Anita M. DeIure

Halifax Inlet is one of a series of estuaries along the Atlantic coast of Nova Scotia that have experienced post-glacial transgression. The following lithofacies are the result of unmixing of poorly sorted submarine and subaerial deposits: (i) pebble/boulder lag deposits, (ii) sands, and (iii) muds.

The study area is situated in the outer harbour, where the predominant sediment type is mud. Two subfacies are distinguished within the muddy facies: (i) bioturbated muds and (ii) muds containing sandy laminae. The occurrence of the latter subfacies corresponds to periods of exceptional storms in Halifax. The individual sandy laminae were deposited as a result of storms with a recurrence interval of 25 to 75 years.

To delineate the effects of storms on local sedimentation, suspended sediment concentrations were monitored from January to June, 1982, a sediment dynamics experiment was carried out in March 1982 and sediment traps were deployed. These data demonstrate: (i) sediment on sand substrates is locally resuspended by waves during winter wind storms; (ii) in shallow water, water turbidity may decrease rapidly, with water movement away from McNab`s Island; (iii) near-bottom and/or mid-depth intrusions of turbid water are present in the outer harbour following storms.

Sediment dispersal patterns are complex. Transport of sediments is from several directions with temporal variability on time scales from seconds to tens of years.

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Supervisor: D. J. W. Piper