428 Transactions of the South African Philosophical Society. 



draw a hard and fast line between the calcareous rock and the sand 

 which lies near it, although it is certain that while parts of the 

 limestone are of very considerable age, reckoning by years, near at 

 hand a similar rock is forming to-day. 



Where exposed to the weather, either inland or on the beach, the 

 limestone is often extremely hard, but this indurated rock is of 

 small thickness, and rapidly graduates into a soft stone beneath, 

 which may be dug out with a spade. At Hoetjes Bay, where the 

 limestone has been largely quarried, there may be seen every inter- 

 mediate variety of rock between one which rings when struck with 

 a hammer and one which crumbles when touched. While the bulk 

 of the calcareous matter of the rock is formed of comminuted marine 

 shells, or of carbonate of lime derived from them, large numbers of 

 unbroken land shells occur in many localities distributed fairly 

 uniformly through the rock. Broken or abraded specimens are 

 very rarely seen, thus contrasting strongly with the marine shells. 

 Accompanying the snail shells are frequently found bones of 

 mammals, such as the elephant, rhinoceros, different kinds of buck, 

 and carnivora. The bones are not water-worn, but in good con- 

 dition so far as outward form is concerned. At the Hoetjes Bay 

 quarry a layer of rootlets was exposed at the time of our visit, some 

 twenty feet below the present surface. These are facts which point 

 to the deposit having been formed on land. 



The limestone always shows some trace of bedding planes ; the 

 beds may be of considerable thickness, or the rock may vary in 

 character four times in a thickness of one inch. 



Where the layers are thin the rock is generally false bedded ; 

 the action of wind and rain brings out this structure very clearly, as 

 the softer layers are eaten away and the harder ones stand out in 

 strong relief. Very fine examples of this occur in the cliff sections 

 on the south coast ; in one place the layers, perhaps, will all be 

 straight, and one set will meet another set at a high angle ; at 

 another place the layers will be curved and may abut almost at 

 right angles against the overlying stratum, or the curved layers 

 may thin out and wedge between two other strata. 



In the Saldanha Bay district the limestone is found as a bank of 

 rock lying on the ground which slopes down towards the shore ; 

 occasionally a kopje of the underlying granite appears through the 

 limestone. As the distance from the shore increases outcrops of 

 limestone become less numerous in hilly country, as that between 

 Saldanha and St. Helena Bays, where a range of granite hills 

 occurs. On the other hand, where the ground is low-lying and the 



