Tuesday, February 22, 2011

The Sands of Time at Cape Romain

You don’t usually get to see geology “happening”.  The Appalachian Mountains were once higher than the Rockies are today, but no one has lived long enough to witness the peaks weathering down to comparative rolling hills, the once great mountains reduced to sand.  You can, however, see that very same sand changing the map daily on the Atlantic coast of North America.

Great Egrets over the Atlantic Surf on Bulls Island, South Carolina

Barrier islands are on the front lines of the war between the sea and land.  They protect estuaries, salt marshes, and calm channels on their back side, but the front face (in this case eastern and southern facing shores) is battered by the ocean.  The shape of the islands is constantly changing with every hurricane, every storm, and even every single wave, even on a calm day.  Sand just doesn’t tend to stay in one place.  In general, sand moves down the east coast of North America from north to south, island to island.  A barrier island like Bulls Island in South Carolina receives sand on its north shore from Cape Island to the north.  Meanwhile, it’s losing sand from its southern portion which is deposited on Dewees Island to the south.  Dewees, in turn, gives sand to Isle of Palms, which shares it with Sullivans Island, and so on.

Notice how each barrier island juts out on its northeast side where it receives sand and tails away on the southwest where it's losing ground.

Every hour of every day these islands are shifting.  When a storm comes along, like the massive Hurricane Hugo in 1989, the islands can be altered dramatically overnight, if not swept into the sea entirely.  But the process will start anew with a donation of sand from a neighbor to the north.

Boneyard Beach, Bulls Island, Cape Romain National Wildlife Refuge

The plant and animal communities on barrier islands must consequently be quick to adapt.  Most vegetation can adapt readily, and birds are versatile in nesting a few yards further up the shore year after year.  Trees don’t have the luxury of moving.  When a forest of oak, cedar, and pine suddenly finds itself with its feet in saltwater, it’s all over for the trees.  The result is something like the Boneyard Beach on Bulls Island.  A forest refuge for migrating warblers one day, a perch for cormorants in the surf the next.

Lone double-crested cormorant perched on a tree skeleton.
Brown Pelicans are common on Bulls Island.  They roost is large numbers two islands south in the marshes behind the highly developed Isle of Palms.

Bulls Island is protected as part of the Cape Romain National Wildlife Refuge.  This is a birder’s, botanist’s, and alligator-watcher’s paradise.  You can catch a boat ride out to Bulls island and spend the day there thanks to the folks at Coastal Expeditions in Mt. Pleasant, South Carolina.  If you really want to get intimate with a barrier island, hire a Coastal Expeditions guide for a barrier island kayak trip.  I can’t say enough good things about their guides.

The mouth of Jacks Creek, Bulls Island's "river". 

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