GLACIAL PROCESSES

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GLACIAL PROCESSES

• I. Glacial Formation
• II. Glacial Mass Balance
• III. Glacial Motion
• IV. Glacial Erosion

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Anatomy of a glacier
Figure 19.4
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GLACIER FORMATION

• First, some snow must survive the summer melting
  season.
• Snowline the elevation above which some winter
  snow survives the summer melt.
• Snowline varies with latitude and with effective
  distance from the ocean (highest inland and in
  tropical areas).
• Next, snow must be converted to ice (snow
  metamorphism)

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Possible elevations for alpine glaciers
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Snowline change with latitude
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Global warming and snowlines
http//www.usgcrp.gov/usgcrp/Library/nationalasses
sment/LargerImages/SectorGraphics/Water/Snowline.j
pg
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Firn
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GLACIAL MASS BALANCE

• Mass balance essentially accounts for gains and
  losses of ice over time.
• In versus Out
• In Accumulation
• Out Ablation

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Figure 19.4
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Glacial ablation
New Zealand http//www.fayette.k12.in.us/chs/Anta
rctica/images/ablation.jpg
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Calving
http//www.astroshow.com/alaska/calf2.jpg
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GLACIER MOTION

• A glacier moves by two processes
• 1. Internal flow or deformation
• 2. Basal slip
• 3. Regelation slip

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GLACIAL EROSION

• 1. Crushing and Fracturing

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chattermarks
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crescentic gouges
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GLACIAL EROSION

• 2. Abrasion

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Striations
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Striations
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glacial polish
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Grooves
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GLACIAL EROSION

• 3. Plucking

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GLACIAL DEPOSITION

• Till
• Glacial deposits, poorly sorted w/ clast sizes
  ranging from clay to large boulders.

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Till