These extend from shore at the mouths of many major rivers that once flowed out onto the exposed shelf. Nearshore areas can have a variety of sediments as a result of local formation. A few localized depressions such as Chedabucto Bay contain pockets of clay. Oceanography The Unit is exposed to the Atlantic Ocean and, for the most part, the influence of the coastal Nova Scotia Current. Conditions in the western portion overlap those in the Bay of Fundy, possibly because of cooler ocean temperatures associated with upwelling induced by tides, but this part of the District differs from the Bay of Fundy by having a reduced tidal regime.
Surface waters are relatively fresh and warm.
Underneath is a cold, more saline intermediate layer, and near the bottom a slightly warmer yet more saline layer with a larger slope water component. The Atlantic Unit has some of the most significant seaweed growth and productivity in the province owing to the availability of suitable rocky bottom and adequate wave energy. Sheltered bays and estuaries have significant Eelgrass beds and tidal marshes. Seaweeds occur in shallow water near shore, and phytoplankton is important throughout the Unit. Encrusting coralline algae cover rock surfaces in the shallower parts.