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The cycle of erosion was a model for stream erosion and landscape development proposed by William Morris Davis in the late 19th century. Davis' ''Stages in the fluvial cycle of erosion'' published in 1909 defined a ''young, mature, and old'' sequence in the development of river valleys and the landscape the rivers were eroding. His basic concept includes a rapid tectonic uplift, followed by cessation of the land, which allows the rivers and streams to reduce the surface to a level close to sea-level. The concept of peneplanation was a part of his model. In his model Davies picked up ideas of John Wesley Powell about limitation of erosion on land and concluded that sea level is the ultimate base level for subaerial erosion. Further he suggested that streams always have at least some gradient and temporary base levels, such as inland-lakes, are controlling points upstream of them. It has three stages of its model, i.e., he stated that the whole geomorphic process takes three stages as young, mature and old stages. Davis stated that the cycle begins with the uplift of mountains. Rivers and streams begin to create v-shaped valleys in their younger stage and during the first stages. At this point the relief is steepest and most irregular in nature. Next, in mature stages the streams are able to carve wider valleys and then begin to meander, leaving only gently rolling hills in old age. The model developed by Davis, though important in historical context, is considered only a ''first approximation''. Developments in the sciences of geology and geomorphology, especially the plate tectonics revolution of the 1960s and 1970s, have confirmed the preliminary nature of the model. ==See also== * List of landforms#Fluvial landforms * Rejuvenation (river) * River * Walther Penck * Ocean 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Cycle of erosion」の詳細全文を読む スポンサード リンク
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