62 SCIENCE IN AFRICA 



covering rocks suitable for road metal and building material: it 

 is economical to take the roads, if possible, through regions where 

 such rocks occur. The structure and nature of underlying rocks 

 and the depth of sound rocks below the surface are of the first 

 importance when deciding on foundations for bridges, large build- 

 ings, dams and breakwaters. 



The geologist makes his contribution to the science of public 

 health by pointing out how the texture and porosity of under- 

 ground strata are related to drainage and springs. In one case 

 the cause of a typhoid epidemic was found to be a night soil depot 

 on one side of a hill, the drainage from which passed through 

 strata of porous rock and over the top of an underlying impervious 

 stratum into a spring on the other side. The spring supplied a 

 village which developed the infection. 



Indeed, geological research, though popularly regarded as a 

 purely academic pursuit, has a striking variety of practical appli- 

 cations. 



ORGANIZATION 



BRITISH 



In the early years of colonial development the gathering of 

 knowledge concerning mineral resources and geological structure 

 was left entirely to prospectors and the few scientists who organized 

 expeditions to study areas of peculiar interest. Later on, minerals 

 surveys were arranged in several areas, under the control of the 

 Imperial Institute, and these led to geological surveys, most of 

 which were established since the war. 



In the Union of South Africa official geological work started much 

 earlier than elsewhere. A Geological Commission for the Cape 

 was set up in 1895, and was followed by independent organizations 

 in the Transvaal and Natal. The Natal survey was short-lived, 

 but the Cape and Transvaal organizations were united in 19 12 to 

 form the Geological Survey of South Africa, which, with the 

 Department of Mines, comes under the general direction of the 

 Secretary for Mines. Of recent years the staff of the geological 

 survey has been considerably increased, and in 1936 comprised 

 a Director, an Assistant Director, twenty geologists, two mineralo- 

 gists and two cartographers. Particular attention is being paid 



