Fauna and Stratigraphy of the Stormberg Series. 457 



above the marls, where there is evidence of a minor unconformity 

 showing contemporaneous erosion. In one place strong current bedding 

 indicating currents from the south is to be seen. In another place an 

 exposed surface is ripple-marked and apparently sun-cracked. Cal- 

 careous concretions and nodules are common. The upper part of the 

 bed is usually dead-white, but it is sometimes stained pale pink. 

 Fossils have only been found at two places. These were vertebrae 

 and portions of a fibula of a small Dinosaur, belonging probably to 

 either Thecodontosanras or Gyposaurus. The Nyamandhlovii Sandstone 

 is intercalated with sheets of basalt which overlie the preceding bed 

 unconformably. The sandstone is false-bedded, of a deep-red to pale 

 chocolate colour, and generally coarse-grained. It is well laminated 

 and cleaves into broad flags. The grains of the sandstone are well 

 rounded and of fairly uniform size. (Macgregor.) 



The Forest Sandstones of the Wankie area, as described by Light- 

 foot, are much finer-grained than the Escarpment Grits, and contain 

 pebbles only rarely. The sandstone is of a deep red colour and is 

 very much false-bedded, forming flaggy bands. It rests on the Es- 

 carpment Grits in irregular patches, some of which are large, and 

 these when viewed from a distance appeal 1 to be outliers. In thin 

 section the rock closely resembles the slides made from the stone at 

 I'asipas, near ISulawayo. 



The rocks of the Pasipas area were described by Molyneux. He 

 describes the sandstone as made up almost entirely of quart/ grains 

 of a common size of O^ mm. in diameter, a few reaching O7 to 1 mm. 

 The rock is generally soft and easily excavated and. unless indurated 

 by the process of silicification or protected by the sheets of overlying 

 basalt, disintegrates rapidly. The normal rock is composed of line 

 grains of quartz joined by interstitial felspathic clay in the upper 

 division and by carbonate of lime in certain lower beds. The basal 

 beds generally represent the weathered state of the rocks of the Ar- 

 chaean complex ; at other places there is a variable amount of sorting 

 by the action of moving water (storm water). The lower division of 

 Molyneux consists of imbedded deposits either with calcareous cement 

 or lenticular beds of limestone, the deposits being mainly sandstones 

 occasionally with calcareous balls and nodules, with a thin layer of 

 pale brown or pink marl. The middle division consists of coloured 

 marl interbedded with sandstones. The upper division is characterised 

 by the non-calcareous nature of its interstitial clay. 



Mennell (1904) says that the sandstone of Thaba 'Sinduna seen 

 under the microscope shows sand grains that are often beautifully 

 rounded and include fragments of perfectly fresh felspar (microline 



