How can glaciated landscapes be viewed as systems? Flashcards
What are glaciated landscapes?
Parts of the Earth’s surface shaped by glaciers, including current glaciers in high latitudes and altitudes, and past glaciated areas.
How can glaciated landscapes be viewed as systems?
They can be viewed as systems with interrelated components (stores) and processes (links) that store and transfer energy and material.
What types of energy are available to glaciated landscape systems?
Kinetic, potential, and thermal energy.
What is the primary material found in glaciated landscape systems?
Sediment on valley floors and in glacial lowlands.
What are the inputs to a glaciated landscape system?
- Heat - thermal energy from the Sun
- Debris - potential energy from material on slopes
- Debris - material from deposition, weathering, and mass movement
- Precipitation - ice from accumulated snowfall
What are the outputs of a glaciated landscape system?
- Glacial and wind erosion from rock surfaces
- Evaporation + sublimation
- Meltwater
What are the processes in glaciated landscape systems?
- Stores: accumulation of ice, water, debris
- Flows: movement of ice, water, and debris downslope
What happens when a system’s inputs and outputs are equal?
A state of equilibrium exists.
What is dynamic equilibrium in glaciated landscapes?
When the system self-regulates and changes its form until equilibrium is restored.
Define glacier mass balance.
The difference between snow and ice accumulation and ablation in a glacier over one year.
What is the accumulation zone in a glacier?
The area where accumulation exceeds ablation.
What is the ablation zone in a glacier?
The area where ablation exceeds accumulation.
What is the equilibrium line in a glacier?
The line where accumulation and ablation are balanced.
What indicates a positive glacier mass balance?
A net gain of ice through the year.
What indicates a negative glacier mass balance?
A net loss of ice through the year.
How do seasonal variations affect glacier mass balance?
Accumulation may exceed ablation in winter, and vice versa in summer.
True or False: A glacier can appear to advance even while in retreat.
True.
What factors influence the development of glaciated landscapes?
- Climate
- Geology
- Latitude and altitude
- Relief and aspect
What is lithology?
The physical and chemical composition of rocks.
What is the significance of structure in geology?
It includes properties like jointing, bedding, faulting, and permeability of rocks.
What is primary permeability?
The ability of porous rocks to absorb and store water.
What is secondary permeability?
Water seeping into rocks through joints.
What is the effect of latitude on glaciated landscapes?
Higher latitudes tend to have cold, dry, climates with stable ice sheets.
What is the temperature decrease rate with altitude?
Approximately 0.6°C per 100 m.
How does relief affect glacier movement?
Steeper relief increases the force of gravity, allowing glaciers to move more rapidly downslope.
What is the impact of slope aspect on glacier mass balance?
Slopes facing the sun may melt faster, decreasing mass balance, while shaded slopes may retain ice, increasing mass balance.
What is the influence of slope aspect on melting rates?
The aspect of a slope affects solar energy received, influencing melting rates and mass balance of glaciers
A slope facing away from the sun tends to have a positive mass balance, leading glaciers to advance.
What are the two types of glaciers?
- Valley glaciers
- Ice sheets
What is firn?
Snow that survives one summer with a density of 0.4 g/cm3.
What is diagenesis in glacier formation?
The process by which low-density snow is converted into higher density ice through compaction over time.
What are the characteristics of warm-based glaciers?
- High altitude locations
- Steep relief
- Basal temperatures at or above pressure melting point
- Rapid rates of movement (20-200 m/year)
What are the characteristics of cold-based glaciers?
- High latitude locations
- Low relief
- Basal temperatures below pressure melting point
- Very slow rates of movement (often only a few meters a year)
What are the main factors influencing glacier movement?
- Gravity
- Gradient
- Thickness of ice
- Internal temperatures
- Glacial budget
What is the pressure melting point?
The temperature at which ice is on the verge of melting, typically at 0°C at the surface but lowered by pressure within an ice mass.
What is basal sliding in glaciers?
Movement facilitated by a thin film of meltwater between the ice and the valley floor, reducing friction.
What are the two types of flow in glacier movement?
- Intergranular flow
- Laminar flow
What is the difference between extending flow and compressing flow in glaciers?
- Extending flow occurs when ice moves over a steep slope and fractures, forming crevasses
- Compressing flow occurs when ice thickens and pushes over slower-moving ice on gentler slopes.
What role does weathering play in glacial environments?
Weathering alters surface or near-surface rock, producing materials that can be eroded or transported.
What is freeze-thaw weathering?
Water enters cracks and expands by nearly 10% when it freezes, causing rock to split.
What is biological weathering?
It involves physical actions like plant root growth and chemical processes like chelation by organic acids.
What is the impact of climate change on weathering processes?
Increasing levels of atmospheric CO2 lead to more acidic rain, which can enhance weathering.
How does the thickness of ice affect glacier movement?
Thicker ice can influence basal temperature and pressure melting point, affecting movement rates.
Fill in the blank: The Antarctic ice sheet covers _______ million km².
13.6
True or False: Cold-based glaciers experience significant seasonal differences in accumulation and ablation.
False
What is the maximum movement rate observed in some glacier surges?
100 m per day.
What is the role of meltwater in warm-based glacier movement?
It reduces friction and facilitates basal sliding.
What happens to the internal temperature of ice as depth increases?
It typically increases, allowing for easier deformation.
What is the typical density range of glacier ice?
Between 0.83 and 0.91 g/cm3.
What is the primary mechanism of movement in cold-based glaciers?
Internal deformation.
What is the significance of a glacier’s mass balance?
A positive mass balance indicates net accumulation, causing the glacier to advance.
