GEOLOGY 67 



geological staff since 191 3 have led to the annual export of dia- 

 monds and manganese to the value of one and three-quarter 

 million pounds (1930), the revenue from which has paid for the 

 upkeep of the department several times over. The story of mineral 

 development in Sierra Leone is even more striking. Until 1926 

 no minerals of economic value were known in that country, but 

 important deposits of gold, diamonds, iron ore and platinum were 

 discovered by the two government geologists during the years 

 1926 to 1 93 1. These deposits are already being worked on a 

 large scale and the annual export of minerals was by 1935 nearly 

 three-quarters of a million pounds in value. The direct revenue 

 received by the Sierra Leone Government from diamonds alone 

 in the year 1935 is more than double the cost of the geological and 

 mines department since its formation. Again, the work of the 

 geological department has contributed to raise the value of ex- 

 ports of minerals from Tanganyika to /^i, 750,000, and the growing 

 revenue from minerals in Uganda has resulted largely from the 

 discoveries of the geological survey. In Nigeria much of the activity 

 of the geologists in recent years has been devoted to water-supply, 

 a service which it is impossible to assess in sterling value, but there 

 can be no doubt that the surveys of underground water carried 

 out there, and the well-sinking operations, will increase prosperity 

 to a marked degree. The department has assisted also in the 

 mineral development. 



Northern Rhodesia as a colony has no geological survey, but much 

 good work has been done by the mining companies. The methods 

 differ strikingly from those followed in territories where the mineral 

 rights are vested in the Crown as in most colonies, or are owned 

 by the native holders of the land, as in the Gold Coast Colony 

 and Ashanti, and deserve to be described in some detail.* The 

 mineral rights in Northern Rhodesia belong to the British South 

 Africa Company, who have granted exclusive prospecting rights 

 over very large areas to three concession companies under definite 

 terms of obligatory expenditure. Their aim is to search for all 

 occurrences of economic minerals and to develop those deposits 

 that can be worked profitably. In 1929 over ninety geologists 



* Information supplied by J. Austin Bancroft, Consulting Geologist to the British 

 South Africa Company. 



