It belongs to the submerged Atlantic Coastal Plain, and its topography was determined by erosional and tectonic processes while it was above sea level. This section falls into two geological provinces. Sediments Middle Shelf areas have sediments derived from glacial activity, and subsequent reworking by an advancing sea level at the end of the glacial period. Bank areas to depths of 110-120 m have coarse sediments of sand, gravel, and occasional boulders. On the bank edges, the bottom is made of sands that have clay and silt.
Basins have clay and localized occurrences of silt.
The shoreward flanks of the basins have glacial till deposits, and a string of moraine deposits extends from off Country Harbour into the Gulf of Maine. Both have the general seasonal pattern described elsewhere for continental shelf areas. Temperatures and salinities in the Middle Shelf tend to be intermediate between those for the Inner Shelf and the Outer Shelf. The influence of the Nova Scotia Current is felt all along the Middle Shelf into the Gulf of Maine. In the Gulf of Maine, there are frontal zones at the northern edge of Georges Bank and a front is induced by tides at the outflow of the Bay of Fundy just offshore.