Niagara Falls[a] is a group of three waterfalls at the southern end of Niagara Gorge, spanning the border between the Canadian province of Ontario and the U.S. state of New York. The largest of the three is Horseshoe Falls, which straddles the international border of the two countries. It is also known as the Canadian Falls.[1] The smaller American Falls and Bridal Veil Falls lie within the United States.
Formed by the Niagara River, which drains Lake Erie into Lake Ontario, the combined falls have the highest flow rate of any waterfall in North America that has a vertical drop of more than 50 m (164 ft). During peak daytime tourist hours, more than 168,000 m3 (5.9 million ft3) of water goes over the crest of the falls every minute.[2]
Bridal Veil Falls is separated from Horseshoe Falls by Goat Island and from American Falls by Luna Island, with both islands situated in New York. Horseshoe Falls is the most powerful waterfall in North America, as measured by flow rate.[3] Niagara Falls is famed for its beauty and is a valuable source of hydroelectric power.
Balancing recreational, commercial, and industrial uses has been a challenge for the stewards of the falls since the 19th century. Niagara Falls is 27 kilometres (17 miles) northwest of Buffalo, New York, and 69 km (43 mi) southeast of Toronto, between the twin cities of Niagara Falls, Ontario, and Niagara Falls, New York. Niagara Falls was formed when glaciers receded at the end of the Wisconsin glaciation (the last ice age), and water from the newly formed Great Lakes carved a path over and through the Niagara Escarpment en route to the Atlantic Ocean.
Characteristics
The larger and taller Horseshoe Falls is about 57 m (187 ft) high,[15] while the American Falls varies between 21 and 30 metres (69 and 98 feet) in drop because of giant boulders at its base. Horseshoe Falls is about 790 m (2,592 ft) wide, while the American Falls is 320 m (1,050 ft) wide. The distance between the American extremity of Niagara Falls and the Canadian extremity is 1,039 m (3,409 ft).
The peak flow over Horseshoe Falls was recorded at 6,370 cubic metres per second (225,000 cubic feet per second).[16] The average annual flow rate is 2,400 m3/s (85,000 cu ft/s).[17] Since the flow is a direct function of the Lake Erie water elevation, it typically peaks in late spring or early summer. During the summer months, at least 2,800 m3/s (99,000 cu ft/s) of water traverse the falls, some 90% of which goes over Horseshoe Falls, while the balance is diverted to hydroelectric facilities and then on to American Falls and Bridal Veil Falls. This is accomplished by employing a weir – the International Control Dam – with movable gates upstream from Horseshoe Falls.
The water flow is halved at night and during the low tourist season in winter months, and only attains a minimum flow of 1,400 cubic metres per second (49,000 cu ft/s). Water diversion is regulated by the 1950 Niagara Treaty and is administered by the International Niagara Board of Control.[18] The verdant green color of the water flowing over Niagara Falls is a byproduct of the estimated 60 tonnes/minute of dissolved salts and rock flour (very finely ground rock) generated by the erosive force of the Niagara River.[19]
The Niagara River is an important bird area due to its impact on Bonaparte’s gulls, ring-billed gulls, and herring gulls.[20] Approximately 100,000 seagulls winter in the region, with it being common to spot 20,000 to 30,000 individuals daily between November and January. The river and waterfalls appeal to the birds due to their position on migratory routes, foraging potential, and unlikeliness to freeze over compared to other bodies of water.[21]
Future of the falls
The current rate of erosion is approximately 30 centimeters (12 inches) per year, down from a historical average of 0.9 m (3.0 ft) per year. At this rate, in about 50,000 years Niagara Falls will have eroded the remaining 32 km (20 mi) to Lake Erie, and the falls will cease to exist.[19][29][30]