On the History of Tropical Geomorphology
Various branches of natural science research in the tropics can be traced back to Alexander von Humboldt. However, the evidence collected by him in the tropics of the New World, including such important geomorphological observations as that on the bedrock
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On the History of Tropical Geomorphology
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The Beginnings Various branches of natural science research in the tropics can be traced back to Alexander von Humboldt. However, the evidence collected by him in the tropics of the New World, including such important geomorphological observations as that on the bedrock rapids in the Orinoco lowlands, where he described iron-manganese rinds far above the present flood marks as proof of formerly higher runoffs (Wilhelmy 1975), on the black- and white-water rivers or the bifurcation of the Casiquiare River, obviously did not induce him to reflect on the peculiar character of the tropical landforms. This may partly be due to the fact that his other travels through the Andean region and Mexico led him to landscapes where, for European eyes, a much more "normal" topography prevailed. Beyond that, Humboldt still largely adhered to the concepts of the so-called theory of catastrophism, which believed that oceanic and freshwater floods, reminiscent of the Deluge of the Bible, were not only the causes of the geological structure of the earth, but were also the dominant landforming processes. It was this theory which delayed the acceptance of "fluvialism", as especially expressed by Hutton and Playfair (at the turn of the 18th to the 19th century) by several decades.
A. Wirthmann, Geomorphology of the Tropics © Springer-Verlag Berlin Heidelberg 2000
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On the History of Tropical Geomorphology
As late as 1850 Dana, an American geologist (reprinted in Schumm, ed.1972), had to face the task of presenting convincing evidence from his studies on some Pacific islands and in Australia that valleys were exclusively the work of rivers. This was still two decades ahead of Swiss geologist Riitimeyer, though, who, as late as 1869, succeeded in having fluvialism accepted in Europe. Dana's work may also be regarded as one of the starting points of tropical geomorphology (Chorley et al. 1964; Douglas and Spencer 1985), which may seem almost blasphemous for many an adherent to the concept of excessive planation in the tropics. Dana especially pointed out how important the presence of vegetation on even the steepest precipices is for the rapid decay of rocks; he also recognized the role linear runoff plays in slope formation, and he further described the erosional effects rainy season discharge has on the thalweg of rivers. Even though he wrote in a descriptive way, he was indeed a precursor of modern process geomorphology. It took another half a century before, thanks to the work of Passarge (since 1895) and Bornhardt (1900), a broader geographic public took notice of the extensive etchplains and inselberg landscapes of tropical shield regions, which have undoubtedly stayed at the center of interest and debate of tropical geomorphology ever since. Hovermann (1978), in much detail, recounted the history of especially German research on these subjects up to World War II, also including the work of Brandt, Freise, von Freyberg, Jaeger, Jessen, Krebs, Krenkel, Mortensen, Nowack, Obst,
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