Glaciated Landscapes
- Created by: Austen Poole
- Created on: 08-05-17 16:53
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- Glaciated Landscapes
- The components of open systems
- Inputs
- Kinetic, thermal and potential energy
- Material from glacial deposition
- Weathering
- Mass movement
- Outputs
- Melting
- Evaporation
- Sublimation
- Throughputs
- Sediment in the glacier
- Basal sliding
- System feedback
- When the outputs and inputs are the same a state of equilibrium exists
- The glacier stays the same
- When the equilibrium is upset the glacier can grow or melt
- If the equilibrium is upset the system changes to restore it - this is called dynamic equilibrium
- When the outputs and inputs are the same a state of equilibrium exists
- Inputs
- Glacier mass balance
- This is the difference between the accumulation and the ablation
- At the top of the glacier you get the accumulation zone
- There will be seasonal changes
- Physical features that affect glaciated landscapes
- Climate
- Wind can erode and transport and deposit material
- These aeolian processes help to shape the landscape
- Precipitation
- This provides the inputs of snow rain and sleet to the glacier
- This determines the mass balance of the glacier
- Temperature
- If temperatures rise above 0 degrees the ice will start to melt
- Wind can erode and transport and deposit material
- Geology
- Lithology
- This is the physical and chemical composition of the rocks
- Rock with a weak lithology has little resistance to erosion
- Structure
- This is the properties of the rock e.g. jointing, fracturing
- This can affect the permeability of the rock
- Lithology
- Latitude and altitude
- High altitude locations are colder
- Locations on high latitudes are colder
- Glaciers here generally form under the influence of stable ice sheets
- Relief and aspect
- The steeper the relief of the landscape, the greater the potential energy so the qlacier will move downhill faster
- If a slope faces away from the sun, the temperature will stay cooler for longer
- Climate
- Different types of Glacier
- Ice sheets
- These are large areas of ice - there are only 2 - Greenland and Antartica
- Valley glacier
- These are confined by valley sides - they follow the course of river valleys
- Warm based
- Usually have:
- High altitude locations
- Steep relief
- Rapid rates of movement
- The base of the glacier is usually above melting point
- e.g. Andes, Rockies
- These are very dynamic
- Usually have:
- Cold based
- Usually have:
- High latitude
- Low relief
- Very slow rate of movement
- Basal temperatures lower that the melting point
- These are not very dynamic
- Usually have:
- Ice sheets
- Glacier ice
- Glacier ice is formed when the snowflakes are compressed and the air is squeezed out - leaving highly dense ice
- Movement
- Factors that influence movement
- Gravity
- Gradient
- Thickness of ice
- Internal temperature of the ice
- Glacial budget
- The sides and the base of the glacier move move more slowly than the middle and the top because of friction
- Basal sliding
- Warm based glaciers
- Slippage - where the ice flows over the valley floor using melt water as a lubricant
- Creep/ relegation - when ice deforms under pressure due to obstacles of the valley floor
- The ice just moulds around the object
- Bed deformation - the ice is carried by saturated bed sediments moving beneath it on gentle gradients
- Internal deformation
- Cold based glaciers where the basal temperature is below zero
- Intergranular flow - when individual ice crystals re-orientate and move in relation to each othe
- Laminar flow - when there is movement of individual layers in a glacier
- Factors that influence movement
- How glaciated landforms develop
- Weathering
- Chemical
- Oxidisation
- Some rocks react with the oxygen in the air
- Carbonation
- Rainwater in weak carbonic acid - it reacts with limestone
- Solution
- Some rocks dissolve in water
- Hydration
- Water is added to minerals to create minerals with a larger volume
- Oxidisation
- Physical
- Freeze-thaw
- Pressure release
- When overlying rocks are removed by erosion and weathering, or when ice melts, the underlying rock expands and fractures parallel to the surface
- Frost shattering/ onion skin
- Water trapped in rock pores freezes and disintegrates the rock into small pieces
- Biological
- Tree roots
- Acids from algae
- Chemical
- Mass movement
- Rock falls
- Slides
- Rotational slides (slumps) - take place along a curved slip plane
- Glacial processes
- Erosion
- Plucking
- Water seeps into cracks along the bottom and sides of the valley - this then freezes and the rock becomes attached to the glacier - pulling it away
- Abrasion
- This is affected by many factors e.g. size of rock particles, thickness of the ice, the hardness of the rock
- Plucking
- Nivation
- Transportation
- Rock falls
- Avalanches can move large rocks
- Debris flows - melting ice can mix with scree, soil and mud
- Aeolian deposits - material moved by the wind
- Plucking
- Abrasion
- Englacial debris is within the glacier
- Subglacial debris is embedded in the base of the glacier
- Deposition
- Till
- Lodgement till
- This is deposited as the glacier advances being pushed into the existing valley floor
- Ablation till
- Left when the glacier retreats
- Usually: angular, unsorted, unstratified
- Lodgement till
- Till
- Erosion
- Weathering
- The components of open systems
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