AND ASSOCIATED KOCKS OF THE SOTJTHEEN TEANSVAAL. 



419 



-^ Ci Ci Cr- a 



2 » 2 c ct> 



O t-* CI> C 85 &i 





^ ^ 



upper one is composed of conglomerates and compact sandstones. 

 The lower set suggest the beds of the Main Eeef Series highly- 

 compressed ; the upper set bear a strong petrological resemblance to 

 the conglomerates and 

 sandstones described as 

 occurring about 5 miles 

 south of Johannesburg, 

 and therefore about 6 

 miles south-west of this 

 hUl. 



The shales {a) dip at 

 an angle of 60° S. Traced 

 westwards from the gully 

 they thin out like a 

 wedge ; eastwards they 

 broaden, ascend the hill, 

 become inten;sely hard, 

 black, and much twisted, 

 and finally end oif against 

 hard white quartzites. 

 There is no sign of break 

 or fault where the junc- 

 tion occurs, nor do the 

 two sets of beds interdi- 

 gitate. This curious phe- 

 nomenon is possibly due § g S ^ ^¥^^>^^ ^ 

 to a thrust-plane. The 



schist and quartzites (6) p • ^ ^M^^'-MS* 



and the conglomerates (c) 

 climb the hill with the 

 black shales and end off 

 similarly against the white 

 quartzites. The reef-like 

 beds (e) consist of very 

 hard white quartzite with 

 a few scattered and broken 

 pebbles. The quartzites 

 and micaceous schist {g) 

 show signs of great pres- 

 sure. The bands of 

 schist are distinctly wedge- 

 shaped, and are caught up 

 and twisted in and out 



among the associated n^ V'' ^^^^N* 



quartzite in a remarkable 

 manner. There is also 

 at this point a change of 



dip from 60° S. below to 'c^>^^ 



not more than 30° S. 

 above. This seems to 



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