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@article{Collier:2015:10.1016/j.gloplacha.2015.11.004,
author = {Collier, JS and Oggioni, F and Gupta, S and Garcia-Moreno, D and Trentesaux, A and De, Batist M},
doi = {10.1016/j.gloplacha.2015.11.004},
journal = {Global and Planetary Change},
pages = {190--206},
title = {Streamlined islands and the English Channel megaflood hypothesis},
url = {http://dx.doi.org/10.1016/j.gloplacha.2015.11.004},
volume = {135},
year = {2015}
}
TY - JOUR
AB - Recognising ice-age catastrophic megafloods is important because they had significant impact on large-scale drainage evolution and patterns of water and sediment movement to the oceans, and likely induced very rapid, short-term effects on climate. It has been previously proposed that a drainage system on the floor of the English Channel was initiated by catastrophic flooding in the Pleistocene but this suggestion has remained controversial. Here we examine this hypothesis through an analysis of key landform features. We use a new compilation of multi- and single-beam bathymetry together with sub-bottom profiler data to establish the internal structure, planform geometry and hence origin of a set of 36 mid-channel islands. Whilst there is evidence of modern-day surficial sediment processes, the majority of the islands can be clearly demonstrated to be formed of bedrock, and are hence erosional remnants rather than depositional features. The islands display classic lemniscate or tear-drop outlines, with elongated tips pointing downstream, typical of streamlined islands formed during high-magnitude water flow. The length-to-width ratio for the entire island population is 3.4 ± 1.3 and the degree-of-elongation or k-value is 3.7 ± 1.4. These values are comparable to streamlined islands in other proven Pleistocene catastrophic flood terrains and are distinctly different to values found in modern-day rivers. The island geometries show a correlation with bedrock type: with those carved from Upper Cretaceous chalk having larger length-to-width ratios (3.2 ± 1.3) than those carved into more mixed Paleogene terrigenous sandstones, siltstones and mudstones (3.0 ± 1.5). We attribute these differences to the former rock unit having a lower skin friction which allowed longer island growth to achieve minimum drag. The Paleogene islands, although less numerous than the Chalk islands, also assume more perfect lemniscate shapes. These lithologies therefore
AU - Collier,JS
AU - Oggioni,F
AU - Gupta,S
AU - Garcia-Moreno,D
AU - Trentesaux,A
AU - De,Batist M
DO - 10.1016/j.gloplacha.2015.11.004
EP - 206
PY - 2015///
SN - 0921-8181
SP - 190
TI - Streamlined islands and the English Channel megaflood hypothesis
T2 - Global and Planetary Change
UR - http://dx.doi.org/10.1016/j.gloplacha.2015.11.004
UR - https://www.sciencedirect.com/science/article/pii/S0921818115301223?via%3Dihub
UR - http://hdl.handle.net/10044/1/28426
VL - 135
ER -
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