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U.S. Geological Survey Open-File Report 2010–1007

Sea-Floor Geology and Character Offshore of Rocky Point, New York


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Thumbnail image of figure 1 and link to larger figure. A map of the location of bathymetric and backscatter surveys completed in Long Island Sound. Figure 1. Location of the bathymetric and backscatter surveys completed in Long Island Sound. Surveys by the NOAA ships Thomas Jefferson and Rude are shown in light gray and include H11043—Poppe and others (2004, 2006a); H11044—McMullen and others (2005); and H11045—Beaulieu and others (2005); H11255—Poppe and others (2006c); H11250—Poppe and others (2006b, 2007a); H11252/H11361—Poppe and others (2007b, 2008); H11441/H11442/H11224/H11225—Poppe and others (2010); H11445—McMullen and others (2010). Sites of USGS sidescan-sonar surveys are shown in dark gray and include Norwalk—Twichell and others (1997); Milford—Twichell and others (1998); New Haven Harbor and New Haven Dumping Grounds—Poppe and others (2001); Roanoke Point—Poppe and others (1999a); Falkner Island—Poppe and others (1999b); Hammonasset—Poppe and others (1997); Niantic Bay—Poppe and others (1998c); New London—Lewis and others (1998), Zajac and others (2000, 2003); Fishers Island Sound—Poppe and others (1998b).
Thumbnail image of figure 2 and link to larger figure. A map showing prominent points along the north shore of Long Island. Figure 2. Locations of prominent points along the north shore of Long Island east of Port Jefferson, the Harbor Hill-Roanoke Point-Orient Point Moraine, and National Oceanic and Atmospheric Administration survey H11251.
Thumbnail image of figure 3 and link to larger figure. Photograph of the Research vessel used in this study. Figure 3. Port-side view of the National Oceanic and Atmospheric Administration Ship Thomas Jefferson at sea. The 8.5-m survey launch normally stowed on this side of the ship has been deployed.
Thumbnail image of figure 4 and link to larger figure. A photograph of Launch 3102 which was used in this study. Figure 4. The National Oceanic and Atmospheric Administration (NOAA) Launch 3102 being deployed from the NOAA Ship Thomas Jefferson.
Thumbnail image of figure 5 and link to larger figure. A photograph of Launch 3102 which was used in this study. Figure 5. Starboard-side view of the National Oceanic and Atmospheric Administration Launch 3102 at sea.
Thumbnail image of figure 6 and link to larger figure. Photograph of the sidescan-sonar system mounted to the hull of a launch. Figure 6. A Klein 5000 sidescan-sonar system hull-mounted to a National Oceanic and Atmospheric Administration launch.
Thumbnail image of figure 7 and link to larger figure. Photograph of the bathymetric sensor 8101 mounted to the hull of Launch 3102. Figure 7. The RESON SeaBat 8101 hull-mounted to the National Oceanic and Atmospheric Administration Launch 3102.
Thumbnail image of figure 8 and link to larger figure. Photograph of the bathymetric sensor 8125 mounted to the hull of Launch 3101. Figure 8. The RESON SeaBat 8125 hull-mounted to the National Oceanic and Atmospheric Administration Launch 3101.
Thumbnail image of figure 9 and link to larger figure. Photograph of the Conductivity-temperature-depth (CTD) profiler. Figure 9. Sea-Bird Electronics, Inc. SEACAT conductivity-temperature-depth (CTD) profiler. Data derived from frequent deployments of this device were used to correct sound velocities for the multibeam data.
Thumbnail image of figure 10 and link to larger figure. Photograph of the research vessel Rafael. Figure 10. A port-side view of the U.S. Geological Survey research vessel Rafael, which was used to collect bottom photography and sediment samples in the vicinity of Rocky Point, New York.
Thumbnail image of figure 11 and link to larger figure. A photograph of the Seabed Observation and Sampling System (SEABOSS). Figure 11. The small Seabed Observation and Sampling System (SEABOSS), a modified Van Veen grab sampler equipped with still and video photographic systems, mounted on the aft starboard side of the research vessel Rafael. Note the winch mounted on the davit (left) and the take-up reel for the video-signal and power cable (right).
