ALKALI ROCKS IN THE TRANSVAAL 773 



In the Annual Report of the Geological Survey of the Transvaal 

 for 1903, A. L. Hall 1 gives an account of the rocks from Leeuw- 

 fontein [320] and Zeekoegat [287] which is followed by a petro- 

 graphical description of these rocks and those on Walmansdal [116] 

 and the newly discovered occurrence on Franspoort [426]. 



On Leeuwkrall [396], about 5 km. to the northwest of Hamans- 

 kraal station, H. Kynaston 2 discovered two occurrences of syenitic 

 rocks, the southern one locally graduating into nepheline syenite. 

 It is a porphyritic foyaite similar to some of the dike rocks which 

 occur to the southeast of the Pilandsberg. On Rietfontein [451] 

 and Spitskop [463] an interesting occurrence of nepheline syenites 

 within the red granites was discovered by Hall 3 in 19 10; and 

 Wagner 4 mentions the occurrence of a dike of basic camptonite 

 cutting through the Waterberg sandstones on Buffelspruit [1920], 

 which means probably that nepheline syenites occur at a deeper 

 level. 



The intrusion on Leeuwfontein [320]. — To the east of Pretoria, 

 near Franspoort [426], the ridges of quartzite belonging to the 

 Pretoria series bend to the southeast; the Magaliesberg quartzites 

 have been extended in length, while the Daspoort and Timeball 

 quartzites were strongly pressed in a direction slightly oblique to 

 the strike of the strata. 



In describing the dislocations connected with the intrusion of 

 the igneous complex of the Bushveld, Molengraaff 5 supposed that 

 at those places where the circumference of the complex shows a 

 convex curve interesting phenomena may be expected. We saw 

 that the Pilandsberg intrusion is located where the Pretoria series, 



1 A. L. Hall, "On the Area to the North of the Magaliesberg Range and to the 

 East of the Pietersburg Railway Line," Annual Report of the Geol. Survey of the Trans- 

 vaal, 1903, p. 38. 



2 H. Kynaston, "On the Area Lying North-West of Pretoria, between the Maga- 

 liesberg Range and the Salt Pan," Annual Report of the Geol. Survey of the Transvaal, 

 ioos, p. 29. 



3 Annual Report of the Geol. Survey of the Transvaal, 19 10. 



4 P. A. Wagner, "Note on an Interesting Dyke Intrusion in the Upper Waterberg 

 System," Trans. Geol. Soc. South Africa, 191 2. 



sG. A. F. Molengraaff, Proc. Geol. Soc. of South Africa, 1905; "Criticism on 

 Messrs. A. L. Hall and F. A. Steart: On Folding and Faulting in the Pretoria Series," 

 Trans. Geol. Soc. South Africa, VIII (1905), 7-15. 



