ST. LAWRENCE. The river St. Lawrence, in North America, with the five fresh-water inland seas (see GREAT LAKES), Superior, Michigan, Huron, Erie and Ontario, forms one of the great river systems of the world, having a length of 2,100 m. from the source of the river St. Louis (which rises near the source of the Mississippi and falls into the head of Lake Superior) to Cape Gaspe, where it empties into the Gulf of St. Lawrence. The river is here considered as rising at the foot of Lake Ontario, where the name St. Lawrence is first applied to it.
The river, to the point where it crosses 45° N. in its north easterly course, forms the boundary line between the State of New York and the province of Ontario; thence to the sea it is wholly within Canadian territory, running through the province of Quebec. At Point des Monts, 26o m. below Quebec, it is 26 m. wide, and where it finally merges into the Gulf of St. Lawrence, 15o m. farther on, it is 90 m. wide, this stretch being broken by the large island of Anticosti, lying in the mouth. The character of the river banks varies with the geological formations through which it runs. Passing over the Archaean rocks of the Laurentian from Kingston to Brockville the shores are very? irregular, and the river is broken up by protrusions of granite and gneiss into a large number of picturesque islands, "The Thou sand Islands," frequented as a summer resort. From Brockville to Montreal the river runs through flat-bedded Cambro-Silurian limestones, with rapids at several points, which are run by light draught passenger boats. For the up trip the rapids are avoided by canalization. From Montreal to Three Rivers the course is through an alluvial plain over-lying the limestones, the river at one point expanding into Lake St. Peter, 20 m. long by 1 o m. wide, with a practically uniform depth of io feet. Below Three Rivers the banks grow gradually higher until, after passing Quebec through a cleft in slate rocks of Cambrian age, the river widens, washing the feet of the Laurentian mountains on its north shore; while a more moderately hilly country, terminating in the Shick shock mountains of the Gaspe Peninsula, skirts its south shore.
the new Welland canal of the same depth leads to the Upper Lakes.
In the stretch between Montreal and Quebec the ship channel is a national work, and improvements have been undertaken to secure everywhere a minimum depth of 3o ft. and a width of 450 feet. The river from Kingston to the sea is well supplied with aids to navigation. In the dredged portions lights are arranged in pairs of leading lights on foundations sufficiently high and solid to resist the pressure of ice movement, and there is an elaborate system of fog alarms, lighted and other buoys, as well as tele graphic, wireless and telephonic communication, storm signal, weather and ice-reporting stations and a life-saving service.
Montreal, at the head of ocean navigation, the largest city in Canada, is an important distributing centre for all points in western Canada, and enjoys an extensive shipping trade with the United Kingdom. Quebec is the summer port used by the largest steamers in the Canadian trade. There are numerous flourishing towns on the river, from Kingston, a grain transfer ring port, to the sea. Large quantities of lumber are handled at mills along the river.
A natural highway between all points west of the Maritime Provinces and Europe, the St. Lawrence permits ocean traffic to penetrate i,000 m. into the heart of the country. It is, moreover, the shortest freight route from the Great Lakes to Europe. From Buffalo to Liverpool via New York involves rail or barge canal transport of 496 m. and an ocean voyage of 3,034 nautical miles. Via Montreal there is a 14-ft. transport of 348 m. and river and ocean voyage of 2,772 nautical miles. From Quebec to Liverpool by Cape Race is 2,801 nautical miles, while the route by Belle Isle, more nearly a great circle course, usually taken between July and October, is only 2,633 nautical miles. On the other hand the St. Lawrence is not open in winter and the average time be tween the arrival of the first vessel at Montreal from sea and the departure of the last ocean vessel is seven months. From Kingston to Quebec the river freezes every winter, except at points where the current is rapid. Below Quebec, although there is border ice, the river never freezes. Efforts have been made to lengthen the season of navigation by using specially constructed steamers to break the ice ; and it is claimed that the season of navigation could be materially lengthened, and winter floods pre vented by keeping the river open to Montreal. Winter ferries are maintained at Quebec, between Prince Edward island and Nova Scotia, and between Newfoundland and Sydney, Cape Breton.