Marloth Park Management Plan. - Nkomazi Local Municipality

Not withstanding the fact that these soils are shallow, the weathered products of the surface
layers seem to be fairly well leached of its soluble ingredients. The decomposition of certain
minerals of the parent material seems to be very intense but the surface erosion keeps pace with
the weathering of the underlying rocks. The heavy downpours causing run-off, and the high
evaporation associated with high temperatures in the summer months, reduce the efficiency of
the relatively high precipitation. All these factors are responsible for the shallow soils.
The soils occurring in this area are closely associated with the underlying parent material and
may be divided into two different macro soil associations (Land type map 2530 - Baberton). The
land types identified on Marloth Park and Lionspruit Game Reserve are from land types Fb 64
and Ea 75 (Figure 7).
Land type Fb 64 overlaying geology of Potassic gneiss and migmatite, Timbavati gabbro and
Biotite trondhjemite gneiss is the most dominant and extends over most of Marloth Park and
Lionspruit Game Reserve. Shallow, coarse, sandy soils of the Glenrosa form (orthic A-horizon
over a lithocutanic B-horizon) occur on the extensive crests and mid-slopes. These soils are
bordered by a narrow zone of moderately deep, bleached, coarse and sandy, Cartref soils (orthic
A-horizon over E-horizon over a lithocutanic B-horizon). In the valley bottoms are areas of
duplex soils of the Sterkspruit form (orthic A-horizon over a prismacutanic B-horizon). This clay
complex has poor drainage with low leaching. The resultant high sodium concentration increases
the pH to a level where calcium carbonate precipitates. The soils develop a hard impermeable
structure, impeding internal drainage and causing seasonal build-up of surface water. Bleached
sandy soils are formed under these conditions due to a reduction in iron oxide and the lateral
removal of both oxide and clay particles. This distinctive down-slope pattern of soils is
maintained by the subsurface through-flow of water. The sandy crestal soils allow rapid
infiltration of rainfall and good drainage with down slope subsurface flow.
Land type Ea 75, with geology of predominantly mafic and ultramafic lavas and schists with
banded ironstone and chert of the Tjakastad Formation, Onverwacht Group, occurs only as a
relatively small area on Lionspruit Game Reserve. The low hills are characterised as extremely
stony, dark, calcareous clays of the Arcadia form (vertic A-horizon over an unspecified B-
horizon) and Bonheim form (melanic A-horizon over a pedocutanic B-horizon). Lower
elevations are characterised by moderately deep, dark, calcareous clay soils of the Mayo (melanic
A-horizon over a lithocutanic B-horizon), Bonheim and Arcadia forms. Red, structured clays of
the Shortlands (orthic A-horizon over a red structured B-horizon) and Arcadia forms are also
encountered. These soil groups have a high magnesium and calcium content and are base
saturated.
© Ecological Associates/ Marloth Park 17