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

Main features and landforms of glacial erosion.

Extracts from this document...

Introduction

Main features and landforms of glacial erosion. MICRO-SCALE: Striations: When a glacier moves across the underlying rock, the process of abrasion wears it away. It is the fragments of rock held in the ice that do the abrading, scraping across the rock surface like nails across a wooden desk top. Larger rock fragments leave deep scratch marks behind them. These scratch marks are straight parallel lines that reveal the direction of ice movement. Freshly exposed striations have a preferred orientation of rock grains. By lightly running a finger along the striation it is possible to discover that when moving one way along it, the rock feels smooth, but when moving the other way it feels coarser. The moving ice leaves the rock grains aligned with the direction of movement, so when the striation feels smooth, your finger is moving in the direction of ice flow. When the striation feels rough, you are moving against the ice flow. This test doesn't always work, and won't work on striations that have been exposed for a long period of time. Crag and tail: A crag and tail is a larger rock mass than a Roche moutonnee. ...read more.

Middle

Glacial Grooves: Grooves are common on recently exposed bedrock, and on stones that have been transported by glaciers. These have classically been used to infer ice flow direction over bedrock, but as some of the examples illustrate, this can be misleading Rock Basins: The floor of a glacial trough is uneven. It usually consists of a series of depressions or rock basins - with a reverse gradient at the lower end, separated from the next by a rock bar or step. The formation of such basins is not fully understood, but two theories seem likely: They correspond to areas of the valley floor where the bedrock was weak and thus more easily eroded. Or they correspond to areas where erosion by the glacier increased due to the sudden addition of ice possibly from a tributary glacier. Subglacial meltwater: When subglacial meltwater drains through tunnels, it defines stream systems similar to surface streams. Those subglacial streams may deposit sediment just as a surface stream would, but confined to the tunnel. The result is a ridge of gravel termed an esker, often sinuous (snake-like), which wanders across a formerly glaciated region. The gravel in an esker may have been transported and even eroded by the glacier, but the subglacial stream sorts the fine material out and carries it away. ...read more.

Conclusion

The tributaries are left high above the main valley, hanging on the edges, their rivers and streams entering the main valley by either a series of small waterfalls or a single impressive fall. Truncated Spurs: Spurs that projecting into the original river valley are cut short, their lower ends being destroyed by the moving ice. They may be cut back right to the edges of the new valley, or still project slightly into the valley. This shortens the spurs, or truncates them. They are then known as Truncated Spurs Areal Scour: The most extensive, but unspectacular, erosional landscape left behind by a continental ice sheet is that of "areal scour". The landscape spreads out for miles with little relief on either erosional or depositional topographic features. Local depressions may be scour features in weak or jointed rock, or small kettles. This picture from the Canadian Shield is typical of the areal scour left by large ice sheets. Crag and tail: A crag and tail is a larger rock mass than a Roche moutonnee. Like a Roche moutonnee, it is formed from a section of rock that was more resistant than its surroundings. On the lee side of the resistant rock, the bed rock was protected from the erosional power of the glacier. Kreeshan Annauth Geography 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. Peer reviewed

    Explain where and why depositional landforms occur along the course of a river.

    3 star(s)

    Straight channels seldomly persist for long in a river. In the middle section of a river, typically between the turbulent headwater streams and its estuary where it reaches base level, its channels begin to form meanders. River channels quickly form into sinuous patterns.

  2. To what extent are fluvio-glacial deposits and landforms distinctive?

    This leaves a Hanging Valley, a drop to the bottom of the main valley floor from the end of the tributary glacier. This feature is formed specifically due to varying rates of erosion from glacier to glacier. Stickle Tarn is a small lake that sits in a previous corrie feeder

  1. Fluvioglacial Landforms

    Outwash (or Sandur) is that name that is given to the flat stretches of sediment found in proglacial areas. It is formed as the melt water streams gradually loose their energy and begin to deposit their load. This deposited material is sorted by size, with the larger particles being deposited first.

  2. fluvioglacial and glacial variations

    Kames and drumlins can also be differentiated by digging into the feature. If you were to dig into a drumlin you would find similar material all the way through. However by digging into a Kame you would find sedimentary layers from temporal differences.

  1. Free essay

    Movement of Ice Sheets during the last glacial advance in the UK

    The weight of the glacial ice caused a rotational movement allowing the ice to move through the hollow, enlarging it further to form a true cirque. The movement of the glacial ice allows plucking to occur which steepens the back wall and also allows debris to be collected in the base of the glacial ice.

  2. River cross sections

    at a river, and 'cut' it in half to see how it is shaped. Of course, this is physically impossible to do, so we use the measurements of the river we took to plan out an accurate cross section. An example of a cross section can be seen when cutting

  1. To assess whether the modified channel of the river ash is effective in reducing ...

    has been more time for vertical erosion to take place and thus make the banks taller. However, I expected to find that the modified channel had higher banks as it was designed to take as much water away as possible and if the banks were taller more water would be

  2. Rivers shape their valleys by eroding and depositing sediments. The structure of the underlying ...

    are more typical in the middle section of such valleys. Slopes as low as 2 cm/km (1 in/mi) can be found in rivers close to the ocean. Through the dynamic interplay of erosion and deposition, most rivers develop a longitudinal profile that generally becomes less steep as the river flows from its headwaters to the sea.

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