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Glaciers➔ Types:

1. Valley Glaciers2. Continental Glaciers

Glaciers➔ Valley Glaciersaka, Alpine Glaciers: Glaciers found high in mountain valleys, above the snow-line, that move downward through the valleys.

Example: Glacier National Park in Montana

➔ Continental Glaciersaka. ice fields or ice sheet: Glaciers made from large ice sheets that cover relatively flat ground that flows outward from where the greatest amounts of snow and ice accumulate. Greenland’s Continental Glaciers thickness is more than 3000 meters (10,000ft) and depresses the bedrock below sea level.

Origin/Formation of Glacial Ice

Firn: Like packed snowballs

Glaciers form only on land… water is too warm for glacier formation.

Why do glaciers form in the mountains?

Today: ● Glaciers cover about 10% of the land surface on Earth● In Earth's recent history, glaciers covered as much as

30% of the land surface.

Scientists’ detective work:● Signs of Glaciers in the past

○ Observe ways the land has been eroded ○ Look at deposits that have been left behind

● Discover the different erosional features formed by alpine glaciers.● Discover the processes by which glaciers change the underlying rocks.● Discover the sorting and types of particles deposited by glaciers as they

advance and recede.● Discover the landforms created by glacial deposits.

Fastest

Movement: factors: 1. amount of ice in field, 2. steepness of the slope, 3. roughness of the ground surface

Where pressure is so great … undergoes plastic flow where lubricated by water at bottom due to melting.

Glacial Movement

Plastic flow … from ice pressure

Glacial slip -- glacier slides over underlying surface.

Movement: factors: 1. amount of ice in field, 2. steepness of the slope, 3. roughness of the ground surface

Where pressure is so great … undergoes plastic flow where lubricated by water at bottom due to melting.

Erosion from Glacier movement:

abrasionScraping of the underlying bedrock, produced as ice flows against it.

pluckingRemoval of blocks of underlying bedrock by the glacier as meltwater seeps into cracks and freezes.

• As a glacier moves, rocks that are stuck in the ice are dragged across the exposed bedrock. This causes deep scratches and gouges in the bedrock called striations

• The direction of the striations shows the path of movement of the glacier

There were 2 periods of glaciations here. Can you tell which was first? Which directions did the 2 glaciers

move?

Glacier movement creates landforms by weathering and deposition:1. Abrasion2. Plucking3. Bulldozing… Movement of large boulders that have

been transported into the area by the glacier… often different in mineral composition than the bedrock of the area.

Boulder in Yellowstone National Park:6 Feet tall.

Glacial Erosion by valley glaciers creates various landform features:

“U” Shaped valleys : in Glacier National Park

Glacial Erosion by valley glaciers creates various landform features:

Hanging Valleys: with smaller glaciers meeting and creating river water that cascades down steep valley walls forming waterfalls

Bridalveil Falls in Hanging Valley

Glacial Erosion by valley glaciers creates various landform features: cirque

Steep-sided, bowl-shaped depression formed as a glacier plucks and erodes underlying bedrock.

Glacial Erosion by valley glaciers creates various landform features:

hornSharp-sided, angular peak formed as glaciers move away from a central peak.

The Matterhorn in Switzerland is the most famous example of this type of erosion

Glacial Erosion by valley glaciers creates various landform features:

arêteSteep-sided, sharp-edged ridge that forms as two glaciers erode in opposite directions.

Glacial Erosion by valley glaciers creates various landform features:

roche moutonnéeAsymmetrical hill of bedrock formed by abrasion and plucking of the moving glacier.

Glacial Erosion by valley glaciers creates various landform features:

roche moutonnéeAsymmetrical hill of bedrock formed by abrasion and plucking of the moving glacier.

ArêteCirque

U-Shaped Valley

Arête

Moraines

Horn

Deposition by Glaciers

Depositional Features of Glaciers:

glacial till

Any unsorted deposit of sediment deposited by glacial ice.

Glacial till - unsorted

Glacial till forms when glaciers melt more than they flow forward… The melted glaciers deposit all the big and small bits of rocky material they have been carrying.

Depositional Features of Glaciers:

Moraines: Deposit of unsorted, rocky material on, under or left behind by glacial ice.

Lateral moraine: rocky material at the edge of a glacier.

Medial moraine: where two glaciers join together… forming in the middle of a glacier.

Depositional Features of Glaciers:

Depositional Features of Glaciers:

Terminal moraine

Unsorted pile of glacial till that marks the furthest reach of a glacier's advance.

Depositional Features of Glaciers:

ground moraine

Thick layer of sediment deposited under a flowing glacier.

Depositional Features of Glaciers:

drumlin

An asymmetrical hill formed from sediments under the flowing glacier.

esker

Long, curving, upside-down 'V' shaped ridge of sediment deposited under a glacier by meltwater.

Outwash plain

Broad band area of stratified drift blankets the region just beyond the furtherest reach of the glacier, as meltwater streams spread material outward

Depositional Features of Glaciers:

Kettle LakeDrumlins

Esker

Outwash

plain

Glacial Stream

TillMoraine-dammed lake

Terminal Moraine

Drumlins- long, smooth hills made of glacial till. - formed when a glacier runs over a moraine made by a previous glacier, “smearing” it out. - The drumlin points in the direction that the glacier is moving

drumlins

Outwash Plains- melt water from the bottom of the glacier carries sorted sediment out in

front of the glacier

Outwash Plain

Kettles- circular lakes. Chunks of ice often break off the glacier and are buried in the ground by sediment. As the buried ice melts, the sediment sinks into the

hole and the water fills it up

Another type of lake, found in New York, is called a moraine-dammed lake. This is formed when a

glacial moraine blocks a river valley from draining. The river floods the valley and forms a long,

narrow lake. Ex. the Finger Lakes in upstate New York.

Depositional Features of Glaciers:

• The tremendous weight of these glaciers causes it to slowly move outward from the center (some only moving centimeters per year)

• When the glacier reaches the sea, chunks break off and become icebergs (this is called calving)

• *Smaller ice sheets are called ice caps ➢GREENLAND: 1.7 Million SQ MI , 3 KM thick➢ANTARCTIC: 12.5 Million SQ MI, 5 KM thick

Important in understanding global scale climate changes since related to 5 of Earth’s systems:

1. Exosphere (outermost region of plant’s atmosphere)… regulates sunlight exposure

2. Hydrosphere (water on Earth’s surface) glacial ice is frozen water

3. Geosphere (Lithosphere, hydrosphere, and atmosphere) glacial ice flow modifies landscape

4. Atmosphere (gases surrounding Earth) … regulates global atmospheric patterns and temperatures

5. Biosphere (animal and plants)

Interrelationships to Earth’s Systems