1. 5-3 Notes
Waves and wind Erosion

2. Think About…
How do you think these pillars of rock formed?

3. Waves and Currents
The rock pillars were formed by constant action of waves slowly wearing the rock away.

4. Waves and Currents
In the future, waves will most likely wear away the pillars completely.

5. Waves and Currents
Waves are powered by wind and can wear away rock and move thousands of tons of sand.

6. Shorelines
High, rocky coasts tend to get worn AWAY by waves, while low coastlines are often BUILT UP.

7. Shorelines
When a stream flows into an ocean or lake, it deposits sediment near its mouth.

8. Shorelines
This sediment mixes with the sediment formed by waves crashing against the shore.

9. Shorelines
Waves and currents move this sediment along the shore, building up beaches.

10. Shorelines
Longshore drift: the zigzag movement of sand along a beach.

11. Shorelines
Waves hit the beach at an angle due to the direction wind is blowing.

12. Shorelines
Gravity then pulls the sand straight back down to the water

13. Shorelines
This process eventually shifts the sand down the beach in a zigzag pattern.

14. Shorelines
Longshore current: movement of water along a shore as waves strike the shore at an angle.

15. Shorelines
The direction of the longshore current can change as the direction of the waves striking the shore changes.

16. Sandbars and Barrier Islands
Longshore currents often deposit sand along shorelines.

17. Sandbars and Barrier Islands
Sometimes the sand can build up to form a sandbar-a completely or partially submerged ridge of sand.

18. Sandbars and Barrier Islands
Spit- A sandbar that has built up above the water’s surface and is joined to land at one end.

19. Sandbars and Barrier Islands
Barrier islands-long narrow islands that develop parallel to a coast (start out as sandbars).

20. Sandbars and Barrier Islands
Barrier islands get their name from the fact that they create a barrier between ocean waves and the shore of the mainland.

21. Wind Shapes Land
Wind has the power to transport and deposit sediment.
Wind is less powerful than water but it still shapes landforms, especially in dry regions or regions with few plants.

22. Wind Shapes Land Wind can: Build up dunes Deposit layers of dust
Make a land surface as hard as pavement

23. Dune Formation
Dune-a mound of sand built up by wind.

24. Dune Formation
Even a light breeze can carry dust.

25. Dune Formation
A moderate wind can roll and slide grains of sand along a beach.

26. Dune Formation
Only a very strong wind can pick up and carry sand particles.

27. Dune Formation
When the wind dies down or hits something (e.g. a cliff or hill) it drops the sand.

28. Dune Formation
Over time, the sand builds up to create dunes.

29. Dune Formation
Some dunes start out as ripples that grow larger.

30. Dune Formation
Others form as wind-carried sand settles around a rock, log, or other obstacle.

31. Dune Formation
Dunes vary greatly in size and shape and can reach heights of 300 m!

32. Dune Formation
Some dunes are curved; others are straight.

33. Dune Formation
There is usually a gentle slope on the side facing the wind and a steep slope on the side facing away from the wind.

34. Loess
Wind also changes the soil over large regions of Earth by depositing dust.

35. Loess
A strong windstorm can move millions of tons of dust.

36. Loess
Loess: deposits of very fine wind-blown sediment. (pronounced LOH-uhs)

37. Loess
In some regions, deposits of loess have built up over thousands or even millions of years.

38. Loess
Loess is a valuable resource because it forms good soil for growing crops.

39. Loess
Loess covers about 10% of Earth’s land surface.

40. Desert Pavement Wind can shape land surfaces by removing dust.
When wind blows away all the smallest particles from the soil, it leaves behind a hard layer of stone and gravel.

41. Desert Pavement
This is called desert pavement because it looks like cobblestone.

42. Review
1. In which of the following areas is wind a major erosion agent?
A. a grassy field
B. an area covered with pine trees
C. sand dunes in the desert
D. a hillside covered with plant life

43. Review 2. A dune is a sand mound built up primarily by A. gravity
B. running water
C. glaciers
D. wind

44. Review 3. Strong winds can transport large quantities of A. gravel
B. wet sand
C. dry sand
D. clay