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Tides and Currents

The periodic rise and fall of the water along ocean coasts is a phenomenon familiar to all of us. Even those who have never been to the seashore have heard enough about the tides to know that they follow a rhythmic daily pattern. We also know that the tide has a profound effect on navigation and harbor construction.

It seems therefore surprising that the knowledge of tides, and the forces causing them, is of very recent origin. One of the reasons for this is that the tides in the Mediterranean - the cradle of Europe's ancient civilizations - are too small to be readily noticeable. Another is that the mechanism of tides can be understood only through knowledge of astronomical forces and the shape of the world's oceans, knowledge which was not acquired until modern times.

Canada, with its far-flung Arctic Archipelago, has more than 100,000 miles of seacoast, and it has also some of the most interesting and peculiar tides. For the guidance of ship captains and fishermen, the Canadian Federal Government began to study the tides along the eastern and western seaboards before the turn of the century, a job that has been tremendously expanded and refined by the Canadian Hydrographic Service of the Department of Fisheries and Oceans, which is the Federal Government agency charged with charting the navigable waters of Canada. 1

1 Tides in Canadian Waters, G.C. Dohler, Canadian Hydrographic Service, Department of Fisheries and Oceans © Government of Canada Publications, Cat. No. Fs 72-40/2007-E, ISBN 978-0-660-19749-4.