Geological features of ice

Geological Features of Ice

1. Geological Feature of Ice

2. • Glacier
> a mass of ice composed of recrystallized
compacted snow that flows under its own
weight on land.
• Presently glaciers cover of the
Earth's surface.
• Glaciers occur in Greenland and
Antarctica and in higher mountain
ranges.
• Glacier
> a mass of ice composed of recrystallized
compacted snow that flows under its own
weight on land.
• Presently glaciers cover of the
Earth's surface.
• Glaciers occur in Greenland and
Antarctica and in higher mountain
ranges. 11
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1010 Glaciers and Glaciation Glaciers and Glaciation

3. Glaciers-
Important in understanding global scale climate change
Related to all 5 of the Earth’s systems
Exosphere-changes in the amount of sunlight cause
glaciations
Hydrosphere-glacial ice is frozen water, part of the
hydrosphere
Geosphere-Glacial ice flows over and modifies land
Atmosphere-alteration of global atmospheric patterns
contributes to glacial ice formation
Biosphere-ice displaces animals and plants

4. •Glacial times represent significant time
periods in Earth's history
•Represent major climatic departures
from the modern on a Global Scale
•Cyclic in Nature
•Man's Influence???
•Glacial Ice contains records of
atmospheric changes
•Glacial times represent significant time
periods in Earth's history
•Represent major climatic departures
from the modern on a Global Scale
•Cyclic in Nature
•Man's Influence???
•Glacial Ice contains records of past
atmospheric changes
Importance
Proterozoic, Pennsylvanian, Pleistocene

5. • Snowflakes are melted & deformed by the pressure of
overlying snow, becoming granular snow, then firn, and
finally interlocking crystals of glacial ice. Origin of ice

7. Descriptive classification of GlaciersDescriptive classification of Glaciers
• Valley (or Alpine) Glaciers are confined
to mountain valleys.
> may eventually cover the entire mountain range
becoming a mountain ice sheet
> may also spill onto low flatlands becoming
Piedmont glaciers
• Continental (or Ice Sheets)
> cover vast areas of more than 50,000 km .
Today, continental glaciers are only found in
Greenland and Antarctica.
> Not so in the geological past
• Valley (or Alpine) Glaciers are confined
to mountain valleys.
> may eventually cover the entire mountain range
becoming a mountain ice sheet
> may also spill onto low flatlands becoming
Piedmont glaciers
• Continental (or Ice Sheets)
> cover vast areas of more than 50,000 km .
Today, continental glaciers are only found in
Greenland and Antarctica.
> Not so in the geological past
22

9. Response of a Glacier to Changes in Glacial Budget
If accumulation = ablation, then no advance or retreat, but continues to flow
If accumulation > ablation, then glacier advances while flowing
If accumulation < ablation, then glacier retreats, but continues to flow

10. Effects of GlaciersEffects of Glaciers
• Fills in the low spots
> valleys and basins get filled in w/ sediment
• Knocks down the high spots
> mountains and hills get eroded
• Reroutes the drainages
> valley filling may block streams, causing
new paths to be taken
• Deposits accumulate in specific
places related to flow and meltwater
characteristics
• Fills in the low spots
> valleys and basins get filled in w/ sediment
• Knocks down the high spots
> mountains and hills get eroded
• Reroutes the drainages
> valley filling may block streams, causing
new paths to be taken
• Deposits accumulate in specific
places related to flow and meltwater
characteristics

11. • James Lobe and Glacial Lake Agassiz

13. Erosional ProcessesErosional Processes
･Important erosional
processes associated
with glaciers include
plucking, abrasion, and
bulldozing.
･Plucking and abrasion
are most common
>can form a landform
called a roche
moutonnee
･Important erosional
processes associated
with glaciers include
plucking, abrasion, and
bulldozing.
･Plucking and abrasion
are most common
>can form a landform
called a roche
moutonnee

14. Erosional features
Roche Moutonnée

16. Erosional features
•Hanging Valley
•Horn
•Arete
•Cirque
•U-shaped trough
•Col
•Truncated Spurs

17. Glacial DepositsGlacial Deposits
•glacial drift-A general term
refering to sediment formed by any
glacial action.
•Till(Diamicton)poorly sorted,
unlayered material directly
deposited by a glacier;
•Stratified drift (Outwash)sorted,
layered sediment usually
deposited by meltwater streams.
•Glacial drift-A general term
referring to sediment formed by
Anyglacial action.
•Till(Diamicton)-poorly sorted,
unlayered material directly
deposited by a glacier; ice contact
•Stratified drift (Outwash)-sorted,
layered sediment usually
deposited by meltwater streams.
Proglacial or ice contact

18. A glacial erraticDepositional features-glacial erratic
6 ft
Yellowstone Park

19. Sediments-
Glacial Till exposed in Iowa

20. Moraine formation-made of Till, deposited by ice
Depositional features-moraines

21. Moraine formation-made of Till, deposited by ice
Depositional features-moraines

22. Moraine formation-made of Till, deposited by ice
Depositional features-moraines

23. ･Lateral and Medial
Moraines are sediment
eroded from the valley
sides and deposited by
a glacier. They often
appear as dark stripes
in a glacier.
･Lateral and Medial
Moraines are sediment
eroded from the valley
sides and deposited by
a glacier. They often
appear as dark stripes
in a glacier.
Lateral
moraines
Lateral
moraines
Medial
moraines
Medial
moraines

24. Depositional features-distribution of moraines

25. Depositional features-Kames, eskers, kettle lakes,
drumlins, outwash plain (sandur)

26. Depositional features-Kames, eskers, kettle lakes,
drumlins, outwash plain (sandur)

27. Outwash with kettles
Kettle
lakes
Outwash
moraine
Kame
terrace

28. Outwash Plain
with eskers and a
braided stream

29. Pleistocene GlaciationPleistocene Glaciations
•The Pleistocene "ice age" began
~1.96 million years ago
•Several glacial and interglacial
episodes.
>Glacial-a period of ice advance, generally
interpreted as a globally cool period.
>Interglacial-a period of ice retreat, generally
interpreted as a globally warm period.
•The Pleistocene "ice age" began
~1.96 million years ago
•Several glacial and interglacial
Episodes have occurred.
>Glacial-a period of ice advance, generally
interpreted as a globally cool period.
>Interglacial-a period of ice retreat, generally
interpreted as a globally warm period.
We are in an interglacial period right now

30. Milankovitch Orbital Theory
•Proposed to account for the cyclical
nature of Glaciations.
•Astronomer & Mathematician Milutin
Milankovich attributed the glaciation to
variation in three parameters of the
Earth's orbit.
•Proposed to account for the cyclical
nature of Glaciations.
•Astronomer & Mathematician Milutin
Milankovitch attributed the glaciation to
variation in three parameters of the
Earth's orbit.

31. eccentricity
precession
Obliquity-not shown

32. warm
warm
cold
cold
1 3 54

33. Erie
Lobe