ABSTRACT

Coastal sedimentation along Nova Scotia’s eastern shore is dominated by a rising sea level, restricted drumlin sediment supply, and inherited glacial topography. Evolution of barrier systems follows a 500-1,000 year cyclic sequence of: (1) generation from marine erosion of glacial deposits, (2) transgression resulting from ongoing sea level rise and depletion of original sediment sources, and (3) landward removal following an estuarine retreat path to new sites of reconstruction. The dominant sediment transfer mechanism operating during this transgressive cycle is landward dispersal by tidal inlet, overwash, and eolian process.

Vibrocore, surface sampling, marine geophysics, and underwater photography were used to investigate the potential for eastern shore coastal deposits to be incorporated into the shelf stratigraphic record. High-resolution seismic profiles from the inner continental shelf reveal a lower acoustic unit interpreted as Wisconsinan glacial deposits. Overlying the lower unit is a discontinuous upper unit 1-2 m thick, which occupies topographic depressions and is composed of sand, silty sand, and a coarse gravel lag. Side-scan sonar and underwater photographs show large gravel ripples covering the upper acoustic unit in water up to 30 m deep. The upper acoustic unit is interpreted as the remnants of reworked coastal barriers, drumlins, and till.

Transgressive sedimentation on the eastern shore of Nova Scotia, therefore, conforms to the concept of shoreface retreat. Coastal sediments here are poorly preserved, except in linear shelf valleys, because of a high-energy wave climate and prior landward transfer into tidal deltas, washovers, and associated back-barriers deposits.

This content is PDF only. Please click on the PDF icon to access.

First Page Preview

First page PDF preview
You do not currently have access to this article.