KARROO ROCKS IN THE MAFUNGABUSI. 253 



III. — FooiTATH Notes. 



On approacliing' the TTmniati River, at the Mzongwe 

 coiiHueuce from the east, tlie flatness of the country it here 

 drains is very evident. It is clad by mopani trees of big- f>'irth, 

 hjng' grass and knob-thorns, forests of ig'onti and open gdades 

 or dambos. Four miles east of the river is the first indica- 

 tion of the Karroo boundary in an outcrop of angular grit 

 (12G8)* and many loose pebbles. In the river itself, here half 

 a mile wide, a resemblance to the Escarpment grit is evident 

 in a mass of felspathic coarse sandstone, holding jjebbles of 

 quartz and quartzite, both well rounded and sub-angular 

 in shape. 



A similar grit also appears in the position of an overlap on 

 the pre-Karroo floor at the confluence of the Xyaripakwe and 

 Umuiati — the bed of the smaller stream showing a mass of 

 grit with pebbles of sliar]) white quartz only, and of pea and 

 haricot size. Sejjarated from it on the south by a ridge of 

 schist three miles wide is a mass of grit and a thin bed of 

 I)ebble conglomerate of fragments of quartz and red banded- 

 ironstone. A jne-Karroo conglomerate (1-329, I80I) outcrops 

 to the south of this occurrence, and strikes N. 40 E. with a 

 dip of 60 degrees to the north-west. 



Six miles up the Mzongwe is a clift: showing 20 feet of 

 coarse, gritty sandstone, iiregularly jointed and overlying, 

 in descending order the following: Light yellow clay, 1 f oot ; 

 pink or French grey shale, 3 feet; grey clay, 2 feet; grey 

 shale, with carbonaceous matter on some layers, the bottom 

 not being seen (1209/ 72). IJeniform nodules of argillaceous 

 ironstone weather out of the shales (cf. iiifrd). The beds dip 

 slightly to the south-west, and seem to belong to the highest 

 Matabola beds, and are the lowest strata laid bare on the 

 IJmniati side of the mountains. * They indicate a pre-Karroo 

 basin to the west deep enough for the deposition of the 

 Matabola beds, the edge of the depression being covered by 

 an overlap of what was piobably the Escai^i^nient beds (Fig. 3). 



Taking the path from the Mzongwe to Gorodema one 

 passes over a gritty soil and flat country until one rises over 

 broken-down grits and Forest sandstone to the poort between 

 Denamwe and Chidomwe, where there is an interbedded sheet 

 of basalt overlain by a red sandstone of IVyamandhlovu tyiie. 

 Another basaltic sheet forms the summit of the tableland. 

 Descending* towards the Gorodema basin the lower basalt 

 (1327) is seen to overlie fine flaggy red and white and sharp- 

 grained transition sandstones (1325) with, underneath, a soft 

 pinkish sandstone with typical white siliceous concretions and 

 kernels (1320) that are doubtless of Forest sandstone position. 

 These fine beds form terraces in front of the major escarpment 

 and its talus of basalt. The path descends further and crosses 

 a raised area of pebbles that must represent an outcrop of the 



* High inimbors refer to rock specimens in the author's collections 



