Filled Valley - Maisekikoku

A valley whose bottom is covered by thick sediments. The bottom of a buried valley is flat and wide, and the boundary with the valley wall shows a clear change in slope. A buried valley is formed when the river is no longer able to carry its load due to subsidence or sea level rise, a declination in the direction of the river, a decrease in the amount of water or an increase in the supply of debris due to climate change or river competition, or the supply of volcanic ejecta, and the valley is filled in by sediments. A valley before it is buried is called a buried valley or fossil valley.

[Shigemi Takayama]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

谷底が厚い堆積(たいせき)物に覆われている谷。埋積谷の谷底は平坦(へいたん)で幅が広く、谷壁との境界は明瞭(めいりょう)な傾斜の変換を示す。地盤の沈降または海面上昇、流路方向の減傾斜的傾動運動、気候変化や河川争奪による水量の減少ないし岩屑(がんせつ)供給量の増加、火山噴出物の供給などによって河流が荷重を運びきれなくなり、谷が堆積物によって埋め立てられて生ずる。埋没する前の谷を埋没谷または化石谷という。

［髙山茂美］

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