Steephead valley
Encyclopedia
A steephead valley, steephead or blind valley is a deep, narrow, flat bottomed valley with an abrupt ending. Such valleys arise in limestone
or karst
landscapes, where a layer of permeable rock lies above an impermeable substrate such as marl
. 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. At the head of the valley the stream emerges from the rock as a spring. Notable examples can be found in the Jura
region of France
, for example the Reculée de Baume at Baume-les-Messieurs
and the Reculée d'Arbois with its head at Les Planches-près-Arbois
and its exit at Arbois
.
In North America
, blind valleys (the preferred American term) are found in the Driftless Area.
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
or karst
KARST
Kilometer-square Area Radio Synthesis Telescope is a Chinese telescope project to which FAST is a forerunner. KARST is a set of large spherical reflectors on karst landforms, which are bowlshaped limestone sinkholes named after the Kras region in Slovenia and Northern Italy. It will consist of...
landscapes, where a layer of permeable rock lies above an impermeable substrate such as marl
Marl
Marl or marlstone is a calcium carbonate or lime-rich mud or mudstone which contains variable amounts of clays and aragonite. Marl was originally an old term loosely applied to a variety of materials, most of which occur as loose, earthy deposits consisting chiefly of an intimate mixture of clay...
. 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. At the head of the valley the stream emerges from the rock as a spring. Notable examples can be found in the Jura
Jura mountains
The Jura Mountains are a small mountain range located north of the Alps, separating the Rhine and Rhone rivers and forming part of the watershed of each...
region of France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
, for example the Reculée de Baume at Baume-les-Messieurs
Baume-les-Messieurs
Baume-les-Messieurs is a commune in the Jura department in Franche-Comté in eastern France.The village lies within the most extensive of the steephead valleys of the Jura escarpment, the Reculée de Baume. It is therefore almost surrounded by limestone cliffs about 200m high. The River Seille has...
and the Reculée d'Arbois with its head at Les Planches-près-Arbois
Les Planches-près-Arbois
Les Planches-près-Arbois is a commune in the Jura department in Franche-Comté in eastern France.-References:*...
and its exit at Arbois
Arbois
Arbois is a commune in the Jura department in Franche-Comté in eastern France. The Cuisance River passes through the town, which has some pretty streets lined with ancient houses...
.
In North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, blind valleys (the preferred American term) are found in the Driftless Area.