Bore is a wall of swift-running water formed in a bay or river mouth by a rapidly rising tide. Such tides occur in shallow river mouths and bays where there is a wide range between high and low tides. The incoming tide builds up into a wall of water 11/2 to nearly 30 feet (0.5 to 9 meters) high. The largest bore in the world occurs in the Qiantang River, near Hangzhou, China. A large bore also occurs in the Amazon River in South America. In North America, a bore occurs in the Petitcodiac River in New Brunswick. That river empties into the Bay of Fundy. In the United Kingdom, a bore called the Severn Bore sweeps up the River Severn at the head of the Bristol Channel. See also Amazon River ; Bay of Fundy ; Tide .
