Sediments The Gulf of St. Lawrence, including Northumberland Strait, has patches of reworked sand and gravel, glacially derived marine silt, and clays at greater depths. Sediments originated largely during the post-glacial period as the sea transgressed the area and reworked material deposited during the glaciation, but sediments originate locally through erosion of coastal bedrock. Local sand deposits in the littoral zone arise in part from sandstone deposits along the coast. Little sediment is supplied to the coast by rivers owing to the small size of the drainage systems. The major driving forces for circulation are freshwater runoff, winds, and tides.
Currents are generally weak and shallow depths prevail.
The ocean environment exhibits a large temperature range from winter to summer. The Northumberland Strait has warmer water temperatures in summer than other continental shelf regions of Nova Scotia. Temperatures in winter are comparatively colder due to extensive winter ice and low surface salinities in spring. Beaches and intertidal zones are affected by ice from mid-December to April or May of each year. Plants Seaweeds are diverse and moderately abundant on exposed rock surfaces but not as abundant as in other Inner Shelf areas because of winter ice scouring.