Glacial Erosion Ice Push

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Glacial ErosionIce Push

• Glacier acts as bulldozer,may push limited amount
  of debris into ridge known as
• ICE-PUSH MORAINE.

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Glacial ErosionAbrasion

• Grinding by transported grains of silt and
  larger sizes.
• Effects polish, striations, grooves.
• Embedded fragments shared these features as
  well as facets.

Longitudinal glacier flow
Debris particle paths
Diverging ice flow
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Glacial ErosionAbrasion

• Replenishment of Debris

Longitudinal glacier flow
Movement towards glacier bed equal to amount
of basal melting
Path taken by particle
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Glacial ErosionPlucking (Quarrying)

• Pulling out large blocks of rock along fractures.
• May be dragged free or refrozen to base of
  glacier (regelation).

GLACIER Flow
Preassure-induced Melting
Refreezing
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Glacial ErosionFeatures Produced by Ice Sheets

• Formation of Whalebacks

Fast erosion
Flowing ice
Little erosion beneath stagnant or slowly moving
ice
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Glacial ErosionFeatures Produced by Ice Sheets

• Characteristics of Roche Moutonees

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Glacial ErosionFeatures Produced by Ice Sheets

• Rock Basins

gabbro
slate
0
80 km
diabase sills
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Glacial ErosionFeatures of Alpine Areas

• The largest and otherwise most significant
  glacial landform of alpine areas is the glacial
  trough.
• Longitudinal profiles of glacial troughs are
  steep in their upper parts and are also stepped
  and are commonly stepped.
• Paternoster lakes may occupy the floors of the
  steps.

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Glacial ErosionFeatures of Alpine Areas

• Glacial Steps

Riegels
Riegels
Basins
Riegels
Basins
Basins
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Glacial ErosionFeatures of Alpine Areas

• Glacial Troughs
• Transverse profiles are said to be U-shaped but
  vary in actual shape.

V-shaped
ParabolaW/2Dlt1
Semi-circleW/2D1
W/2Dgt1
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Glacial ErosionAlpine Feature - Cirque

• Half-bowl shaped scoup just below highest
  mountains.

Headwall
Snowline
Threshold
Basin
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Glacial ErosionAlpine Areas - Cirques

• Expand into cirque as glacier forms and advances.

Bergsrund
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Glacial ErosionAlpine Areas - Cirques

• Cirque Aspect
• NE aspect in Northern Hemisphere favors
• 1) Protection from sun
• 2) Receives wind-driven snow

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Glacial ErosionAmounts

• Area Erosion (in ft)
• Canadian Shield 10-50
• Scandinavia 80
• New England 10-15
• Valleys, B.C. 200
• Yosemite 650
• Finger Lakes 1400

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