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Literature review
The soils of the Sandveld and Bushmanland are derived from aeolean reworking of
marine or fluvial deposits, whereas the soils of the Kamiesberg and Richtersveld
range is derived from in situ weathering of the underlying parent material (DESMET,
2007). The sands of the inland margin of the coastal plain below the Hardeveld range
has been reworked through time to produce a variety of sand types, ranging from
white, calcareous sands to deep red, acidic sands (DESMET, 2007).
2.6.8 Soils of Nieuwoudtville
R. sabulosa is restricted to the clay and sandy soils of the Bokkeveld escarpment
west of Nieuwoudtville in renosterveld (MANNING & GOLDBLATT, 2001). Many
other species in this genus including R. monadelpha and R. flava also occur in the
vicinity of Nieuwoudtville, making this an area of interest.
Not only the plant life, but also the soils of the Nieuwoudtville region are diverse
(BRAGG et al., 2005). In the west, along the Bokkeveld escarpment exposed Table
Mountain Sandstone (TMS) is prominent, while tillite and shales covers the
underlying TMS in the east (BRAGG et al., 2005). Tillite is defined as a sedimentary
rock composed of indurated (rendered hard by heat, pressure or cementation) till,
which is an unstratified and unsorted sediment carried or deposited directly by or
under a glacier. Shale can be defined as finely stratified consolidated sediment
mainly composed of clay-sized particles (SOIL CLASSIFICATION WORKING
GROUP, 1991).
A dolerite sill intrudes into tillite in the vicinity of Nieuwoudtville (BRAGG et al., 2005).
Dolerite is an igneous rock that has risen from under the earth crust as magma and
mostly solidified as intrusions such as dykes and sills before reaching the surface
(SOIL CLASSIFICATION WORKING GROUP, 1991). In this case the sill is visible as
a rocky ridge. On the moist east slopes of this ridge, the dolerite has weathered
through time to form self-mulching clay soils (BRAGG et al., 2005).
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