Vol. 6^."] GEOLOGY OF THE ZAMBEZI BASIN. 165 



An excellent report on the geology of Southern Rhodesia 1 by 

 Mr. F. P. Mennell, F.G.S., published in 1904, deals more especially 

 with the country around Bulawayo, which is illustrated by a 

 geological map ; but it also contains a general sketch of a much 

 wider region, and includes some references to the rocks in the area 

 now under description. In this report, and in an earlier paper, 2 

 Mr. Mennell records the petrographical characters of the Batoka 

 Basalts and of other Rhodesian rocks. 



The ' Proceedings of the Rhodesian Scientific Association ' 

 (Bulawayo : vols, i-v, 1899-1905) contain some further information 

 respecting Khodesian rocks, though not directly referring to the 

 tract within my traverses. 



In 1904 was published the important work of Dr. S. Passarge, 

 entitled ' Die Kalahari,' 3 in which all the available data regarding 

 the great interior basin of Central South Africa are summarized and 

 discussed. In the light of his extensive personal researches in the 

 Kalahari desert between the years 1896 and 1898 while acting as 

 mining expert to the British West Charterland Company, Dr. Passarge 

 skilfully brings together the scanty material contained in the records 

 of previous travellers, and evolves an admirable interpretation of the 

 geological structure and physiographical development of the whole 

 basin. Although his bold generalizations frequently rest upon 

 slender evidence, and are likely to require much modification, this 

 remarkable work enables us to grasp the essential elements and 

 probable significance of the structure of this vast territory. Dis- 

 regarding the usual geographical limitations of the term, lie 

 includes within ' the Kalahari ' the whole region wherein ' half- 

 steppe ' or * semi- arid ' conditions prevail. Thus, Barotseland and 

 a wide contiguous tract north of the Zambezi are entitled by him 

 the 4 Northern Kalahari ' ; and his ' Middle Kalahari ' embraces a 

 great belt of country south of the Zambezi, extending from the 

 inner margin of Matabeleland to the western watershed of the 

 continent. The country which I traversed falls therefore within this 

 latter division ; and its geological structure is described, and in part 

 represented on a geological map, based mainly on the accounts given 

 by Chapman and Livingstone. I shall have occasion frequently 

 to revert to Dr. Passarge's work in the context. 



III. Physical Features. 



Though complex in detail, the broader features of the region 

 under examination are simple. Above the Victoria Falls, the 

 Zambezi is a wide placid river flowing at an elevation of about 



1 ' The Geology of Southern Rhodesia ' Special Report No. 2, Rhodesia 

 Museum (Bulawayo, 1904) pp. 42, with geological map. 



2 'Contributions to South African Petrography' Geol. Mag. dec. 4, vol. ix 

 (1902) pp. 356-66 (description of basalt from Victoria Falls and Deka, with 

 figure, p. 358). 



3 ' Die Kalahari, Versuch einer physisch-geographischen Darstellung der 

 Sandfelder des siidafrikanischen Beckens ' Berlin, 1904, pp. 822 & Kartenband. 



