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.
Laura