Robert K. Hall
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M. Sc. Thesis
Inner Shelf Acoustic Facies and Surficial Sediment Distribution of the Eastern Shore, Nova Scotia
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The Eastern Shore of Nova Scotia is a fjord type coastline comprised of glacial sediment undergoing a marine transgression. This study is based on interpretation of high resolution seismic reflection profiles, side-scan sonar, surface grab samples, underwater photographs, and vibracore data from the inner Scotian Shelf, between Hartlen Point and Jeddore Head.
Side-scan sonar of the acoustic basement reveals bedding planes that have been truncated by fractures and faults. Analysis of high resolution seismic reflection profiles reveals the presence of three acoustic units interpreted as sediment facies deposited in three distinct environments. Thickness (to 33 meters), stratigraphic position, and lack of acoustic internal reflectors indicate that the lower acoustic unit represents a Pleistocene glacial deposit. The middle acoustic unit can be up to 32 meters thick where it has filled in channels and basins, and is interpreted as a tidal inlet-estuarine deposit. The upper acoustic unit has an average thickness of 1-2 meters, is discontinuous and occupies shallow depressions over the inner shelf. In the nearshore it forms a landward thickening wedge at the base of beaches and inlets. This unit is interpreted to be the product of the reworking of coastal barriers, drumlins and till during the Holocene transgression.
High resolution seismic reflection profiles, side-scan sonographs, underwater photographs, and sediment samples show that Pleistocene and Holocene sediment are poorly preserved in the inner shelf stratigraphic record except in basins and linear shelf valleys. This poor preservation indicates that marine processes during the Holocene transgression were able to erode topographically high areas but were unable to scour out low-lying areas.
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