Bore

Bore, Tidal, the heaping up of the tidal waters in a narrowing channel, generally the estuary of a river. In the Trent, where it reaches Nottingham, it is called the aegir, from a Scandinavian river-god. In the Severn it is a wave 9 feet high; in the Seine, where it is called mascaret, 10 feet, with a velocity of 13 miles an hour; in the Amazon, where it is called pororoca, 12 or 13 feet; in the Hooghly, 20 to 25 feet; and in the Tsien-tang, 30 feet, with a velocity of 25 miles per hour. Notable bores also occur in the Elbe, Weser, Dordogne, Garonne, and Orinoco.