COASTAL SUSTAINABILITY REFLECTED IN THE HOLOCENE EVOLUTION OF THE CENTRAL SOUTH CAROLINA COASTAL AREA

The modern coastal region, comprising the offshore, barrier islands and headlands, estuaries, rivers, and mainland areas, provides approximately 40% of the world’s population a place to live, and has a significant impact on the world economy. With an increase in the number of sinking cities along the US East Coast, understanding the evolution of the Holocene system is important because it provides a setting over which the modern system will migrate.

The current intersection of coastal barriers and the sea responds to interactions between the forces of winds, waves, tides, and sea-level rise; the palimpsest of multiple marine terrace systems; and the input of sediment from rivers and cannibalized coastal components. Using high-resolution aerial photos, lidar, vibracores, marine geophysics, grain sizes, and various geochronologic methods, this investigation focuses on the dynamic nature of the classic, mixed-energy system within the central South Carolina coastal area. Data are included from multiple student projects and previously reported datasets to provide context to the temporal framework of barrier island evolution and sediment influx to the region.

In general, from the Santee R. to Edisto Is., it is clear from this study (and from the literature) that the initial establishment of the mid-Holocene coastal system was from 5 to 15 km inland from the modern coastline approximately 6 ka (this study) ago. Several distinct sets of island orientation, and changes in that orientation through time, are documented, linking to sediment dynamics along the coast. North of Charleston Harbor, the system consists of sand ridges less than 1.5 ka old, with the areas south of Charleston providing a more refined understanding of the 3 to 6 ridge systems of successively younger shorelines. These distinct sand ridges provide an understanding of sediment dynamics for the region throughout the Holocene, with broader implications from recent studies to the north in Long Bay from Little R. to Winyah Bay and down to the southern coastal areas.

Unraveling the intricacies of Quaternary evolution in central SC not only sheds light on the dynamic interplay of forces shaping this modern coastline, but also serves as a testament to the imperative of sustainable coastal management for the 21st century along the US East Coast and worldwide.