Theory question 206
Rivers and River Landforms(a) List any two types of delta. (b) Explain four conditions favourable for the formation of delta. (c) Describe three main characteristics of a delta.
Show the model answer
(a) Arcuate (fan-shaped), e.g. Niger, Nile; bird's-foot, e.g. Mississippi; estuarine/cuspate, e.g. Tiber.
(b) The river carries a large load of sediment; the sea or lake at the mouth is calm, with weak tides and currents; shallow, gently sloping sea floor; no strong currents to carry sediment away; slow speed of the river at its mouth; salt water helps the clay particles to flocculate and settle.
(c) Low, flat land of fine alluvium; the river splits into many distributaries; swamps, lagoons and creeks; fertile soils; builds out into the sea; mangrove vegetation in the tropics; triangular or fan shape.
Give a named example of each type.