A few hours in the Seychelles with Alex du Toit in 1938

Abstract

Alexander Logie du Toit (1878–1948) was South Africa’s most famous geologist during his lifetime, having authored five books which brought him world renown. In December 1937 to January 1938, accompanied by his wife Evelyn, he visited India in order to attend the Jubilee Indian Science Congress in Calcutta and to do field work in coal and diamond mines. On the return journey to Africa by ship, they stopped for a few hours in Port Victoria on Mahé Island in the Seychelles archipelago. They also passed by Silhouette Island. Du Toit recorded his activities in a diary, and his geological observations in a notebook, where he also drew a sketch of Mahé, and recorded steep structures on the east coast of Silhouette. Although he had not visited the Seychelles before, his deep understanding of the problems of Seychelles geology resulted from his comprehensive research on Indian Ocean geology for his 1937 book Our Wandering Continents. He made remarkably accurate observations on the geomorphology and structure, some of which were only confirmed decades later when the Seychelles were mapped in the 1960s to 1990s. His bold and prescient ideas on the breakup of the Gondwana continent, and on the formation of the Indian Ocean, have been amply confirmed by modern studies, especially by those of Lewis D. Ashwal and his collaborators.

Significance:

• South African geologist Alexander Logie du Toit’s impressions of the Seychelles in 1938 are recorded for the first time, based on entries in his diaries. His observations of structures on Mahé and Silhouette Islands were prescient. His deep understanding of Seychelles geology was the result of his research for his 1937 book Our Wandering Continents. His bold conjecture that the Mascerene Ridge, made of continental crust, was the nucleus of Mauritius, was finally proved in 2017.