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Outline the geomorphological process of nivation. - AQA - A-Level Geography - Question 4 - 2020 - Paper 1
Question 4
Outline the geomorphological process of nivation.
Worked Solution & Example Answer:Outline the geomorphological process of nivation. - AQA - A-Level Geography - Question 4 - 2020 - Paper 1
Step 1
Nivation is a weathering and erosional process
Answer
Nivation is a geomorphological process that primarily occurs in cold environments. It involves both weathering and erosion, and is particularly associated with the freeze-thaw action. This action plays a critical role in shaping landscapes, especially on slopes.
Step 2
Main process: Freeze-thaw action
Answer
The key aspect of nivation is the freeze-thaw cycle, during which snow is compacted. The process begins when snow collects in hollows, forming a névé or snowfield. This accumulated snow undergoes cycles of freezing and thawing, leading to significant surface and subsurface changes.
Step 3
Weathering of rock and formation of nivation hollows
Answer
As the freeze-thaw cycle continues, it leads to the weathering of underlying rock. The constant expansion and contraction of frozen water exert pressure on the rock, which contributes to its breakdown, resulting in the formation of nivation hollows.
Step 4
Erosion during thawing periods
Answer
During warmer thawing periods, meltwater can erode sediment from the bottom of these hollows. This erosion can result in further landscape modifications, and may also cause the deposition of sediment in other areas, contributing to the dynamic nature of the geophysical environment.