‘Marks of extreme violence’: Charles Darwin's geological observations at St Jago (São Tiago), Cape Verde islands
P. N. Pearson, C. J. Nicholas, 2007. "‘Marks of extreme violence’: Charles Darwin's geological observations at St Jago (São Tiago), Cape Verde islands", Four Centuries of Geological Travel: The Search for Knowledge on Foot, Bicycle, Sledge and Camel, P. N. Wyse Jackson
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The first stop on Charles Darwin's famous voyage around the world in HMS Beagle was at Porto Praya (Praia), the principal town on the island of St Jago (São Tiago) in the Cape Verde archipelago. From 16 January to 8 February 1832, Darwin enjoyed his first substantive opportunity to study the natural history of an exotic place. Darwin himself regarded this occasion as a significant turning point in his life because, according to his autobiography, it was here that he decided to research and publish a book on the geology of the places visited on the voyage. He also recalled that it was here, the very first port call, that convinced him of the ‘wonderful superiority’ of Charles Lyell's uniformitarian geology over the doctrine of successive cataclysms that he had been taught in England. Later commentators have generally accepted this account, which is significant for understanding the intellectual background to the Origin of Species, at face value. In this paper we reconstruct some of Darwin's observations at St Jago based on his contemporaneous notes and diary, and in the light of our own visit made in January 2002. We find little evidence to substantiate the claim that he interpreted the geology in Lyellian terms at the time. Instead, he formulated a theory involving a great cataclysm to explain the dramatic scenery in the island's interior. He speculated that a torrent of water had carved the main valleys of the island, leaving deposits of diluvium in their beds. It is indisputable that Darwin came to embrace gradualist thinking enthusiastically during the voyage. Some of his observations made on St Jago, especially relating to uplift of the coast, were instrumental in this change of view, but the conversion was gradual, not sudden. His later published works make no mention of his original catastrophist interpretations.
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In the last four centuries geologists have traversed the globe, searching for economically important materials or simply to satisfy their intellectual curiosity. Geologists have often been at the vanguard of scientific exploration.
The microscopist Robert Hooke explored the Isle of Wight, and Charles Darwin the Cape Verde islands and parts of South America. The volcanic wonders of Italy and central France attracted native and foreign visitors including Lyell and Murchison. The Tyrrell brothers faced great hardship in northern Canada, as did the actor and mineralogist Charles Lewis Giesecke in Greenland. The development of Sydney, Australia depended on finding limestone for building. French geologists relied on camels in the Sahara, and Grenville Cole trusted his tricycle to carry him across Europe.
Four Centuries of Geological Travel: The Search for Knowledge on Foot, Bicycle, Sledge and Camel focuses on the complexities of geological exploration and will be of particular interest to Earth scientists, historians of science and to the general reader interested in science.