EQ3: Glacial processes Flashcards
What are the inputs of a glacial system?
Inputs include:
* Direct snowfall and precipitation
* Meltwater from melting snow and ice
* Rock fragments from erosion
* Avalanches and wind-blown deposits
* Solar energy with high albedo effect
What are the outputs of a glacial system?
Outputs include:
* Meltwater during spring and summer
* Sublimation and evaporation
* Meltwater streams transporting eroded material
* Calving into lakes and the sea
* Solar energy reflected in the albedo effect
Define mass balance in the context of glaciers.
The mass balance of a glacier is the relationship between accumulation and ablation, which can change over time.
What happens when accumulation is greater than ablation?
The glacier gains mass and the glacier snout advances.
a positive balance/ positive regime
What happens when ablation is greater than accumulation?
The glacier loses mass and the glacier snout retreats.
a negative balance/ negativ regime
What is an equilibrium line on a glacier?
An equilibrium line is where the amount of accumulation equals the amount of ablation, also known as the firn line.
Where does most accumulation occur on a glacier?
Most accumulation occurs at the upper end of a glacier due to colder temperatures at higher altitudes.
What are the temporal variations in a glacial budget during winter?
During winter months, there is a net accumulation in the glacial budget, causing the glacier to expand.
What are the temporal variations in a glacial budget during summer?
During summer months, there is a net ablation in the glacial budget, causing the glacier to reduce in size.
What is positive feedback in glacial systems?
Positive feedback occurs when an increase in snowfall from lower temperatures increases albedo, leading to further cooling and more accumulation.
What is negative feedback in glacial systems?
Negative feedback occurs when higher temperatures increase evaporation and precipitation, leading to more snow accumulation that balances losses from ablation.
What is the effect of altitude on glacier movement?
The potential energy gained from height can increase glacier movement, but high-altitude glaciers are more likely to be cold-based for longer periods, resulting in less movement.
Cold-based glaciers are those that remain at temperatures below freezing, which inhibits movement.
How does slope influence glacier movement?
Steeper sloped valley glaciers have higher rates of flow.
Slope affects gravitational pull, leading to faster movement.
What role does lithology play in glacial movement?
Lithology influences bed topography; easily eroded rocks (e.g. sandstone) can create deformations that may slow down glacier movement.
Bed topography refers to the physical features of the ground beneath the glacier.
What is the relationship between mass balance and glacier movement?
Areas of accumulation have slower rates of movement than areas of ablation.
Accumulation refers to the process where snow and ice build up, while ablation refers to melting and loss.
Define basal slip in the context of glacial movement.
Basal slip is linked to pressure melting of ice at the glacier’s base, creating a thin film of water that reduces friction and allows sliding.
This process is crucial for the movement of temperate glaciers.
What is regelation creep?
Regelation is the re-freezing of water under a glacier when pressure reduces after an obstruction, allowing the glacier to slide downhill.
This process involves both pressure melting and regelation occurring on different sides of an obstruction.
What is internal deformation in glaciers?
Internal deformation is the most common form of movement in cold-based glaciers, where ice crystals align with the glacier’s movement and slide past each other along cleavage planes.
Cleavage planes are lines of weakness within the ice structure.
Fill in the blank: Areas of _______ have slower rates of movement than areas of ablation.
[accumulation]
True or False: All glaciers move at the same rate.
False
Glacial movement varies significantly based on several factors, including altitude, slope, and lithology.
What is a key factor that allows glaciers to slide over bedrock?
A thin film of water (basal meltwater) created by pressure melting allows glaciers to slide over bedrock.
This film acts as a lubricant, reducing friction.
