Glacial systems

Accumulation zone

Area where most precipitation falls

Where is the accumulation zone?

At the top of the glacier

Firn

Snow transitioning into ice

Equilibrium line

Area of glacier where accumulation and ablation are balanced

Ablation zone

Area at bottom of glacier where ablation is happening at a higher rate to accumulation

Snout

Very end of the glacier at the lowest point possible

Carving

Ice lost that falls off a glacier

Outputs of glacier

Meltwater, evaporation

Inputs of glacier

Precipitation, avalanches

Storage of glacier

Water

What is the mass balance?

The net change of the glaciers mass balance over a balance year or a fixed year

Formula for net value total

Total accumulation - total ablation

PMP = ?

Pressure melting point which is the temperature at which the ice is verging on melting at

PMP is determined by what?

Temperature + thickness of the glacier

Which factors influence the movement of a glacier?

Gravity, gradient, thickness, internal temperature of ice, glacial mass balance

Creep

Occurs if obstacle is in its path, build up of pressure

Surges

Build up of subglacial meltwater/ avalanche. Rare but may move 30m / day

Why do thrusts form?

Glacier surface slows as gradient changes, glacier overlaps

Why do crevasses form?

Glacier speeds up as gradient increases

Why do bergschrund form?

Where moving ice separates from stagnant ice, results in a crevasse

Describe plucking

Water at base of glacier freezes onto rock on the valley base, glacier moves, rock pulled away from valley base

Weathering is caused by…

Temperature change + the action of rainfall and happens in one place

Erosion is caused by…

The force of water/ ice when it is moving

Biological weathering processes are…

Tree roots, organic acids

Mechanical weathering processes are…

Freeze thaw, frost shattering, pressure release

Chemical weathering processes are…

Oxidation, solution, carbonation, hydrolysis, hydration