Theory question 203
Wind and Desert LandformsWith the aid of suitable diagrams, describe the characteristics and mode of formation of any two of the following (a) Ox-bow lake (b) Zeugen (c) Block mountain
Show the model answer
Any two, each with diagrams:
Ox-bow lake – horseshoe-shaped lake beside a meandering river on the flood plain; formed as erosion on the outer banks narrows the neck of a meander; in flood the river cuts through the neck, deposits seal off the old loop, leaving a lake that later becomes swamp
Zeugen – tabular ridges of hard rock resting on softer rock, separated by furrows, up to 30 m high, in deserts; formed where horizontal hard rock overlies soft rock: joints in the cap are widened by weathering, wind abrasion cuts down into the soft rock, leaving ridges and furrows
Block mountain (horst) – steep-sided, flat-topped upland bounded by faults (e.g. Vosges, Ruwenzori); formed when tension or compression creates parallel faults and the middle block is raised or the land on either side sinks
Each answer needs a labelled diagram.