1. Weathering The breakdown do the materials of Earth’s crust into smaller pieces. http://vle.whs.bucks.sch.uk/course/view.ph p?id=3204

2. Mechanical Weathering

3. Photo A Photo B

4. Abrasion The grinding and wearing away of rock surfaces through the mechanical action of other rock or sand particles. Caused by wind, water, & gravity.

5. http://geology.com/rock-tumbler/rock- tumbler-grit.shtml

6. TUMBLING GRIT: Silicon Carbonate is harder than the rocks you are tumbling and will therefore smooth off the rough edges.

7. http://geology.com/rock-tumbler/rock-tumbler-grit.shtml

8. Rocks before they are tumbled.. And after they are tumbled.

9. How did the pebbles get this way? Why are they not sharp?

10. Flowing Water As rocks and pebbles roll along the bottom of flowing water, they bump and scrape against each other, causing these rocks to become rounded and smooth.

11. 2. Water River carries rocks and pebbles that bump and scrape against each other, eventually wearing them down. (This makes them smooth & rounded).

12. National Geographic Photos

13. WIND wind blows sand and silt against exposed rock eventually wearing away the rock’s surface.

14. 3. Wind Blows and silt across exposed rock, wearing down the rock’s surface.

15. http://www.cbc.ca/news/canada/british-columbia/story/2008/07/30/bc-highway-rockslide-whistler.html

16. 3. Gravity Rocks pulled down and falling on top of each other – Ex. Rockslide (rocks falling down a mountain or cliff )

17. GRAVITY Rocks grind against each other during a rock slide, creating smaller and smaller rock fragments. Anytime one rock hits another rock, abrasion takes place.

18. Frost Wedging

19. Frost Heaving

20. ICE Water seeps into cracks during warm weather. When the temperature drops, the water freezes and expands, causing the ice to push against the sides of the crack. * This causes the crack in the rock to widen.

21. 5. Plants Roots grow into cracks in the rocks. As the roots grow, they press on sides & break apart the rock – Ex. Tree roots breaking up sidewalk

22. PLANTS The roots grow through existing cracks in rocks. The growth causes the root to expand, forcing the crack to widen. The force can eventually split the rock apart.

23. 6. Animals Burrowing animals loosen sediment & push it to the surface. This exposes it to other forces of weathering. Ex. Rabbits, worms, ants, coyotes, & mice

24. Animals Animals that live in the soil (moles, prairie dogs, insects, worms, gophers), cause a lot of weathering. By burrowing in the ground, these living creatures brake up soil and loosen rocks to be exposed to further weathering

25. Question Time 1. For each question, tell what type of mechanical weathering is happening. 2. Write on dry erase board the agent causing the weathering. 3. Discuss with your partner & explain how that agent caused what you see in the picture.

26. What agent of mechanical weathering is at work here?

27. Flowing Water As rocks and pebbles roll along the bottom of flowing water, they bump and scrape against each other, causing these rocks to become rounded and smooth.

28. What agent of mechanical weathering is at work here?

29. WIND wind blows sand and silt against exposed rock eventually wearing away the rock’s surface.

30. What agent of mechanical weathering is at work here?

33. ICE Water seeps into cracks during warm weather. When the temperature drops, the water freezes and expands, causing the ice to push against the sides of the crack. This causes the crack in the rock to widen.

34. Ice- Wedging

35. What agent of mechanical weathering is at work here?

36. Animals Animals that live in the soil (moles, prairie dogs, insects, worms, gophers), cause a lot of weathering. By burrowing in the ground, these living creatures brake up soil and loosen rocks to be exposed to further weathering

37. Animals

38. What agent of mechanical weathering is at work here?

39. PLANTS The roots grow through existing cracks in rocks. The growth causes the root to expand, forcing the crack to widen. The force can eventually split the rock apart.

40. Temperature Change Cold causes rock to contract (shrink). Heat causes rock to expand (grow slightly). Demos: https://sites.google.com/site/sed695b/project s/demonstration-equipment/expanding-ball-- ring--thermal-expansion https://www.youtube.com/watch?v=hX2Y2IDj uGI

41. Plants