1. EROSION: The force that shapes the Earth!
Erosion: What is it?
Erosion: The MOVEMENT of SEDIMENTS by natural FORCES
Agents of Erosion: Forces that move sediments
There are SEVERAL AGENTS of erosion…
EROSION: The force that shapes the Earth!

2. AGENT 1: Erosion by Gravity
CREEP…Gravity pulls the soil down slope…
Very…
Very…
Very…
Slowly
Creep causes… (see diagram)
EROSION: The force that shapes the Earth!

3. Agent 1: Erosion by Gravity
Slump
Don’t build your house on a steep slope!
Landslide
These are both caused by gravity!
EROSION: The force that shapes the Earth!

4. Agent 1: Erosion by Gravity
Rock Fall: LARGE sediments fall or slide off a mountain
All gravity erosion is also called MASS MOVEMENT!
EROSION: The force that shapes the Earth!

5. EROSION: The force that shapes the Earth!
Summary
1. What is erosion? How is it different than weathering?
2. Natural forces that move sediments are called what?
3. All forms of gravity erosion are called what?
EROSION: The force that shapes the Earth!

6. EROSION: The force that shapes the Earth!
Agent 2: Erosion By Wind
Small sediments (like sand) get blown around!
Large sediments (like cobbles and boulders) get left behind!
Large sediments get “sandblasted” They look pitted and frosted…
EROSION: The force that shapes the Earth!

7. Agents 2: Erosion By Wind
A beautiful ARCH formed by WIND EROSION blew sand against the bedrock and wore it away
EROSION: The force that shapes the Earth!

8. Agents 2: Erosion By Wind
SAND DUNES form by wind erosion!
Which way does the wind blow?
EROSION: The force that shapes the Earth!

9. EROSION: The force that shapes the Earth!
Summary
1. How is wind an agent of erosion?
2. Compared to gravity, the size of the sediments eroded by wind are MUCH ____
3. Why is wind a major erosion agent in dry areas?
EROSION: The force that shapes the Earth!

10. Agent 3:Erosion By Waves
Terraces Cliffs
Waves crash on the shore and break apart the bedrock
EROSION: The force that shapes the Earth!

11. Agent 3:Erosion By Waves
Arch
Waves wrap around the front and break apart the bedrock
EROSION: The force that shapes the Earth!

12. Agent 3: Erosion By Waves
Stack
Most of the rock from the arch has completely eroded
EROSION: The force that shapes the Earth!

13. Agent 3: Erosion By Waves
Waves bend parallel to the shore and take sand with them!
This is called long shore current
The “groin” was built to stop beach erosion!!
EROSION: The force that shapes the Earth!

14. EROSION: The force that shapes the Earth!
Summary
1. Why are waves agents of erosion?
2. Which agent can erode larger sediments, wind or waves?
3. Which agent can move larger sediments, waves or gravity?
EROSION: The force that shapes the Earth!

15. Agent 4: Erosion by Glaciers
A GLACIER is a large MASS of MOVING ICE
GLACIERS can be found in two places…
HIGH ALTITUDES…
ALPINE glaciers
HIGH LATITUDES…
CONTINENTAL glaciers
EROSION: The force that shapes the Earth!

16. Agent 4: Erosion by Alpine Glaciers
Flowing ice picks up
Sediment and rocks...
...And carries them along
Scraping the bedrock along
the way!
An excellent way to cause ________
EROSION!
EROSION: The force that shapes the Earth!

17. Features left by Alpine Glaciers
Glaciers erode valleys into a “U” shape
EROSION: The force that shapes the Earth!

18. Features left by Alpine Glaciers
The landscape left behind by alpine glaciers!
U-shaped Valleys
EROSION: The force that shapes the Earth!

19. EROSION: The force that shapes the Earth!
Summary
1. Where are alpine glaciers found?
2. Ridge caused by glacial erosion:
3. Sharp peak left at top of mountain:
4. Shape of valley left by glacier:
EROSION: The force that shapes the Earth!

