• 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...


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.


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.


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. Fluvioglacial Landforms

    However, while this is the most accepted explanation of how these landforms are formed, others suggest that kettles holes may not be formed by fluvioglacial deposits and that they are formed by supraglacial deposits instead. Eskers are long ridges found on the valley floor which are formed when material is

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

    These fractures and joints can then be exploited via plucking during a period of re-glaciation; glacial advance. The impacts on the landscape of the processes of glacial erosion vary greatly in size and scale, and occur over a variation of time periods; dependent on the cyclic nature of glaciers with seasonal advance and retreat, as well as glacial periods.

  2. Glacial landforms.

    lacustrine deposits marking the extent of Lake Pickering and, most significantly, a glacial diversion of drainage. Other landforms that would become distinctive from their roundness/smoothness, and layered material are such things like eskers, that are ridges of sands and gravel's formed in a sub-glacial tunnel.

  1. 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.

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

    * The pebbles in the Natural channel are shorter and a higher percentage have a low sphericity. * The speed of flow became slower as the gradient became higher. * The deeper the channel, the faster the velocity. While completing the methods a number of things could have and did go wrong and may have affected my results.

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

    A further factor is the tendency for the size of material being carried by rivers to decrease downstream as particles are weathered and abraded.

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

    The results that we get can then be used to draw a hydrograph and then compared with my low flow graph. Throughout my visit to the sites I used my camera to take pictures of my sites. We wore Wellington boots and waterproof clothing to keep us dry while we were in the water.

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