The Horseshoe Falls drop about 188 feet (57 m), while the height of the American Falls varies between 70–100 feet (21–30 m) because of the presence of giant boulders at its base. The larger Horseshoe Falls are about 2,600 feet (790 m) wide, while the American Falls are 1,060 feet (320 m) wide. The distance between the American extremity of the Niagara Falls and the Canadian extremity is 3,409 feet (1,039 m).
The volume of water approaching the falls during peak flow season may sometimes be as much as 225,000 cubic feet (6,400 m3) per second. The average annual flow rate is 85,000 cubic feet (2,400 m3)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 100,000 cubic feet (2,800 m3) per second of water traverses the falls, some 90% of which goes over the Horseshoe Falls, while the balance is diverted to hydroelectric facilities. This is accomplished by employing a weir with movable gates upstream from the Horseshoe Falls. The falls flow is further halved at night, and during the low tourist season in the winter, remains a minimum of 50,000 cubic feet (1,400 m3) per second. Water diversion is regulated by the 1950 Niagara Treaty and is administered by the International Niagara Board of Control (IJC).
The verdant green colour of the water flowing over the 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 itself. The current rate of erosion is approximately 1 foot (0.30 m) per year down from a historical average of 3 feet (0.91 m) per year. It is estimated that 50,000 years from now, even at this reduced rate of erosion, the remaining 20 miles (32 km) to Lake Erie will have been undermined and the falls will cease to exist.....
Geology..
The features that became Niagara Falls were created by the Wisconsin glaciation about 10,000 years ago. The same forces also created the North American Great Lakes and the Niagara River. All were dug by a continental ice sheet that drove through the area, deepening some river channels to form lakes, and damming others with debris.Scientists argue that there is an old valley, buried by glacial drift, at the approximate location of the present Welland Canal.
Aerial view of Niagara Falls, showing parts of Canada (left) and the United States (upper right).
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. Because of the interactions of three major rock formations, the rocky bed did not erode evenly. The top rock formation was composed of erosion-resistant limestone and Lockport dolostone. That hard layer of stone eroded more slowly than the underlying materials. The aerial photo on the right clearly shows the hard caprock, the Lockport Formation (Middle Silurian), which underlies the rapids above the falls, and approximately the upper third of the high gorge wall.
Immediately below the hard-rock formation, comprising about two thirds of the cliff, lay the weaker, softer, sloping Rochester Formation (Lower Silurian). This formation was composed mainly of shale, though it has some thin limestone layers. It also contains ancient fossils. In time, the river eroded the soft layer that supported the hard layers, undercutting the hard caprock, which gave way in great chunks. This process repeated countless times, eventually carving out the falls.
Submerged in the river in the lower valley, hidden from view, is the Queenston Formation (Upper Ordovician), which is composed of shales and fine sandstones. All three formations were laid down in an ancient sea, their differences of character deriving from changing conditions within that sea.
About 10,900 years ago, the Niagara Falls was located between present-day Queenston, Ontario, and Lewiston, New York, but erosion of their crest has caused the waterfalls to retreat approximately 6.8 miles (10.9 km) southward. The Horseshoe Falls, which are approximately 2,600 feet (790 m) wide, have also changed their shape through the process of erosion; evolving from a small arch, to a horseshoe bend, to the present day gigantic inverted V. Just upstream from the falls' current location, Goat Island splits the course of the Niagara River, resulting in the separation of the mostly Canadian Horseshoe Falls to the west from the American and Bridal Veil Falls to the east. Engineering has slowed erosion and recession...
History..
There are differing theories as to the origin of the name of the falls. According to Iroquoian scholar Bruce Trigger, "Niagara" is derived from the name given to a branch of the locally residing native Neutral Confederacy, who are described as being called the "Niagagarega" people on several late 17th century French maps of the area.According to George R. Stewart, it comes from the name of an Iroquois town called "Ongniaahra", meaning "point of land cut in two" Henry Schoolcraft reported:
"Niagara Falls. This name is Mohawk. It means, according to Mrs. Kerr, the neck; the term being first applied to the portage or neck of land, between lakes Erie and Ontario. By referring to Mr. Elliott's vocabulary, (chapter xi) it will be seen that the human neck, that is, according to the concrete vocabulary, his neck, is onyara. Red Jacket pronounced the word Niagara to me, in the spring of 1820, as if written O-ne-au-ga-rah."