Thumbnail image of figure 12 and link to larger figure. A map of the location of sampling and photograph stations. Figure 12. Locations of stations at which bottom samples and photographs were taken during cruise 09059 of research vessel Rafael to verify bathymetric and backscatter data.
Thumbnail image of figure 13 and link to larger figure. A chart showing the relationships among sediment sizes. Figure 13. Correlation chart showing the relationships among phi sizes, millimeter diameters, size classifications (Wentworth, 1922), and American Society for Testing and Materials and Tyler sieve sizes. Chart also shows the corresponding intermediate diameters, grains per milligram, settling velocities, and threshold velocities for traction.
Thumbnail image of figure 14 and link to larger figure. A diagram showing the Sediment-classification scheme. Figure 14. Sediment-classification scheme from Shepard (1954), as modified by Schlee (1973).
Thumbnail image of figure 15 and link to larger figure. A map showing the digital terrain model of the sea floor. Figure 15. Digital terrain model of the sea floor produced from the multibeam bathymetry collected during National Oceanic and Atmospheric Administration survey H11251 and gridded to 2 m. Image is sun-illuminated from the north and vertically exaggerated 5X. Warmer colors are shallower areas; cooler colors are deeper areas. See key for depth ranges.
Thumbnail image of figure 16 and link to larger figure. A map showing locations of detailed planar views of the digital terrain model. Figure 16. Locations of detailed planar views of the digital terrain model and sidescan-sonar mosaic (yellow polygons) and profiles of sand-wave symmetry (green lines). Seaward extent of the sidescan-sonar data (red line) and directions of net sediment transport (blue arrows) interpreted from obstacle marks and bedform asymmetry are included. Profiles A-E are shown in figures 22 and 23.
Thumbnail image of figure 17 and link to larger figure. An illustration showing bathymetry of the bouldery sea floor off Rocky Point, New York. Figure 17. Detailed planar view of the bouldery sea floor off Rocky Point, New York, from the digital terrain model produced during National Oceanic and Atmospheric Administration survey H11251. Boulders rest on the winnowed upper surface of the submerged Harbor Hill-Roanoke Point-Orient Point moraine. Location of view is shown in figure 16.
Thumbnail image of figure 18 and link to larger figure. An illustration showing bathymetry the bouldery sea floor along the shoreline in the vicinity of Inlet Point. Figure 18. Detailed planar view of the bouldery sea floor along the shoreline in the vicinity of Inlet Point from the digital terrain model produced during National Oceanic and Atmospheric Administration survey H11251. Location of view is shown in figure 16.
Thumbnail image of figure 19 and link to larger figure. A map showing the interpretation of the bathymetry. Figure 19. Interpretation of the digital terrain model and sidescan-sonar mosaic from National Oceanic and Atmospheric Administration survey H11251 off Rocky Point, New York. Areas characterized by boulders, large bedforms, and a shipwreck are shown. White areas within the study area are primarily nondescript reworked Holocene sediment.
Thumbnail image of figure 20 and link to larger figure. An illustartion showing details of obstacle marks off Rocky Point, New York. Figure 20. Detailed planar view of obstacle marks from the digital terrain model produced during National Oceanic and Atmospheric Administration survey H11251 off Rocky Point, New York. Asymmetry in the scour indicated net sediment transport at this location is toward the northeast. Location of view is shown in figure 16.
Thumbnail image of figure 21 and link to larger figure. An illustartion showing bathymetric details of Orient Shoal. Figure 21. Detailed planar view of Orient Shoal from the digital terrain model produced during National Oceanic and Atmospheric Administration survey H11251 off Rocky Point, New York. Blue arrows show direction of net transport interpreted from sand-wave asymmetry. Location of view is shown in figure 16.
Thumbnail image of figure 22 and link to larger figure. A diagram showing cross-sectional views of sand waves around Orient Shoal. Figure 22. Cross-sectional views of sand waves around Orient Shoal from the digital terrain model produced during National Oceanic and Atmospheric Administration survey H11251 off Rocky Point, New York. Sand-wave asymmetry in profiles A and B indicate net sediment transport is westward along the southern side of the shoal and eastward along the northwestward side in profile C. Locations of profiles are shown in figure 16.
