Hans Keidel and Alexander du Toit's relationship and its impact on Wegener's Continental Drift hypothesis

This work presents research that we intended to publish jointly with Maarten de Wit on the importance of Hans Keidel in the definition of the Gondwanides and in his pioneering proposal of correlation between the Sierras de la Ventana mountain system in the province of Buenos Aires, Argentina, and its counterpart in the Cape System in South Africa. Keidel's proposals were used by Wegener in the 1920 second edition of his ‘Theory on Continental Drift’. Keidel's role and his ideas of correlation were recognized and strengthened by du Toit's fieldwork in 1923 in the Sierras de la Ventana and which he left behind in his field notebook. Du Toit has the credit of being the first to carry out fieldwork on both continents. His observations and his precise correlations confirmed Keidel's hypotheses through his 1927 publication and his book on the Wandering Continents. It is noteworthy that after Wegener's death in 1930, du Toit defended the Theory of Continental Drift for years almost alone. The work is documented with photographs from du Toit's trip to South America, the originals of which have been lost in the devastating 2021 fire at the Jagger Library at the University of Cape Town.