See more from this Division: Topical Sessions
See more from this Session: Response of Coastal Environments to Accelerated Sea Level Rise
Abstract:
Eighteen vibracores were collected from the nearshore of the Outer Banks, North Carolina from within and outside a previously identified shore-oblique bar field. Cores from shore-oblique bars/troughs show greater variability in median grain size than those taken from a convex shoreface. Geophysical data show a coarser underlying stratum that is exposed from the axis of the trough and on flanks of shore-oblique bars. Sediment analysis indicates that this stratum is coarser within the field of shore-oblique bars. Changes in the cross-sectional morphology of bars through time indicate a possible feedback between bar-associated sand and coarser trough sediment over interannual timescales. The observed lithologic heterogeneity is directly related to an underlying paleofluvial channel. A literature review reveals an association of paleochannels with sand ridges from sites worldwide. Based on the combination of our data and existing observations, we suggest that shore-oblique bars serve as precursors to storm-generated sand ridges. In our conceptual model, heterogeneous sediments derived from relict strata mediate the formation and preservation of the ridge precursor and may help to explain the existence of sand ridges in locations where their presence is unsupported by existing models.
See more from this Division: Topical Sessions
See more from this Session: Response of Coastal Environments to Accelerated Sea Level Rise