172 ME. G. W. LAMPLUGH ON THE [May I907, 



pleasing to find a pebble or two of grey granite in the stony flood- 

 bars of this river, along with much mica, felspar, and pink quartz 

 in its sand-banks. I may here mention also that among the larger 

 blocks strewing the same river-bed were some masses of red basaltic 

 breccia full of scoriaceous and bomb-like inclusions, more like a true 

 eruptive breccia than any portion of the basaltic series in situ that 

 came under my notice. 



In the next stream, the Namaruba, a few miles farther east, 

 extraneous pebbles became very numerous, varied, and of large size, 

 nearly one half of the stones being other than basalt ; and not only 

 was there a varied assortment of igneous rocks among these, 

 including pink and grey granites, pegmatite, syenite, gneissose 

 schist, etc., but also many fragments of coarse reddish and grey 

 sandstones and pebbly grit. This gravel was not confined to the 

 stream-bed (a shallow trough on the plateau), but was also scattered 

 plentifully over the slopes and eastward over a low watershed into 

 the deeper valley of the Gwemanzi, 2 or 3 miles farther east. It 

 is, therefore, a little uncertain whether the streams derived the 

 material directly from outcrops of rock in their higher reaches, or at 

 second hand from an ancient river-gravel ; but in either case the 

 source must have lain to the northward, and at no great distance. 



The sandstone-fragments must, I think, imply the presence of 

 a belt of sedimentary rocks to the northward, between the Batoka 

 Basalts and the ancient massif ; and this inference receives support 

 from other scraps of evidence, notably from the reported discovery 

 of coal-bearing deposits in the country between the Victoria Falls 

 and Kalomo. Judging from the conditions observed in the Wankie 

 coalfield (see Section 2 of PI. XYII) and from the resemblance of 

 the sandstone-fragments to the sandstones and grits associated with 

 the Wankie coal-measures, it is probable that these sedimentary 

 deposits north of the Zambezi rest directly upon the ancient 

 complex, and are themselves overlain by the basalts ; but the 

 junctions may, of course, be affected by faults of which I have no 

 knowledge. As the railway has, since my visit, been carried north- 

 ward past Kalomo to the Kafue River and beyond, we may expect 

 ere long to obtain more definite information regarding the geology 

 of this region ; and meanwhile I have ventured to draw the hypo- 

 thetical boundaries shown on the map, interpolating the Wankie 

 Series between the Batoka Basalts and the Fundamental Complex, 

 as an indication of the present state of our knowledge, and as 

 an incentive to anyone who may find opportunity of proving its 

 inaccuracy. 



If we turn now to the country south of the Zambezi, we shall 

 find that, on the strength of a statement by Chapman, 1 Dr. Passarge 

 has inserted on his map 2 an inlier of the ancient rocks, surrounded 

 by the basalts, near the head of the Deka river-basin. With the 

 hope of learning in this quarter something of the rocks underlying 



1 ' Travels in the Interior of South Africa ' vol. ii (1868) p. 212. 



2 ' Die Kalahari ' 1904, Kartenband, Blatt ii. 



