The tremendous tides cause the periodic rises and falls of the ocean in this area. Tides are caused by the gravitational interaction between the Earth and the Moon. The moon’s gravitational attraction causes the oceans to bulge toward the moon with another bulge occurring on the opposite side. When this bulge is coupled with the funnel shape of the Bay of Fundy the tides become extreme. Since the earth is rotating while this is happening, two large tide events happen each day.
The reversing salt-water falls occurs near Mahar Point in West Pembroke was one of the most interesting. This half-mile long set of falls is formed when the water rushes through a 300-meter gap which alternately fills and drains both Whiting and Dennys Bays. As the salt water, racing at speeds up to 25-knots, passes over jutting rocks it causes the "waterfalls" effect. The reversing falls actually are rapids, which are caused by large boulders and ledges in a narrow passage of water. The boulders and ledges, in addition to the narrow passageway between the shores of the mainland and Falls Island, form a bottleneck, causing a rise in the depth of water on the neap side of the falls. As the tidal current slows, the roar of the water gradually diminishes until at slack tide, for a short period of time, the channel is like a mirror. Gradually, the direction of the water changes and the seaweed is swept in the opposite direction, ripples appear around the jutting rocks and within ten minutes the six-hour long roar has begun again.
Reversing Falls often attracts seals and eagles as the churning waters provide abundant food that makes visiting this earthcache a special treat.
To log this Earthcache: You must visit the area and answer an earth science question. There is no container or logbook for you to sign just a beautiful and unique natural feature to observe. You must post a photo of yourself and your GPS with one of the water features in the background and then to log this cache you must record the time of your visit as it relates to the tides and what you observe, an example of a log might be, Arrived at 4:30 p.m. which was 1 hour after high tide, and the water was running upstream forming turbulence with wave up to two feet high. There were several eagles fishing at the time of our visit. Over time as the logs accumulate visitors will realize if they want to have the best view of this tidal falls phenomenon the time that they should visit. Tidal charts are available at: Tidal Charts you will want to use Eastport for reference as you will find the tide is about an hour later then Eastport.
This location is hazardous to
boaters and is off limits to swimmers!
If you enjoy this earthcache you may want to check the Maine Geological Survey located at http://www.youtube.com/watch?v=OK8VDsPKz5E&feature=relmfu They have developed a number of information sheets or field localities giving a great deal of information about geologic features. They also have a number of books and maps about Maine’s natural history/ geology that you might find interesting.