glaciated landscapes 1

Question 1

glaciers and types of glaciers

Answer 1

• a glacier is a body of land based ice that moves under its own weight, cover 10% of earth and are 30-100km long.
• an ice sheet is a large accumulation of over 50,000 km2 ice, possess 69% of world’s ice.
• we live in the Quaternary period, the last ice age is the Pleistocene - lasted from 2 million years a go to 11,700 yrs a go.
• warm-based glaciers: high altitude, steep relief, reach PMP, ice moves freely.
• cold based glaciers - high latitudes, low relief, ice is frozen at base, little water or movement.

Question 2

glaciers as a system

Answer 2

Glaciated landscapes are seen as open systems: meaning moth matter and energy can be transferred across the boundary into the surrounding environment.
INPUTS: precipitation, debris, ice, snow, thermal energy, potential and kinetic.
PROCESSES: abrasion, plucking, ftw.
OUTPUTS: meltwater, evaporation, icebergs, sublimation, water vapour, debris, thermal energy.

Question 3

how does a glacier form and move?

Answer 3

1 - snowfalls and accumulates in layers. 2 - there is compression forcing air out and ice forms in diagenesis. 3 - accumulation of snow turns into neve or firn then glacial ice.
- accumulation zone - upper zone accumulation>ablation. Ablation zone: lower altitudes: ablation>accumulation.
- mass balance: difference between the total amount of accumulation and ablation in 1 year. Positive mass balance in winter and negative in summer due to warm temps and melting.

Question 4

different movements of glacier

Answer 4

• PMP is point at which ice is on verge of melting, at surface ice melts at 0 C but as pressure increases PMP decreases, ice can melt at -1.6 C.
• Basal sliding: main type of movement in WBG: slippage: PMP means meltwater acts as lubricant and glaciers slips. Regelation: When meets a rock it compresses before it reaching PMP so melts and goes over it like putty refreezing on the other side. Bed(substrate) deformation; meltwater present and percolates rock below, if rock is saturated it acts as a lubricant and ice slides.
• internalde deformation: overlying weight of ice causes crystals to change shape due to compaction they become flat and slide over each other.
• laminar flow: ice can flow within layers. Layers of neve, ice and snow create lines of weakness allowing ice to move under gravity.

Question 5

physical factors affecting the system

Answer 5

1 - geology: areas of soft rock have more erosion, hard rock has less. geology affects deposition rates: WBG reach PMP lubricating the base and causing quicker erosion.
2 - relief; WBG glacier on steep relief: more kinetic and potential energy = quicker = more erosion. CBG = less energy = less erosion.
3 - altitude & latitude: CBG at high lats so are colder and don’t reach PMP, less erosion and energy. WBG: high alts: reach PMP more erosion.
4 - climate: high latitude means low temps doesn’t reach PMP so less erosion, moves via internal deformation. WBG have seasons: mass balance change, also reach PMP and move via basal sliding therefore erode more.