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Wind-twisted trees at the edge of the beach on Hunting Island
Trees on the beach edge,
Hunting Island State Park

Sea Islands:
Erosion Remnant Islands and Barrier Islands

Dennis Adams
Information Services Coordinator

Horse Island, an erosion remnant island,
seen from the Town of Port Royal, Port Royal Island

Photograph by Dennis Adams (August 7, 2002)

Beaufort County's
Sea Islands

See also: Beach Sand: What It Is, Where It Comes From and How It Gets Here
Gullah Dialect and Sea Island Culture

Beaufort County's Sea Islands

The Hilton Head Island Packet named a number of the larger sea islands in Beaufort County: Dolphin Head (in Hilton Head Plantation), Pine Island, Pinckney Island, Spring Island, Dawes Island, Lemon Island, Port Royal Island, Parris Island, St. Helena Island and Fripp Island. Buck Island, Potato Island and Pilot Island are among the area's smaller islands.

Large or small, Beaufort County’s islands are part of the Sea Island complex stretching over 100 miles from the Santee River delta to the coast of Georgia. Charles A. Kovacik and John J. Winberry, in South Carolina: A Geography (Westview Press, 1987) wrote that "toward the south (of the Edisto River) the islands are separated from the mainland and from each other by embayments, such as Port Royal and Saint Helena Sound; numerous tidal inlets; and extensive interior waterways." Joe Noll of the Beaufort County Geographic Information Systems Department noted that Beaufort County "could easily be half water (at high tide)".

North of the Edisto, it is marshes that divide the islands.

Joe Noll confirmed that there are 68 inhabitable islands in Beaufort County (any larger totals count mere fragments of land dotting our waterways and marshes). In Tideland Treasure (Deerfield, 1983), Todd Ballantine noted that South Carolina – with 35 barrier islands amounting to 144,150 acres) – ranks second only to Florida (80 islands) in the number of these islands (around 295 major barrier islands line the Eastern Atlantic and Gulf coasts, from Maine to Texas). Barrier islands are found the world over, but our American chain forms the most extensive system on earth.

In its editorial "Inventory of All Islands an Overdue Tool for State: More Information Needed to Protect Coastline" (June 4, 2003), the Hilton Head Island Packet cited findings by the S.C. Coastal Conservation League that "95 percent of the 340 undeveloped marsh islands thought to be in Beaufort County are large enough for residential development." The editorial spoke of the near completion of a two-year study by the state's Office of Ocean and Coastal Resource Management and the S.C. Department of Natural Resources that catalogs the County's sea islands.

The Island Packet welcomed the inventory as crucial to effective planning " to protect the coastline from overdevelopment" and to "strengthen regulatory changes based on scientific data" (particularly regarding the "roads and bridges crisscrossing the sensitive marshlands and tidal creeks"). "Islands are valuable to wildlife, seafood and recreational enjoyment of the waterways," concluded the editorial. "The new study must be used to protect that asset."

Erosion Remnant Islands

There are two types of sea islands: the barrier islands and "erosion remnant" islands. Erosion remnant islands lie inland from the ocean and once were part of the mainland. When Ice Age glaciers brought the sea level down, streams cut river valleys into the newly dry land. But after things started warming up (about 10,000 years ago), the glaciers melted and the ocean rose again, flooding the river valleys. That’s how St. Helena and Port Royal islands were born.

Barrier Islands

Dunes behind Folly Field Beach, Hilton Head Island
Photograph by Dennis Adams (August 8, 2002)

Fripp, Hunting, and other barrier islands lie directly on the ocean, shielding the mainland from the first brunt of storms. Kovacik and Winberry wrote that their "origin is much debated". According to the "classic theory", they were offshore sandbars built up as the ocean currents brought sand in on their waves. Another explanation: when the ocean retreated from the coast during the Ice Age, it left the old sand dunes behind and made new ones further out along its new coastline. With the big glacier meltdown, the ocean flooded the dune ridges it had left behind so long ago. The ridges that stayed above water were the "cores" upon which the wind and the waves built the barrier islands.

Sea Oats on a dune behind Folly Field Beach, Hilton Head Island
Photography by Dennis Adams
(August 8, 2002)

Barrier islands tend to have an elongated shape, and one end is usually narrower than the other. Erosion generally occurs on the northern end of barrier islands, with buildup on the southern end. Kovacik and Winberry added that "this erosion is a natural process that will continue to occur, but people seem unaware of this as they vigorously but ineffectively try to arrest the changes with jetties, groins, seawalls, and beach nourishment programs."

Ballantine listed four physical characteristics of our barrier islands: "1) A dynamic beach system with offshore bars, pounding surf and shifting or eroding beaches; 2) A series of grassy dunes behind the beach; 3) Maritime forests with wetlands in the interiors; 4) Salt or tidal marshes on the lee side, facing the mainland" (See also: Beach Sand: What It Is, Where It Comes From and How It Gets Here).

Hilton Head Island is really a "hybrid" sea island. Broad Creek (a long, landlocked tidal marsh) splits the island into two distinct parts, each with its own origin: the southern half is a barrier island, fused to the erosion remnant island at its north!

Area of Major Sea Islands and Water Areas in Beaufort County
(in square miles)

Area of Major Sea Islands in Beaufort County

  • Hilton Head Island (not including Pinckney Island): 46.6 square miles
  • Port Royal Island (including Cat Island, Distant Island, etc.): 46.0 square miles
  • St. Helena Island (including Dataw Island): 44.7 square miles
  • Lady’s Island (including Coosaw Island): 22.7 square miles
  • Parris Island: 12.8 square miles
  • Daufuskie Island: 8.0 square miles
  • Hunting Island: 2.5 square miles
  • Fripp Island: 2.0 square miles
  • Harbor Island: 0.7 square miles

Area of Water Surfaces in Beaufort County

  • Non-forested wetlands: 321 square miles

  • Bay/Estuary areas: 337 square miles.


  • These calculations, provided by Joe Noll of the Beaufort County Geographic Information Systems Department (June 2000), are taken from the "National Wetlands Inventory" and are not official Beaufort County statistics.

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