. The Eastern Bering Sea Shelf : oceanography and resources / edited by Donald W. Hood and John A. Calder. Oceanography Bering debris was winnowed out, leaving behind surface lag gravel deposits (Fig. 70-6a) (Nelson and Hopkins 1972). These deposits remain on the surface of current-winnowed topographic elevations where dep- osition of Holocene muds has been prevented. In the eastern parts of Anadyr and Bering straits as well as along nearshore southwestern Seward Peninsula and St. Lawrence Island, the mineralogy and large grain size of gravel lags, together with early radiocarbon dates (
. The Eastern Bering Sea Shelf : oceanography and resources / edited by Donald W. Hood and John A. Calder. Oceanography Bering debris was winnowed out, leaving behind surface lag gravel deposits (Fig. 70-6a) (Nelson and Hopkins 1972). These deposits remain on the surface of current-winnowed topographic elevations where dep- osition of Holocene muds has been prevented. In the eastern parts of Anadyr and Bering straits as well as along nearshore southwestern Seward Peninsula and St. Lawrence Island, the mineralogy and large grain size of gravel lags, together with early radiocarbon dates (15-40,000 : Nelson, unpub. data) of underlying sediment, indicate deposition under older, high-energy conditions not present today (Nelson and Hopkins 1972, McManus et al. 1974). The coarser grain size and different mineralogy of the Chirikov Basin sand blanket compared to the silty-sized sediment of the main modern Yukon sediment source suggest that Chirikov Basin sand also is relict. Relict physical structures in relict sediments are best preserved in the subsurface sediment of strait areas with the deepest water, where present-day wave effects are minimal, coarse gravel armors the bottom surface, and strong currents prevent burial by modem deposits. Here, box cores have penetrated into older transgressive sediments and even into Pleistocene freshwater deposits with relict lamination (Fig. 70-8d). Coarse-grained relict sediment overlying Pleistocene tills contains flat lamination and asso- ciated high-angle, medium-scale cross bedding that evidently originated during the Holocene shoreline transgression (Figs. 70-6a and b, 70-4, and 70-7). Subsurface shell and pebble horizons in such relict. Figure 70-12b. Serripes groenlandicus that has severe- ly disturbed the box-core surface of Yukon silt. Water depth 18 m. sediments are now in sufficiently deep water and buried deep enough to ensure isolation from modern- day storm-wave and bottom-current effects. These structures ap
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