The Rise and Fall of the Davisian Cycle of Erosion: Prelude, Fugue, Coda, and Sequel

Abstract

The Cycle of Erosion formulated by the American geographer William Morris Davis in the 1880s remained the dominant paradigm in geomorphology well into the 20th century, before it waned in response to improved understanding of Earth's crustal and surface behavior. The Davisian model sought to explain landforms in terms of structure, process, and stage. Following initial rapid tectonic uplift, landforms were presumed to evolve on a quiescent crust through stages of youth, maturity, and old age, to culminate in a peneplain. A new cycle would be initiated by landform rejuvenation in response to a changing base level of erosion. This model was a reflection of its time, of the cycle mania of the 19th century, which in turn was founded on Hutton's limitless "succession of worlds" and dissatisfaction with earlier notions of landscape origins constrained by limited Earth time. Davis's model was derived from ideas regarding orogenic cycles favored by Dana and Le Conte, and of prolonged subaerial denudation toward base-level observed by Powell and Dutton. The model's supremacy was challenged from time to time, notably by the Pencks (father and son) and by alternative cyclic denudation models that invoked pediplanation and etchplanation rather than peneplanation. The relevance of the Davisian model declined after 1940 in response to a growing awareness of Earth's crustal mobility, changing climates and geomorphic processes, and refined dating of geologic time. The subsequent quantitative revolution in geomorphology, with its emphasis on measurement of form and process aided by rapidly improving technologies, and based in part on lingering antecedents, sounded the death knell for the Davisian model but also triggered something of a theoretical hiatus. In recent years, resurrection of the concept of isostasy, defined by Dutton but ignored by Davis, has led to the formulation of a more realistic but more complex model, briefly introduced here, in which landforms may be viewed as responses to more-or-less continuous interaction between tectonic activity, subaerial denudation, and isostatic adjustment.

Keywords:

• geomorphology
• cycle of erosion
• denudation
• tectonism
• isostasy
• Earth-science history