168 Br. F. H, Hatch — Geological History of South Africa. 



It is not likely that at any period since its first upheaval the 

 whole of South Africa has been submerged ; indeed, there is evidence 

 that the northern region remained uncovered and subject to erosion 

 up to the commencement of Karroo times. On the other hand, it is 

 unlikely that the continent has always had its present limits ; the 

 similarity of the remarkable Damuda-Talchir flora of India, the 

 Newcastle flora of Australia, and the Lower Karroo flora of South 

 Africa indicates that in Permo-Carboniferous times South Africa 

 was probably united to India and Australia to form one great 

 continent, which Suess ' has named Gondwanaland. Blanford- 

 even suggests that in Mesozoic times South Africa was also con- 

 nected with South America, so that " a girdle of land may have 

 extended round nearly three-quarters of the earth's circumference," 

 from Peru to New Zealand. 



Volcanoes have played a great role in the geological history of 

 South Africa, and the traces of this igneous activity survive in the 

 form of lavas, with or without volcanic tuffs and breccias, or in the 

 various forms of intrusive igneous material (laccolites, sills, dykes, 

 etc.), or again as volcanic necks and ' pipes.' There are at least 

 five distinct periods in which South Africa has been the theatre 

 of intense igneous activity, and the ages of these may be arranged- 

 as follows : — 



1. Between the close of the Witwatersrand and the commence- 

 ment of the Potchefstroom periods, the period of the eruption of 

 the Ventersdorp lavas, tuflfs, and breccias. 



2. A period commencing after the close of Potchefstroom, and 

 extending into the early Waterberg times, in which the intrusion 

 and eruption of the Red Granite and associated felsite took place. 



3. At the close of the Stormberg epoch, eruption of the 

 Stormberg lavas. 



4. Between the close of the Karroo period and the commence- 

 ment of the Qmtamvuna (Upper Cretaceous) epoch, intrusion of the 

 dolerite dykes and sills. 



5. After the intrusion of the dolerites, formation of the pipe 

 breccias. 



With this summary I must bring my account of the geological 

 history of South Africa to a close, although I have but touched the 

 fringe of the subject. Much remains to be discovered before the 

 secrets of the past can be completely deciphered, and it must 

 be remembered that geology in South Africa is still young. It 

 shows, however, a vigorous growth for all its youth, and I am 

 convinced that in the next few years great progress and many new 

 discoveries will be made. In this progress the Geological Society 

 of South Africa will doubtless have a large share, and uphold or 

 increase the high standing it has already won. 



1 "Das Antlitz der Erde," vol. i, p. 768 ; Vienna, 1885. 



2 AV. T. Blanford: Presidential Address, Proc. Geol. Soc, vol. xlvi (1890), p. 106. 



