DENDRITIC MARKINGS IN QUARTZITE. 



CHAPTEE IV. 



PHASES OF NATURE AROUND PRETORIA (continued). 



Geological features. Dendritic markings. The highlands and the sea. 

 Heavy rains and floods. A protected butterfly and its enemy. 

 Mimicry. Cicadas. Species found both in England and the Transvaal. 

 The Secretary-bird. Vultures. Locust-swarm. The Paauw and 

 other Bustards. The Monitor. Partridges. Evolution and struggle 

 for existence. 



THE geological feature of the country surrounding Pre- 

 toria is quartzite, through which the granites frequently 

 outcrop, as may be best observed by following some of 

 the spruits and smaller watercourses. This quartzite 

 also largely contributes to the rocky mass of the Maga- 

 liesberg mountains, which form so considerable a shelter 

 to Pretoria, as I had a good opportunity of observing 

 during the blasting-operations by which a carriage road 

 was made through the rocky defile called the Daas 

 Poort. Dynamite was the agent used to rend the 

 stratified quartzite, and in the blocks thus detached and 

 broken up dendritic or arborescent markings abounded. 



