We use cookies to give you the best experience possible. By continuing we’ll assume you’re on board with our cookie policy

Describe the Process by Which Glaciers Move Essay Sample

essay
  • Pages: 6
  • Word count: 1,636
  • Rewriting Possibility: 99% (excellent)
  • Category: movement

Get Full Essay

Get access to this section to get all help you need with your essay and educational issues.

Get Access

Introduction of TOPIC

Glacier movement can be characterised into two different categories, movement that occurs in Polar glaciers and movement within Temperate glaciers. Temperate glaciers are common in areas with milder summers allowing melting to occur, and where the relief is steeper for example The Alps, Norway. If the glacier moves, there will be an increase in pressure and friction with the bedrock raising the temperature causing basal sliding to occur.

The resulting meltwater will act as a lubricant allowing the glacier to move more rapidly. If there is an obstacle in the way then the glacier will experience creep as the pressure will increase on the upslope which will cause intragranular movement leading to a plastic flow of the ice around the obstacle. Compression flow is another form of glacier movement that occurs when there is a reduction in the gradient of the valley floor causing the ice to decelerate and become thicker. When sudden rapid forward movements take place, glacier surges are encountered. This is caused when a significant mass imbalance is created between the zone of accumulation and ablation. Glacier movement is most likely to be produced by imbalances between glacier inputs and outputs causing the snout to advance across the firn line. There will be significant downward pressure acting on the glacier (gravity) which will increase levels of friction and consequently continued ablation.

Cold or polar based glaciers also exhibit different types of movement. In very cold climates, the glacier will be frozen to its bed. Without any friction or an increase in pressure there will be no melting so internal flow is the primary type of movement. This occurs when proportions of ice within the glacier move past each other under the force of gravity. This involves the internal deformation of the ice and takes place by Intragranular movement, stress and Intragranular movement between ice grains.

Examine how landscape evidence can be used to identify the direction and extent of ice movement

There are many different types of landscape evidence that can be used to identify the direction and extent of ice movement over a region. 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. 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. The material that has been transported englacially by the movement of ice will at one stage have been deposited. These deposits include boulders, clay, gravels and sands which may be subdivided into Till. Till includes all the material deposited directly by the ice and glacifluvial material. Glacifluvial material includes deposits which may have been deposited initially by the ice and then later picked up and redeposited by meltwater. This deposition occurs in lowland areas and in upland valleys. A study of drift deposits helps to explain the nature and extent of the ice advance, the frequency of the ice advances, sources and directions of ice movement and postglacial chronology. This is why drift is such a vital piece of evidence used to explain ice movement as can be clearly identified on the landscape.

Till often refers to all materials deposited by the ice but it is more accurately used to mean an unsorted mixture of rocks clays and sands. The composition of till reflects the character of the rocks over which it has passed; East An

glia, for example is covered by chalky till because the ice passed over a chalk escarpement. Most of

Sorry, but full essay samples are available only for registered users

Choose a Membership Plan
the material transported sub-glacially by the till is deposited as ground moraine. The East Anglian Till Sheet completely masks the underlying sedimentary bedrock. The average thickness of the till is about 30m, though in the north it exceeds 70m. it comprises a variety of different till deposited by separate advances during each of the major glaciations. A threefold sequence of drift deposits associated with the Anglian Glaciation has been located in a cliff section at Corton in north-east Suffolk. This information is an excellent account as to the appearance of erratics form northern Britain and Scandinavia which indicates an early advance of ice form the north. The upper layer of bluish-grey, chalky Lowestoft Till suggests that the parent ice mass carried these deposits from the chalk scarplands to the west.

Another type of till can also be included to account for the direction and extent of ice movement. Ablation till refers to material carried anglacially or supraglacially that has been deposited when the glacier melted. The orientation of the long axis of the till lines up with the direction of ice flow which produces a distinct line that can visually explain where the ice has come from. Initially the stones will be deposited horizontally but if there is a subsequent glacier re-advance the stone will be pushed forward from behind tilting them upwards.

Till fabric analysis is another source of information which explains how the orientation of deposited material attempts suggests where the ice sheets originated from. In Glen Rossa on the Isle of Arran, a sample of 50 stones was taken from the till deposits. Their orientation indicated that the direction of the glacier flow NNW/SSE. The stones had been pushed upwards to an angle of 25*, indicating a glacier re-advance after the initial deposition. Most of the stones matched up with the lithology on the mainland of Scotland.

This evidence will be more apparent in areas where the mass of the ice was thicker as more material could be transported either englacially or supraglacially which will have had a greater effect on the shaping of the landscape. This is because areas with a denser proportion of ice submerging the landscape will have greater downward forces acting on the land. The landscape will then be subject to various stresses causing deformation resulting in the creation of features such as drumlins. Furthermore, the material transported will be larger so these deposits will be more clearly identified.

