Niagara Falls [ a ] is a group of three waterfalls at the southern end of Niagara Gorge , spanning the border between the province of Ontario in Canada and the state of New York in the United States. 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. Lawrence River , the combined falls have the highest flow rate of any waterfall in North America that has a vertical drop of more than 50 m ft.
During peak daytime tourist hours, more than , m 3 5. Balancing recreational, commercial, and industrial uses has been a challenge for the stewards of the falls since the 19th century. 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. Horseshoe Falls is about 57 m ft high, [ 4 ] while the height of the American Falls varies between 21 and 30 m 69 and 98 ft because of the presence of giant boulders at its base.
The larger Horseshoe Falls is about m 2, ft wide, while the American Falls is m 1, ft wide. The distance between the American extremity of Niagara Falls and the Canadian extremity is 1, m 3, ft. This is accomplished by employing a weir β the International Control Dam β with movable gates upstream from Horseshoe Falls. Water diversion is regulated by the Niagara Treaty and is administered by the International Niagara Board of Control. The Niagara River is an important bird area due to its impact on Bonaparte's gulls , ring-billed gulls , and herring gulls.
Several thousand birds migrate and winter in the surrounding area. The features that became Niagara Falls were created by the Wisconsin glaciation about 10, years ago. When the ice melted, the upper Great Lakes emptied into the Niagara River, which followed the rearranged topography across the Niagara Escarpment. In time, the river cut a gorge through the north-facing cliff, or cuesta.
The caprock formation is composed of hard, erosion-resistant limestone and dolomite of the Lockport Formation Middle Silurian. That hard layer of stone eroded more slowly than the underlying materials.
