• As 14 billion tons (14 cubic kilometres) of sea water flow into Minas Basin twice daily, the Nova Scotia countryside actually tilts slightly under the immense load!
• Near mid-tide at Cape Split, one may hear the "voice of the Moon" in the form of the roar emitted by turbulent tidal currents.
• At mid-tide, the flow in Minas Channel north of Blomidon equals the combined flow of all the rivers and streams on Earth!
• Small Atlantic tides drive the Bay of Fundy/Gulf of Maine system near resonance to produce the huge tides.

"The World's Highest Tides occur twice a day in the Bay of Fundy's Minas Basin"

The tides on Earth are strongly influenced, in addition to astronomical factors, by the sizes, boundaries, and depths of ocean basins and inlets, and by Earth's rotation, winds, and barometric pressure fluctuations. Tides typically have ranges (vertical high-to-low) of a metre or two, but there are regions in the oceans where various influences conspire to produce virtually no tides at all, and others where the tides are greatly amplified. Among the latter regions are the Sea of Okhotsk, the northern coast of Australia, the English Channel, and in Canada at the Ungava Bay in northern Quebec and the Bay of Fundy between New Brunswick and Nova Scotia. The tidal ranges in these regions are of the order of 10 metres.The highest tides on Earth occur in the Minas Basin, the eastern extremity of the Bay of Fundy, where the average tide range is 12 metres and can reach 16 metres when the various factors affecting the tides are in phase (although the highest tides occur typically a day or two after the astronomical influences reach their peak).

The primary cause of the immense tides of Fundy is a resonance of the Bay of Fundy-Gulf of Maine system. The system is effectively bounded at its outer end by the edge of the continental shelf with its approximately 40:1 increase in depth. The system has a natural period of approximately 13 hours, which is close to the 12h 25m period of the dominant lunar tide of the Atlantic Ocean.
Like a father pushing his daughter on a swing, the gentle Atlantic tidal pulse pushes the waters of the Bay of Fundy-Gulf of Maine basin at nearly the optimum frequency to cause a large to-and-fro oscillation. The greatest slosh occurs at the head (northeast end) of the system. Because Earth rotates counterclockwise in the Northern Hemisphere, the tides are higher in Minas Basin (Wolfville-Truro area) than in Chignecto Bay (Amherst-Moncton area).

Although it is the gravitation of the Moon and Sun that raises the tides, the energy in the churning waters is extracted from the rotational energy of Earth spinning on its axis. Near Annapolis Royal, Nova Scotia, a tiny portion of this energy is being converted into commercial electrical energy in the only tidal power plant in the Western Hemisphere. The peak output of the Annapolis Basin generator is 20 megawatts, about 1% of Nova Scotia's electrical power capacity.

Tidal friction both lengthens the day and increases the size of the orbit of the Moon. The day is lengthening by about 1 second every 40,000 years, imperceptible on a human time scale, but of profound significance to Earth's rotation over a few billion years. If the Sun does not first incinerate our planet, in the distant future there will come a day that is as long as the lunar month (each then equal to about 40 present days) and a more distant Moon will stand stationary in the sky, as does Earth now in the lunar sky. But this situation will not endure, for solar tides will still be present and will cause the Moon to approach Earth once more.

Perhaps the most awesome display of the tides on our planet occurs at Cape Split, on the southern side of the entrance to Minas Basin (Cape Split may be reached by a pleasant two-hour walk along a popular hiking trail from the village of Scots Bay, which is a 30-minute drive north of Wolfville). Here at the time of the mid-point of an incoming tide, for a considerable distance the forest on the towering cliffs is filled with a hollow roar produced by the turbulence of the waters surging over the submarine ridges below. The currents exceed 8 knots (4m/s), and the flow in the deep, 5 km-wide channel on the north side of Cape Split equals the combined flow of all the streams and rivers of Earth (about 4 cubic kilometres per hour). Three hours later the spectacle pauses, and then begins flowing in the opposite direction.

Text by Dr. Roy Bishop