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Titel |
10Be history of cliff retreat: theory and example from the English Channel |
VerfasserIn |
Vincent Regard, Thomas Dewez, Didier Bourlès, Anne Duperret, Stéphane Costa, Laetitia Leanni, Eric Lasseur, Kevin Pedoja, Grégoire Maillet |
Konferenz |
EGU General Assembly 2010
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 12 (2010) |
Datensatznummer |
250035021
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Zusammenfassung |
What if coastal cliffs recession rates could be measured 60 times further in time than with
classical methods? Coastal cliff evolution prediction for the next century would then not be so
much of a stretch. In this work, we present a new method based on measurements and
modelling of 10Be concentration transect across present-day shore platforms to establish the
recession rate of coastal cliff for the last ca. 6000 years. The numerical model predicts the
shape of 10Be concentration transects to be expected as a function of a given cliff recession
rate, vertical coastal platform down-wearing rate and assumed time of sea level
reestablishment to present-day level since deglaciation. Two independent transect features
serve to fit long-term recession rate model to field observations: a major 10Be concentration
drop is predicted where the cliff was abandoned for ca. 100k years, during the glacial
period, and a characteristic dome shape directly related to the recession rate of the
cliff.
A retreating cliff site from the English Channel coast of France at Mesnil Val serves as a
demonstrator of this method. Retreat rates were too fast to pinpoint the predicted glacial cliff
position but 10Be concentrations sampled across the shore platform nevertheless indicate that
the cliff retreat rate since the mid-late Holocene is comprised between 10-30 cm/yr, with a
preferred value at 25 ± 5 cm, which turns out to be fully coherent with a 30-years-long
assessment. |
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