FROM DIFFERENT TO OPPOSITE: AN EXAMPLE FROM TWENTIETH CENTURY GEOMORPHOLOGY

In the mid-twentieth century, some geomorphologists, notably A.N. Strahler (1918-2002), began calling for a major change in how the study of landforms should be undertaken. By the early 1950s, after more than 60 years of dominance of W.M. Davis's (1850-1934) geographical cycle theory of landscape evolution, a growing number of geomorphologists were turning to the process approach. Process geomorphology applied basic principles of physics and chemistry to help understand landforming processes instead of focusing on a landscape's theoretical stage of development, as emphasized in Davis's approach. Process geomorphology stood in sharp contrast to Davis's geographical cycle. The Davisian approach was qualitative, theoretical, and focused on temporal stage of landscape development. Process geomorphology was quantitative, analytical, and sought to understand how applied forces and resisting materials interact to create landforms. The process approach advocated in the mid-twentieth century soon became closely associated with G.K. Gilbert (1843-1918), a geomorphologist who had been a contemporary of Davis. Gilbert was an accomplished and highly respected earth scientist who, instead of the popular Davisian approach, had relied on observation, mechanical analyses, and testing of multiple working hypotheses to postulate explanations of geomorphic phenomena. After 1950, geomorphologists and historians of science characterized Davis and Gilbert in increasingly opposing terms that began to misrepresent the two geomorphologists, especially Gilbert. Those accounts overlook Davis's close ties to geology, and that Gilbert was a geographer and a geologist, studied landscape change over time as well as process geomorphology, and was not only a field geologist but also an educator and administrator. Generalizations serve a purpose, and indeed are necessary, but artificially extending two researchers' different tendencies into a characterizations of polar opposition impedes full appreciation of the individuals and their accomplishments.