20. Agent 4:Continental Glaciers
2.0x106 to 1x104years ago
Four periods of continental glaciers growing and melting
Only found at high latitudes now!
Each ice advance lasted for 40,000 to 200,000 years
Warm spells lasted 10,000 to 30,000 years
Are we living in a warm period now between ice ages?
EROSION: The force that shapes the Earth!

21. Continental Glaciers and Landscapes
Sheets of ice
advance...
And then melt
back...
Leaving behind
a very cool
landscape!
Pittsford area is LOADED with these features!
EROSION: The force that shapes the Earth!

22. Features of Continental Glaciers
Striations are scratch marks
made as ice drags rocks across bedrock
They show the glacier’s direction of motion
EROSION: The force that shapes the Earth!

23. Features of Continental Glaciers
Glaciers carved valleys and melted…
Fill the valley with water!
Finger Lakes!
Show the glacier’s
direction motion when
it melted!
EROSION: The force that shapes the Earth!

24. EROSION: The force that shapes the Earth!
Summary
1. Most soil in Western NY was deposited by glaciers. Is it transported or residual?
2. A boulder with scratches on it was most likely transported here by what agent of erosion?
3. Finger lakes and striations show that the last glaciers in North America moved in what direction?
EROSION: The force that shapes the Earth!

25. DEPOSITION: The Opposite of EROSION
EVERY EROSIONAL AGENT must DROP the sediments it erodes!
Deposition: When sediments are deposited
Deposition and Erosion always happen together!
EROSION: The force that shapes the Earth!

26. DEPOSITION: SORTED or UNSORTED
Deposit of all different shape and size sediments is called UNSORTED
Deposit arranged by SIZE or SHAPE is called SORTED sediments
SORTED UNSORTED
EROSION: The force that shapes the Earth!

27. Deposition by Glaciers
The Glacier melts....
Sediments are deposited at the melting edge…
And piled up!
The PILE is called a Moraine
EROSION: The force that shapes the Earth!

28. Deposition by Glaciers
BIG PILE of SEDIMENTS Left by a GLACIER
Sediments are UNSORTED…
Moraines are formed by both glacier types
EROSION: The force that shapes the Earth!

29. Deposition by Glaciers
A HUGE boulder left by a GLACIER
What’s this granite boulder doing here? It’s an________
ERRATIC
EROSION: The force that shapes the Earth!

30. Deposition by Glaciers
This long narrow hill left by a glacier is called an ___________
ESKER
EROSION: The force that shapes the Earth!

31. Deposition by Glaciers
This canoe shaped hill left by a glacier. It’s called a ________
DRUMLIN
EROSION: The force that shapes the Earth!

32. EROSION: The force that shapes the Earth!
Summary
1. How do glaciers cause deposition?
2. Are glacier deposits sorted or unsorted?
3. Large boulder left behind by glaciers…
4. Funny-shaped hills left behind by glaciers (3 types). Are these made of sorted sediments?
EROSION: The force that shapes the Earth!

33. EROSION: The force that shapes the Earth!
Deposition by WIND
PILES of sand left behind from WIND EROSION are called ______
DUNES
Dunes are SORTED sediments…sizes are sorted out!
EROSION: The force that shapes the Earth!

34. Deposition by WAVES
Sediments left behind from WAVE EROSION are called a __________
BEACH
WAVE deposits are SORTED
EROSION: The force that shapes the Earth!

35. GRAVITY sediments are UNSORTED because they are all mixed up!
Deposition by GRAVITY
PILES of sediments left behind from at the bottom of a slope from GRAVITY EROSION
GRAVITY sediments are UNSORTED because they are all mixed up!
EROSION: The force that shapes the Earth!

