The Main Physical Processes in a Peri-Glacial Area

The Main Physical Processes in a Peri-Glacial Area

Currently 20% of the earth is peri-glacial; therefore we can assume

that 20% of the earth’s processes are peri-glacial. The dominant

process is that of freeze thaw weathering, which occurs due to

fluctuations in temperatures around 0°C, these fluctuations can occur

periodically in seasons, or variations between day and night

variations. Freeze thaw is concerned with the fact that as water

freezes, it expands by 9% exerting pressures of up to 2100kg/cm3 on

the rock and that most rocks can only withstand pressures up to

210kg/cm3, the splitting of the rock by freeze thaw action is known as

congelifraction.

Frost heave is yet another process whereby water freezes in the soil

and physically pushes the surface upwards; there are three criterion

which need to exist for frost heave to occur,

1. A sufficiently cold climate to allow freezing temperatures to

penetrate below the surface

2. A supply of water from below, above or laterally into the

freezing zone.

3. A soil material that is frost susceptible and is lying within the

freezing zone.

The heaving itself is caused by the formation of ice lenses in the

soil below, which refers to the growth of ice

crystals in the soil.

Solifluction is concerned with the movement of the active layer, and

is also termed congelifluction. In winter, water freezes within in the

soil causing expansion of the soil and segregation of individual soil

particles, then, in spring the ice melts forming the active layer

which will flow downhill, as it can not infiltrate the impermeable

permafrost, somewhat imitating a mass m...

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...nd, and the shelter-forest network was

stabilizing the sand, reducing sandstorms and protecting crops.

We can see that peri-glacial areas do create challenges for human

inhabitants, whether these are agricultural challenges, habitation

challenges or challenges regarding resources; man can still limit the

challenge by using appropriate technology such as engineered stilts in

Alaska or projects such as those in Northen China.

F.A.O Liz

A-Level Geography Results-AQA B-MOHEEN KHAN

AS GGB1 The Dynamics of Change 106/120

AS GGB2 The physical Option-Glaciation 90/90

AS GGB3 The Human Options 72/90

A2 GGB4 Global Change 70/90

A2 GGB5 Synoptic Module 75/120

A2 GGB6 Practical Paper 54/90

As you can see the theory I’m OK in, however it’s the synoptic ideas I

find difficult to get to grips with.