Systems Approach to Glaciers
- Glaciers are defined as:
Large rivers (mass) of ice, moving downhill, under the influence of gravity
- Glaciers are open systems with inputs and outputs to external systems, including fluvial and atmospheric systems
- There are flows of energy, ice, water and sediments between stores
Glacial System
Inputs | Outputs | Stores | Flows |
Energy - Kinetic from wind and moving glacier. Thermal from the Sun and geothermal heat from the earth Atmospheric - Snow from precipitation, avalanche or blown-in. Condensation of water vapour. Sublimation of vapour directly to ice crystals Rock debris from weathering and transportation |
Energy through evaporation and sublimation Meltwater Water vapour through sublimation of ice and snow Icebergs and ice blocks Glacial and fluvio-glacial sediments Snow - blown away |
Accumulated debris from weathering, erosional and depositional processes Ice of the glacier itself Meltwater - stored on and within the glacier (supraglacial lakes are on top of a glacier) Potential energy stored from movement of glacier |
Debris flow through glaciers from surface storage to landforms Kinetic energy from movement of glacier Meltwater flow Glacial movement through gravity |
Diagram showing the features of an open glacial system
- A glacial system has positive and negative feedback loops to keep it in dynamic equilibrium
- E.g. sediment on the glacier absorbs insolation and begins heating
- This leads to the melting of the ice
- Exposing more sediment and increasing the rate of insolation absorption
- This is a positive feedback loop
- Output through ablation (melting) is balanced by glacial input of accumulation (usually snow)
- Equilibrium of the glacier is maintained when input and output are balanced - neither a gain nor loss of ice and the glacier remains the same size
- All these factors combined, create the distinctive glacial landscape, that is made from a range of erosional and depositional landforms