Geography A-Level AQA Glaciated Systems and Landscapes

Positive Feedback

Progressively greater change from the original condition of the system

Negative Feedback

The system is returned to its original condition

Glacial budget (Mass balance)

The difference between annual accumulation and annual balance (= net balance)

Polar regions

Northern and Southern extremes of the Arctic and Antarctic

Alpine regions

High relief (generally over 3000m)

Glacial regions

Currently covered by ice sheets and glaciers. There is ice throughout the year

Periglacial regions

Dry, high latitude areas. May not be permanently covered by snow/ice but is permafrost.

Internal deformation (ice movement)

Ice crystals orientate themselves in the direction of the glacier movement and slide past each other

Rotational flow (ice movement)

Ice rotates as it starts to move downhill

Compressional flow (ice movement)

Thickening of ice mass and slowing of movement

Extensional flow (ice movement)

Thinning of ice mass and acceleration of movement

Basal sliding (ice movement)

Meltwater acts as a lubricant and ice flows more quickly

Abrasion (erosion)

Material in the glacier rubs away at the valley floor and sides

Plucking (erosion)

Glacier freezes onto/into rock outcrops. As the ice moves away, it plus off pieces of rock

Supraglacial (transportation)

On the surface (transportation)

Englacial (transportation)

Within the ice (transportation)

Subglacial (transportation)

At the base of the glacier (transportation)

Solifluction (mass movement)

Surface layer becomes very wet due to summer melt. Soil particles become lubricated and will move down slopes.

Frost creep (mass movement)

The gradual movement of individual soil particles due to freeze thaw

Rock falls (mass movement)

The movement of large amounts of scree produced by freeze thaw

Glacial troughs

U shaped valley (straight, wide based, steep sides)

Rouches moutonnes

Resistant rock on the valley floor which has not been completely removed

Ribbon lakes

Rock basins filled with water to form lakes

Erratics

Boulders picked up and carried by ice before being deposited in an area of different geology

Lateral moraine

Moraine at the sides of the glacier

Medial moraine

Moraine caused by the merging of 2 lateral moraines

Terminal moraine

Moraine at the snout of the glacier

Recessional moraine

Moraine that marks an interruption in the retreat of the ice

Push moraine

Moraine that occurs when the climate deteriorates and the ice advances

Till plains

Wide areas of flat relief where there is a covering of glacial till

Kames

Undulating, winding mounds of unevenly deposited sand and gravel (fluvioglacial landforms)

Kame terraces

Flat areas formed along the side of valleys (fluvioglacial landforms)

Eskers

Long, narrow ridges of sorted, stratified, coarse sand and gravel (fluvioglacial landforms)

Outwash plains (sandur)

Deposits by meltwater streams running from the snout (fluvioglacial landforms)

Kettle holes

When ice blocks are washed onto the plain and then melt, leaving a gap in sediments (fluvioglacial landforms)

Block fields (periglacial landforms)

Flat, expansive areas of angular boulders (periglacial landforms)

Solifluction (periglacial landforms)

Large amounts of water can not drain away which leads to lubrication on soils so the soil can move on slopes (periglacial landforms)

Lobes (periglacial landforms)

Where solifluction forms on steeper slopes, tongue-like lobes extend down the slope (periglacial landforms)

Terracettes (periglacial landforms)

Narrow steps with a small tread which run parallel to the contours of a slope (periglacial landforms)

Thermokarst (periglacial landforms)

When ice melts within permafrost, depressions form in the ground. They are a result of temperature change (periglacial landforms)

Pingo (periglacial landforms)

Dome shaped, ice-cored mounds of earth (periglacial landforms)