1. Erosional Forces FACTORS SUCH AS WIND AND WATER MOVE MATERIALS !

3. Through the process of deposition, sediments are dropped by erosion agents as they lose energy.

4. Mass movement occurs as gravity moves materials down a slope as one large mass.

5. Slump: material slips down a curved surface as one large mass.

6. Sediments slowly shift down hill in the process of creep.

7. Rockfalls and rock slides occur when rocks break off or slip suddenly down a hill.

8. A mudflow is a thick mixture of water and sediments flowing downhill.

10. Sometimes builders and residents make slopes ,more unstable by making them steeper.

11. Another source of instability is the removal of vegetation.

13. Steep slopes can be made safer with vegetation, drainage pipes, and walls of concrete or railroad ties.

14. Glacier: large mass of ice and snow; moves slowly

15. Glaciers are the most powerful erosion agent.

16. As glaciers move they pick up boulders, gravel and sand in an erosion process called plucking.

19. As a glacier moves forward over land it can transport huge volumes of sediment and rock .

20. When glaciers melt and retreat they leave behind till (boulders, sand, clay and silt)

21. A moraine is a ridge, or pile, of deposit left at the end of a glacier

22. Outwash: material deposited in layers by the meltwater of a glacier, with largest pieces closer to the glacier.

23. Esker: type of outwash deposit formed as meltwater rivers within the ice deposit sand and gravel within their channels.

24. Continental glacier: huge masses of ice and snow now covering only about 10% of Earth in areas near the poles.

25. In the past, as much as 28% of Earth was covered with glaciers.

26. Ice ages: periods of widespread glaciation over the last 2 million to 3 million years.

27. The average air temperature on Earth was about 5 degrees Celsius lower during ice ages than today

28. The last major ice age was about 18,000 years ago.

29. Valley glaciers exist in mountains.

30. Cirques: bowl-shaped basins in the sides of mountains, created by valley glaciers.

31. Arete: long ridge that forms when two valley glaciers erode a mountain side by side.

32. Horn: forms when valley glaciers erode a mountain from several directions.

33. Glacially eroded valleys have a U shape, as opposed to the V shape left by stream erosion.

34. Glaciers have changed, and continue to change, the shape of Earth’s surface.

47. A mound of sediments drifted by the wind is called a dune