how can glaciated landscapes be viewed as a system

Question 1

describe earth today in terms of glaciation

Answer 1

• glaciers cover 10% of earth’s surface
• we are currently in an interglacial called the Holocene where ice coverage has retreated to polar areas
• 85% of total glacier ice is found in Antactica
• 75% of all fresh water on earth is stored in glaciers

Question 2

describe earth in terms of historical glaciation

Answer 2

• the last ice age was known as the Pleistocene glaciation which started 2 million years ago and was part of the quaternary period, ice covered 30% of earth’s surface
• there was a mini ice age between 1750 and 1850
• during an ice age there are glacials (periods of very cold and dry climate when large sea and ice masses grow) and interglacials (warmer periods during which the ice masses and valley glaciers retreat)

Question 3

describe glacier systems

Answer 3

• comprises inputs outputs and stores
• glaciated landscapes store and transfer energy of scales that can vary from a few days to a millennium
• energy in glacial systems includes thermal (heat), potential (position relative to others) and kinetic (motion), this energy enables work to be carried out by the natural processes that shape the landscape
• the material in glacier systems is mainly sediment found on valley floors
• glaciated landscapes are open systems
• this means energy can be transferred from neighbouring systems as inputs and outputs

Question 4

name four outputs and inputs of glacial systems

Answer 4

• inputs (avalanches, snow, rock debris from erosion of slopes, hail)
• outputs- sublimation (transition of substance directly from solid to gas), calving (ice breaking away, iceberg formation), melting, debris being transported and deposited

Question 5

describe accumulation and ablation zones

Answer 5

accumulation zone is the part of a glacier, usually at higher elevations, where accumulation exceeds ablation which subsequently turns into firn and glacier ice
-ablation zones, part of a glaciers surface, usually at lower elevations, where ablation exceeds accumulation

Question 6

describe the growth of glaciers in terms of system feedback

Answer 6

• glaciers grow or recede as a function of the balance between accumulation (inputs) and ablation (outputs)
• when a systems inputs and outputs are equal , a state of equilibrium will exist and the glacier will stay the same size (does not happen in real life)
• the equilibrium line is the line or zone on a glaciers surface that separates a glaciers accumulation and ablation zones
• when the equilibrium is disturbed, the system will undergo self regulation to restore it. This is known as dynamic equilibrium.

Question 7

describe the mass balance of a glacier

Answer 7

• the mass balance or budget is accumulation - ablation annually
• positive figure indicates net gain of ice, increasing the volume of the glacier therefore it will advance and the equilibrium line will move down the valley
• negative figure indicates a net loss of ice throughout the year, the glacier will contract and retreat up the valley along with the equilibrium line
• seasonal variations in a budget mean that even when a glacier has net gain there will be some retreat and when there is net loss there will be some advance
• even when in retreat, the glacier might move forward under gravity even though it is shrinking in mass