. Collected reprints / Atlantic Oceanographic and Meteorological Laboratories [and] Pacific Oceanographic Laboratories. Oceanography 122 Continental Margins rhythmic perturbations in the form of shoreface- connected sand ridges occur on the shoreface, in response to perturbations in the storm flow field of downwelling, southerly trending shoreface cur-. Fig. 6. Shoreface-connected ridge field of the Delmarva Coast. Ridges are nourished by storm current erosion of the shoreface. Ridges are migrating southeast (downcoast and offshore), while extending crest lines to maintain contac
. Collected reprints / Atlantic Oceanographic and Meteorological Laboratories [and] Pacific Oceanographic Laboratories. Oceanography 122 Continental Margins rhythmic perturbations in the form of shoreface- connected sand ridges occur on the shoreface, in response to perturbations in the storm flow field of downwelling, southerly trending shoreface cur-. Fig. 6. Shoreface-connected ridge field of the Delmarva Coast. Ridges are nourished by storm current erosion of the shoreface. Ridges are migrating southeast (downcoast and offshore), while extending crest lines to maintain contact with the shoreface. As trough grows through headward and axial erosion, storm currents in trough become more in- tense, and eventually cut saddle. Perturbation of sea floor* continued as new ridge downcoast, resulting in stepwise crest line (compare lower diagram with crestlines in map}. rents, and the nearly symmetrical surge of high storm waves (Figs. 1 and 6; Swift et al., 1972a; Duane et al., 1972). Each ridge is nourished by storm erosion of the up-current shoreface. Head- ward and axial erosion of the troughs during region- al retreat of the shoreface results in periodic isola- tion of ridge segments on the deepening inner shelf floor, an important form of small-scale downdrift bypassing. The resulting stratum is a ridged sand sheet whose structures and textures reflect the course of the Holocene transgression. This pattern of shelf valley complex alternating with shoreface retreat blanket, characteristic of the Middle Atlantic Bight, is replaced by alternative patterns farther north and south (Swift and Sears, in press). To the north, the shelves have been glaciated and relief is greater. Here shelf highs are cuestas and similar erosional forms; river-cut val- leys are only partially filled with estuarine deposits. Glacial basins in the Gulf of Maine and Scotian Shelf are presently accumulating mud. To the south, off the Carolina salient, cape shoal-retreat massifs ext
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