“The cycle of erosion is the time required for streams to reduce a newly formed land mass to base-level. The Geomorphic cycle is the topography developed during the various stages of a cycle of erosion.” Worcester. According to Wooldridge and Morgan, “a landscape has a definite life history during which it shows a series of sequential forms to an ultimate form.
We may broadly group the many stages of youth, maturity, and old age. Landscape evolution takes place as a cycle which runs through a definite course of development.”
William Morris Davis organised his evolutionary sequences of events into the concept of a cycle. Actually the term cycle was introduced by Lawson in 1894, but Davis was to use it as his central theme.
The concept of the cycle of erosion was developed by Davis in 1889, and it began ideally with the uplift of a land surface which caused rejuvenation and incision of the drainage pattern.
However, he went on modifying and extending his views in various ways for the next 30 years. Davis coined the familiar phrase; ‘Landforms are function of structure, process and stage’. He explained how the cycle of erosion operated.
According to this concept, an initial flat or nearly flat landscape is rapidly uplifted. Erosion then proceeds under conditions of prolonged tectonic stability and the landscape passes through the stages of youth, maturity and old age, each stage having distinctive and recognisable characteristics.
The end product the peneplain is the same as the initial land surface- a flat or nearly flat landscape. Thus, a cycle of events has truly been completed. The processes eroding the landscape were grouped together under one heading ‘normal’. Davis examined the effect of repeated minor uplifts, and stated that many landscapes are polycyclic in origin.