Some of the landform characteristics of glacial deposition include erratics that are boulders picked up and carried by the ice, often for many kilometres to be deposited in areas of completely different lithology. By determining where the boulders came from, it is possible to track ice movements and also the extent of their movements. For example, volcanic material form Ailsa Craig in the Firth of the Clyde has been found 250kms to the south of the Lancashire plain, while some deposits on the north Norfolk coast originated in southern Norway. This is a very good piece of evidence as it is the only explanation that can be used to elucidate how large boulders of solid material can be transported without the aid of any human intervention for hundreds of kilometres. This is also a good explanation as to the spatial potential the ice had. By recording the lithology of an area of land and then measuring how far material with the same lithology has been able to travel gives an indication as to the extent of the advance of the ice.

The final piece of evidence that can be used to justify ice movement over prolonged periods and distances are Moraines. A moraine is a type of landform that develops when the debris carried by a glacier is deposited. It is not therefore the material that is being transported by the glacier. The only exception to this is medial moraine which is a term which refers to a landform both on the glacier and in the valley after glacial recession.

To mark the extent of the glacier movement, terminal or end moraine is a source that can be used to mark the maximum advance of the glacier ice sheet. This is a high mound of material which extends across a valley, or lowland area at right angles. A series of terminal moraines stretches for hundreds of kilometres across the North German Lowlands. Six different groups have been identified, the most predominant being the Pomerian, Frankfurt-Oder and Brandenburg. Glen Rossa in Scotland is a more local example of a terminal moraine that extends most of the way across the floor of the valley. It marks the limit of the Loch Lomand advance. Lateral moraine can help to identify how debris derived from frost shattering of the valley sides can be carried along side the glacier. When the glacier melts, however, it leaves an embankment of material along the valley side. Other moraine deposits, such as medial, recessional and push moraines are also good sources of supporting evidence for glacier movement.

From the analysis of till to the existence of moraines, it is clear that the landscape is an excellent source of evidence for identifying the direction and extent of ice movement. The unusual appearance of erratics on the Yorkshire Dales are great historical landmarks that provide geologists with resources that tell more about the history of the area than any textbook and the distance that they cover can be used to mark the extent of the ice movement. These and many more landscape features are windows through which the past can be viewed past and will continue to be a great resource for researchers in the future.

We can write a custom essay on

Describe the Process by Which Glaciers Move Essay ...
According to Your Specific Requirements.

Order an essay

You May Also Find These Documents Helpful

7 non-respiratory air movements

1. Name and define 7 non-respiratory air movements and explain their mechanism and result. (7 pts. ) 1) Cough is taking a deep breath, glottis is closed, and air is forced against the closure; suddenly the glottis is opened, and a blast of air passes upward. This rapid rush of air removes the substance that triggered the reflex from the lower respiratory tract. 2) Sneeze is triggered by a mild irritation in the lining of the nasal cavity. A sneeze is a result of a depressed uvula closing the oral cavity off from the pharynx and routing air upward through the nasal cavity; sneezes clear upper respiratory passages. 3) Crying is inspiration (inhalation) followed by release of air in a number of short expirations (exhalations); crying is an emotionally induced response of sadness. 4) Laughing is a deep breath released in a series of short expirations; laughing is an emotionally...

Movement and sense refinement

One of the most defining characteristics of Maria Montessori’s methodology is the training of the senses. The importance of sense refinement, discrimination and awareness is often taken for granted. Montessori believed that by learning to classify and discriminate what you are perceiving, man will make himself connected to the environment and increase his ability to create order; both internally and externally. “The aim is an inner one, namely, that the child train himself to observe; that he be led to make comparisons between objects, that he be led to make comparisons between objects; to form judgments, to reason and to decide; and it is in the indefinite repetition of this exercise of attention and of intelligence that a real development ensues. ” (Dr. Montessori’s Own Handbook, 71) Montessori found that children between the ages of 0 and 6, experience a sensitive period or window of opportunity, for order, language, movement...

Development of The Civil Right Movement's Tactics

In what ways did the campaign methods used by the Civil Rights movement in the southern states of the USA change and develop in the 1950's and the early 1960's . During the early 1950's the Civil Rights movement started challenging de jure segregation in the South by legal means through organisations like the National Association of the Advancement of Coloured People (NAACP) .Realizing that the deep rooted nature of racism needed a more direct attack. The movement, guided by the peaceful principles of Martin Luther King, opted for non-violent direct action. As the movement gained experience it learned to manipulate the media, create situations where the federal government was forced into action and that mass action equals concessions .The broadening of the movement to include the Southern Christian Leadership Conference (SCLC) and the Student Non-violent Coordination Committee (SNCC) revitalized it with a range of tactics ,from boycotts and sit-ins...

Popular Essays

logo

Emma Taylor

online

Hi there!
Would you like to get such a paper?
How about getting a customized one?