president's address. 17 



Evidence of Plants and Animals. 



The evidence of climatic conditions afforded by the remains 

 of plants and animals in this country during post-Cretaceous 

 times is very meagre. The only plants yet found which belong to 

 that long period are the siliceous rocks of Komgha containing 

 oogonia of Chara as well as gastropods of fresh-water type ; the 

 obscure plant markings in the surface quartzites of the Cape Flats ; 

 some silicified wood in Bushmanland, the undetermined leaves 

 in the Knysna lignites, and the diatoms in certain limestones in 

 the Kalahari.^" No useful information has been got from them. 

 The few discoveries of extinct late Tertiary or Quarternary land- 

 animals in the Vaal Eiver gravels and elsewhere^" throw no fresh 

 light on climate; they could, so far as we know, exist under 

 present conditions. There are a few marine shells in the raised 

 beach deposits of Little Brak Eiver which are not found in the 

 adjoining sea, but which are still living in warmer water on the 

 east coast." Whether the presence of these shells indicates gener- 

 ally warmer water on the south coast at that time, a greater 

 volume of the Mozambique current, or merely record a change in 

 the area occupied by the species may be difficult to decide. 



The enormous numbers of large mammals in South Africa 

 and the apparently scanty vegetation is discussed by Charles 

 Darwin in his Journal.'^" He unfortunately never saw the interior 

 of the country, for he travelled inland only a few miles from the 

 coast, and he had to depend on the observations of naturalists 

 like Andrew Smith and Burchell as well as of earlier travellers. 

 Darwin quotes the conditions in South Africa as directly contra- 

 dicting the prejudice, derived from the East Indies, that large 

 animals require luxuriant vegetation, and as indicating that the 

 surroundings under which lived the abundant animals whose 

 remains were found at Punta Alta in South America may not 

 have differed much from the present desert in that neighbourhood. 

 It has been said that the bones of hippopotamus, rhinoceros, 

 eland and quagga found in the alluvium of Karroo rivers indicate 

 that tropical animals, requiring vast amounts of food, formerly 

 lived there and that tliey could not live there now." This is an 

 entirely unwarranted conclusion ; the animals mentioned are not 

 peculiar to the tropics, and there can be no doubt that but for 

 the spread of the destructive combination of man, the dog and 

 the gun the Karroo and the Fish Eiver valley would now have 

 as many of these animals as they had four or five generations ago. 

 The fact is that the prolonged coexistence in any area of a farming 

 population and great game is impossible. What happened in 

 the KaiToo in the 18th and the first half of the 19th century is 

 happening in our time in the Waterbei'g and other districts which 

 are not yet closely settled. It has long been recognised that the 

 advent of man with his adaptability and mental power, which he 

 has not yet learnt to use without detriment to his descendants, is 

 a very potent factor in the change of other inhabitants of a 

 country and of its surface. He increases the run-off not only by 

 burning vegetation generally and destroying it along narrow 



