. Collected reprints / Atlantic Oceanographic and Meteorological Laboratories [and] Pacific Oceanographic Laboratories. Oceanography SAND STORAGE IN INNER SHELF RIDGE FIELDS 295. FIGURE 39. Tide-maintained ridge typography on the inner Anglian shelf. Shoreface-connected ridges separate ebb- and flood- dominated channels. Ridges tend to migrate southward with time, and to detach from retreating shoreface. Ridges are nourished at the expense of shoreface, hence constitute cases of downdrift by- Bight, the nearshore zone of sand storage is not a sta- tionary one but is translating l
. Collected reprints / Atlantic Oceanographic and Meteorological Laboratories [and] Pacific Oceanographic Laboratories. Oceanography SAND STORAGE IN INNER SHELF RIDGE FIELDS 295. FIGURE 39. Tide-maintained ridge typography on the inner Anglian shelf. Shoreface-connected ridges separate ebb- and flood- dominated channels. Ridges tend to migrate southward with time, and to detach from retreating shoreface. Ridges are nourished at the expense of shoreface, hence constitute cases of downdrift by- Bight, the nearshore zone of sand storage is not a sta- tionary one but is translating landward in response to postglacial sea-level rise and erosional shoreface retreat. The primary element of storage is again a shoreface- connected sand ridge (Fig. 39). The angle between these ridges and the coast opens northward, into the direction of the advancing coastal tidal wave, and there- fore the trough opens into the flood-dominated residual tidal flow. Downwelling may also occur during the flood tide, since the high velocity axis of trough flow will tend to converge with the rising trough axis. The outside of the ridge is shielded from the flood tide, and therefore experiences ebb discharge. This diversion of flow might be expected to result in a sand circulation cell, with sand moving obliquely up the inner flank and over the crest during the flood tide, to be returned along the seaward flank during the ebb tide. As in the case of storm-maintained shoreface-connected ridges, probably any initial perturbation of the shoreface would result in such a self-maintaining system. As in the case of the Middle Atlantic Bight, the ridges tend to migrate offshore and downcoast, in the direction of the residual tidal flow (Robinson, 1966), and tend to become detached and isolated on the inner shelf floor. However, unlike storm-maintained ridges, tidal ridges on the inner shelf floor tend to be unstable. Variations in the rate of offshore migration along the length of th
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