This study delineates the sources and prevalent paths of sediment movement on Sable Island Bank on the outer edge of the continental shelf off Nova Scotia. With the exception of shell fragments, microfossils, and minor amounts of glauconite, most of the unconsolidated sediment cover on this broad shallow platform is relict Pleistocene glacial material. The sediments were derived largely from the inner Nova Scotian shelf and the Maritime Provinces 100 mi and more north and northwest of the study region. The predominantly coarse arenaceous material was transported onto a periglacial outwash plain. Good sorting was produced by fluvioglacial and eolian processes and, subsequently, by reworking by marine agents during the Holocene rise in sea level. Several submarine terraces, including two low ones at depths of 66 and 87 fm, attest to eustatic sea-level oscillations during glacial epochs. These oscillations also caused distinct mineralogical and textural variations with depth.

Correlation of textural, mineralogical, and faunal parameters with vectorial properties of sedimentary structures, such as large submarine sand waves, and with physical oceanographic data make possible some interpretations concerning modern dispersal patterns on the bank top. Tidal and wave currents acting against the island and shallow bars cause nearshore sand to move westward on the south of the island and eastward north of the island. Sediment movement is particularly intense adjacent to the island and on the southern part of the bank. Sediment in the region north of Sable Island does not appear to undergo as much reworking as that on the south. Sediment in the northern sector is modified by the activity of abundant organisms, especially the sand dollar Echinarachnius parma.

Although seasonal attrition of the coast and seaward transport of sediment from the island occur, particularly in winter, sediment eventually is returned shoreward in a cyclical manner, thus preventing the rapid destruction of the island. Areas of deposition on the bank are present southwest and east of Sable Island and north of the submerged east bar. Sand is moved off the bank into highly dissected areas on the north, into The Gully submarine canyon on the east, and onto the Nova Scotian slope and rise on the south.

Oysters and other molluscan species, no longer living on the bank, and peat are found in some offshore samples and on the beaches of Sable Island. These suggest that environments of deposition around the Island, and possibly the climate as well, have changed considerably during the Holocene.