ABSTRACT

The morphology, water mass properties, and sediments in a small fjord-like inlet on the Atlantic coast of Nova Scotia, the North West Arm, were examined in an attempt to evaluate processes related to the reworking of glacial drift in the marine environment. The Arm, an open system with physical, chemical, and biological exchanges with areas beyond its mouth, is not a simple "sediment trap." The present sediment distribution conforms closely with morphological features and with patterns of current flow. The original Pleistocene diamictite till deposits (gravel to mud admixtures) have been mechanically reorganized during the period following submergence of the former glaciated valley. Winnowing and by-passing, when carried to completion, result in the formation of gravel pavements in ar as strongly affected by currents and in the deposition of fine-grained material on less current-agitated bottoms. Less well-sorted textural varieties result from incomplete winnowing, and from the introduction of fine-grained material on coarse gravel "lag" pavements. These intermediate sediment types, gradational between original till deposits and better sorted mud and gravel end-members, clearly do not fall in either relict or modern sediment categories as usually defined.

The patchy nature of the sediment distribution and the wide range of textural types observed in the Arm are characteristics common of submerged coastal embayments and shelves off glaciated regions in general. It is quite likely that some of the processes still active in the North West Arm are of the type that modified Pleistocene glacial drift on continental margins during early phases of the transgression by the Holocene sea.