Seven generalized sedimentary-facies types were defined for a unified comparison of core data from the entire study area. All seven color-coded facies for the entire study are shown in the Explanation below. However, not all facies necessarily are present on each transect. Core photographs present individual cores cut into 1-m sections from top (upper left) to bottom (lower right). Discrepancies in core length between the photographs and the diagrams are due to compaction during the coring process. Offshore cores (left) are aligned at core tops. Core locations were chosen to sample thicker Holocene sections and to aid in identifying pre-Holocene stratigraphy. Core elevations were determined from water depth and tide tables. The datum for the barrier-transect cores is the mean lowest low water (MLLW). Core photographs are shown for USGS-95-43 (most seaward) and CAL-1 (most landward).

Offshore vibracore retrieval ranged from a little over 1 m to approximately 2.5 m in length. Although the vibracores penetrated to bedrock, there is often little indication of a bedrock reflection seen in the seismic data. A poor impedance contrast between well-sorted shelf sands and the underlying exposure surface appears to be responsible for the lack of a well-defined seismic boundary at the base of the Holocene section.

Offshore cores contain a surface layer dominated by quartz sand. The facies is interpreted to have been deposited under modern open-marine conditions. In the seaward most core, the quartz sand unit is underlain by a muddy sand unit with numerous visible burrows. The muddy sand is interpreted to have been deposited in a back-barrier environment. Radiocarbon dates indicate that it was deposited 8,300 ±90 years before present (YBP).

In the two landwardmost cores, the Miocene limestone surface was penetrated immediately below the surficial sediment/sand layer, once again indicating the paucity of sediments on this part of the shelf.

The barrier-island transect cores, taken across the prograding southern end of the barrier, record a transition from back-barrier and overwash sedimentary facies containing a more abundant shell and mud fraction, to cleaner sands in the beach and dune sedimentary facies. On cross sections where cores do not penetrate to bedrock, the control is based on probe-rod data. The expanded coastal cross section to the right includes general environmental interpretations.