notes.

2. Weathering and Soil

3. Weathering • Mechanical weathering occurs when physical forces break rock into smaller and smaller pieces without changing the rock’s mineral composition. • In nature three physical process are especially important causes of weathering: frost wedging, unloading, and biological activity.

4. Mechanical Weathering • Frost wedging is the mechanical breakup of rock caused by the expansion of freezing water in cracks and crevices. Ice Heaving. • Sections of rock that are wedged loose may tumble into large piles called talus, which typically form at the base of steep, rocky cliffs.

5. Examples of Frost Wedging and Ice Heaving

6. Abrasion • Def: the wearing away of rock material by grinding action • Water, wind and ice are capable of moving rocks. • Sand is a product of abrasion.

7. Continue • Unloading is the reduced pressure on igneous rock causes it to expand and allows slabs of outer rock to break off in layers in a process called exfoliation. • Biological the activity of organisms, including plants, burrowing animals, and humans, can also cause mechanical weathering.

9. Upward Expansion Examples

10. Chemical Weathering • Chemical weathering is the transformation of rock into one or more new compounds. • Spheroidal causes the corners and edges of rock to be more rounded

11. Rate of Weathering • Mechanical weathering affects the rate of chemical weathering. • By breaking the rocks into smaller pieces, mechanical weathering accelerates chemical weathering by increasing the surface area. • Two other factors affecting the rate of weathering are rock characteristics and climate. • Rock characteristics • Mineral composition and solubility • Physical features such as joints

12. Continued 2. Climate • Temperature and moisture are the most crucial factors. • Chemical weathering is most effective in areas with high temperatures and abundant moisture. • Differential Weathering • Caused by variations in composition • Creates unusual and spectacular rock formations and landforms

13. Check for Understanding Explain the difference between weathering, erosion, and deposition What powers the rock cycle? What happens to a rock’s mineral composition during mechanical weathering? How does chemical weathering affect the compounds in rock? Why is chemical weathering slow in arid and polar regions?

14. Soil • Soil is part of the regolith that supports the growth of plants. • Regolith is the layer of rock and mineral fragments that covers most of Earth’s land surface. • Soil has four major components: mineral matter, or broken-down rock; humus, which is the decayed remains of organisms; water; and air.

15. Q: What’s the difference between soil and dirt? A: Location, location, location! Soil is not DIRT!

16. Why the different colors? Hematite: red Goethite: yellowish brown Ferrihydrite:reddish brown Calcite: off white Quartz:white Organic matter:black

17. Soil Color Variation • Did you know ?????? ….and each one tastes different There are more than 20,000 different soil types in the United States

18. Dr. Greg Pillar, Queens College

19. Soil Formation! Results from the continuous weathering (mechanical and chemical) of rocks into smaller and smaller pieces) combined with water, living organisms, air, decaying organic material (humus).

20. Parent rock is the bedrock from that when weathered rock breaks down and begins the process of soil formation. Takes 100’s to 1000’s of years to form 10cm of soil.

21. Extremely important to organisms, decomposition is the source of nutrients and water for all living things

22. Soil composition • 80% are rock particles. There are three basic particle sizes. • Sand (0.05mm to 2mm size) • - good drainage and aeration, doesn’t store water well; unsuitable for plants • Silt (0.002mm to 0.05mm size) • - good drainage and aeration, stores water well; suitable for plants • Clay (0.002mm and smaller) • - holds water well, doesn’t drain well, few air spaces; unsuitable for plants

23. Percentage of the 3 particle sizes in the mixture determines soil type and characteristics of soil. • Sandy at the beach, red clay in the Piedmont of NC. • Loamy soil has equal parts of all 3 particle sizes and is the optimal soil type

24. Fine Texture - Clay Dr. Greg Pillar, Queens College https://www.soils.org/lessons

25. Course Texture - Sand Dr. Greg Pillar, Queens College https://www.soils.org/lessons

26. Soil Texture Diagram Practice • (1) Loam • (2) Sandy clay • (3) Silty clay loam What type of soil has: • 20% clay, 40% silt, 40% sand • 40% clay, 10% silt, 50% sand • 30% clay, 60% silt, 10% sand Find the % of each particle at: • A • B • C A • 60%clay, 20%silt, 20%sand • 30%clay, 40%silt, 30%sand • 10%clay, 30%silt, 60%sand B C

27. Why is Soil Texture Important?

28. Soil Horizons/Soil Profile • As weathering progresses, distinct soil layers form. The more time involved the more mature the soil. • Takes 1000’s of years to form mature soil.

