The St. Lawrence is an enormous river, having much the largest estuary
of any river on the globe, the tidal current flowing five hundred
miles up the stream, and its mouth spreading ninety-six miles wide. It
is the outlet of the greatest body of fresh water in existence,
draining seven vast lakes--Nepigon, Superior, Michigan, Huron, Erie,
Ontario and Champlain--besides myriads of smaller ones, including the
Central New York lakes, hundreds in the Adirondack forests, and
thousands in the vast Canadian wilderness. The St. Lawrence basin
covers a territory of over four hundred thousand square miles, and has
been computed as containing more than half the fresh water on the
planet. The main St. Lawrence river is seven hundred and fifty miles
long from Lake Ontario to the head of the Gulf, while the total length
of the whole system of lakes and rivers is over two thousand miles,
and has been computed by some patient mathematician to contain a mass
of fresh water equal to twelve thousand cubic miles, of which one
cubic mile goes over Niagara Falls every week. The early geographers
usually located the head of the system in Lake Nepigon, north of
Superior, but it is thought the longer line to the ocean is from the
source of St. Louis River, flowing through Minnesota into the
southwestern extremity of Lake Superior at Duluth. The bigness of the
wonderful St. Lawrence is shown in everything about it. Thoreau, who
was such a keen observer, has written that this great river rises near
another "Father of Waters," the Mississippi, and "issues from a
remarkable spring, far up in the woods, fifteen hundred miles in
circumference," called Lake Superior, while "it makes such a noise in
its tumbling down at one place (Niagara) as is heard all round the
world." The geologists, however, who usually upturn most things,
declare that it did not always reach the sea as now. Originally the
St. Lawrence, they say, flowed into the ocean by going out through the
Narrows in New York harbor, and its immense current broke the passage
through the West Point Highlands in a mighty stream, compared with
which the present Hudson River is a pigmy. Professor Newberry writes
that during countless ages this enormous river, which no human eyes
beheld, carried off the surplus waters of a great drainage area with a
rapid current cutting down its gorge many hundred feet in depth,
reaching from the Lake Superior basin to the Narrows, where it
dispersed in a vast delta, debouching upon a sea then much lower in
level than now, and having its shore-line about eighty miles southeast
of New York. By some stupendous convulsion this channel was changed,
drift banked up the old valley of the Mohawk, and the outflow was
deflected from the northeast corner of Lake Ontario into the present
shallow and rocky channel, filled with islands and rapids, followed by
the St. Lawrence down to Montreal.
The system of navigable water ways from Duluth and Port Arthur on Lake
Superior to the Strait of Belle Isle is twenty-two hundred miles long.
At Lake Ontario the head of the St. Lawrence River is two hundred and
thirty-one feet above the sea level, and its current descends that
distance to tidewater chiefly by going down successive rapids. There
are ship canals around these rapids and around Niagara Falls, and also
connecting various lakes above. The Sault Sainte Marie locks and
canals, at the outlet of Lake Superior, have already been described.
The admirable systems conducting navigation around the rapids in the
river below Lake Ontario also carry a large tonnage. Between
Ogdensburg and Montreal, a distance of about one hundred and twenty
miles, the navigation of forty-three miles is through six canals of
various lengths around the rapids, each having elaborate locks. The
Gulf of St. Lawrence is also constructed upon an enormous scale,
covering eighty thousand square miles, and with the lower river
having a tidal ebb and flow of eighteen to twenty-four feet. The mouth
of the river and head of the Gulf are usually located at Cape Chatte,
far below the Saguenay, and from the Cape almost up to Quebec the
river is ten to thirty miles wide. In front of Quebec it narrows to
less than a mile, while above, the width is from one to two and a half
miles to Montreal, expanding to ten miles at Lake St. Peter, where the
tidal influence ceases. Above Montreal the river occasionally expands
into lakes, but is generally a broad and strongly flowing stream with
frequent rapids. The largest ocean vessels freely ascend to Montreal,
at the head of ship navigation, Lachine rapids being just above the
city. For several months in winter, however, ice prevents.