Catastrophic flooding origin of shelf valley systems in the English Channel.
Nature
; 448(7151): 342-5, 2007 Jul 19.
Article
en En
| MEDLINE
| ID: mdl-17637667
Megaflood events involving sudden discharges of exceptionally large volumes of water are rare, but can significantly affect landscape evolution, continental-scale drainage patterns and climate change. It has been proposed that a significant flood event eroded a network of large ancient valleys on the floor of the English Channel-the narrow seaway between England and France. This hypothesis has remained untested through lack of direct evidence, and alternative non-catastrophist ideas have been entertained for valley formation. Here we analyse a new regional bathymetric map of part of the English Channel derived from high-resolution sonar data, which shows the morphology of the valley in unprecedented detail. We observe a large bedrock-floored valley that contains a distinct assemblage of landforms, including streamlined islands and longitudinal erosional grooves, which are indicative of large-scale subaerial erosion by high-magnitude water discharges. Our observations support the megaflood model, in which breaching of a rock dam at the Dover Strait instigated catastrophic drainage of a large pro-glacial lake in the southern North Sea basin. We suggest that megaflooding provides an explanation for the permanent isolation of Britain from mainland Europe during interglacial high-sea-level stands, and consequently for patterns of early human colonisation of Britain together with the large-scale reorganization of palaeodrainage in northwest Europe.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Desastres
/
Geografía
Tipo de estudio:
Prognostic_studies
Límite:
Humans
País/Región como asunto:
Europa
Idioma:
En
Revista:
Nature
Año:
2007
Tipo del documento:
Article
Pais de publicación:
Reino Unido