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ST. LAWRENCE INFO
Lower Estuary and Gulf
The lower estuary, over 230 km long and an average 42 km wide, empties into the Gulf of St. Lawrence, a semi-inland sea dotted with large islands (Anticosti Island, the Magdalen Islands, Bonaventure Island, and the Mingan and Sept-Îles archipelagos). The Laurentian Channel rapidly reaches a depth of 350 m downstream of the Saguenay River and varies from 100 to 400 m in the Gulf, except in the Magdalen Shelf, where depths rarely exceed 70 m, and in the area around Cabot Strait, where depths are greater than 500 m (SLC, 1996).
This hydrographic region is the marine area of the St. Lawrence. The lower estuary begins upstream, in the deepwater upwelling zone located at the mouth of the Saguenay River, and at the head of the Laurentian Channel, an underwater valley of more than 350 m in depth.
A number of factors influence the complex process of water mass circulation and mixing in this hydrographic region, including the tide, barometric pressure, air temperature, wind, local freshwater inputs, coastal relief and the rotation of the Earth. In summer, three different layers of water masses of different temperatures and salinity levels are superposed; in winter, two superposed layers are seen (SLC, 1996).
Back to the hydrographic divisions of the St. Lawrence River |
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