1. Earth Science Chapter 8 Section 3
Glaciers
Earth Science
Chapter 8
Section 3

2. Moving Masses of Ice Glacier Large, moving mass of ice
Form near Earth’s poles and mountainous areas
Extreme latitude and elevations
Regions with year round temperatures of 0° C
Moving Masses of Ice

3. Cold temperatures keep fallen snow from completely melting
Each year new snow accumulates in snow field
Thickness increases as years pass
Extreme weight and pressure turn the snow into ice
Moving Masses of Ice

4. Valley Glaciers Form in valleys high in the mountains
Movement occurs when ice mass becomes so heavy it holds its shape and begins to flow
Usually begins when accumulation is over 20 m
Valley Glaciers

5. Speed of valley glacier depends on slope of the valley floor and temperature of the ice
Sides and bottom move slower than the middle
Movement is slow
Carve U-shaped valleys
Valley Glaciers

6. Deep cracks in the surface of the ice
Crevasses

7. Continental Glaciers Glaciers that cover broad, continent-sized areas
Form in cold climates
Snow accumulates over many years
Thickest at its center
Weight of the center forces rest of ice out in directions
Greenland and Antarctica
Continental Glaciers

8. Move outward when snow gathers when snow accumulates at the zone of accumulation
A location in which more snow falls than melts
Valley glaciers- top of mountains
Continental glaciers- center of the ice sheet
Glacial Movement

9. Glacial Erosion Most powerful erosional agent
Large size, weight and density
Plucking- when a glacier breaks off a piece of rock
The embedded rock adds to the erosional impact
Glacial Erosion

10. Striations and grooves on underlying rock are caused when rocks carried by the glacier “scratch” underlying rocks.
Striations

11. Cirques Deep depressions carved out by valley glaciers
Arête: when two cirques on opposite sides of a valley meet
Sharp steep ridge
Horn: when glaciers are on three or more sides of a mountain
Carve steep pyramid shaped peak
Cirques

12. Formed when tributary glaciers converge with primary glacier and then retreat
Primary glacier so large it meets the tributary glaciers
When they melt, the smaller valleys are left above the valley of the primary glacier
Hanging Valley

13. Till- unsorted rock, gravel and sand that glaciers carry
Moraines- the deposited till left when a glacier retreats
Terminal moraines- found along retreating edge of the glacier
Lateral moraines- located parallel to the glacier
Glacial Deposition

14. Outwash Melt water that floods the valley below the glacier
Contains gravel, sand and fine silt
Sediment sorted by particle size
Outwash plain- leading edge of glacier where outwash flows and deposits sediment
Outwash

15. Drumlins Continental glaciers that move over older moraines
Elongated landforms are created
Drumlins

16. Kames and Eskers Kames Eskers
Mound of layered sediment deposited at the retreating glacier face conical in shape
Streams flowing under melting glaciers leave long winding ridges of layered sediments
Kames and Eskers

17. Glacial Lakes Blocks of ice break off a continental glacier
Surrounding area is covered by sediment
When ice block melts the kettle hole fills with water
Common in New England, New York and Wisconsin
Glacial Lakes

18. Cirque lakes form when cirques fill with water
Glacial Lakes

19. Moraine-dammed lakes form when a terminal moraine blocks off the valley and the valley fills with water
Great Lakes and finger lakes
Glacial Lakes