A contribution to the periglacial morphology of Lesotho, southern Africa
DOI:
https://doi.org/10.26485/BP/1973/22/8Keywords:
solifluction, needle ice, thufurs, polygonal soils, grazingAbstract
During April-May 1971, a field survey was carried out in the mountains of Lesotho, at elevations between 1,800 m and 3,485 m, the summit of Tabana Ntlenyana. A variety of active periglacial forming processes was observed, such as pipkrake, turf exfoliation, terracette formation, and thufurs, mainly above about 2,800 m, and downslope sludging of individual stones, stone sortings, polygon soils, and tilting of stone plates above 3100 m. The destructive effect of needle ice is seemingly aided by the intensive grazing of mountain slopes, which began at the turn of the century. Fossil solifluctional mantles reach down to at least about 2,700 m, and solifluctionally shaped cirque morphology is found at elevations around 2,900-3,100 m. Available climatological observations are presented in relation to the observed altitudinal zonation of geomorphic phenomena.
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