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A palaeochannel or paleochannel is a remnant of an inactive river or stream channel that has been either filled or buried by younger sediment. The sediments that the ancient channel is either cut into or buried by can be either unconsolidated, semi-consolidated, consolidated, or lithified. The word palaeochannel is formed from the words "palaeo" or 'old', and channel; i.e.; a palaeochannel is an old channel. This may be synonymous with palaeovalley and palaeoriver. == Recognition == A palaeochannel is distinct from the overbank deposits of currently active river channels, including ephemeral water courses which do not regularly flow (such as the Todd River, Central Australia). A palaeochannel is distinct from such watercourses because the river bed is filled with sedimentary deposits which are unrelated to the normal bed load of the current drainage pattern. Many palaeochannels are arranged on old drainage patterns which are distinct from the current drainage system of a catchment. For example, palaeochannels may relate to a system of rivers and creeks which drained east-west and the current drainage direction is north-south. Palaeochannels can be most easily identified as broad erosional channels into a basement which underlies a system of depositional sequences which may contain several episodes of deposition and represent meandering peneplain streams. Thereafter, a palaeochannel may form part of the regolith of a region and, although it is unconsolidated or partly consolidated, is currently part of the erosional surface. Palaeochannels can also be identified according to their age. For example, there are deposits of Tertiary lignites situated in Tertiary river systems which are preserved on top of Archaean basement in the Yilgarn Craton of Western Australia.〔(【引用サイトリンク】title=Anand, R. and Paine M. Regolith Geology of the Yilgarn Craton, Western Australia (abstract) )〕 These river systems have laid in place for ~15 to 50 million years and would be considered palaeochannels. 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「palaeochannel」の詳細全文を読む スポンサード リンク
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