36. EROSION: The force that shapes the Earth!
Summary
1. What is DEPOSITION?
2. Deposition from glaciers and gravity tend to be sorted or unsorted? Explain?
3. Deposition from wind and waves tends to be sorted or unsorted? Explain?
EROSION: The force that shapes the Earth!

37. Agent 5:STREAMS A SYSTEM of Erosion and Deposition
Streams are the MAJOR AGENT of erosion on Earth!
Streams cause erosion by moving sediments when water velocity is high!
Streams cause deposition when they leave those sediments behind when the water velocity decreases!
Streams are erosional-depositional systems!
EROSION: The force that shapes the Earth!

38. EROSION: The force that shapes the Earth!
Erosion by Streams
Streams are moving water. As they flow the water cuts down through the bedrock
Stream Valleys are cut into a “V” shaped
EROSION: The force that shapes the Earth!

39. EROSION: The force that shapes the Earth!
Erosion by Streams
DOWNCUTTING… The stream erodes down through the soil and rock… Makes the channel deeper
EROSION: The force that shapes the Earth!

40. EROSION: The force that shapes the Earth!
Erosion by Streams
Streams also erode the banks of their channels
Erosion and deposition happen in different places…
To the other
The stream channel moves from one side
EROSION: The force that shapes the Earth!

41. EROSION: The force that shapes the Earth!
Erosion by Streams
Erosion happens on outside of curve…
Deposition happens on the inside of curve…
Stream velocity is higher there!
Stream velocity is lower there!
The curves are called meanders!
EROSION: The force that shapes the Earth!

42. EROSION: The force that shapes the Earth!
Erosion by Streams
These meanders have been cut down through hundreds of meters of bedrock!
EROSION: The force that shapes the Earth!

43. Erosion by Streams Don’t build your house on the outside of a meander!
The water velocity is HIGH THERE and will cause erosion!
EROSION: The force that shapes the Earth!

44. Deposition by Streams
When the stream floods it deposits sediments on either side!
This wide, flat area is a floodplain!
It has AWESOME soil!
EROSION: The force that shapes the Earth!

45. Deposition by Streams Don’t build your house on a floodplain!
Floodplain deposits are sorted!
EROSION: The force that shapes the Earth!

46. This is called a _________
Deposition by Streams
Stream enters the ocean …
Its velocity decreases
And it deposits the sediments it was transporting
This is called a _________
delta
EROSION: The force that shapes the Earth!

47. Deposition by Streams Delta deposits are definitely sorted!
Deltas make really fertile soil!
Would you build your house on a delta?
EROSION: The force that shapes the Earth!

48. Sediments Deposited by Streams
Rounded and Sorted
These stream sediments are sorted by size
Deposits are sorted because larger sediments settle first!
How Streams Work

49. Horizontal Sorting: Large sediments deposited first (near shore) followed by small sediments
Stream enters ocean, velocity decreases
Ocean
Larger sediments deposited first near mouth
Small sediments deposited last away from shore
This is how DELTAS form!
How Streams Work

50. EROSION: The force that shapes the Earth!
Summary
1. Streams cause erosion by downcutting. Explain…
2. Streams erode the outside of meanders. Why?
3. Deposition happens at the inside of meanders. Why?
4. Sediments deposited by streams tend to be sorted or unsorted?
5. What shape valley do streams make?
EROSION: The force that shapes the Earth!

51. Deposition by Continental Glaciers
Ice Tunnel inside the glacier…Are these sediments sorted or unsorted?
EROSION: The force that shapes the Earth!

52. FEATURES left by Alpine Glaciers
Alpine glacier fills a mountain valley
Break and move rocks and sediments
Sediments are left behind
And a CIRQUE formed!
EROSION: The force that shapes the Earth!

53. Features left by Alpine Glaciers
Alpine glaciers form in mountain valleys
Glaciers melt away and leave behind cirques
An Arête is left between them
A HORN is left at the top
EROSION: The force that shapes the Earth!