Studying Barrier Islands from Pamlico Sound to South Australia
David Lewis, class of 2006 | Majors: Earth and Ocean Sciences and Public Policy Studies | Extracurricular: student paper, Duke football team manager, peer tutoring, K’ville, intramural sports, reading, traveling, running | Home: Gettysburg, PA
In David’s Words:
Barrier islands on the open ocean like those along the East Coast of the U.S. have been the subject of a vast amount of literature in recent years, but geologists have overlooked analogous barriers in low energy (i.e., small wave) environments such as estuaries, bays, lagoons, and river deltas. For my senior project, I am studying the distribution and morphology of such barrier islands. I am analyzing satellite imagery, maps, and photos of low energy environments around the world, investigating the distribution of these islands, and classifying them according to various morphological parameters.
I have conducted fieldwork in Pamlico Sound, Delaware Bay, Chesapeake Bay, and the Spencer Gulf in South Australia. At each location, I chartered a small plane to take low-altitude digital photos of the barrier islands and visited several dozen sites on the ground to make observations. From simple observations, it is possible to determine which processes are the most important in forming and shaping the islands’ features. I collect sediment for grain size and compositional analysis, but the most complicated tools I use are a spade for digging trenches and an auger for collected cores. In depositional environments like estuaries and river deltas, the vertical strata of sediments records the modern geologic history of the area, so a hand-dug trench and augered cores are the best means for going back in time to recreate the genesis of the feature.
Barrier islands in the U.S. range from heavily developed to distantly remote. I have braved both crowds of summer sunbathers—who are curious to see men digging trenches on the beach (an explanation that we are searching for buried treasure always sends kids scrambling for their own beach shovels)—and swarms of bloodthirsty marsh mosquitoes—who are not curious at all, but are sure glad we came.
In South Australia just about everything is remote, so I either bounced across the outback past kangaroos, sheep, and dingoes or clung to the railing of a hired fishing boat navigating violent 3-foot seas and 60mph winds to access field sites. Sheep are not smart enough to understand the complexities of a shovel, and kangaroos are scared of the 4x4 bearing down on them, but dolphins can spot a fishing boat from miles away and circle closely and smile innocently in hopes of a handout.
Mud and rising tides, in both the U.S. and Australia, are constant concerns when traveling across marsh and tidal flats, as both can leave an unprepared geologist stranded for hours (not that I would know). Australia’s nude beaches possess interesting contours warranting further study—geologically speaking, of course.
