Bay of Fundy

Fundy National Park

Alma, New Brunswick, Can.

Sept. 14, 2001

Fundy National Park is a beautiful park located in the town of Alma, New Brunswick. The 206 square kms protected in Fundy is a sample of the Maritime Acadian Highlands. This includes an area from the Bay of Fundy shoreline with its spectacular tides to the moist forest covering the rolling plateau cut by deep valleys and fast-flowing streams. We chose to stay in a campground in the park and it was lovely. In addition to the beautiful hills and streams one of the biggest draws to the park is the Bay of Fundy. The Bay of Fundy has some of the greatest rise and fall of tides of anywhere in the world. To understand why this happens we have to look first at what causes tides. Tides are affected by the pull of the moon. The moon's gravity pulls everything on the earth slightly towards it. Large bodies of water, such as oceans, move enough that we can detect their rise and fall. The Atlantic Ocean tide rises by 1m (approximately 3 ft.), and depending on the local shoreline geography, this tide can be exaggerated (as here in the Bay of Fundy) or diminished to the point where it is unnoticeable. The moon is not the only celestial body that pulls the water on the earth. The sun's gravity pulls the water too. the sun provides 17% of the force in the Bay of Fundy. We may wonder why the tide is later each day. The earth revolves in 24 hours returning Alma to its starting position, which is a little short of where the moon is. This means that the earth has to revolve an additional 50.5 minutes for Alma to catch up to the moon's new position. Since high tide follows the moon, high tide is almost an hour later each day. Each day usually has two high and two low tides. There is a high tide directly under the moon and another on the opposite side of the earth. At any given time, each point on the earth is a different distance from the moon and so experiences slightly different amounts of gravitational pull. Water slides slightly over the surface of the planet in response to this varying force and accumulates in high tides at two locations. Understanding all of this, we must next ask ourselves why does the Bay of Fundy have such giant tides. One of the major reasons is the length of the bay. As the tide rises in the Atlantic every 12.5 hours, due to the moon's gravitational pull, it pours a huge surge of water into the mouth of the Bay of Fundy. This causes the water in the bay to rock up in the bay and back to the mouth---just like the sloshing of water in a bathtub. The Bay of Fundy's 13-hour period, or seiche (pronounced "sesh", meaning the rocking of liquid in a basin), almost equals the time between the high tides in the Atlantic Ocean. Imagine giving a gentle push to a child on a swing. Just a very small push is required to keep the swing moving. Similarly, the bay's seiche is sustained by a well-timed pulse from the ocean tides. This resonance effect is the secret of Fundy's giant tides.Next we need to look at whether the shape of the bay adds to the giant tides. The shape of the Bay of Fundy is a secondary factor causing the bay's giant tides. Shaped like a funnel, the Bay of Fundy is wide and deep at the mouth but becomes narrower and shallower at the head. This causes incoming tides to be forced higher as they approach the head of the bay.

Although it takes only a few seconds for a slosh of water to move from one end of a bathtub to the other, it takes about 13 hours for a swell of water to rock from the mouth of the bay to the head of the bay and back again. Although it's difficult to portray via pictures the power of nature in the tidal change at the Bay is simply awesome. For me, it reminded me once again of how small man is, when facing the majesty of nature. We really enjoyed the Park and the Bay and would highly recommend it to anyone who enjoys nature.

Good Luck! Have Fun! and Stay Safe!