HR: 1330h
AN: OS23B-07    [Abstracts]
TI: Distribution, Character, and Importance of Sedimentary Furrows in South-Central Long Island Sound
AU: * Poppe, L
EM: lpoppe@usgs.gov
AF: USGS, 384 Woods Hole Road, Woods Hole, MA 02543 United States
AU: Doran, E
EM: elizabeth.doran@po.state.ct.us
AF: CT DEP, 79 Elm Street, Hartford, CT 06106 United States
AU: Moser, M
EM: marc.s.moser@noaa.gov
AF: NOAA Ship Thomas Jefferson, 439 West York Street, Norfolk, VA 23510 United States
AU: Forfinski, N
EM: nicholas.a.forfinski@noaa.gov
AF: NOAA Ship Thomas Jefferson, 439 West York Street, Norfolk, VA 23510 United States
AU: Stewart, H
EM: helen.stewart@noaa.gov
AF: NOAA Ship Thomas Jefferson, 439 West York Street, Norfolk, VA 23510 United States
AU: Gardner, U
EM: Uther.Gardner@noaa.gov
AF: NOAA Ship Thomas Jefferson, 439 West York Street, Norfolk, VA 23510 United States
AU: Keene, J
EM: jennifer.keene@noaa.gov
AF: NOAA Ship Thomas Jefferson, 439 West York Street, Norfolk, VA 23510 United States
AU: Christman, E
EM: emily.b.christman@noaa.gov
AF: NOAA Ship Thomas Jefferson, 439 West York Street, Norfolk, VA 23510 United States
AU: Ackerman, S
EM: sackerman@usgs.gov
AF: MA CZM, 384 Woods Hole Road, Woods Hole, MA 02543 United States
AB: The U.S. Geological Survey, in cooperation with the Connecticut Department of Environmental Protection and the National Oceanic and Atmospheric Administration, is producing detailed geologic interpretations of the sea floor in Long Island Sound to improve our understanding of the processes that control the complex distributions of sedimentary environments and benthic habitats. Although the deeper waters of the south-central Sound are generally characterized by relatively weak bottom currents and by depositional conditions, multibeam data reveal the presence of sedimentary furrows. These erosional bedforms occur in fine-grained cohesive sediments and cover an elongate east-west trending area (~80 km2) that lies approximately 5 km off Herod Point, NY, in water depths of 31-41 m. The furrows are irregularly spaced, trend east-northeast, average 9 m wide and 0.4 m deep, and can exceed 1.9 km long. Although most of the furrows appear to taper out gradually, some furrows show a "tuning fork" joining pattern. Most of these junctions open toward the east, indicating net westward sediment transport, but a few junctions open westward suggesting that the tidal regime is important to furrow formation and that the furrows can form when water flows in either direction. The sedimentary furrows in south-central Long Island Sound, which are similar to those we have previously described along the Connecticut side of the estuary, form under recurring directionally stable tidal currents, constrained by the elongate geometry and regional bathymetry of the Sound. These conditions, in turn, produce the secondary helical and turbulent flow patterns conducive to the formation of erosional furrows. Concurrently, bioturbation by crabs not only suspends sediment, but also nutclam shells and other coarse biogenic debris, which are aligned by the secondary flow and abrade the furrows as they saltate in the oscillating tides. Through resuspension due to biological activity and the subsequent development of these furrows, fine-grained cohesive sediment can be remobilized and made available for transport farther westward into the Sound.
DE: 3022 Marine sediments--processes and transport
DE: 3045 Seafloor morphology and bottom photography
DE: 4219 Continental shelf processes
DE: 4243 Marginal and semienclosed seas
SC: Ocean Sciences [OS]
MN: 2005 Joint Assembly