1. Glaciers and Glacial Landforms

2. Glacier - Mass of ice that persists throughout the year.
Accumulation and compaction of snow into ice.
Ice deforms and flows outward responding to gravity.
Flow generally from high to low altitude or high to low latitude.
Ice advance stops where melting equilibrates with flow.
Retreat by melting.
Alpine glaciers - ice fills and flows down valleys.
Ice caps - ice covers mountain peaks.
Ice sheets - ice covers most of continent.

3. Ice movement in a glacier
Snow falls
Ice melts
eroded boulders
Zone of accumulation
Zone of wasting

4. Ice movement in a glacier
Snow falls
compacts to ice
Ice melts
Zone of accumulation
Zone of wasting

5. Ice movement in a glacier
If rate of accumulation is greater than melting, glacier will advance.
Snow falls
Glacier advances
compacts to ice
Ice melts
Ice flows
Flowing ice carves the landscape
Zone of accumulation
Zone of wasting

6. Ice movement in a glacier
When rate of melting equals rate of accumulation, glacier stops advancing.
Equilibrium
Snow falls
Glacier stops advancing.
Ice melts
Ice flows
Zone of accumulation
Zone of wasting

7. Ice movement in a glacier
in equilibrium, glacier does not appear to change position.
ice is always in motion.
ice accumulation equals ice melting.
Glacier acts like a conveyor belt, eroding and carrying rock, sediments, and soil to its terminus.
Snow falls
terminus
Zone of accumulation
Zone of wasting

8. Ice movement in a glacier
If melting increases, glacier will retreat, even though ice is still flowing.
Rate of melting is greater than rate of accumulation.
Melting ice deposits rock and sediment.
Glacial deposits create distinctive landforms.
Snow falls
Glacier retreats
moraine
Ice flows
Zone of accumulation
Zone of wasting

9. Ice movement in a glacier
If melting increases, glacier will retreat, even though ice is still flowing.
Rate of melting is greater than rate of accumulation.
Melting ice deposits rock and sediment.
Glacial deposits create distinctive landforms.
Snow falls
Glacier retreats
moraine
Ice flows
Zone of accumulation
Zone of wasting

10. Zone of ablation (wastage)
(more melting than snowfall)
Zone of accumulation
(more snow falls then melts per year)

11. Glaciers - agents of erosion
Glaciers are highly effective agents of erosion.
Abrasion - rock debris embedded in base of ice.
Polishing, grooves and striations.
Plucking / Quarrying - removal of large chunks of rock debris.
Bedrock surface polished by glacial ice.

12. Glaciers - Erosional Landforms
Cirque - semicircular hollow with steep headwall carved by glaciers into an alpine valley head.

13. Glaciers - Erosional Landforms
Arete - steep, knife-edge ridge between glacial valleys.
Col - gap in an arete where two cirques meet.
Horn - steep peak carved out by cirques.

14. Glaciers - Erosional Landforms
Glacial trough - wide, parabolic valley carved by ice flow (also called a “U-shaped” valley).

15. Mountains during glaciation

16. Mountains after glaciation

17. Fjiord - glacially carved valley flooded by the sea.
Norway
Hudson River

18. Glacial Striations - linear glacial scratch marks on bedrock.

19. Glaciers - Agents of Deposition
Glaciers are highly effective agents of deposition.
Drift - rock debris deposited by glaciers.
Glacial Lake Deposits - pebble, sand, clay and silt sediments accumulated in meltwater lakes.
Loess - very fine, wind-blown rock flour.

20. Till - Nonstratified, poorly sorted drift deposited directly from glacial ice.

21. Stratified drift - sorted, layered sediments deposited by glacial meltwater - outwash.

22. Glaciers - Depositional Landforms
Ice contact deposits - sediments melted directly out from the ice.
Outwash deposits - sediments deposited by meltwater flowing from the ice.

23. Kame - mound of till released by melting ice.

24. Esker - serpentine ridge of stratified drift deposited inside of ice meltwater tunnel.
Esker - Manitoba

25. Drumlin - tear-drop-shaped hill created by ice flow over and around till deposit.

26. Drumlins - Manitoba

27. Moraine - linear ridge of till deposited at ice margin.

28. Glaciers - Depositional Landforms
Outwash features - deposition by meltwater in the outwash plain (region in front of ice receiving flow of meltwater).
Erratics - boulder size and larger blocks of rock deposited by melting glacial ice.

29. Landscape during glaciation
Kettles - depressions formed as stranded ice blocks melt in outwash.

30. Landscape after glaciation
Kettles - depressions formed as stranded ice blocks melt in outwash.
moraines
Outwash plain in front of moraine.

31. Features of a glacial moraine
kame
kettle
outwash

32. Ice Caps and Ice Sheets - unconfined by topography.
Ice Cap - less than 50,000 km2.
Ice Sheet - cover major portion of a continent.
Ice thicker than topography.
Ice flows in direction of slope of the glacier.
Greenland and Antarctica to 4000 m thick ( thousand feet or 1.5 to 2 miles!)

34. Alpine Glaciers - developed on mountain peaks and valleys.
Cirque glacier - small glacier occupying valley head.
Valley glacier - river-like glacial occupying valley.
Piedmont glacier - valley glacier that flows out onto the flatlands.
Fjord glacier - valley glacier with base below sea level.
Ice field - region of interconnected alpine glaciers.

35. Piedmont Glaciers - lobate lowland glacier fed by alpine glaciers .