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

Wind is an important agent of Deposition and transportation. It's role as an Eroder remains questionable.

Extracts from this document...

Introduction

Wind is an important agent of Deposition and transportation. It's role as an Eroder remains questionable. No deserts are completely rainless although parts of the Libyan and Chilean deserts approach complete aridity. In such places erosion is extremely slow, although occasional showers can have sudden catastrophic effects. Trujillo in Peru received only 1.4 inches of rain between 1918 and 1925, but during March 1925 it received 15.5 inches, of which 8.9 inches fell in the three days 7-9 March. Such events apart, the present work of landscape development are controlled by the wind. (Outside the true deserts, vegetation prevents wind from being a significant agent or erosion), although it can carry enormous quantities of dust far beyond the deserts and can move sand and dust into characteristic depositional forms. It is certain that wind cannot be responsible for most of the eroded landforms of present day deserts, and it is also certain that many of the landscape features of the African and Asian deserts were produced in times of wetter climate. In the Sahara, for instance, there are numerous old lakebeds, which have been dry for a great length of time. ...read more.

Middle

Two of the largest hollows attributed to deflation by wind are the P'ang Kiang hollow in Mongolia which is 5 miles wide and 200 to 400 feet deep, and the Big Hollow in Wyoming, USA, which is 9 miles long, 3 miles wide, and 150 feet deep. It is probable that, although there is no general base-level of erosion for wind deflation, wind cannot be effective below the level of the water table so there is a local limit to the depth of deflation hollows. The main action of wind is not erosive, but in transport and deposition. Wind picks up dry dust and can carry it high into the atmosphere. Nearly a quarter of a million square miles of northern-eastern China are covered with Loess, or wind-borne dust, which has been carried out of the Gobi Desert by winds associated with the winter high pressure system. It was deposited in areas of the increased rainfall and bound by the growing steppe grasses. The grains of loess are often cemented together with calcium carbonate, and being very porous loess preserves steep slopes in the face of many cliffs where cave habitations have been cut. ...read more.

Conclusion

Seif dunes are long sand ridges of irregular shape and variable length. Many seifs in the Egyptian desert are up to 300 feet and 1800 feet wide; some are over 200 miles long. While these figures may represent the largest known, they do, at least indicate that seif dunes are very large features, especially when compared with the barchans. Seifs seem to be developed where there are dominant winds from a different direction from the prevailing ones, which have accumulated the sand. The figure below, shows the development of a barchan into a small seif by the action of wind from two directions. Both seifs and barchans tend to form in families, but the two types are seldom found in association with each other. In contrast with mobile barchans and seifs Bagnold recognised several other types of sand accumulation all of which are stationary. Whalebacks, or flat topped sand ridges extending parallel to the wind direction, occur particularly in Egypt where they may be 100 miles long, 2 miles wide and 150 feet high. Bagnold regarded whalebacks as remnants of seif dunes. Much smaller features are the sand-shadows, which accumulate in the lee of obstructions and are built up by wind is funnelled round them, as at the exits of Wadis. Both shadows and drifts are destroyed if they move downwind (see below) ; ...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. glacial eroded landforms

    Glaciated areas offer both constraints and opportunities for settlements. Upland glacial areas have difficulties for settlement because of the rugged terrain and the lack of flat space to build on. As well as the lack of flat land, infrastructure for transport and communication is also more costly to build, as pyramidal peaks and valleys have to be constructed round them in order to connect two settlements.

  2. Free essay

    Outline the major landforms associated with Periglacial landscapes and discuss their formation.

    Another landform that is due to the process of gelifluction is that of gelifluction lobes. This sees the land bulge and creates a "staircase profile". Rock streams are created on the slopes of block fields. They are created by the process of gelifluction which sees the downslope movement of rocks and soils.

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

    This picture shows bed 11, bed 12, bed 13, bed 14 and bed 15 Bed 15: This bed is near identical to the one above it, it is .5 metres thick, grey and shows lamination, however this one has shale layers interspread in between it, so I have marked it

  2. Rock types.

    * This causes the bits of the rock to break away. Chemical - THE ACID RAIN * The rain is naturally acidic due to carbon dioxide in the air but pollution make it more acidic. * When the acid rain falls onto carbonate rocks such as limestone, a CHEMICAL REACTION occurs breaking the rocks down.

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

    were from a different school, so there could be people going to the Pen Y Fan footpath from different schools as well. Conclusion Now that I have all my primary data and secondary data, I have come to my conclusion.

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

    5 Tuff, buff in colour. Cross bedding Northeast from present day and graded bedding. Cross bedding produced by wind or water current action moving sediment into a series of angled layers. Graded bedding produced when the energy of a current decreases allowing sediment grains to be deposited, with the largest at the bottom and the finest at the top.

  1. Wind is an important agent of transport and deposition. It's effectiveness as an eroder ...

    where fine and coarse-grained sand particles are lifted. They may rise for several centimetres before returning to the ground in a relatively flat trajectory of less than 12o. As the wind continues to blow, the sand particles bounce along, leapfrogging over one another.

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

    I have also included a brief summary of the three different types of rock: - Igneous rocks contain crystals both large and small. It is formed when magma cools underground and crystallizes or when it erupts unto the surface of the ground, cools and crystallizes.

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