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Threshold of erosion of submarine bedrock landscapes by tidal currents

Auteur(s) et Affiliation(s)

MITCHELL, N.C.
School of Earth, Atmospheric and Planetary Sciences, univ., Manchester, Royaume-Uni
HUTHNANCE, J.M.
National Oceanography Centre, Proudman Oceanographic Lab., Liverpool, Royaume-Uni
SCHMITT, T.
Service Hydrographique et Océanographique de la Marine, Brest, France
TODD, B.
Geological Survey of Canada (Atlantic), Natural resources, Dartmouth, Canada


Description :
The AA. examine multibeam sonar datasets from areas of extreme tidal currents to see if there is any evidence for erosion of bedrock. A dataset of shear stresses beneath typically strong tidal currents is developed and compared with a dataset for bedrock-eroding rivers. In the Minas Passage (Bay of Fundy), Canada, the Bristol Channel off Nash point, UK, and in the Straits of Messina, Italy, sonar data are collected and discussed. Holocene tidal currents have apparently been generally ineffective at eroding bedrock. The AA. examine this issue further by compiling extreme tidal streams around the UK and from them estimate shear stresses, representing a macro-tidal environment where peak surface currents reach 9-7 knots. Those data are compared with shear stresses in mountainous rivers where long-term rates of erosion are comparable with tectonic uplift rates and are thus geomorphologically significant. The vertical faces in the Minas Passage may represent the onset of abrasion. Given this limited evidence for abrasion, the AA. explore conditions in the geological past for tides that may have locally eroded bedrock.


Type de document :
Article de périodique

Source :
Earth surface processes and landforms, issn : 0197-9337, 2013, vol. 38, n°. 6, p. 627-639, nombre de pages : 13, Références bibliographiques : 2 p.

Date :
2013

Editeur :
Pays édition : Royaume-Uni, Chichester, Wiley

Langue :
Anglais
Droits :
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