REMAINS OF ANCIENT LAGOON SURFACE
ON JEKYLL’S NORTH BEACH
BY STEVE NEWELL, Ph. D.
Jekyll’s north beach, between the Beachview Club and the Oceanfront Resort, is witnessing a remarkable phenomenon – the emergence of an ancient salt marsh, replete with recognizable remnants of the stems of salt marsh grass (Spartina alterniflora) and shells of marsh bivalves. Covered by compacted, jagged organic material, with peaks and craters reaching an amplitude of nearly three feet, segments of the affected beach resemble a moonscape in miniature. The phenomenon, which has become much more pronounced in recent years, is visible at low and middle tide but otherwise under water, making it dangerous to the unsuspecting island visitor who might attempt to wade a few yards into the ocean at high tide.
Why has Jekyll’s ancient salt marsh resurfaced now, thousands of years after it was claimed by the island’s shifting sands? Well, the standard pattern of long-term change in Georgia's coastal barrier islands is for their sand to shift to the southern from the northern parts of the islands. There is also a tendency for barrier islands to shift west, as a counter to the slow, steady rise in sea level that is now occurring (about 3 mm per year).
As a consequence of these two slow movements of sand, the islands will slowly cover portions of the salt marshes that flourish in Atlantic-side inlets and between the western edges of the islands and the mainland shore to the west. After thousands of years have passed, the once-buried, ancient salt marshes can be exposed again, as the sand above them is shifted south.
The extent of reappearance of ancient marshland can be especially pronounced if beach erosion is severe, as is the case with Jekyll Island State Park's northeastern beaches. It is this erosion that has created "Driftwood Beach" at the northeastern corner of the Park. The large dead trees there are not truly "driftwood"; rather they are fallen from the maritime forest to the west of the beach because of the severe loss of beach and terrestrial sand.
One reason for the extreme nature of this beach erosion is the existence of the deep shipping channel between Jekyll Island and St. Simons Island. Sand that would ordinarily move south to Jekyll Island across the gap between the islands is instead trapped in the deep channel and flushed out to sea. The excessive loss of sand on some of Jekyll's northeastern beaches is worsened by another factor: the rock armoring (the "Johnson Rocks" rip-rap) placed at the western edge of beaches east of the northeastern residential areas of the Park. Sand from behind the rock armoring cannot fall into the sand-distribution system, and this leads to the removal of sand lying above ancient salt marsh.
For those of you who would like to take a look at the affected beach, please note that the phenomenon, while observable year round, is far more impressive in the winter and spring months, when the prevailing northeast winds accelerate the shift of sand from north to south.
[Steve Newell earned his PhD in Biological Oceanography from the University of Miami School of Marine & Atmospheric Sciences. He received the F. G. Walton Smith Award for outstanding dissertation research. Newell served on the faculty at the School for 7 years. In Miami (and the nearby Bahama Islands), Newell focused his research on the microbes of the mangrove ecosystem. In 1979, he moved to the University of Georgia Marine Institute on Sapelo Island, and transferred his research focus to the microbes of the salt marsh ecosystem. He spent the next 26 years living on Sapelo Island, developing information on the ways in which microbes interact with marsh plants and animals and promote the cycling of carbon and nutrients in the marsh. His work contributed to a new and stronger understanding of the production of animals by the marsh ecosystem. Newell retired with Emeritus status from the Marine Institute in 2005, after serving 3 years as Director, having published over 100 peer-reviewed articles and book chapters. He moved to Jekyll Island State Park, where he devotes time to advocating the protection of the natural ecosystems of the Park, especially the critical nesting habitat of loggerhead turtles, a species threatened with extinction. Newell is currently a member of IPJI’s Advisory Council.]