The Richtersveld: An Ancient Rocky Wilderness

Abstract

The Richtersveld, in northwest South Africa, is located at the transition from the coastal plain to the elevated interior plateau and adjacent to the Orange River. Despite this positioning, the primary landscape features of the Richtersveld reflect the much more humid conditions of the Cretaceous period 100 million years ago. Subsequent aridification of the southern African west coast during the Cenozoic resulted in lower landscape denudation rates that left the topography of the Richtersveld largely unaffected, except for periodic changes in climate when increased run-off incised the lower Orange River through the Great Escarpment and into the continental interior. Sea-level fluctuations during the Cenozoic also contributed to river incision, as well as the development of river terraces and marine benches that host economically important diamond placers. Three landscape terrains can be defined along a west–east profile, inland from the coast. The western Richtersveld forms the coastal plain that was cut to near sea level across all lithologies, irrespective of composition and hardness, and is covered by alluvial debris derived from the escarpment and aeolian sands from the coast. The central and eastern terrains form a linear corridor of high topographic relief and dissection that characterises the Great Escarpment. The great antiquity and long-term preservation of the Richtersveld landscape reflects its long geologic and climatic history and is today protected as a wilderness region.