And Yet It Moves…: Du Toit’s South American Journey

Abstract

In the introduction to A Geological Comparison of South Africa with South America, Du Toit begins by confronting the prevailing theory of “land bridges” that had been used to explain the similarity of fauna and flora on continents separated by vast oceans. While this is not disputed in some cases such as, for instance, the Bering Strait that allowed the migration of humans and flora from the Old World to the New when sea levels were low, there was a tendency to assign any fossil or floral similarity to hypothesised land bridges with little substantiating evidence. For Du Toit, his challenge to the “land bridge” explanation takes on three forms: the first is the similarity of land-based rather than marine-based fossils; secondly, across the southern continents there exists a markedly similar stratigraphy suggesting a similar climate which, at the outset, was marked by ice sheets but became increasingly dry, culminating with the formation of desert environments. His final point here was that, based on an analysis of marine fossils found on land, the oceans themselves were relatively young.