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

Distinguish between abrasion and plucking

Extracts from this document...


6a) Distinguish between the glacial erosion processes of abrasion and plucking. Plucking occurs high on the glacier, well into the zone of accumulation, because for plucking to occur the temperatures have to have slight fluctuations around the melting point of the ice. Plucking occurs usually at the bottom of the glacier where, because of the pressure pushing down on the ice from above, the ice is at the pressure melting point. When there is a rock with a crack in it, the melted ice fills the crack and then refreezes. The refreezing exerts a pressure on the rock and weakens it but the water also freezes to the bottom of the glacier and is pulled away. When the frozen water in the crack is pulled away so is the rock. Abrasion however can occur anywhere along the profile of the glacier. Abrasion is the sandpapering of material. Debris can be put into the glacier by many methods including plucking and the material is then dragged along the bed of the glacier. ...read more.


But the amount of debris also varies along the profile of the glacier. As at the top of the glacier in the zone of accumulation there will be alot of debris because of the temperature fluctuations at altitude, though not all of the debris is at the base of the glacier. Further down the the glacier the rocks will have had time to make their way to the base of the glacier by melting down to the base or falling down crevasses. Along the middle and lower part of the profile is where most of the basal erosion will occur. The size of the debris is also a major factor though not as much as the amount because the amount depicts the surface area where as size may affect the surface area of exposed rock but also the volume. Lots of small rocks would mean there is a large surface area and hence a large amount of erosion, but a lot of large rocks means that little of the rock is grinding along the bed and more of the rock is held in the ice. ...read more.


This means the ice moves more and there is more abrasion and a better chance of plucking as well. This happens in the temperate climate, such as the glacier d'Argenti�ne which moves at 250m yr-1 and is 100m thick abraded a marble plate up to 36 mm yr-1. A polar glacier however, Breidamerkurj�kull in Iceland, abraded a marble plate at only 3 mm yr-1 when it was moving at 9.6 m yr-1, however it is only 40m thick. If Breidamerkurj�kull were to accelerate to 15.4 m yr-1 then the rate of erosion increased up to 3.75 mm yr-1. This means that velocity plays a bigger part than the thickness of the ice. In conclusion the all aspects are important to the rates of glacial erosion, but the most important are the velocity of the ice and the hardness of the particles in relation to the bed rock. The amount of the debris is not as important and the size and shape are the least important factors in the rate of erosion. ?? ?? ?? ?? ...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 Rocks & Weathering 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 Rocks & Weathering essays

  1. Determining the paleoenviroment and tectonic history of a small area (Cocklawburn Beach)

    This is the end of the first cyclotherms in the beds, as can be seen from the cycle limestone -> coal.

  2. I am trying to find out how footpath erosion on Pen Y Fan which ...

    taken at 5 different points along the footpath about 20 - 40 metres apart. Accessability for Pen Y Fan Pen Y Fan is easily accessed by the A470 main road. You can turn into a car park, which is signposted on the main road.

  1. The aim of this report is to define the geological evolution of the area ...

    Clearly marked are the locations of the three field sites and also line AB shown below as a cross section. (See Solid Geology Map in Annex.) Site 1 Site 2 & 3 Looking at Fig 5.0 we can see the effect of faulting on the report area.

  2. In this Essay I will inform you of the social, economic and environmental advantages/ ...

    It rests on habitats and animals furs and skins, and because of the limestone's colour it destroys the animals chance of survival because it stunts the animals camouflage in its surroundings. This allows the animals predator(s) to seek destroy and eat a lot easier, increasing in the numbers of predators and seriously reducing in the numbers of prey.

  1. Construct two Graphic Log Sections, one on the eastern exposure (ST 3375 6645) and ...

    Banding shows differing layers in texture of colour. 9 Limestone Corals, bivalves and slikenslides. This limestone was probably formed in relatively shallow water as a reef. The evidence for this is, the fossils that are found within it, corals and bivalves. Slickensides happen when the surface of the rock has become polished or striated from the grinding or sliding motion of an adjacent rock mass.

  2. My aims are to investigate the factors affecting Lava Flows.

    Put 2 grams into the beaker. Put the bowl underneath the drainpipe so the paste goes into it and not onto the desk. Get the stopwatch ready. Now put the Paste in to the beaker with the water in immediately start stirring with the mixing rod and start the stopwatch.

  1. 'I think that sedimentary stones will be more affected by weathering than igneous stones.' ...

    - Sedimentary Rock forms from particles, called sediment, that are worn off other rocks. The particles are sand, silt, and clay. Sand has the largest particles while clay has the smallest. If there are a lot of pebbles mixed with the sand, it is called gravel.

  2. Find out why there is no Carboniferous Limestone visible around the Somerset area.

    The Carboniferous Limestone does exist in Somerset somewhere because of Cannington Outcrop and Kilve Beach. The Permian and the Triassic are generally put together because of the similar conditions and there is very little change. Britain lay in north tropical latitudes on a huge continent of Pangaea.

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