114 GEOLOGICAL SECTION, BULAWAYO TO VICTORIA FALLS. 



see iu and around Bnlawayo. As I do not know of any outcrop 

 of banded ironstone on the Matopo road, I will not say 

 anj^thing- further about it. 



About half-way between Bulawayo and the Dam Hotel 

 you will pass over stretches of pale sandy loam. This is the 

 soil overlying- some metamorphosed acid igneous rocks, which 

 are generally spoken of as felsites. In many instances they 

 are intrusive into the greenstones and banded ironstones, and 

 appear to be closely related to the granites. 



The granite of the Matopo and the g-ranite north-west of 

 Bulawayo are medium-grained biotite granites containing a 

 considerable percentage of oligoclase felspar, and have not as 

 a rule a strongly marked gneissic banding. The Hillside mass 

 is a small one, and exhibits many variations of composition, 

 some of which are without quartz, the mass being spoken of 

 as the Hillside syenite. 



The crystalline rocks exposed between Dett and Wankie 

 include massive granite, as well as strongly-banded gneissic 

 varieties, some of which are graphitic. The pegmatites cutting- 

 these gneisses contain, in some places, large plates of mica; 

 in others, tourmaline and traces of tinstone. The relation of 

 these rocks to the greenstones and granites of tlie liigli veld 

 is not known. 



The rocks of Karroo age show three types of development. 

 The oldest Karroo rocks containing GJossopieri.s are exi)Osed 

 around Wankie, and consist of a succession of grits, sand- 

 stones and black shales with coal. In the station yard at 

 Wankie you will see the top of the black shale group in which 

 the Main Coal-seam lies overlain bj" a thick bed of silicified 

 fire-clay. 



Above these sandstones and shales is about 700 feet of 

 grey shales (Madumabisa Shales), with argillaceous limestone 

 bands overlain by -300 to 400 feet of reddish pebbly grits. 

 These Escarpment grits form the cappings of the higli tabular 

 hills which surround Wankie, and actually you will pass over 

 them in the train near Lukosi before reaching Wankie. 



On the high veld the Karroo rocks are of Stormberg age, 

 as proved by reptilian remains. The succession consists of a 

 fine white sandstone about 200 feet thick overlain by four 

 basalt lava flows, between each of which there are in places 

 lenticular beds of red sandstone with oblique bedding- 

 (Nyamandhlovu Sandstone). These sandstones, with basalts 

 above and below", may be seen from the train on descending- 

 the scarp just before reaching Sawmills. An important point 

 which this section does not prove is the relation of tlie high 

 veld facies to the succession in the Wankie coalfield. The 

 two facies come together in the Gwaai Valley, east of Malindi. 

 I had hoped to liave visited the area and settled the point 

 before this meeting-, but have not been able to do so. 



Between the Deka fault and tlie Victoria Falls you will 

 pass over a great tliickness of basaltic lavas, which are almost 

 certainly of the same age as the basalts of the high veld. 

 Xear Deka thin sandstones are interbedded with the l)asalt 

 as on the high veld, but thev have not yet been found at the 



