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

The nature and evolution of screes?

Extracts from this document...


The nature and evolution of screes? This essay will take a holistic approach to the study of screes. It will aim to identify the key processes at work on scree slopes, the evolution of their form and how varying climatic conditions affect these variables. Before any detailed analysis of scree formation and its evolution can be discussed, a simple definition of a scree will be given. According to The new Penguin dictionary of geology, a scree can be described as, "A sloping accumulation of loose clasts of granule grade or larger, generally in the form of a wedge, metres to hundreds of metres in height, at the base of a steep rock face from which the clasts fall as a result of weathering and erosion." However it must be recognised that debris produced by these weathering and erosional processes are too coarse to be easily removed by streams, glaciers, or waves. Once a scree has been formed, the rock debris can be characterised by the spacing between the joints in the cliff material and the rock type, and hence the strength, and also the comminution that it experiences whilst being transported until it is deposited. ...read more.


Selby (1982). He also comments on the size of material on talus slopes, comparing tabular and cubic fragments, and the different processes of how the different types of debris reaches the talus slope, whether it be by falls of individual clasts as blocks or by catastrophic events, such as dry and wet avalanches. He also raises the issues of how differing talus slopes, acted upon by different climatic conditions, experience different processes on the talus surface, "...the processes acting to modify the talus surface include...creep and rolling of particles caused by collisions; creep caused by needle ice; subsidence caused by melting caused by melting of buried snow and ice." Selby (1982). It has been identified that the formation of talus slopes have differing geomorphic processes acting on them, in contrasting climatic conditions. Attention will now be given to three general models of talus accumulation and redistribution. The talus creep model devised by Thornes (1971) sighted in Gerrard (1990), suggests that talus behaves like a conveyor belt with material moving down as more material is added to the top, however he argues that this process has little empirical data to support it. The rock fall model, developed especially by Kirkby and Statham (1975) ...read more.


Gerrard (1990) identifies three more types of fabric. The first, a partly open work fabric which is caused by the in filling of voids of an open work fabric and also by the washing down of small grains. Secondly a closed clast support fabric which has all its voids filled with fine grain material which is a result of washing down of small fragments. Thirdly, he identifies a matrix supported fabric which are most commonly created by debris flows, solifluction, or by a wash. In conclusion it is evident that the study of talus slope production and theis evolution has many grey areas. The contrasting geomorphic and topographic processes, the time of deposition or the varying climatic/microclimatic conditions, make applying simple and universal models some what inadequate. This point is raised in Gerrard's (1990) work "...it is unlikely that the evolution of any scree slope is dominated by the operation of a single process...". It should also be recognised that in many area talus slopes are inactive. Selby (1982), explains how many slopes have reached a state of equilibrium. He also points out that many slopes have become essentially fossilised by the formation of soil on the talus slope, leading to the growth of vegetation. ...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 Coastal Landforms 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 Coastal Landforms essays

  1. "An investigation into the methods of coastal management along Brighton's Coastline and the reasons ...

    Visit Brighton again: This pie chart shows if the questioned people would consider visiting Brighton at least once more. It looks to me that a staggering 87% of the people who were questioned would want to. 20% of the people said they wouldn't visit Brighton whatsoever and 0% of the people were unsure.

  2. How can human activity affect slopes?

    However, having identified some possible human causes to disasters associated with slopes, it is rarely one action that induces accidents, it is often the accumulation of activities that cause disasters. It is found that urban areas are more susceptible to mass movement disasters and having occurred, the repair of various articles is expensive.

  1. Is Dawlish Warren is threaten by human impacts and marine processes.

    The question that needs to be asked now is, should local councils protect the coast, or leave it to nature? And how does protection affect the people and the environment of Dawlish Warren? In some places the foot of the cliff has to be protected from wave action.

  2. Gradation Processes

    Humans had modified the landscape for conservation, recreation, transportation/communication, scientific/educational, or residential purposes. At Lowlands beach there were car parks, roads, lookouts, walking tracks, powerlines, toilets, fishermen, signs, and litter. Each of these having a direct affect on the environment either positive or negative.

  1. In my studies I will try and determine how and why management strategies have ...

    In order to evaluate and conclude upon my findings I will take each question that I investigated and look at how well I researched and collected data, also concluding on the results which were obtained... Why does Brancaster need managing?

  2. Investigate the effects of costal processes on Porlock Bay in Somerset and also to ...

    To extend the investigation I worked out the mean length of the rocks and the angle of the pebbles, the results of which are as follows - The average mean pebble at Gore Point is 13.5 cm long The average mean pebble at Hulstone Point is 9.2 cm long The

  1. Coastal landforms and features are related to the rock type (geology) of the area ...

    Therefore: Tan of angle a = length c . Distance d So length c = distance d x tan a Once we had length c we could measure the height of the person who shot the gun and add it to length c to obtain the height of the cliff.

  2. Coastal Processes

    Page 29 * Photo of working groups --------------------------------------. Page 29 * Pebble length results -----------------------------------------. Page 30 * Pebble length results analysis -------------------------------- Page 30 * Pebble shape results ------------------------------------------ Page 30 * Pebble shape results analysis --------------------------------- Page 30 * Results graph -------------------------------------------------- Page 31 * Average results sheet ----------------------------------------.

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