Glaciation Pack A Flashcards
What is a glacier?
A large, perennial accumulation of crystalline ice, snow, rock, sediment and often liquid water that originates on land and moves down slop under the influence of its own weight and gravity
How are glaciers useful to humans?
They provide resources, such as:
- HEP
- Drinking water
- Irrigation
- Rocks for building
How does snow become ice and where is the most compression?
- Glacier ice is made from compacted snow
- Granular snow is compacted to make firn or neve
- This is then compacted to make glacier ice
- Most compression happens at the base of the glacier
What conditions are needed for ice to form?
- Low average annual temperatures
- Large amounts of snow
- Temperatures that don’t get too high throughout the year
Where are glaciers and ice sheets found nowadays?
Ice sheets:
- Greenland
- Antarctica
Ice caps:
- Iceland
Glaciers:
- Alps
- Iceland
What is a system?
A set of interrelated components working together
A system has:
- Inputs
- Outputs
- Stores
- Processes
- Equilibrium
- Feedback
- Tipping points
What are the inputs to and the outputs from a glacier?
Inputs:
- Precipitation
- Avalanches
- Energy
- Meltwater and debris
Outputs:
- Meltwater and sediment
- Calving
- Sublimation
What is the glacial budget?
The balance between the inputs to and outputs from a glacier. It refers to the annual growth and retreat of the glacier (accumulation and ablation).
What affects the mass balance of a glacier?
Accumulation and ablation
What causes positive and negative regimes?
More ablation than accumulation = negative regime
More accumulation than ablation = positive regime
Equal accumulation and ablation = equilibrium
What does the annual mass balance diagram of a glacier look like?
Accumulation peaks in winter and is lowest in summer
Ablation peaks in summer and is lowest in winter
Where is the equilibrium line on a glacier and why does it move up or down the glacier?
The equilibrium line is where accumulation = ablation
It moves up the glacier when there is a negative regime and moves down the glacier when there is a positive regime
What is the line of equilibrium on a mass balance graph and when does it occur?
It occurs in autumn and spring when accumulation = ablation
Where on a glacier does melting happen and why?
Surface - solar radiation
Sides - friction
Subglacially - pressure and ground heat
Snout - where it reaches the sea (+ calving may happen)
What are glacials, interglacials, stadials and interstadials?
Glacials = periods of colder climate (>100,000 years)
Interglacials = periods of warmer climate (>10,000 years)
Stadials = colder times within glacials and interglacials (<1,000 years)
Interstadials = warmer times within glacials and interglacials (<10,000 years)
