THE INTRUSIVE DOLERITES AND ALLIED ROCKS 265 



A number of these hills possess three horizontal sheets 

 of dolerite, the uppermost of which alone makes any 

 marked feature, the lower ones usually weathering at 

 the same or even at a greater rate than the sediments 

 above and below them. Such examples are Beyers Berg 

 and Aasvogel Kop (Victoria West) (Plate XVII.) and 

 the Khenoster Berg (De Aar). 



From Fraserburg to the Stormberg conical moun- 

 tains with flat tops of dolerite or with pinnacles, the 

 remnants of former table-shaped summits, are fre- 

 quently met with. Two particularly good instances are 

 Theebus (" Tea-caddy ") and Coffeebus (" Coffee-caddy "), 

 between Rosmead and Ste'ynsburg, while the "Three 

 Sisters " at the railway station of that name are well 

 known. 



There are some very considerable ranges of mountains 

 that run more or less parallel to the main watershed in 

 the Eastern Province and divide the country south of 

 that watershed into two parts, a northern (Middelburg, 

 Cradock, Tarka, Queenstown), drained by the main 

 branch of the Great Fish Kiver and the Kei ; and a 

 southern part (Graaff Keinet, Somerset East, Bedford, 

 King William's Town, etc.), drained by the Sunday's 

 Kiver, tributaries of the Great Fish, Kei, Keiskamrna 

 and Buffalo Rivers. These mountains branch from the 

 main watershed at the Compass Berg (8,208 feet) ; they 

 are called the Sneeuwbergen, Tandjes Berg, Bank Berg, 

 Winterbergen, and Amatolas in different parts of their 

 course. They all appear to owe their existence to the 

 presence of thick inclined sheets of dolerite that have 

 protected the sedimentary rocks from destruction. There 



