1. Glaciers Explain how glaciers move.
Compare and contrast glacial erosion and deposition.

2. Glaciers

3. Glaciers
Glacier: Large mass of ice and snow moving on land under its own weight.

4. Glaciers Glaciers are agents of erosion.
Glacial erosion and deposition change large areas of Earth’s surface.
As glaciers move forward over land they can transport huge volumes of sediment and rock.

5. Glaciers How do glaciers move?
The weight of the glacier causes the ice to flow outward like pancake batter on a griddle.

6. Glaciers
Plucking: process that adds gravel, sand, and boulders to a glacier’s bottom and sides as water freezes and thaws, breaking off pieces of surrounding rock.

7. Glaciers
These plucked rock fragments and sand at a glaciers base scour and scrape the ground below like sandpaper against wood.
Glacial striations.

8. Glaciers
Glacial grooves occur when bedrock is gouged deeply by rock fragments.

9. Glaciers When glaciers melt they can no longer carry much sediment.
The sediment is deposited on land.
As the glacier retreats it leaves a mixture of boulders, sand, clay and silt called till.

10. Glaciers Till deposits can cover huge areas of land.
Enough till has been left behind in the U.S. to fill valleys completely.
Iowa, Montana, parts of Ohio, Indiana, Illinois and New England contain till.

11. Glacial Till

12. Glaciers
Moraine deposits: Rocks and soil deposited at the end of a glacier creating a ridge.
These deposits occur much like a grocery store conveyor belt as it piles up items at its end.

13. Glaciers Outwash: material deposited by the meltwater from a glacier.
Eskers: outwash deposits resulting in winding ridges of gravel and sand.

14. Types of Glaciers Continental Glaciers: Cover 10% of the Earth.
Mostly near the poles.
Huge masses of ice and snow.

15. Types of Glaciers
Continental glaciers in the past covered 28% of the Earth.
This period was known as the Ice Age.

16. Types of Glaciers
Glaciers have advanced many times during the last 2 million to 3 million years.
The last major advance of glaciers was about 18,000 years ago.

17. Types of Glaciers
Valley Glaciers: Occur in high mountains where the average temperature is low enough to prevent snow from melting.
Valley glaciers grow and creep along.

18. Types of Glaciers Valley glaciers erode mountains creating valleys.
Glacially eroded valleys are U-shaped.
Stream eroded valleys are V-shaped.

19. Types of Glaciers
Valley glaciers

20. Glaciers Question: How do glaciers cause erosion?
Rock fragments and sand scour the soil and bedrock eroding the ground below.

21. Glaciers