The islands weren’t a result of Blackbeard’s curse; they had always been there. But like the best buried treasure spot, their locations weren't common knowledge.
“The study developed as newer and higher resolution sources of free satellite images were made accessible to the public,” geoscientist Mathew Stutz of Meredith University told Discovery News.
Stutz was one of the authors of a study published in the Journal of Coastal Research. The study added 657 islands to the world’s list of barrier islands by the researchers from Duke University and Meredith College. The grand total is now 2,149.
"Needless to say, the people who lived in these areas knew they were on islands, but the geographic/geologic classification into barrier islands was not in their realm. All in all, this was very exciting, to 'discover' new islands," geologist and co-author Orrin H. Pilkey of Duke University told Discovery News.
Barrier islands form on the coasts of landmasses and provide important protection against erosion and storm damage. They are also important habitats for wildlife. A majority of the islands, 75 percent, exist in the northern hemisphere.
Barrier islands are often long, low, narrow deposits of sand and sediment (such as the thin arc of beaches boarding the northern rim of Wrangle Island in the image at right). They also tend to erode away or build up over time due to waves, tides and ocean currents. That can make them hard to find and pin down on a map.
An earlier survey missed these 657 “new” islands. “The 2001 study relied on topographic maps and the first generation of NASA's Geocover Landsat Program,” Stutz said. “The initial Geocover was compiled from 1990-era Landsat 4/5 images, with 30-meter resolution. Small or narrow islands were still difficult to detect, a few were obscured by clouds.”
“Even today, a few regions of the world (primarily Russia) are not included in this dataset,” Stutz said.
"When the actual work was done for the first study, Google Earth was not available, at least not in its current form," Pilkey said. "We started out looking at maps and charts, which was quite an education."
Even public historical charts such as the New York Geographical Society's collection and the British Admiralty's survey of the continental shelf off the Pacific coast of Colombia missed many islands Pilkey and Stutz found using modern eyes in the sky.
“By 2004 NASA completed a Landsat 7 dataset (with 15-meter resolution) using 2000-era images and did include all the world's coasts. Prior to this program, hundreds if not thousands of satellite images would have to have been purchased individually at prohibitive cost for such a large scale survey,” Stutz said.
Read more at Discovery News
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