Periglacial landscapes Flashcards
What are periglacial environments?
Environments on the edge (outskirts) of a glacial landscape
Characterized by distinctive processes influenced by cold temperatures.
Where are periglacial environments primarily found?
High latitudes and altitudes, on the fringes of polar regions
Less common in the Southern Hemisphere due to the absence of land masses.
Why are periglacial environments found at high altitudes?
Because temperatures are low, falling by 1°C for every 100 m of height
Example: Himalayan Plateau.
What is permafrost?
Permanently frozen ground
Divided into three types based on depth and temperature.
What are the three types of permafrost?
- Continuous permafrost
- Discontinuous permafrost
- Sporadic permafrost
Each type varies by area covered and temperature range.
What characterizes continuous permafrost?
Covers largest areas with air temperatures below -5°C and can be frozen to depths of several hundred metres
Found in regions with consistently low temperatures.
What characterizes discontinuous permafrost?
Occurs over smaller areas with mean air temperatures between -5°C and -1.5°C, with depths up to 35m
Surface tends to melt in summer.
What characterizes sporadic permafrost?
Covers smallest areas where mean air temperatures are between -1.5°C and 0°C
Occurs only in markedly cold spots.
What is the active layer of permafrost?
The upper layer of permafrost that seasonally melts
Depth varies from a few centimetres to several metres.
What can happen to the active layer during summer?
It can become waterlogged, causing instability and movement
Even on low angle slopes.
What are periglacial processes dependent on?
freezing and thawing of meltwater
Highly seasonal in nature.
What is nivation?
The collection of seasonal snow in hollows that encourages frost weathering beneath
Important for shaping landscapes in periglacial environments.
What is frost heave?
The upward movement of soil due to the growth of ice lenses in the soil
Ice lenses grow from capillary movement of water.
What is freeze-thaw weathering?
The alternate freezing and thawing of water in rock cracks causing them to split
A key process in weathering in cold environments.
What is solifluction?
The downslope movement of saturated soil on gentle slopes
Can occur even on slopes with a gradient as low as 1 degree.
What does erosion by high winds refer to?
The removal of fine particles by strong winds on featureless plains
A significant process in arid and periglacial regions.
What is meltwater erosion?
The strong flows of meltwater washing away weathered material and eroding river banks
Particularly prominent in spring and summer.