A number of figures have been suggested as first circulating an eyewitness description of Niagara Falls. The Frenchman Samuel de Champlain visited the area as early as 1604 during his exploration of Canada, and members of his party reported to him the spectacular waterfalls, which he described in his journals. The Finnish-Swedish naturalist Pehr Kalm explored the area in the early 18th century and is credited with the first scientific description of the falls. The consensus honoree for the first description is the Belgian missionary Louis Hennepin, who observed and described the falls in 1677, earlier than Kalm, after traveling with the explorer René Robert Cavelier, Sieur de la Salle, thus bringing the falls to the attention of Europeans. Further complicating matters, there is credible evidence that the French Jesuit Reverend Paul Ragueneau visited the falls some 35 years before Hennepin's visit, while working among the Huron First Nation in Canada. Jean de Brébeuf also may have visited the falls, while spending time with the Neutral Nation........
Man and woman on Canadian side of Niagara Falls, circa 1858
Arthur Parton, Niagara Falls (Brooklyn Museum)
View of the falls, 1913.
During the 18th century, tourism became popular, and by mid-century, it was the area's main industry. Napoleon Bonaparte's brother Jérôme visited with his bride in the early 19th century. In 1837 during the Caroline affair a rebel supply ship, the Caroline, was burned and sent over the falls. In March 1848, ice blockage caused the falls to stop; no water (or at best a trickle) fell for as much as 40 hours. Waterwheels stopped, mills and factories simply shut down for having no power. Later that year demand for passage over the Niagara River led to the building of a footbridge and then Charles Ellet's Niagara Suspension Bridge. This was supplanted by German-born John Augustus Roebling's Niagara Falls Suspension Bridge in 1855. After the American Civil War, the New York Central railroad publicized Niagara Falls as a focus of pleasure and honeymoon visits. With increased railroad traffic, in 1886, Leffert Buck replaced Roebling's wood and stone bridge with the predominantly steel bridge that still carries trains over the Niagara River today. The first steel archway bridge near the falls was completed in 1897. Known today as the Whirlpool Rapids Bridge, it carries vehicles, trains, and pedestrians between Canada (through Canadian Customs Border Control) and the U.S.A. just below the falls. In 1912 much of the water coming over the American Falls froze, though there was still a trickle and the falls ran at the other two sites.
In 1941 the Niagara Falls Bridge Commission completed the third current crossing in the immediate area of Niagara Falls with the Rainbow Bridge, carrying both pedestrian and vehicular traffic between the two countries and Canadian and U.S. customs for each country.
After the First World War, tourism boomed again as automobiles made getting to the falls much easier. The story of Niagara Falls in the 20th century is largely that of efforts to harness the energy of the falls for hydroelectric power, and to control the development on both sides that threaten the area's natural beauty.
A team from the U.S. Army Corps of Engineers dammed the falls in June 1969 in order to clear rock from the base of the falls. Rockslides had caused a significant buildup of rock at the bottom of the American side of the falls, and the engineers were to clean up the rock and repair some faults to prevent eventual erosion of the American side of the waterfall. A temporary dam was constructed to divert the flow of water to the Canadian side; the dam measured 600 feet (180 m) across and was made of nearly 30,000 tons of rock. The engineers cleared the rock debris and tested for safety, finishing the project in November of that year. Water flow was restored on November 25, 1969.
Before the late 20th century the northeastern end of the Horseshoe Falls was in the United States, flowing around the Terrapin Rocks, which was once connected to Goat Island by a series of bridges. In 1955 the area between the rocks and Goat Island was filled in, creating Terrapin Point. In the early 1980s the United States Army Corps of Engineers filled in more land and built diversion dams and retaining walls to force the water away from Terrapin Point. Altogether 400 feet (120 m) of the Horseshoe Falls was eliminated, including 100 feet (30 m) on the Canadian side. According to author Ginger Strand, the Horseshoe Falls is now entirely in Canada. Other sources say "most of" Horseshoe Falls is in Canada.............