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Close-up stereo photographs of abyssal bedforms on the Nova Scotian continental rise

Marine Geology
Publication Date
DOI: 10.1016/0025-3227(85)90036-2
  • Biology


Abstract Close-up stereo photographs of the seafloor were taken at five stations on the Nova Scotian rise. Stereo viewing reveals abundant relief with heights in the range 1–50 mm which are not apparent in oblique monoscopic pictures. Objects with dimensions of 0.1 mm can be resolved, and areas up to 1.0 cm 2 can be viewed. Photogrammetric contour mapping at one millimeter intervals of longitudinal ripples gives in-situ dimensions of 12 cm height, 90 cm full width, and 410 cm 2 cross-sectional area. A field of ripples spaced at 5 m with a sediment density of 0.7 g cm −3 contains 5.7 kg dry sediment per m 2. Seafloor roughness on the scale of centimeters in abyssal, high-energy boundary layers reflects both recent sedimentary and biological processes. The spatial density of eight classes of bed relief varies on scales of tens of kilometers downslope and is consistent with downslope trends in the occurrence of larger bedforms, texture of surface sediments, and bottom boundary layer conditions. Most relief is biogenic, directly or indirectly, and most is streamlined.

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