Glacial Processes
Basic summaries of ice formation, ice movement, and weathering.
- Created by: Punani Patrol
- Created on: 02-03-14 16:14
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- Glacial Processes
- Ice movement
- Internal deformation- Cold based glaciers move 1-2cm/day mainly by internal deformation. Ice crystals orientate themselves in the direction of ice flow, allowing them to slide past one another.
- Basal slippage- Pressure and friction increase temperature, causing basal ice to melt, the melt water acts as a lubricant allowing ice to move 2-3cm/day (mainly temperate glaciers).
- Regelation- Ice melts under high pressure upwards of an obstacle, acting as a lubricant for more ice to pass over, and refreezes under lower pressure on the downstream side of the obstacle, creating a regelation layer.
- Extending flow- Steep gradient makes ice flow faster and become thinner and more spread out. Less erosive.
- Compressing flow- gentle gradient makes ice flow slower and become thicker and less spread out. More erosive.
- Ice formation
- Layers of snowfall compress lower snow and force out air to form neve. Eventually forming ice. Mleting and refreezing of old snow can assist the process.
- Weathering
- Freeze thaw- Most effective when temperature fluctuates around 0°c, water in cracks in rock expands by 9% when frozen, causing rock to shatter. More active in periglacial environments than polar.
- Abrasion- Angular, frost-shattered rocks below glacier sandpaper the bedrock, and can form striations indicating direction of ice movement.
- Plucking- Angular, frost shattered rocks are pulled out of the bedrock by meltwater refreezing around them. Common downslope of obstacles where lowered pressure causes refreezing.
- Ice movement
- Extending flow- Steep gradient makes ice flow faster and become thinner and more spread out. Less erosive.
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