OCR A Level GL - 1. OCR A Level GL 2.1a Glaciers as Systems Flashcards
What is a glaciated system?
an area covered by ice made up of components (stores) and processes (links). These systems store and transfer energy and material on a variety of time scales from days to millennia.
What materials are found in glaciated systems?
- Ice 2. Meltwater 3. Rock debris
Where is supraglacial material found?
on top of a glacier
Where is englacial material found?
within a glacier
Where is subglacial material found?
underneath a glacier
What types of energy are available to a glaciated landscape?
- kinetic 2. potential 3. thermal
What is kinetic energy?
energy which a body possesses by being in motion.
When is kinetic energy evident in glaciated landscapes?
avalanches rockfalls mass movements basal sliding in a glacier
What is potential energy?
the energy that is stored in an object due to its position relative to others.
What is thermal energy?
the energy that comes from heat. This heat is generated by the movement of tiny particles within an object. The faster these particles move, the more heat is generated.
What is an open system?
a material system in which mass or energy can be lost to or gained from the environment.
What are the inputs into glaciated landscape systems?
Materials Precipitation Avalanches Rock Debris Energy Gravity Solar Radiation Geothermal heat
What are the outputs in glaciated landscape systems?
Materials Meltwater Calving Sublimation Rock Debris Energy Heat
What are throughputs in glaciated landscape systems?
Materials
Movement of snow, ice, meltwater and rock debris through the system
Energy
Gravitational energy to kinetic energy
Frictional heat energy
Regelation
What is glacial deposition?
material is no longer transported
What is weathering?
the breakdown of rocks in situ.
What is mass movement?
the transport of soil, bedrock, rock debris or mud on steep coastlines usually via a rockfall, landslide, mudflow or slump.
What is glacial erosion?
the gradual destruction or diminution of something.
What is evaporation?
the process of turning from liquid into vapour.
What is sublimation?
When a solid turns into a gas without first becoming liquid.
What is equilibrium?
When a system’s inputs and outputs are equal
What is dynamic equilibrium?
when a system undergoes self-regulation and changes until equilibrium is restored
What is negative feedback?
negative feedback ensures that, in any control system, changes are reversed and returned back to the set level.
What is glacier mass balance?
the advance or retreat of a glacier based on the ratio of inputs (accumulation) and outputs (ablation).
Why is the mass balance of a glacier important?
they provide the key link between atmospheric processes and glacier extent helping to explain how climate change results in a change in extent and the formation of glacial features such as terminal and recessional moraines.
What is accumulation?
when more ice and snow forms than melts.
What is the accumulation zone?
in the upper reaches of a glacier where snow builds up year after year (accumulation exceeds ablation)
What is ablation?
when ice and snow melts
What is the ablation zone?
in the lower reaches of a glacier where more snow and ice melt than form (ablation exceeds accumulation)
What divides the accumulation zone from the ablation zone?
the equilibrium line
How do you calculate the annual budget of a glacier?
total accumulation - total ablation
What is a positive mass balance and how would it be seen in a glacier?
a net gain of ice in a glacier over a year resulting in glacial advance
What is a negative mass balance and how would it be seen in a glacier?
a net loss of ice in a glacier over a year resulting in glacial retreat
What is freeze-thaw weathering?
in the daytime, water enters rock cracks and freezes (so expands) at night. Continued expansion and contraction exerts pressure and cracks the rock
What is glacial erosion?
break-up and transport away of the valley floor and sides, caused by the enormous weight of a glacier and embedded rocks scraping away.
What is an ice sheet?
a large expanse of continental glacial ice covering at least 50,000 km2.
What is a valley glacier?
a large mass of ice, fed by larger bodies of ice, and corrie glaciers.
What is internal deformation?
glacier movement that occurs when ice crystals orientate themselves in the direction of flow and slide past each other.
What is a warm based glacier?
fast-moving, ‘temperate’, ‘alpine’ glaciers- meltwater at the base lubricates the glacier, reducing friction.
What is a cold-based glacier?
slow moving, ‘polar’ glaciers- glaciers are frozen to their beds, and little meltwater is available.
What is basal sliding?
movement of a glacier lubricated by meltwater below the ice- as pressure is great, the ice can melt at lower temperatures than normal.
What is glacier ice?
blue ice with trapped air, formerly snow, but compressed overtime, flows downhill.
What is subglacial meltwater?
the result of ice melting, changing to liquid at the base of a glacier, due to increased pressure at the base.
What are subglacial tunnels?
eroded conduits beneath a glacier allowing for the flow of water under pressure and debris transport.
What is subglacial till?
angular rocks and loose debris found at the base of a glacier, formed by erosional processes below the ice.
