206 ME. G. W. LAMPLTJGH ON THE [May 1907, 



indicate the fact, despite my searches in the apparently favourable 

 stream-beds and trenched loam-flats of the plateau. The African 

 climate, aided perhaps by insect- and other low forms of life, 

 appears to bring about the rapid disintegration of animal-remains, 

 even of the hardest teeth. 1 Supposing similar conditions to have 

 prevailed in the past, it is easy to understand the deplorable lack of 

 fossils in most of the African sedimentarv rocks. 



V. Summary and Conclusion. 



1. The predominant feature in the geology of the Zambezi basin 

 around the Batoka Gorge is the wide development of the Batoka 

 Basalts, a great series of lava-flows of undetermined age, but pro- 

 bably Mesozoic. These basalts stretch southward into the Kalahari 

 Desert, and westward beyond the great bend of the Zambezi above 

 the Liny an ti Flats ; but their extreme limits in these directions is 

 not yet known. They are terminated northward by the emergence 

 of the older rocks which form the Batoka upland. 



2. The basalts are cut off on the east by the Deka Fault, which 

 brings in the sandstones and shales ('Wankie Series') of the Wankie 

 coalfield (= Matobola Beds, probably Permo-Carboniferous). This 

 great dislocation, striking east-north-east where seen, is probably 

 continued far to the north-eastward of the country examined, and 

 constitutes a governing feature in the structure of the district. 



3. The Wankie coal-measures rest directly upon the ancient 

 schistose, metamorphic, and igneous rocks of Iihodesia ; and an 

 equivalent series of sandstones, etc., probably occupies a similar 

 position along the northern margin of the basalts. 



4. Superficial material, principally unconsolidated red sand (' Kala- 

 hari Sand ') and chalcedonic ' surface-quartzite,' overspreads large 

 areas of the basaltic plateau, and denotes great changes of conditions 

 in the central basin in late Tertiary and in Quaternary times. 



5. The main element in the physiography of the country is the 

 rejuvenation of the sluggish plateau-drainage, consequent upon the 

 erosion of the Batoka Gorge by the Zambezi. The singularly 

 zigzagging courses followed by the rejuvenated streams are due to 

 certain structural characters of the basalts. 



It remains for me to render sincere acknowledgments for 

 assistance rendered to me by many friends. 



To the Council of the British Association I am initially indebted 

 for the opportunity of undertaking this pleasurable investigation 

 in a new field. 



1 That mammalian remains may, however, be preserved, under exceptional 

 circumstances, is proved by the occurrence of calcareous bone-breccia in the 

 ' Ehodesia Broken-Hill ' mining district in the ' hook ' of the Kafue Eiver 

 (N.W. Ehodesia). The country-rock of this district, in places, is limestone. 

 Specimens of this bone-breccia were obtained by Mr. A. Bromwich, of the 

 British South Africa Company, during a recent visit to the locality, who 

 kindly brought it to my notice. The much-desired recovery of specimens 

 indicating the South African fauna antecedent to that of recent times is 

 therefore not quite hopeless. 



