84 THE CAMPBELL RAND SERIES 



grains, small spherical bodies composed of concentric 

 layers of carbonate of lime. The original structure of 

 these grains has usually been destroyed by the recrystal- 

 lisation of the carbonate, and occasionally by the replace- 

 ment of the carbonate of lime by silica. 1 



The limestone is often ferruginous, and the iron com- 

 pounds are not always distributed uniformly through 

 the bed, but occur as haematite in more or less spherical 

 masses, or they are spread through variously arranged 

 bands of limestone, probably in the form of carbonate of 

 iron. Neither in the limestone itself, nor in any of the 

 shale bands which are particularly frequent in the lower 

 part of the series, have any determinable fossils been 

 found, though a shell, probably a brachiopod, has been 

 found in the limestone near Schmidt's Drift. The 

 thorough change in the minute structure of the lime- 

 stone due to recrystallisation of the carbonates has 

 probably destroyed most of the fossils. It is hardly to 

 be doubted that the limestone is of marine origin. 



The limestones in the Kaap Plateau are traversed by 

 fissures, joints widened by the solvent action of water, 

 and from some of these water issues in the form of 

 strong springs. The spring from which Kuruman is 

 famous comes from one of these fissures which can be 

 followed more than 300 feet underground. Its plan 2 

 shows that it is due to the enlargement of joint cracks. 

 No large caves, like those of Wonder Fontein near Pre- 

 toria in the same group of rocks, have been found in this 

 formation in Cape Colony. 



1 See R. B. Young, T. G. S. S. A., ix., 57 ; and G. C., xi , 24. 



2 G. C., xi., p. 26. 



