Asteephead valley,steephead orblind valley is a deep, narrow, flat bottomedvalley with an abrupt ending. Such closed valleys may arise inlimestone orkarst landscapes, where a layer of permeable rock lies above an impermeable substrate such asmarl. Water flowing through a steephead valley leaves via one or moreponors[1] orsinkholes.
Blind valleys are typicallydry at their lower ends.[2] If the ponor cannot contain the high runoff during a flood event an intermittent flow may continue through the valley beyond the sink. Such a landform is called a semi-blind or half-blind valley.[3]
They are created by a stream flowing within the permeable rock and eroding it from within, until the rock above collapses opening up a steep narrow valley which is then further eroded by the stream running across the impermeable valley floor.[citation needed] At the head of the valley the stream emerges from the rock as a spring. Notable examples can be found in theJura region ofFrance, for example the Reculée de Baume atBaume-les-Messieurs and the Reculée d'Arbois with its head atLes Planches-près-Arbois and its exit atArbois.
InNorth America, blind valleys (the preferred American term) are found in theDriftless Area and other karst regions.
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