1. Geography for competitive
III B.Sc Geography
date : 24/09/2020
time : 9.30 to 10.30
Topic : Glacier erosional LANDFORMS
Dr.K.Indhira
guest Lecturer
department of geography
government college for women (a)
kumbakonam
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.
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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
6.
7. Descriptive classification of Glaciers
Descriptive 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
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8.
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 Glaciers
Effects 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
13. Erosional Processes
Erosional 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
17. Glacial Deposits
Glacial 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
Any glacial 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
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
29. Pleistocene Glaciation
Pleistocene 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. Milankovich Orbital Theory
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.
