While strong seasonal hurricanes have devastated many of the Caribbean and Bahamian islands this year, geologic studies on several of these islands illustrate that more extreme conditions existed in the past. A new analysis published in Marine Geology shows that the limestone islands of the Bahamas and Bermuda experienced climate changes that were even more extreme than historical events. In the interest of our future world, scientists must seek to understand the complexities of linked natural events and field observations that are revealed in the geologic record of past warmer climates.
While strong seasonal hurricanes have devastated many of the Caribbean and Bahamian islands this year, geologic studies on several of these islands illustrate that more extreme conditions existed in the past. A new analysis published in Marine Geology shows that the limestone islands of the Bahamas and Bermuda experienced climate changes that were even more extreme than historical events. In the interest of our future world, scientists must seek to understand the complexities of linked natural events and field observations that are revealed in the geologic record of past warmer climates.
In Bermuda and the Bahamas, the geology of the last interglacial (LIG; approximately 120,000 years ago) is exquisitely preserved in nearly pure carbonate sedimentary rocks. A record of superstorms and changing sea levels is exposed in subtidal, beach, storm, and dune deposits on multiple islands. Extensive studies by the authors over the past decades on these islands have documented stratigraphic, sedimentologic, and geomorphic evidence of major oceanic and climatic disruptions at the close of the last interglacial.
Dr. Paul J. Hearty, a retired Associate Professor at the University of North Carolina at Wilmington, and Dr. Blair. R. Tormey, a Coastal Research Scientist at Western Carolina University conducted an invited review of published findings. It demonstrates that during a global climate transition in the late last interglacial, also known as marine isotope substage 5e (MIS 5e), abrupt multi-meter sea-level changes occurred. Concurrently, coastlines of the Bahamas and Bermuda were impacted by massive storms generated in the North Atlantic Ocean, resulting in a unique trilogy of wave-transported deposits: megaboulders, chevron-shaped, storm-beach ridges, and runup deposits on high dune ridges.
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Image: The image on the left shows eolian (lower) and runup bedding (upper) exposed in a roadcut on Old Land Road on Great Exuma Island (road elevation +23 meters). On the right are thick beds with fenestral porosity, or “beach bubbles,” showing that massive waves ran up over older dunes exposed in a roadcut on Suzy Turn Road along the Atlantic Ocean east side of Providenciales, Turks and Caicos Islands, BWI.
Image Credit: Marine Geology
