Theory question 202
Rivers and River Landforms(a) With the aid of suitable diagrams, describe the appearance and formation of any two of the following landforms (i) delta (ii) river capture (iii) waterfall (iv) inselberg (b) Show one way in which each of the two features in (a) above is of importance to man
Show the model answer
(a) Delta: low, flat, fan/arcuate or bird's-foot shaped land at a river mouth cut by many distributaries (Niger, Nile); formed where a river carrying much load enters a sea or lake with weak currents/tides and deposits it; sheltered coast, gentle offshore slope.
River capture: a stronger river with more vigorous headward erosion cuts back through the divide and diverts the headwaters of a weaker river; leaves elbow of capture, wind gap, misfit/beheaded stream.
Waterfall: steep or vertical drop of a river over a hard rock band, with a plunge pool below; formed where hard rock overlies soft rock, at fault scarps or plateau edges; the soft rock is undercut and the fall retreats upstream (Kwa Falls, Victoria Falls).
Inselberg: isolated steep-sided, dome-shaped rock hill rising from a plain (Idanre, Zuma Rock); formed when surrounding weaker rock is weathered and removed, leaving resistant granite.
Diagrams for the two chosen.
(b) Delta: fertile farmland, fishing, oil; river capture: wind gap as a route; waterfall: HEP and tourism; inselberg: tourism, quarrying, defence.
Pick two features and include a labelled diagram for each.