474 GEOLOGY OF CAPE COLONY 



Limestone. It will be^sufficient merely to enumerate 

 the principal occurrences of limestone, referring the 

 reader to the account of the formation in which each is 

 found. 



In the Campbell Kand series blue-grey crystalline 

 limestone, usually somewhat dolomitic in character, 

 covers an area of thousands of square miles in northern 

 Cape Colony and constituting the Kaap Plateau. 

 Similar limestone occurs in the Cango area in Oudt- 

 shoorn ; in the main outcrop are situated the celebrated 

 Cango Caves. 



In Van Khyn's Dorp the Aties (Malmesbury) lime- 

 stones make numerous outcrops along the Troe-Troe 

 and Olifant's Eivers. White crystalline limestone (mar- 

 ble) is known to occur in Namaqualand. The Malmes- 

 bury series is generally deficient in calcareous matter 

 in the south-west of the Colony, but, as already men- 

 tioned, crystalline limestone crops out in several locali- 

 ties between Porterville and Hermon, at Boberfcson, arid 

 near Port Elizabeth. 



The lower portion of the Karroo formation contains 

 a good deal of calcareous matter usually forming nodules 

 and concretions, and but seldom collected together to 

 form beds of any thickness or continuous for any dis- 

 tance. Much of the limestone is argillaceous and when 

 burnt yields a fairly good hydraulic cement. Such 

 limestones are frequently burnt for local use and are 

 commonly known as " cement-stone ". 



Upper Cretaceous limestone is worked at Need's 

 Camp on the Buffalo Eiver above East London. 



Porous limestones of recent age are well developed 



