1. 8.3 Glaciers Types of glaciers Alpine Small glaciers that form valleys
Ice sheets
Enormous glaciers that can cover entire continents

2. Glacier Formation Describe the steps Firn: Thick, dense compacted snow
Glacial ice:
Firn compacts into glacial ice
Advancing:
A glacier growing faster than it is melting
Retreating:
A glacier melting (receding) at the leading edge faster than its growing. It’s NOT traveling backwards.

3. Glacier Movements Plastic Flow Describe:
Deep within, there is a huge amount of pressure due to weight of ice pressing down.
50 meters thick of ice creates enough pressure to cause ice to flow through the center of a glacier very slowly.

4. Glacier Movements Basal Slip
Water beneath glacier acts as a lubricant, so entire glacier can slide. This movement can cause a large crevasse (crack), to form.
Describe:
Rate of movement:
Typically a few meters/ day, but can have faster surges.

5. Glacial structures from erosion
Striation
Long scratch marks found in rocks due abrasion caused by rocks & gravel dragged by glacial movement.
Describe:
U-Shaped Valleys
Describe:
V-shaped valleys that are widened by glaciers.

6. Glacial structures from erosion
Horn peaks
Describe:
When several cirques converge, the part that is not cut out looks like a horn sticking out of the ground.
Cirques
Describe:
Valleys that look like giant armchairs because they have 3 steep sides & one open side.

7. Glacial structures from erosion
Fjords
Describe:
Very steep inlets to the ocean.
Roche moutonnees
Landforms w/ 1 rough side & 1 side that has been abraded smooth.
Describe:

8. Glacial Drift Till Describe:
The coarsely graded sediment deposited by glaciers
Till
Describe:
Unsorted glacial sediment

9. Structures Formed Morraines Glacial Erratics Describe:
Big rocks deposited by a glacier into an area w/ a different type of rock.
Morraines
Describe:
Piles of boulders, rocks, pebbles, & clay left behind by a glacier.

10. Structures Formed Drumlins Terminal Moraines Describe:
form at the edge of glaciers.
Drumlins
Smooth, egg-shaped hills left behind by continental ice sheets.
Describe:

11. Stratified Drift kettles Structures Formed: Eskers Define:
Deposits left by melted water coming off a glacier.
Structures Formed:
kettles
Describe:
When large blocks of ice get trapped under stratified drift, the ice melts and leaves large holes.
Eskers
Describe:
Winding ridges of sand & gravel left behind by receding glaciers.

12. Earth’s Orbit Precession Effects:
Change in Earth’s orbit around the sun cause slight temperature variations.
Precession
Effects:
The tilt of Earth’s axis changes over time & can affect the amount of sunlight reaching different parts of earth.

13. Current ice age theory Last ice age Explain:
Changes in the Earth’s axis of rotation can work together to alter the temperatures. This is thought to lead to the formation of large glaciers & put Earth into ice ages.
Last ice age
2 million years ago, & peaked 20,000 years ago.