Malolotja Nature Reserve - Geology/Soils/Hydrology
The geology of Malolotja is very diverse and includes some granites (Lochiel Granite, estimated to be about 3 000 million years old), but is predominantly made up of metamorphosed sedimentary rock formations of the Barberton Mountains, including the Onverwacht, Fig Tree and Moodies series of rocks. These rocks are thought to be about 3500 million years old, and are thought to contain fossils of the earth's oldest life forms - blue-green algae. It is in these mountains that the ironstones, talc schists and other metal bearing rocks are found, where the various mining activities have been carried out over the last hundred years.
Malolotja is situated on the great southern African escarpment where it embraces the ecotone between the highveld and middleveld. Ironstones and quartzites are common and, because of their greater resistance to erosion, give rise to the rugged relief of the region and stand up as high mountain ranges and peaks. The best examples include Ngwenya Mountain, Silotfwane Mountain and the Mgwayiza Range. The more gentle undulating hills and slopes are composed of softer rocks such as soapstones. This has given rise to landscapes such as the upper Malolotja and Majolomba river valleys and the Malolotja Vlei. Younger rocks, such as the granites, are found along the eastern border of the reserve. Some of the granite formations are crossed by dolerite dykes and these are also resistant to erosion. The most prominent of these formations would include the big boulders near the log cabins, the Majolomba Picnic Site and Tjomoloti Hill just below the Nkomati Viewpoint. Outside the reserve boundary, overlooking the Malanti valley, is an almost vertical exposed face of rock made up entirely of granite. This magnificent feature can be seen from the Nkomati Viewpoint road inside the reserve.
The mountainous scenery which is the outstanding feature of the reserve results from a combination of the geology of its rocks and the subsequent landshaping erosion which together have produced the most dramatic and varied scenery in Swaziland.
The only information currently available with regard to soil classification is the 1:250 000 soils map for Swaziland, with its associated information (Murdoch, 1970). Most of the soils in the reserve are classified as "rock outcrops and stony ground: raw mineral soil", and are thin, leached and not suited to agriculture. The area is very susceptible to soil erosion, and old roads and tracks have resulted in the formation of large gullies in some areas.
The reserve has innumerable perennial streams and rivers. In addition there are several upland vleis that retain water throughout the year, the most important of which is the Malolotja vlei. The reserve includes virtually the entire catchment area for the Malolotja, Mgwayiza and Mhlangamphepha rivers, and the Nkomati river cuts through the reserve, running from west to east. Prior to the establishment of the reserve a number of dams, weirs and barrages were built on the rivers. No boreholes have been sunk anywhere in the reserve and no artificial watering points for animals have been made, although various artificial impoundments within or on the boundary of the reserve are undoubtedly used by animals. Water quality is generally good and requires little or no treatment, apart from the Nkomati and Mkomazane Rivers. There is also some pollution of the Malolotja river from the portion of its catchment which lies outside the reserve boundary.
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