72808
Temperate Glaciers
- The Alps and Rockies
- Conditions
- Usually high altitude
- Areas of high
accumulation in winter,
rapid ablation in
summer - large
volumes of ice move
over the firn line (firn is
partially compacted
neve)
- Milder climate - summer
melting, fluvial glacial
features
- Base temperature of
0C, at or below pressure
melting point
- Often steeper gradients
- Rapid
movement
20-200 m per
year
- Powerful erosive agent
- Usually high altitude
- The main mechanism for movement in temperate glaciers is basal slippage
- Represents 80% of glacial movement. Most
temperate glaciers are at pressure melting
point at their base and sometimes within the
glacier itself.
- Friction and pressure within the bedrock raises the temperature above 0C so
meltwater acts as a lubricant, enabling ice to move slowly, picking up material and
erode. At PMP as ice on point of melting and deforms more easily.
- Friction and pressure within the bedrock raises the temperature above 0C so
meltwater acts as a lubricant, enabling ice to move slowly, picking up material and
erode. At PMP as ice on point of melting and deforms more easily.
- Basal Slippage - Relegation slip
- Basal ice is forced against a rock obstacle,
pressure melting point may be reached due to
increase in pressure. Meltwater released at
base, enabling ice to move over obstacle.
Meltwater quickly refreezes on other side due
to reduction in PMP.
- Basal ice is forced against a rock obstacle,
pressure melting point may be reached due to
increase in pressure. Meltwater released at
base, enabling ice to move over obstacle.
Meltwater quickly refreezes on other side due
to reduction in PMP.
- Basal slippage - creep
- Where ice comes across an obstacle, increase in
pressure can cause ice to behave like plastic and
deform to flow around obstacle.
- Where ice comes across an obstacle, increase in
pressure can cause ice to behave like plastic and
deform to flow around obstacle.
- Represents 80% of glacial movement. Most
temperate glaciers are at pressure melting
point at their base and sometimes within the
glacier itself.
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