1. EROSION

2. What is Erosion?
The transport of sediments from one location to another

3. Erosion of Montauk Point Lighthouse
1838
1990
200 feet of land lost in 200 years

4. EROSION IS DRIVEN BY THE FORCE OF
GRAVITY

5. What are the agents of erosion?

6. Gravity
Landslides, Avalanches

8. Avalanche

9. Gravity
Fallen rocks are sharp and angular

11. Landslide

12. Wind Erosion

13. Wind Erosion occurs primarily in arid climates

15. Wind Erosion:
When the wind picks up and carries away loose particles it is known as deflation.
Abrasion
exposed rock is worn away by wind blowing particles.

16. Wind Erosion
Ventifact: a loose rock particle (too heavy to be carried by the wind) that are abraded by wind blown particles.

17. Wind Erosion

18. Factors Affecting Wind Erosion
Speed
-The faster the wind blows  the larger the particles it can transport
Particle size
-The larger the particles the greater the abrasion of exposed surfaces
Length of time
-The longer the wind blows  the more wind erosion

19. Desert Sandstorm

20. Glaciers
ICE

21. Glaciers

22. exposed rock is worn away by smaller particles carried by the ice.
Glaciers erode the surfaces over which they move by:
Abrasion:
exposed rock is worn away by smaller particles carried by the ice.
2. Plucking: loosening rocks, picking them up and carrying them away

23. Small sediments (such as clay and silt) carried by glaciers smooth and polish the rock surface
below.

24. Larger sediments carried by glacier scratch and striate the rock surface below.

25. Glaciers create parallel striations in the bedrock.
Direction of glacial movement is indicated by striations

26. Polished and Striated Bedrock

27. Glacial erratics are large rocks that have been transported by glacial ice without being broken into pieces

28. Running Water
Streams, Rivers, Oceans

29. Running water is the primary agent of erosion!!!
Water affects more of the Earth’s surface than any other agent of erosion.

30. Running water: Rounds and smoothes the rock
Makes the rock smaller because jagged edges are broken off due to abrasion.

33. Each agent of erosion produces its own
characteristic shape and texture in rocks.

34. Stream Basics
Stream: any body of running water moving downhill due to gravity in a narrow channel
Discharge: the volume of water in the stream at any given location during a specific amount of time.
Stream Bed: the bottom of the stream channel and each side is known as the stream bank.
Stream source: area where streams begin, usually in mountains or hills where rain water collects.
Stream mouth: the place where a stream ends up – usually in a lake, sea or ocean.
Stream gradient: the change in elevation from a stream’s source to its mouth.

35. The velocity of a stream depends on…
Stream Discharge
-The more water in the stream, the faster the stream will flow

36. Gradient:
the steepness of the slope down which the stream is flowing.
-The more of a hill there is the faster the water will flow.

37. Flat gradient = slow moving water
Merrill ES Snyder Feather Hesser
Flat gradient = slow moving water

38. Steeper slope = faster moving water

39. Particle Size
The faster the stream moves, the bigger the particles it can transport.

40. Relationship of Transported Particle Size to Water Velocity
R.T. pg. 6
Relationship of Transported Particle Size to Water Velocity
ESRT

41. What happens to the size of the particle
What happens to the size of the particle the stream can carry as the velocity of the stream increases?
-The particle size increases.
What happens to the size of the particle

42. The minimum velocity needed to carry a pebble is:
90 cm/sec

43. WHAT IS THE MINIMUM VELOCITY NEEDED TO CARRY A BOULDER?
325 cm/sec

44. Boulder What is the largest size particle that can be
carried by a stream flowing 400 cm/sec?
Boulder

45. If a stream is flowing 150 cm/sec, what is the largest size sediment it can carry?
Pebbles

46. Name all of the sediments a stream can carry if it is flowing 50 cm/sec?
Clay, silt

47. PARTICLES ARE CARRIED IN SEVERAL WAYS DEPENDING ON THEIR SIZE
EROSION BY WATER:

48. Four ways streams transport materials:
Solution: sediments are dissolved in water (salt ions)

49. 2. Suspension: sediments are held in the middle of the stream but not dissolved. (clay, silt, sand)

50. 3. SaltationRolled, bounced, or dragged along stream bed (pebbles, cobbles, boulders)

51. Floatation
Some sediments float on the surface of the water.

52. Smaller sediments are dissolved
or are suspended
Larger sediments are rolled or
dragged on bottom

53. The fastest flowing water in the stream is the area with the least friction.
Friction from air
Friction
Friction
No Friction
from side
from side
Friction
from bottom