12 THE PRESIDENTIAL ADDRESS. 



sphere. The central position of Africa in relation to those lands gives not 

 only special opportxmities but also special responsibilities for meteoro- 

 logical observation and research. For the sake both of South Africa 

 and of Science in general I would venture to express the hope that this 

 second visit of the British Association will give as powerful a stimulus to 

 Meteorology as did the first to Astronomy. 



Next, I would refer to Africa's potential contributions to Geological 

 Science. Africa is a continent, portions of which have always had a special 

 interest for the geologist because of the great diversity of the geological 

 phenomena manifested, and the vast mineral wealth which, as its ancient 

 workings so abundantly prove, has attracted man's industry from the very 

 earliest times. But in our day the opportunities which it offers to the 

 geologist to make contributions to the wider problems of Science are 

 coming to be more fully realised than ever before. Of special interest 

 in this connection is the light which African Geology, more especially in 

 the form of the study of ancient glacial deposits, can throw on the Wegener 

 hypothesis of continental drift. In the past our geologists have thought 

 mainly of the correlation of our formations with those of Europe. It 

 is time that they paid more attention to their possible affiliations with 

 those of the continents to east and west of us. If Geology can establish 

 the hypothesis that Africa is the mother continent from which India, 

 Madagascar, and Australia on the one side and South America on the other 

 have been dislodged, it will give a new orientation to many branches of 

 scientific activity. For that investigation also Africa occupies a central 

 and determinative position in relation to the other continents, such as we 

 have noted to be the case in the sphere of Meteorology. There are many 

 other geological problems on which Africa can probably shed much light. 

 There is, for instance, the constitution of the earth's deeper sub-strata, in 

 regard to which, as Dr. Wagner has recently pointed out, the study of the 

 volcanic Kimberlite pipes, so numerous throughout Africa south of the 

 Equator, and of the xenoliths they contain, including the determination 

 of their radium and thorium contents, may be of the greatest significance. 

 There is the possibility that the exploitation of Africa's great wealth in 

 potentially fossil-bearing rocks of presumably pre-Cambrian age will yet 

 yield us remains of living beings more primitive than any yet discovered ; 

 there are the great opportunities of study which the African deserts ofier 

 in the field of desert Geology and Morphology, and there is the assistance 

 which African Geology has rendered to vertebrate and plant Palaeontology, 

 and can render to African Anthropology in the investigation of this great 



