1. How can glaciated landscapes be viewed as systems?

Glaciated landscapes as open systems

Energy and matter can be transferred from neighbouring systems as an input and can also be transferred to neighbouring systems as an output.

Inputs in a glaciated system

Kinetic energy from wind and moving glaciers
Thermal energy from heat of sun
Potential energy from position of material on slopes
Material from deposition, weathering and mass movement
Accumulated snowfall

Outputs in a glaciated system

Glacial and wind erosion from rock surfaces
Evaporation, sublimation and meltwater

A state of equilibrium

When a system's inputs and outputs are equal.
When equilibrium is disturbed, the system undergoes self-regulation.

Dynamic equilibrium

When the system produces its own response to the disturbance (negative feedback)

Glacier mass balance

The difference between the amount of snow and ice accumulation and the amount of ablation occurring in a glacier over a one year time period

Névé

When the fresh snow gradually starts to become more compact

Firn

As snow become more compact than a névé after a year or more.

Why does glacial ice appear blue

Ice eventually becomes so compact that most of the air is squeezed out

Accummulation

Overall gain of mass

Ablation

Overall loss of mass

Surges

Periods of very rapid advancement

Why do most glaciers move

Due to gravity

Where on the glacier does most accumulation occur

At the upper end of a glacier

Where on the glacier does most ablation occur

At the lower end of a glacier. This additional weight at the upper end gradually pushes the glacier downhill/downslope.

Crevasses

Fractures that are caused by the movement and bending of ice over obstacles or uneven relief

Basal slip

When gravity pulls a glacier downhill, the ice often slips over the surface. This is helped by meltwater, which acts as a lubricant.

Where are cold based glaciers found

In high latitudes such as Antarctica

Temperatures at cold based glaciers

Below PMP
Meltwater not present

How do cold based glaciers move

Internal processes
Frozen to bedrock and they consequently move only very slowly and there is little erosion

Where are warm based glaciers found

Lower latitudes and areas of high altitude and steep relief like the Swiss and French alps

How do warm based glaciers move

A layer of meltwater lubricates the ice/surface contact that facilitates slippage in addition to internal flow causing basal movement
These are faster moving glaciers

Examples of internal processes

- Plastic flow
- Intergranular movement

Examples of basal slippage and related processes

- Basal slippage
- Regelation

What is plastic flow

When the ice is under pressure it can deform and mould itself like plastic

What is intergranular movement

Ice crystals can slip against each other and movement can occur within crystals along lines of weakness called cleavage planes

What is basal slippage

A layer of meltwater acts as a lubricant that helps the ice to slide over bedrock

What is regelation

As ice moves it can be forced against an obstacle. Pressure on the upstream side leads to melting, this liberated water can then move to the downstream side where refreezing occurs. In this way movement can occur within a glacier, with the meltwater aiding basal slip.

What is extending flow

Where there is an increase in the gradient, the ice accelerates and become thinner.
Crevasses develop as the ice acts in a brittle way due to the quicker movement

What is compressing flow

Where the gradient becomes more gentle, the ice decelerates and the ice becomes thicker

What is laminar flow

The movement of individual layers within the glacier

What is the snow line

The level above which snow will lie all year

How does glacial ice form

- When snowflakes form they have an open feathery appearance, and have low density
- It becomes compressed by the weight of subsequent falls and gradually develops into a firn or névé
- In temperate latitudes, summer meltwater percolates into the firn only to freeze at night or during the following winter, thus forming an increasingly dense mass. Air is progressively squeezed out and after 20-40 years the firn will have turned to solid ice. This same process may take several hundred years in Antarctica and Greenland where there is no summer melting
- Once ice has formed, it may begin to flow downhill under the force of gravity as a glacier

What is Pressure melting point (PMP)

The temperature at which ice is on the verge of melting
PMP is normally 0 degrees C on the surface of a glacier but it can be lower within a glacier (due to an increase in pressure caused by either the weight or the movement of ice)

Why do warm based glaciers move much more than cold based glaciers

Movement is facilitated by the production of meltwater
No meltwater, no movement.
So most warm-based glaciers are at PMP at the base of the glacier and sometimes within the glacier itself.
In cold-based glaciers, temperatures are below PMP and so movement is limited

