• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

How and why do glaciers erode?

Extracts from this document...

Introduction

How and why do glaciers erode? Glaciers are found where temperatures have stayed below 0?C for a period of time long enough that the snow from one winter survives the following summer. Then it will be covered with fresh snow in the winter. As the amount of snow falls it is compacted, and through partially melting and refreezing air is removed. Over time a glacier will form. Before an area is glaciated it will be affected by tundra conditions. These are extremely important, with regard to the later erosion processes, because they determine the amount of debris available for use in abrasion. The more joints in rocks that are exploited by freeze-thaw weathering then there will be an increase in the tools available for erosion when the glacier forms. If the area is tectonically active or the rocks are well jointed then the amount of glacial erosion may be increased (or continued) due to the increase in (or constant supply of) ...read more.

Middle

There are two main ways in which glaciers erode the bedrock that they are passing over, abrasion and plucking. Abrasion occurs when the debris being carried by the glacier moves to the base of the glacier and is carried across the bedrock. So long as the debris being carried is not sufficient to stop impede the movement of the glacier then there will be erosion of the bedrock by the debris. For there to be effective glacial erosion due to abrasion there must be a continuous flow of particles to the bed of the glacier, otherwise the debris becomes polished and ineffective. The second main form of glacial erosion is 'plucking' this involves two processes, deformation and regelation. In deformation the glacier passes over the bedrock and surrounds a particle on the surface of the bed, the tractive force of the glacier then overcomes the frictional force holding particle into the bedrock and 'plucks' it away from the rock. ...read more.

Conclusion

If the mass balance of the glacier is increased then the movement of the glacier will be increased proportionally. For there to be an increase in the mass balance then there must be more accumulation (inputs: e.g. direct precipitation or avalanches) than ablation (outputs: melting, evaporation, wind deflation or carving of ice from the glacier). In 1950 Shumski said that the mass balance of a glacier was 'the energy of glaciation', this can be seen (combined with Weertman's statement) to be the case by comparing the Franz Joseph and Meserve glaciers, where the higher mass balance of the Franz Joseph (due to the higher precipitation) leads to melting at the base because the glacier reaches the pressure melting point. This increased meltwater makes the glacier move faster, as does the increased size of the glacier, and so it erodes more than the cold based Antarctic glacier. There may also be seasonal differences within glaciers, where ablation or accumulation may increase or fall due to the seasonal change in weather conditions. ?? ?? ?? ?? Page 1 ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Hydrology & Fluvial Geomorphology section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Hydrology & Fluvial Geomorphology essays

  1. Marked by a teacher

    Examine the factors influencing the movement of glaciers.

    4 star(s)

    They move instead mainly by internal deformation where the ice deforms under its own weight because of gravity, due to the sum of tiny movements on the faces of the ice crystals making up the glacier. This mechanism has two elements.

  2. Hydrology and Fluvial geomorphology. (Q&A)

    The amount of pore space available will depend on the type of soil - for example, sandy or clay-rich - its texture and also its structure.

  1. Describe the process by which glaciers move

    There are many useful sources of information that I will be able to use in supporting my account. Glacial deposition is a main source of evidence as to the direction of ice movement. Drift is a term used to refer collectively to all glacial deposits.

  2. Do the Characteristics of a river change downstream?

    every 1.5 metres or so. We decided against this idea because it would not provide clear results and a good picture of what the valley profile really looked like. Instead we chose to measure the distance of the slope when a break occurred. This way we got a good picture of the valley profile and accurate results to go with it.

  1. How are Glaciers formed and what land forms do they form ?

    This valley would be V-shaped and there would be a river at the bottom of it. As the glacier advances it erodes the side of the valley forming a U-shaped valley. The bottom of the valley is known as the Glacial Trough.

  2. Describe the processes by which glaciers move. (6 marks).

    As stress builds up in the glacier when it comes into contact with an obstacle, it acts like plastic and flows over and around it, this is called creep.

  1. Glacier movement.

    an inch or two a day so you can hardly notice the movement. No matter how slowly it is moving, when the ice field begins moving it is officially a "glacier." As the ice moves over the ground it starts to bend and crack because it is so big and it is moving over land that is not flat.

  2. Examine how a glacier operates as a system (25)

    In the late 1960s/early 1970s, the ice fields slipping down Mont Blanc and the surrounding mountains of the European range covered some 375 sq km. By the late 2000s, this area had fallen to about 275 sq km. The glacier also has stores.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work