Prof. T. Rupert Jones — Diamond Fields of S. Africa. 51 



In Mr. Bain's geological map and sections of South Africa (Trans. 

 Geol. Soc, 2nd ser., vol. vii., pi. 20 and 21), the middle strata of his 

 great " Karoo formation" range up to the Orange Eiver in Lat. 

 29° 30' S., thence along the Modder River, and, skirting the north 

 side of the Winburg Road, they extend for a great distance to the 

 north-east, thereby including the. diamond-fields near Hopetown 

 and Fauresmith ; whilst that near Winburg lies on the upper portion 

 of the Karoo series, according to his map and his section "No. 3." 

 Whether or no the Karoo beds extended as far as the Vaal, was not 

 clear when his work was published. Since then, however, more 

 information has been obtained by Eubidge, Wyley, Higson, Gilfillan, 

 Stow, Griesbach, and others. 



Dr. Rubidge ^ noticed the occurrence of the Dicynodont strata in 

 the Vaal Yalley at Winburg and Harriesmith, also in the Draaken- 

 berg, and in the Transvaal at Magaliesberg. 



Mr.^ A. Wyley (in " Notes of a Journey across the Colony in 

 1857-8 ") described the Hopetown district as consisting of sand- 

 stones and shales, intersected by dykes of igneous rocks, and as the 

 same as the Karoo series to the south. 



Mr. Gilfillan (" Grahamstown Journal," July, 1870) has noted the 

 occurrence of horizontal, hard, blue shales (Karoo) between Hope- 

 town and Litkatlong. Mr. Higson has satisfactorily described the 

 Karoo beds on the Modder and the Vaal (see further on, p. 52). 



Mr. Stow, in a paper lately read before the Geological Society of 

 London, indicates that the Karoo beds pass northwards across the 

 Free State. Lastly, Mr. Griesbach has informed me that he has seen 

 sections of Karoo beds on the Vaal, and in its branches or "spruits" 

 coming from the north; and not only that these beds exist in the 

 Transvaal (Magaliesberg), but also further north on the Zambesi. 



It is observable that such scattered information as is given respect- 

 ing the valley of the Vaal refers to a striking difference of scenery 

 between that of the Cape Colony and that of the Orange River Free 

 State ;^ where low and often rounded hills, in flat sandy tracts, have 

 taken the place of high flat-topped hills, sharp points, and steep- 

 sided valleys, of sandstones, shales, and trap-rocks. Such rocks, 

 however, as have been observed in place in the Vaal Valley, where 

 the superficial deposits have been removed by wind and rain, are 

 referred (by Mr. Gilfillan, as above noticed) to " hard blue schist," 

 north of Hopetown, between the Orange and the Modder, and to 

 "yellow schist and conglomerate," at the junction of the Modder 

 and the Vaal, with igneous rocks at both places. These, taking 

 " schist " to mean hard shale, are not different from some of the 

 Karoo beds further south, and their intrusive dykes, especially as 

 the bedding is said to be horizontal. Quartzite (" quartzose crys- 

 talline sandstone "), however, is alluded to by Dr. John Shaw,^ 



^ Quart. Journ. Geol. Soc, vol. xii. p. 237 ; 1856. 



* Mr. Bain incidentally mentions that between the Bambiis Bergen and " the 

 magnificent Nu Gariep or Orange River . . . detached hills, separated by extensive 

 and dreary plains," are the features of the country. Trans. Geol. Soc, 2nd ser., vol. 

 Tii., p. 58. 



^ "Grahamstown Journal," January 20, 1869; "Cape Monthly Magazine," 

 September, 1869; "Nature," November 3, 1869. 



