Theory question 204
Earth Movements and Vulcanicity(a) Describe the formation of (i) Erosional plains; (ii) Dissected plateaux (b) Highlight two advantages and two disadvantages of plains.
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(a)(i) Erosional plains (peneplains/pediplains): agents of denudation (rivers, wind, weathering) wear down highlands over a very long time; hills are lowered and slopes retreat; the surface becomes almost flat, with a few resistant remnants such as inselbergs or monadnocks.
(ii) Dissected plateaux: a high, fairly level plateau is cut into by rivers and glaciers through vertical erosion; deep valleys and gorges separate flat-topped remnants (mesas, buttes), giving a rugged surface, e.g. Jos Plateau edges, Fouta Djallon.
(b) Advantages: easy to farm and mechanise; fertile alluvial soils on flood plains; cheap to build roads, railways and towns; support dense population. Disadvantages: liable to flooding; may be waterlogged; poor natural defence; some plains are barren (outwash plains, sandy plains).
Explain the agents of erosion that produce each landform.