What is bed deformation

This is the movement accomplished by the deformation of soft sediment or weak rock beneath a glacier

Why does the middle of the glacier move faster

Because there is less friction

What is a glacial surge

The periodic collapse of a glacier when the mass and slope angle of ice builds up to a critical level within the accumulation zone. When the critical mass is reached
A change in the hydrological regime is also associated with surging glaciers

potential influences on glaciated landscape systems - climate, including precipitation totals and patterns

• Wind is a moving force and as such is able to carry out erosion, transportation and deposition. These aeolian processes contribute to the shaping of glacial landscapes - particularly by acting upon fine material previously deposited by ice or melting.

• Precipitation totals and patterns are key in determining the mass balance of a glacier as precipitation provides the main inputs for of snow, sleet and rain
  
  - In high latitude areas precipitation totals may be very low whereas in high altitude locations they may be a lot higher.
  
  - Also significant seasonal variation with rates of precipitation, more varied precipitation the more varied the mass balance of the glacier will be.

• Significant factor
  
  - If temp rises above 0 degrees, accumulated snow and ice will begin to melt and become an output of the system
  
  - High altitude areas may experience significant periods in the summer months of above 0 temps and melting
  
  - High latitude areas temps may never rise above 0 and therefore means that no melting occurs - explains why ice sheets are so thick in polar regions, despite low precipitation inputs

• Antarctic Ice Sheet – Despite low annual precipitation, glaciers remain due to consistent sub-zero temperatures preventing melting.

• The Alps, Europe – Seasonal precipitation variation leads to mass balance fluctuations, affecting glacial advance and retreat.

potential influences on glaciated landscape systems - geology, including lithology and structure

• lithology is the physical and chemical composition of rocks

• Rock types which have weak lithology have less resistance to erosion, weathering and mass movements as the bonds between the particles that make up the rock are quite weak (as in clay).
  
  - Other materials such as basalt are made of dense interlocking crystals and are very resistant and will form more prominent glacial landforms such as arêtes and pyramidal peaks.
  
  - Some, such as limestone are predominantly composed of calcium carbonate and is soluble in weak acids and so is vulnerable to decay by the chemical weathering process of carbonation, especially at low temperatures.

• Structure:

• Properties of the individual rock, such as jointing, bedding and faulting which affects the permeability of rocks.
  
  - In porous rocks such as chalk tiny air spaces separate the mineral particles. These pores absorb and store water known as primary permeability.
  
  - Carboniferous limestone is also permeable because of its many joints (water seeps into the joints) - this is secondary permeability - these joints are easily enlarged by solution
  
  - Structure also effects the angle of dip of rocks and can have a strong influence on valley side profiles. Horizontally bedded strata support steep cliffs with near vertical profiles. Where strata incline, profiles tend to follow the angle of dip of the bedding planes.

potential influences on glaciated landscape systems - latitude and altitude

Locations at high latitudes tend to have cold and dry climates with little seasonal variation. Higher the latitude the more apparent this is.

- Glaciated landscapes at these latitudes develop under the influence of large and relatively stable ice sheets.

Differ from the landscapes formed in high latitudes because altitudes glacial landscapes develop under the influence of dynamic valley glaciers that are in lower lat but higher alt.

- These locations have higher precip input and more variable temperatures meaning an increased melting in summer time

- Decrease in temp with altitude of approx 0.6degrees/100m means that glaciers are even found near the equator in the Andes. High altitude locations may receive more relief precipitation.

potential influences on glaciated landscape systems - releif and aspect on microclimate and glacier movement.

• aspect - the direction a slope faces

• Where air temp is closer to 0 it has a significant impact on the melting of snow and ice and the behaviour of glacier systems.
  
  - If the aspect of a slope faces away from the general direction of the sun it is likely to remain below 0 for longer as less solar energy is received and so less melting occurs. Mass balance in such areas tend to be positive meaning they advance.
  
  - Opposite is likely to be true in areas with an aspect facing towards the sun - these differences not only effect the mass balance but will, as a result, influence the shaping of the landscape.
  