Thumbnail image of figure 23 and link to larger figure. A diagram showing cross-sectional views of sand waves west of Rocky Point. Figure 23. Cross-sectional views of sand waves west of Rocky Point from the digital terrain model produced during National Oceanic and Atmospheric Administration survey H11251. Sand-wave asymmetry indicates net sediment transport is southwestward. Profile D crosses a barchanoid sand wave. Locations of profiles are shown in figure 16.
Thumbnail image of figure 24 and link to larger figure. A map showing sidescan-sonar imagery in the study area. Figure 24. Sidescan-sonar imagery produced from data collected during National Oceanic and Atmospheric Administration survey H11251. Light tones indicate hard returns and generally coarser grained sediments; dark tones indicate softer returns and generally finer grained sediments.
Thumbnail image of figure 25 and link to larger figure. An illustartion showing detailed sidescan-sonar imagery north of Rocky Point, New York. Figure 25. Detailed planar view north of Rocky Point, New York, of the sidescan-sonar mosaic produced during National Oceanic and Atmospheric Administration survey H11251. High-backscatter targets with shadows are interpreted to be boulders. Lines with white cross hatches are sonar artifacts caused by nadir (the track directly under the vessel) not removed during sidescan-sonar processing. Location of view is shown in figure 16.
Thumbnail image of figure 26 and link to larger figure. An illustration showing details of relatively straight to sinuous alternating bands of high and low backscatter from the sidescan-sonar mosaic. Figure 26. Detailed planar view of relatively straight to sinuous alternating bands of high and low backscatter from the sidescan-sonar mosaic produced during National Oceanic and Atmospheric Administration survey H11251 off Rocky Point, New York. Tiger-stripe pattern is indicative of transverse sand waves and megaripples. Location of view, which is northeast of Orient Shoal, is shown in figure 16.
Thumbnail image of figure 27 and link to larger figure. A map of station locations used to verify the acoustic data, color-coded for sediment texture. Figure 27. Station locations used to verify the acoustic data, color-coded for sediment texture. Warmer colors are coarser grained sediments; cooler colors are finer grained sediments. See key for sediment classifications and data sources.
Thumbnail image of figure 28 and link to larger figure. Two photographs of the sea floor showing fauna and flora covering boulders at stations RP17 and RP26. Figure 28. Sessile fauna and flora covering boulders at stations RP17 and RP26. These organisms are commonly absent from cobble-sized and smaller gravel that are mobile in high-energy environments. Station locations are shown in figure 12.
Thumbnail image of figure 29 and link to larger figure. Two photographs of the sea floor showing gravel covering the sea floor in the high-energy environments at stations RP8 and RP24. Figure 29. Gravel armors the sea floor in the high-energy environments at stations RP8 and RP24. Station 24 is in the trough of a large barchanoid sand wave. Station locations are shown in figure 12.
Thumbnail image of figure 30 and link to larger figure. Two photographs of the sea floor from stations RP16 and RP14 showing current-rippled sand that is prevalent in areas characterized by sedimentary environments of coarse-bedload transport. Figure 30. Bottom photographs from stations RP16 and RP14 of current-rippled sand that is prevalent in areas characterized by sedimentary environments of coarse-bedload transport. Note the concentration of detritus in the ripple troughs and the scour around obstacles. Station locations are shown in figure 12.
Thumbnail image of figure 31 and link to larger figure. A photograph of the sea floor from station RP25. Figure 31. Bottom photograph from station RP25. Current ripples are fainter and burrows more common offshore of Rocky Point, New York, in the limited areas where lower energy environments are prevalent. Station locations are shown in figure 12.
Thumbnail image of figure 32 and link to larger figure. Two photographs of the sea floor showing shell beds off Rocky Point, New York. Figure 32. Shell beds off Rocky Point, New York. The beds at station RP11 are composed of mussel shells; beds at station RP19 are composed of slippersnail (Crepidula) shells. Station locations are shown in figure 12.


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