Theory question 304
Rivers and River Landforms(a) List three landforms found in the upper course of a river valley. (b) With the aid of diagrams, describe the characteristics and mode of formation of an ox-bow lake.
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(a) V-shaped valley; gorge; waterfall; rapids; potholes; interlocking spurs.
(b) Characteristics: crescent (horse-shoe) shaped lake; found on the floodplain in the lower course; cut off from the main river; shallow and often becomes a swamp as it silts up.
Formation: the river forms large meanders; erosion on the outer (concave) bank and deposition on the inner (convex) bank make the meander loop bigger and the neck narrower; during a flood the river cuts through the narrow neck and takes the shorter straight course; deposition seals off the ends of the old loop, leaving an ox-bow lake. Diagrams: meander with narrow neck; river breaking through; ox-bow lake left beside the new channel.
Draw the stages in order.