This conversion of tidal flats into rich farmland began with Acadian settlers in the seventeeth century. Today long dykes and thousands of hectares of productive level fields may be seen in the vicinity of Grand Pre, Wolfville, Port Williams and Canard. A bore forms where the incoming tide pushes its way upstream against the outgoing freshwater flow of the river. Three hours later the spectacle pauses, and then begins flowing in the opposite direction. The Mystery in the Moon Tides were known to the ancients, but an understanding of their origin came only three centuries ago with the publication of Issac Newton's Principia.
Tides originate in the fact that the force of gravity decreases with distance from a massive body.
Similarly, Earth itself accelerates more than the waters on the far side and falls ahead of these waters. Thus two aqueous bulges are produced, one on the side of Earth facing the Moon, and one on the side facing away from the Moon. As Earth rotates on its axis beneath these two bulges, the rise and fall of the oceans results. If Earth had not rigidity, the entire planet would flex freely in the same fashion, the ocean bottoms would rise and fall too, and there would be virtually no water tides. The very existence of the tides indicates that on a time scale of several hours, our planet displays considerable rigidity.