Surficial geology and geophysical investigations of the Capers Inlet, South Carolina (USA) 7.5-Minute Quadrangle

Abstract

Surficial geology and geophysical investigations of the Capers Inlet, South Carolina (USA) 7.5-Minute Quadrangle is a compilation of geological and geophysical data collected in the Caper's Inlet Quadrangle, situated along the central coastline of South Carolina, USA. The 1:24,000 scale map area encompasses marine environments in the shallow nearshore and offshore (constituting approximately 80% of the study area) and terrestrial barrier island and Pleistocene upland environments (20% of the study area). The geologic map was compiled by overlaying existing topographic maps with data from high-resolution sidescan sonar, subbottom profiler, and GPR surveys supplemented with surficial sediment grabs and vibracore samples. These data were collected in 2009 and early 2010 for an MSc thesis project conducted through the Department of Geology and Environmental Geosciences at the College of Charleston, South Carolina. The resulting maps illustrate the spatial variability of surficial seafloor geology in the area, with sediment distribution ranging from a coarse shell hash to fine-grained mud. The shallow stratigraphy is characterized by a thin layer of modern sediment overlying the boundary between the Quaternary and Tertiary as well as the presence of several paleochannels in the backbarrier and shallow offshore. By portraying both seafloor geology and shallow stratigraphy, maps and accompanying information provide scientists and coastal managers with a better understanding of the relationship that exists between stratigraphy, sediment distribution, and geomorphology in the area.

An analysis and comparison of observed Pleistocene South Carolina (USA) shoreline elevations with predicted elevations derived from Marine Oxygen Isotope Stages

“…Based on this stratigraphic context, we preferred an age less than that of the well dated Princess Anne Formation. However, that does not agree with studies citing ages of~100 ka for the Silver Bluff (Zayac, 2003;Harris et al, 2005;Luciano and Harris, 2013). We are not able to resolve the age of the formation, but rather include the ages to allow comparisons for these two possibilities and the size of the offsets.…”

A New Mechanism for Submarine Groundwater Discharge From Continental Shelves

“…The seismic data were examined for evidence of paleochannels because they are considered important conduits for SGD (Evans et al, 2000; Mulligan et al, 2007). Our Edgetech 512i data were integrated with previously published high‐resolution Chirp surveys collected by an Edgetech 216 s subbottom profiler with a frequency range of 2–16 KHz (Luciano & Harris, 2013). In our analysis of both data sets, paleochannels were defined as concave up seismic reflectors extending at least 200 m horizontally and 0.5 m vertically.…”

Small Muddy Paleochannels and Implications for Submarine Groundwater Discharge near Charleston, South Carolina, USA

“…Net longshore transport on the Georgia Bight moves sediment from north to south, but there are local areas of sediment transport reversal caused by tidal inlets and the refraction of waves around ebb-tidal deltas [33][34][35]44,45]. The Isle of Palms sits at the transition from low aggradation to the north to higher aggradation going south [16,44].…”

“…During our survey, a frequency range of 0.5-10 kHz was used at a towing speed of 4 knots at a constant instrument depth of 1 m below sea surface to maximize sub-bottom penetration with this system. In addition, we used previously published Edgetech 216s CHIRP sub-bottom profiler data acquired a frequency range of 2-10 kHz [33]. The similar frequency range results in comparable sub-bottom resolution, although the 216s has a lower sediment-penetration depth.…”