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The topography of the Chukchi Sea continental shelf south of Herald Shoal is and has been dominated since at least Wisconsin time by Hope Valley (which trends northwest through the central part of the area) and by structural and sedimentary spit-like features trending offshore from Point Hope and Cape Prince of Wales. During the Wisconsin time of lowered sea level, Hope Valley was retrenched and most pre-Wisconsin Pleistocene sediments were stripped from the interfluves. The drainage system was considerably more complex than indicated by the present bathymetry. High-frequency (12 kHz) subbottom profiles and gravity and piston core sediments indicate 1-26 cm post-Wisconsin sediment deposited mostly in a large estuarine environment produced as Hope Valley was inundated. The main sources of sediment initially were the Kobuk-Noatak river system and the shores; smaller amounts were derived from lateral river discharge. Approximately 13,000-14,000 years ago, sea level had risen sufficiently to connect the Bering and Chukchi Seas. After the 2 seas were connected, a major source of sediment was introduced from the Yukon through Bering Strait into the central Hope Valley estuary. A period of rapid deposition followed. Deltaic deposits came from both the Noatak-Kobuk and Yukon sources. In addition, significant deposition north of Point Hope and Cape Prince of Wales resulted from the prevailing current established through Bering Strait. Transgressive sands, open-shelf facies, paralic sediments, and residual deposits can be recognized when related to the modern shelf sediment environment. The total post-Wisconsin deposition has buried numerous small Wisconsin stream valleys, displaced Hope Valley northward through the building of the Bering Strait "delta," produced thick deposits of current-derived sediment on the downstream lee sides of Point Hope and Cape Prince of Wales, and subdued the more rugged Wisconsin subaerial topography.
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