  - Glaciers with a positive mass balance are more likely to be larger with more erosive power and much more erosive than small ones and those in retreat due to a negative mass balance.

• relief - The steeper the relief of the landscape, the greater the resultant force of gravity and the more energy a glacier will have to move downslope.

flows of energy through a glaciated landscape system

1. Kinetic Energy (Energy from Movement)

• Glaciers flow downhill under gravity, converting potential energy into kinetic energy.

• This movement enables glacial processes such as abrasion (scraping of rocks against bedrock) and plucking (removal of rock fragments).

2. Thermal Energy (Energy from Heat Sources)

• Solar Radiation:

  • Glaciers absorb energy from the sun, increasing surface melting and albedo effects (lighter surfaces reflect more energy, darker debris absorbs more).

• Geothermal Heat:

  • Heat from the Earth's core slightly warms the base of glaciers, contributing to meltwater production, which can lubricate glacial movement.

• Latent Heat:

  • Energy involved in phase changes (melting, freezing, sublimation).

  • Meltwater refreezing releases heat, potentially warming subglacial environments.

3. Potential Energy (Stored Energy Due to Elevation)

• Higher-altitude glaciers store potential energy, which is released as they move downslope.

• This energy contributes to erosional force, carving out deep U-shaped valleys like those found in the Swiss Alps.

4. Energy Exchanges in Glacial Systems

• Sensible Heat Transfer: Direct energy exchange between ice, atmosphere, and surrounding land.

• Turbulent Energy Transfer: Wind redistributes heat, affecting sublimation and melting rates.

• Radiative Energy Balance:

  • Incoming shortwave radiation from the sun is partially absorbed.

  • Outgoing longwave radiation releases heat back into the atmosphere.

Feedback Loops Affecting Energy Flow

• Positive Feedback Loop:

  • Ice loss reduces albedo, leading to greater absorption of solar energy and accelerating melting.

• Negative Feedback Loop:

  • Increased snowfall can stabilize ice mass, balancing melt rates.

flows of material through glaciated landscape systems

Ice and Water Flows

• Inputs:

  • Snowfall: Adds mass to glaciers through accumulation.

  • Avalanches: Transport material from higher elevations into glacial zones.

  • Condensation: Water vapor forms ice, adding to mass balance.

• Outputs:

  • Meltwater: Flows into rivers and streams, contributing to hydrological cycles.

  • Calving: Icebergs break off glaciers, transferring ice to oceans.

  • Sublimation: Ice directly turns into vapor, affecting moisture availability in polar regions.

2. Sediment Transport Mechanisms

Glaciers transport sediment through three main pathways:

1. Supraglacial (On the Surface):

   • Material (rocks, soil, debris) is carried on the glacier’s surface.

   • Sources: Rockfalls, dust deposition, and wind-blown sediments.

   • Example: Himalayan glaciers collect large amounts of supraglacial debris from steep valley walls.

2. Englacial (Within the Glacier):

   • Sediments become trapped inside the ice as glaciers flow.

   • Ice deformation can shift material deeper within the glacier.

   • Example: Alpine glaciers often contain layered debris within ice strata.

3. Subglacial (Beneath the Glacier):

   • Basal sliding moves sediment at the glacier base.

   • Meltwater channels can flush sediments beneath glaciers.

   • Example: Greenland Ice Sheet transports sediments through subglacial rivers.

3. Glacial Deposition

• Till (Unsorted Sediment):

  • Dropped directly by glaciers as they retreat.

  • Creates features like moraines, drumlins, and erratics.

• Outwash (Sorted Sediments):

  • Carried by meltwater streams, leading to the formation of outwash plains and eskers.

  • Example: The Skeiðarársandur outwash plain in Iceland showcases large-scale meltwater deposition.

4. Material Cycling and Feedback Loops

• Erosion Feedback Loop:

  • Glacial erosion increases sediment supply, leading to thicker moraines that insulate ice from melting.

• Meltwater Transport Feedback:

  • Increased melting causes stronger sediment transport, influencing river systems downstream.

• Deposition and Climate Impact:

  • Glacial till alters land surface reflectivity (albedo effect), impacting regional temperatures.