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

Examine how a glacier operates as a system (25)

Extracts from this document...


Examine how glaciers operate as a system. (25) Glaciers can be classified according to the temperature of their base. In warm based glaciers e.g. the Alps, the base is warmer than the melting point of ice. It’s warmer because of the heat from friction caused by the glacier moving, or because of the geothermal heat from the earth. The ice at the bottom of the glacier melts, and the meltwater acts like a lubricant, making it easier for the glacier to move downhill. Ice at the surface also melts if the temperature reaches 0 degrees Celsius, and meltwater moves down through the glacier, lubricating it even more. Therefore, warm based glaciers move rather quickly, lots of movement means lots of erosion so warm based glaciers are highly erosive too. On the contrary, in cold based glaciers e.g. in Antarctica where glaciers cover 13,586,380km, the base is cold and the temperature is usually well below the ice’s melting point, so there’s very little melting and this lack of meltwater means cold based glaciers move very slowly. The ice is frozen to the valley floor which also slows movement. Even in summer the temperature is below freezing, the mean annual temperature of the interior is −57°C, so there’s not a lot of melting at the surface either. Consequently, cold based glaciers don’t erode a lot. A glacier is a system which has inputs, outputs and stores. ...read more.


These inputs and outputs contribute to the size of a glacier. The glacial budget is the balance between a glacier?s inputs and outputs, the dominant process determines the size and movement of the glacier. Accumulation is the input of snow and ice into the glacial system; most accumulation is snow. Ablation is the output of water from the glacier. The glacial budget is the balance between accumulation and ablation over a year ? it shows whether the volume of water in the glacial system has increased or decreased. This determines whether the glacier advances forwards or retreats back. The glacier is divided into two zones, the zone of accumulation at the top of the glacier, where there?s higher precipitation levels, and the zone of ablation at the bottom where melting and sublimation of glacier ice occurs. The place where accumulation and ablation are equal are equal is called the equilibrium point. If there?s more accumulation than ablation over a year, the glacier has a positive regime (or a positive mass balance). If this occurs then the glacier grows and advances forwards, eroding the valley as it progresses and meanwhile depositing moraine/lodgement till (material deposited by an advancing glacier). Despite an advancing glacier eroding and depositing, eroding is a more significant process and an advancing glacier tends not to deposit a lot in comparison. Glaciers erode the valley floor and sides by plucking and abrasion. ...read more.


When it is down the valley away from the glacier it?s not a store in the glacier any more. Finally, glaciers carry debris (rocks, gravel and sand) which are considered a store within the system. There are many processes within a glacier, which either erode or deposit material, or create movement within the glacier, affecting its position and shape. Basal sliding occurs with an abundance of meltwater, so it?s a more common process in temperate regions, with warm based glaciers e.g. the Alps. It?s an external process by which meltwater lubricates the base and the glacier slides over the valley. Similarly, regelation occurs because of meltwater. At a rock outcrop on the valley floor, pressure melting occurs against the rock and meltwater is created, enabling basal sliding. When the water reaches the other side of the outcrop, there?s less pressure therefore lower temperature and thus the water refreezes, this melting and refreezing is called regelation. Laminar flow is an internal movement whereby layers of internal ice slide over one another, this contributes to a high percentage of movement in cold based glaciers since there?s less basal sliding. As well as layers of ice sliding over each other, ice crystals within the glacier do the same process, but with ice crystals the process is called intergranular flow. Furthermore when an ice crystal splits and the two halves slide over each other, this is called intragranular flow. All these processes cause the glacier to move and if the glacier is moving it?s changing shape and eroding the landscape. ...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. Describe the process by which glaciers move

    The main focus of this essay is to cover all of these aspects and make an assumption as to how useful they are as evidence. The landscape features that I will be identifying will be the result Glacial Deposition.

  2. Global warming effect on Ice and Snow resources

    - As a form of employment Ice factories are found around the globe an example of these is Disko Bay in North Greenland it is 300km north of the Arctic Circle, and contains one of the most productive ice floes in the Northern hemisphere.

  1. Glacier movement.

    The rocks also help crack the ice. Even though glaciers are called "rivers of ice" they do not exactly move like a river. A real river is made of flowing water, but a glacier is made of brittle ice. Scientists have studied glaciers for a long time because they were curious about how they moved.

  2. How does Loughton Brook change as it moves downstream?

    This is situated approximately 267m South East of my third site and 1.333 km away from the Field Study Centre. � The fifth site is called the 'Meander Terraces'. This is situated approximately 233m south of my fourth site and 1.467 km away from the Field Study Centre.

  1. Do the Characteristics of a river change downstream?

    For this investigation however, the depth was measured at one metre in from the side instead of from where the water meets the ground. Where the depth was below one metre we measured it in centimetres. This was also the case on the opposite bank.

  2. Needs somebody like a secretary to help him out with his paperwork. But the ...

    Other processes of erosion that are occurring are attrition which is the knocking of rock fragments in the water against one another and then are made into smaller pieces and become smoother. This process is most likely to be happening from about site 6 onwards as this is where the river velocity is at its fastest.

  1. The Nile is 6,690 km long, extending through 35 degrees of latitude as it ...

    Before the building of a dam at Aswan, Egypt experienced annual floods from the Nile which deposited 4 million tons of nutrient-rich sediment which enabled agricultural production. This process began millions of years before Egyptian civilization began in the Nile valley and went on until the first dam at Aswan was built in 1889.

  2. Investigation of the distribution and abundance off reshwater invertebrates in the Tillingbourne River at ...

    They measure the velocity of the water. * Oxygen metre- to measure the levels of oxygen in the middle and edge of the river * Water & Disinfectant- (same purpose as gloves) * Pond net- to catch invertebrates with * A clipboard- to press on when writing * Paper- to write down and record results * Pencil- to write with.

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