CONTRIBUTIONS TO THE GEOLOGY OF BENGUELLA. 523 



older sediments in the Belgian Congo, which have been described in a considerable 

 literature, and especially in the memoirs by Cornet.* Recently F. E. Studt (1914) 

 in a valuable memoir has traced the general distribution of the older sedimentary 

 rocks in southern Africa, has shown that the same general succession occurs through- 

 out, and has correlated the beds of the Congo and Northern Rhodesia with the 

 geological systems of the Transvaal and the Cape. 



The correlation of sedimentary rocks by their lithological characters is necessarily 

 somewhat uncertain, except in the case of beds with exceptional characteristics ; 

 and there are still important differences of opinion as to the relations of the 

 unfossiliferous pre-Karroo deposits of South Africa. These differences will, how- 

 ever, probably disappear with fuller knowledge, and the points of agreement are 

 sufficient to justify the attempt to determine the position of the various Benguella 

 rocks in the general South African succession. 



Cornet has based a recent classification of the Congo beds (1912, No. 1, p. 9) on 

 the extent to which the rocks have been dislocated. The rocks of his oldest division 

 consist of the Archean and Primary rocks, all of which are more or less metamorphosed 

 and all greatly dislocated. Those of the second division, including his Kundelungu 

 System, are but slightly dislocated. His uppermost division, including, in ascending 

 order, his Lualaba, Lubilash, and Bussira Systems, are not dislocated. 



Studt has based his correlation of the rocks of southern Africa upon their general 

 lithological characters, and he attempts to trace the representatives of the South 

 African Systems through Northern Rhodesia into Katanga and the Lower Congo. 

 He considers that representatives of the Karroo, Waterberg, Transvaal, Swazi, and 

 Archean Systems of South Africa can all be recognised in these northern territories ; 

 the only systems missing are the Ventersdorp and Witwatersrand Systems, and their 

 absence leaves a great gap between the Transvaal and Swazi Systems. 



(l) The Bihe Sandstones. — The long succession of unfossiliferous beds ended with 

 the Lualaba beds, which are succeeded by the Lubilash beds. It is agreed that the 

 Lualaba beds are of Lower Karroo age, for they contain coal-seams in North- Western 

 Katanga, and some ehtomostraca from these beds have been described by Leriche as 

 Triassic (Leriche, 1913, pp. 167, 168). According to Cornet (1912, No. 1, p. 4) they 

 are probably Triassic. The position of the Lubilash (or Lubilache) beds is less certain. 

 According to Cornet, who founded it as a " system," it is later than the Lualaba System 

 (cf. Cornet, 1912, No. 1, p. 9) ; but Studt represents it as earlier than the Lualaba 

 beds. The fossils obtained by Ball and Shaler have been examined by E. 0. Ulrich 

 (Ball and Shaler, 1910, pp. 687, 688), who regards them as Triassic or Jurassic, and 

 thus supports Cornet's view. 



I am not aware of the existence of any Lualaba beds in Benguella, but the 

 Lubilash beds may be widely represented. The typical Lubilash beds are sheets of 

 soft, easily disintegrated sandstones. Cornet called this rock " Gres tendres," which 

 * Cf. Cornet, 1894, 1 and 2, 1896, and a later synopsis of his classification, 1912, 1. 