29. Observe this SOIL PROFILE through soil O: Organic material (may be absent) A: Topsoil- Organic material & mineral grains E: Leached zone (may be absent) B: Subsoil – rich in clay, iron, aluminum C: Weathered bedrock Soil layers are horizons and assigned letters R: Bedrock (parent material)

30. SOIL LAYERS • O layer- organic material (ex. Dead leaves, twigs) • A layer - upper layers/topsoil - dark colored; most fertile - where most organisms exist and composed of humus • B layer – subsoil - Mostly clay - 100,000 years to form • C layer – partial weather bedrock and extends to parent rock • R layer- bed rock

32. Soil Color by Horizon Fun Fact: It takes 200 to 1,000 years to form an inch of topsoil. A horizon: organic coatings B horizon: Iron coatings C horizon: little coating

33. Soil Color – Variation by Geography Red soils: Southeast US Dr. Greg Pillar, Queens College

34. Soil Color – Variation by Geography Brown/black soils: Midwest Dr. Greg Pillar, Queens College

35. Soil Color – Variation by Geography White (gypsum) sands: New Mexico Dr. Greg Pillar, Queens College http://www.scienceclarified.com

36. Soil Formation • The most important factors in soil formation are parent material, time, climate, organisms, and slope. • Parent Material • Residual soil—parent material is the bedrock • Transported soil—parent material has been carried from elsewhere and deposited • Time • Important in all geologic processes • The longer a soil has been forming, the thicker it becomes.

37. Soil Formation • Climate-MOST IMPORTANT in soil formation! • Climate has the greatest effect on soil! Variations in temperature and precipitation influence the rate, depth, and type of weathering. • Climate has an effect on the organisms that live on and in that soil. • Organisms • Organisms influence the soil's physical and chemical properties. • Plants are the main source organic matter. • Microorganisms and animals also contribute organic material.

38. Soil Organisms Ex: bacteria, fungi, algae, microscopic worms, protozoa, plant roots, insects, earthworms, moles, snakes, groundhogs, etc.

39. Continued • Slope • Steep slopes often have poorly developed soils. • Optimum slope is a flat-to-undulating upland surface. • Orientation, or direction the slope is facing, influences soil formation. • Soil temperature • Moisture

40. 15.06.b ACTIVITIES THAT THREATEN SOIL FARMING/AGRICULTURE OVERGRAZING REMOVING VEGITATION SOIL CONTAMINATION

41. PREVENTING SOIL EROSION • Agricultural: 10% of the worlds best agricultural land damaged due to soil erosion and overuse over last 50 years. • contour plowing • no-till agriculture (no plowing) • terracing slopes • crop rotation - fallow

42. Mass Movements and Erosion • Mass movements- the downward transportation of weathered materials • Gravity causes materials to fall, slide, or move at slow speeds to lower levels • Erosion- the removal and transport of materials by natural agents such as wind and running water

43. Mass Movements • Landslide- movement of a mass of bedrock or loose soil and rock down the slope of a hill, mountain, or cliff • Steep slopes • Regions near volcanoes and in earthquake-prone regions

44. Landslides • Creep- slow, imperceptible movement of soil down a slope • Causes fence posts, poles and other objects fixed in soil to lean downhill • Slump- a block of land tilts and moves downhill along a surface that curves into the slope • Tends to occur because bottom of slope can no longer support top of slope

45. Creep

46. Slump

47. Earthflows- the downslope movement of a mass of earth materials that have been saturated with water • Slower and less fluid than a mudflow; velocity affected by amount of water present, the composition of the soil, and steepness of slope • Mudflows- the downslope movement of water that contains large amounts of suspended clay and silt • Rapid movement; capable of moving rocks, boulders, trees, and houses.