764 H. A. BROUWER 



boundary between the norites and granites begins against the 

 effusive rocks of the Pilandsberg complex and runs from there in 

 a northeasterly direction. The occurrence of brecciated rocks with 

 granite boulders in the hill behind the Saulspoort Mission station, 

 which was already mentioned in my previous paper, has been 

 studied in detail by Humphrey, 1 who found various types of igne- 

 ous rocks. The relationship between these is very complicated. 

 Syenite is seen to be intrusive into the effusive rocks and fragments 

 of granite are found within the syenites and effusive rocks. Farther 

 up the hill there is an extensive outcrop of granite which extends 

 for some 800 yards along the face of the hill. Above this granite 

 is found a diorite, and the crest of the hill is formed by effusive 

 rocks. Breccias, in which granite occurs as included boulders, 

 and also repeated outcrops of granite were found on Doornpoort 

 [251] and Zuiverfontein [718] in the eastern marginal part of the 

 Pilandsberg. Large boulders of red granite embedded in coarse 

 red syenite are to be seen in the bed of the Rhenosterspruit on the 

 farm Rhenosterspruit [609]. 



Pretoria series: The Magaliesberg Range, which from Rusten- 

 burg strikes in a northeasterly direction, comes to an abrupt end 

 on Mahobieskraal [567], to the southeast of the Pilandsberg com- 

 plex. Then the Pretoria beds bend to the west; near Bechuanaland 

 they have a short northerly direction, and then return again 

 to the east, passing at a distance of about 8 miles to the north 

 of the Pilandsberg complex and forming the northern boundary of 

 the igneous complex of the Bushveld. 



Isolated hills of quartzite are found at several places to the east 

 of the Pilandsberg. On Vogelstruisnek [602] they are in immediate 

 contact with the red syenites. Other hills of quartzite occur on 

 Tweelaagte [180], Vlakfontein [902], behind the native stadt on 

 Mabieskraal [620], on Davidskuil [142], and still more to the north 

 on Bierkraal [545]. From Janskop on Bierkraal the quartzite hills 

 extend still more to the east, where they approach the northern 

 boundary of the igneous complex of the Bushveld. 



Between the Pilandsberg and the Marico River, the Upper 

 Magaliesberg beds are missing from the normal sequence of the 

 Pretoria series. They are represented by the isolated hills of 



1 "The Geology of the Pilandsberg," Annual Report of the Geol. Survey of South 

 Africa, 1911, p. 87. 



