Punda Maria Sandveld on Cave Sandstone Formed by Increasing Pressure and Temperature
Punda Maria Sandveld on Cave Sandstone
Sandstone rocks are those formed by the successive accumulation of sediments mainly of sand and other small particles. Typically this happens in old lakes into which these sediments are washed from rivers feeding the lakes. The lakes eventually dry out.
The increasing pressure due to mounting layers combined with high temperatures starts a process of conglomeration of the small particles that eventually become solid rock. The particles become fused in the presence of different oxides that act as “glue”.
When the sandstone is exposed to the atmoshphere weathering then takes place to reveal all manner of shapes and structures. Soil is also formed this way.
Clarens refers to the geological period concerned. It is hard, for laymen like ourselves, to imagine the time scales involved in these rock forming processes that occur over millions of years.
Location and Geomorphology
Cave Sandstone of the Clarens Formation
Cave Sandstone of the Clarence Formation form outcrops extending from north-east of the Punda Maria to just north of the Levubu River. A small strip of this sedimentary rock also occurs on the contact between the granite and basalt and is particylarly conspicuous near the Timbavati picnic area, between the Olifants and Letaba Rivers and along the Tsende River. This Cave Sandstone forms prominent koppies and is a unique and impressive landscape. Important koppies in the KNP can be associated with this landscape. Good examples are Matikiti, Mangadyane, Nsemane, Mtshatu, Hatlani, Xantangelane, Makahanya, Hutwini and Mashikiri. The most important spruit that drains this landscape in the north is the Nkovakulu. The main component of the landscape is koppies or outcrops with sand plateaus and bottomlands. The altitude varies between 300 and 370 metres and the landscape occupies 117 km/2 or 0.6 percent of the KNP.
The annual rainfall of this landscape varies considerably seeing that it is a long narrow area running throughout the KNP. The applicable rainfall is most likely that of Punda Maria which receives 588 mm annually. The part of the landscape in the vicinity of Letaba most probably receives far less rain. The temperature data for Punda Maria presented in Table 7, is applicable to this landscape.
The soils of this landscape are mainly lithosols or solid rock with a thin layer of soil (Mispah) in the hollow places. On the plateaus and bottomlands, a deep grey to yellow sandy soil, of the Clovelly or Fernwood Forms is present.
The koppies in the landscape accommodate a unique vegetation which includes many rare species (Fig. 35) Van Rooyen (1978) regards the following woody species as characteristic: Stadmannia oppositifolia subsp. rhodesica, Steganotaenia araliacea, Boscia angustifolia, Diospyros lyciodes, Ficus ingens, F. soldanella, F.tettensis, F. sonderi, Commiphora marlothii, Terminalia sericea, Rothmannia fischeri, Maerua angolensis, Kirkia acuminate, Gyrocarpus americanus, Ptaeroxylon obliquum, Strychnos decussate, Commiphora mollis, Manilkara mochisia, Euphorbia tirucalli, Pachypodium saundersii, Antidesma venosum, Hippocratea crenata, Urera tenax, Vepris reflexa, Hexalobus monopetalus, Ochna inermis, Crotn menyhartii, Drypetes gerrardii, Adenium obesum var. multiflorum, Flacourtia indica, Cassia petersiana and Tinnea juttae.
The herbaceous layer of community on the koppies is sparse and includes among others the following: Urginea epigea, Vallia capensis, Cleochloa rehmanniana, Thunbergia hirta, Tinospora fragosa, Felicia bechuanica, Jatropha messinica, Ocimum canum, Gloriosa superba, Portulaca kermesina, Sida hoepfneri, Tephrosia virgata and Limeum fenestratum.
A tall shrub savanna occurs on the deep sandy soils which is dominated by Terminalia sericea and Dichrostachys cinerea (Fig. 34) This community was named by Van Rooyen (1978) as Terminalia sericea/Pogonarthria squarrosa-tree savanna. Other woody species are Cissus cornifolia, Cassia petersiana, Grewia hexamita, Lannea stuhlmannii, Combretum zeyheri, Strychnos madagascariensis, Maytenus heterophylla and Peltophorum africanum. Dominant grasses and forbs are Digitaria eriantha var. pentzii, Brachiaria serrata Pogonarthria squarrosa, Perotis patens, Aristida graciliflora, Schmidtia pappophoroides, Aristida congesta subsp. barbicollis, Clerodendrum ternatum, Commelina africana, C. bengalensis, Vigna triloba, Talinum caffrum, Monsonia glauca, Limeum sulcatum, Merremia tridentate and Stylosanthus fruticosa. Along certain dry slopes, dense stands of Androstachys johnsonii occur which will be discussed in more detail under Landscape 31.
Fig. 34. Landscape 16. Punda Maria Sandveld on Cave Sandstone. – page 61 original document
Fig. 35. Landscape 16. Cave Sandstone outcrop. – page 62 original document
This landscape is relatively poor as far as members of large game is concerned. Elephant and buffalo are the most important animals with kudu and impala omni-present. Steenbok, grysbok and nyala are also regularly found. Due to the hilly nature of the landscape, pairs of klipspringer regularly occur. Baboons are plentiful especially along the rivers