1. Glaciers
Erosive forces

2. Glacier
persistent body of dense ice that is constantly moving under its own weight.
It forms where the accumulation of snow exceeds its ablation (melting and sublimation) over many years.

3. Glacier formation Snowfall
Glaciers form where the accumulation of snow and ice exceeds ablation.
This snow collects and is compacted by the weight of the snow falling above it, crushing the individual snowflakes and squeezing the air from the snow
Firn
left over from past seasons and has been recrystallized into a denser substance
snow repeatedly freezes and thaws, changing into granular ice
Glacial Ice
Once all air has been squeezed from it, the snow is turned into extremely dense glacial ice
When the mass of snow and ice is sufficiently thick, it begins to move due to a combination of surface slope, gravity and pressure.

4. Clicker What is ablation? Melting and sublimation
Melting and evaporation
Freezing and evaporating
Melting and precipitation
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5. Explain what the growth of a glacier depends on
The balance between snow fall received and the amount of ice lost be melting and sublimation(evaporation)

6. Advance v. Retreat Advance Retreat
Snow accumulation is greater than ablation
Retreat
Ablation is greater than snow accumulation

7. Glacier Types Alpine (Valley) Continental Long, narrow wedge shaped
form on the crests and slopes of mountains.
Ex. Alaska, Himalayas, Alps, Andes
Wide, very large millions of km2
Polar regions
Only found in two places
Greenland and Antarctica

8. Clicker Today a continental ice sheet is located in? Eastern Europe
New Zealand
Alaska
Greenland
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9. Glacial Movement Basal Slip Internal Plastic Flow
glacier slides over the terrain on which it sits, lubricated by the presence of liquid water.
Refreezes as pressure removed
Solid ice crystals slip over each other, causing slow forward motion.
Slope
Thickness
Temperature (of Ice)
Surface faster
Friction

10. Erosion Plucking/ Ice wedging :
Plucking: “pluck” material from V sides makes a U shaped valley
Ice wedging: water seeps into cracks and expands leaving larger cracks.

11. Erosion
Abrasion:
Mechanical erosion of rocks (think sand paper) as glacier scrapes over the landscape/ bedrock below

12. Features caused by Erosion
Cirques:
start of a classic valley glacier is a bowl-shaped
Horns:
3 or more cirques or Arêtes that encircle a single mountain (looks like a pyramid)
Arêtes:
Two glacial cirques may form back to back and erode their back walls until only a narrow ridge or “spine” is formed
U-shaped valley:
widened, deepened, and smoothed, by a glacier forming a "U"-shaped glacial valley

13. Features caused by Erosion
Hanging valleys:
when glaciers recede, the valleys of the tributary glaciers remain above the main glacier's depression ( water falls often)
Striations:
Grooves from plucking/ and abrasion
Kettle lake
shallow, sediment-filled body of water formed by retreating glaciers or draining floodwaters.

14. Clicker Cirques are best described as rounded knobs of rock.
bowl-shaped depressions.
sharp, curved peaks.
sharp and jagged ridges.
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15. Deposition
Drumlins:
elongated hill in the shape of an inverted spoon or half-buried egg formed by glacial ice acting on underlying unconsolidated till or ground moraine.

16. Deposition
Eskers:
An esker is a long, winding ridge of stratified sand and gravel.

17. Deposition
Kames:
an irregularly shaped hill composed of sand, gravel and till that accumulates in a depression on a retreating glacier.

18. Deposition
Moraines:
are accumulations of dirt and rocks that have fallen onto the glacier surface or have been pushed along by the glacier as it moves.
End/recessional: between glacier and last moraine
Terminal= farthest
forward motion
Lateral: side (parallel)

19. Glacial sediment Erratics:
are stones and rocks that were transported by a glacier, and then left behind after the glacier melted.

20. Glacial sediment till:
Glacial till is unsorted sediment deposited directly by glacial ice.

21. Glacial sediment Outwash:
Glacial outwash is sand and gravel deposited by running water from the melting ice of a glacier.

22. Michigan’s Glacial History

23. Big idea Great lakes Each of the Great Lakes began as a river.

24. As the climate cooled… The rivers froze.
Glaciers moved through them – widening and deepening them to form today’s “U” shaped lake bottoms.

26. Why do scientists believe that glaciers once covered Michigan?
The unsorted moraine deposits follow the outline of Great Lakes.
Other depositional features such as drumlins and kettle lakes are found throughout Michigan.
Erosional features like striations are found in Michigan as well.

27. Explain what happens to Earth’s crust when a glacier is removed.
Isostatic Rebound
The upward movement of the Earth’s crust

28. Not all people agree…

29. Ok so what does not make sense about this video