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2 April 2018 Superstorms: Comments on Bahamian Fenestrae and Boulder Evidence from the Last Interglacial
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Abstract
Mylroie, J.E., 2018. Superstorms: Comments on Bahamian fenestrae and boulder evidence from the Last Interglacial.Sea level during the last interglacial (Marine Isotope Substage 5e [MIS 5e]) was ∼6 m above present, interpreted to represent a warmer climate, with increased storm intensity and storm frequency. Two hypotheses have been advanced to demonstrate an increase in storm intensity during MIS 5e. The first considers fenestrae in eolian calcarenites at elevations up to 43 m in the Bahama Archipelago to be evidence of superstorm washover. Additional observations include rip-up clasts and loss of bedform and root structures as a result of wave scour. Such an event should produce a tempestite with a wide-ranging footprint, but none exists above 10 m. This paper argues that the fenestrae are rainfall slurries, rip-up clasts are weathering products of calcarenite protosol development, and bed-form and root structure absence or presence reflects transgressive-phase vs. regressive-phase eolian formation, respectively. In the second case, a 2-km section of the coast of Eleuthera Island contains boulders proposed to have been tossed upward onto the land by superstorm waves, creating an age inversion of older boulders lying on younger rock. These boulders are now karrentisch and rest on pedestals produced by denudation. To emplace them would require extreme energies, but other interpretations such as fossil tower karst and boulders rolling downslope remain viable alternatives. The proposed chronology of boulder emplacement at the end of MIS 5e conflicts with the field evidence of a terra rossa paleosol separating the pedestals and the boulders. A recent paper has argued that normal hurricane activity could have emplaced the boulders. Both of these interpretations fail to explain the lack of similar-sized boulders elsewhere in the Bahama Archipelago. The failure to account for past coastline configuration, cave development in the boulders, and post-MIS 5e boulder denudation makes both boulder analyses incorrect, as discussed herein.
©Coastal Education and Research Foundation, Inc. 2018
and John E. Mylroie "Superstorms: Comments on Bahamian Fenestrae and Boulder Evidence from the Last Interglacial," Journal of Coastal Research (JCR) 34(6), (2 April 2018). https://doi.org/10.2112/JCOASTRES-D-17-00215.1
Received: 15 December 2017; Accepted: 21 January 2018; Published: 2 April 2018
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