Situated between the state of New York and the province of Ontario, Niagara Falls is one of the most spectacular natural wonders on the North American continent. The falls are on the Niagara River, which flows between the United States and Canada from Lake Erie to Lake Ontario. The falls are about 17 miles (27 kilometers) northwest of Buffalo, N.Y. The industrial city and tourist center of Niagara Falls, N.Y., is adjacent to the American side of the falls. Niagara Falls, Ont., is across the river.

The falls are divided into two parts by Goat Island. The larger portion, on the southwest side, is the Canadian falls, known as the Horseshoe Falls. It measures 2,600 feet (790 meters) along its curve and drops 162 feet (49.4 meters). The smaller American falls is northeast of Goat Island. It is 1,000 feet (305 meters) across and drops about 167 feet (51 meters). Between the American falls and Goat Island are the small Luna Island and the small Luna, or Bridal Veil, Falls.

Just before flowing over the ledge, the American stream is only about 3 1/2 feet (1 meter) deep. The Canadian stream is about 20 feet (6 meters) deep and carries some 95 percent of the Niagara River's water.

Every minute about 12,000,000 cubic feet (340,000 cubic meters), or 379,000 tons, of water pours in torrents over the cliffs of the falls of Niagara. As the water plunges from the brink of the falls, it fills the air with a silvery mist, which under the sunlight displays many rainbows. The plunging water also sends out a never-ending roar as it strikes the bottom. For this reason the Iroquois Indians called the cataract Niagara, meaning “thunder of waters.”

The plunging water has worn the lower rocks away so that there are caves behind the sheets of water of both falls. Sightseers may enter the Cave of the Winds at the foot of the American falls and get an unusual view. The Canadian falls has carved a plunge basin 192 feet (59 meters) deep.

Both the United States and Canadian governments have built parks, viewing platforms, paths, and highways. The Niagara Reservation State Park was established in 1885 and is New York's oldest state park. It includes an observation tower, elevators that descend into the gorge at the base of the American falls, and boat trips into the waters at the base of the Horseshoe Falls.

The park area has long been a tourist site and a favorite spot for couples to spend their honeymoons. At night colored lights illuminate the falls.

Almost all the drainage from four of the Great Lakes pours over the crest of Niagara Falls. This tremendous volume of water is used to generate power in six hydroelectric plants. They develop a maximum of about 5 3/4 million horsepower, some 55 percent on the American side and about 45 percent on the Canadian. The plants draw water from the river above the falls through canals. Near each plant the water drops through penstocks to powerhouses on the Niagara River below the falls. There it turns turbine generators.

The control of Niagara Falls between the United States and Canada has long offered the world an example of international cooperation. A treaty in 1910 and later agreements fixed the amounts of water that could be diverted. An international Niagara Control Board was established in 1923.

In 1950 the two countries signed a new treaty that specified the minimum flow to be maintained over the falls. This treaty made possible greater hydroelectric development. It provides that 100,000 cubic feet (2,830 cubic meters) per second of water must flow over the falls during the tourist season in the daytime and 50,000 (1,415) at night and during the off-tourist season in the daytime. The remainder is equally divided between Canada and the United States. An average of 202,300 cubic feet (5,729 cubic meters) per second flows over the falls.

Between 1954 and 1958 the United States and Canada completed the Niagara Remedial Works Project. This enormous operation checked erosion with a gated control structure, excavations, and fills.

The Hydro-Electric Power Commission of Ontario completed the Sir Adam Beck-Niagara Generating Station No. 1 in 1925 and No. 2 in 1958. The combined capacity of the plants is 1,443,000 kilowatts.

In 1957 the United States Congress approved the construction of the Niagara Power Project by the Power Authority of the State of New York. It has a capacity of 2,190,000 kilowatts. The first electric current from the project was delivered in 1961.

How Niagara Came to Be

The falls of Niagara are about 25,000 years old. The hard rock (Lockport dolomite) at the brink of the falls is much older. It was made on the bed of an inland sea in the Silurian period, between 395 million and 430 million years ago. Gradually the limy sediment hardened to stone—either limestone or dolomite, a limestone with magnesium.

Later the Niagara region was raised in a widespread uplift centered in Michigan. Streams wore down the land. The layer of tough rock, however, resisted erosion. The edge of the deposit formed a great cliff—the Niagara escarpment. It runs west from Rochester, N.Y., between Lakes Erie and Ontario, then swings northward through the province of Ontario. It is capped by hard Niagara limestone or Lockport dolomite.

Many ages later, glaciers covered the Niagara region (see Ice Age). As the last glacier retreated, it left Lake Erie at its southern edge. Water from the lake began to spill over the Niagara escarpment into the Ontario basin below, just south of where Queenston and Lewiston now stand.

The new falls did not wear away the dolomite caprock as fast as it churned away the softer rock below. From time to time blocks of the undermined caprock broke off. The falls worked back toward Lake Erie, forming a steep-walled gorge.

Niagara's rate of cutting has changed many times. It started slowly, for at first the river drained Lake Erie only. Lakes Superior, Michigan, and Huron had a northerly outlet. The drainage changed as glaciers retreated. Water from all four lakes then poured over the falls. When the river spread to the point where the famous whirlpool now is, it reached an ancient valley that had cut into the dolomite from the west. Later the valley filled with glacial debris. The river wore away the soft material, forming the 60-acre (24- hectare) basin. The Rev. Louis Hennepin, a priest who accompanied the explorer La Salle, was the first European to view the falls of the Niagara River, in 1678. The site was of strategic use to the British and French in the struggle to control the Great Lakes. The British built Fort Schlosser there in 1761.