Tides, marshes help build up islands
The Brunswick News
August 07, 2010


Tim Lang came to Jekyll Island beach a happy man.

He drove from Pennsylvania to Georgia's coast to meet his grandchild for the first time. He also met with his sister to spend time soaking up the sun and watch the small waves roll on the shore. He said his other two children were visiting the beach for the first time.

"We walked the beach looking for sea shells," Lang said. "We saw jellyfish and crabs. We saw unique things we won't see back home."

On the way to Jekyll Island's beach, Lang said his nephew educated him on the 6-mile stretch of marshes.

"I was learning about how the marshes fill up during high tide," he said.

Georgia experiences a significant tide range, from 6 to 8 feet vertically, about double the height seen on other beaches along the east coast, said Dawn Zenkert, coordinator for Tidelands Nature Center, a University of Georgia 4-H program.

"It's because of the Georgia bight," Zenkert said.

The bight is a geographical term describing the curve of Georgia's 100-mile coast, which allows the beaches to collect more water that in turn fills the marshes. She said one-third of the marshes on the east coast reside in the state.

"The marsh is a transitional ecosystem between the mainland and the ocean," Zenkert said. "Because of the curve, a greater volume of water is coming into the marshes, leading to a greater volume of marsh. It's all inter-connected."

Zenkert teaches children who visit the Tidelands Nature Center about the bight's effect on the tide by having them perform physical demonstrations, although sometimes she makes the point just as clear by drawing an illustration in the sand.

She said the south-end beach on Jekyll Island is dynamic, constantly changing its profile. The sand dunes build up during the summer by wind currents that blow the sand in one direction and eventually form a pile held in place by live plant growth, such as sea oats. The marshes also help build the dune by catching the sand before the plants establish their roots.

As the waves come in across a shallow area, they travel a greater distance from the continental shelf because of the bight, which creates smaller waves on Georgia's beaches.

"Gentler waves make for a greater barrier island system, which is protecting what's behind it," Zenkert said.

The unique geographical features of Georgia's 14 barrier islands may not be well known to every beach-goer, but Lang and his sister, Debra Genard, agree Georgia's beaches are special.

"I love the long beaches on Jekyll and how it's not overcrowded or overdeveloped like in other places," Genard said. "It's really neat and awesome to see."