A Reappraisal of the Natal Monocline

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Abstract
The Natal monocline is a Jurassic coastal flexure by which Karroo beds, disposed sub-horizontally throughout most of the province, are caused to bend down eastwards to below sea-level thereby creating the original coastline of Natal. Early and late Tertiary cyclic landsurfaces likewise rise inland from the coast to the monoclinal axis (over 2,000 feet halfway between Durban and Pietermaritzburg) and were thought thence to flatten out westwards in the same way as do the Karroo formations. The series of topographic steps so marked in cross-section through Natal were thus deemed to be a set of cyclic landsurface. successively older from east to west. Upon re-examination, however, the early and late Tertiary cyclic land surfaces have been found not to flatten westward of the Jurassic monoclinal axis, but to continue to rise upon interfluves and residuals until the earlier surface stands near the Drakensberg at 6,000 feet. Beyond this it passes into the smooth crest/ines of the high veld with the late Tertiary cycle forming broadly opened valleys between the smooth crests. This new interpretation involving 5,000–6,000 feet of differential Quaternary elevation upon the Natal monocline, with an axis of maximum upward sited near the present Drakensberg-instead of 2,500 feet maximum along the old Jurassic axis through the “granite belt” of Natal as was previously thoughtentails several re-orientations of viewpoint regarding the evolution of cyclic and non-cyclic denudational surfaces in the Province.

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