Information below graciously provided courtesy of Niagara Parks
Ice Age History of the Niagara River and Whirlpool Rapids
The Niagara River, as is the entire Great Lakes Basin of which the river is an integral part, is a legacy of the last Ice Age. 18,000 years ago southern Ontario was covered by ice sheets 2-3 kilometers thick. As they advanced southward the ice sheets gouged out the basins of the Great Lakes. Then as they melted northward for the last time they released vast quantities of meltwater into these basins. Our water is "fossil water"; less than one percent of it is renewable on an annual basis, the rest leftover from the ice sheets.
The Niagara Peninsula became free of the ice about 12,500 years ago. As the ice retreated northward, its meltwaters began to flow down through what became Lake Erie, the Niagara River and Lake Ontario, down to the St. Lawrence River, and, finally, down to the sea. There were originally 5 spillways from Lake Erie to Lake Ontario. Eventually these were reduced to one, the original Niagara Falls, at Queenston-Lewiston. From here the Falls began its steady erosion through the bedrock.
However, about 10,500 years ago, through an interplay of geological effects including alternating retreats and re-advances of the ice, and rebounding of the land when released from the intense pressure of the ice (isostatic rebound), this process was interrupted. The glacial meltwaters were rerouted through northern Ontario, bypassing the southern route. For the next 5,000 years Lake Erie remained only half the size of today, the Niagara River was reduced to about 10% of its current flow, and a much-reduced Falls stalled in the area of the Niagara Glen.
About 5,500 years ago the meltwaters were once again routed through southern Ontario, restoring the river and Falls to their full power. Then the Falls reached the Whirlpool.
It was a brief and violent encounter, a geological moment lasting only weeks, maybe even only days. In this moment the Falls of the youthful Niagara River intersected an old riverbed, one that had been buried and sealed during the last Ice Age. The Falls turned into this buried gorge, tore out the glacial debris that filled it, and scoured the old river bottom clean. It was probably not a falls at all now but a huge, churning rapids. When it was all over it left behind a 90-degree turn in the river we know today as the Whirlpool, and North America's largest series of standing waves we know today as the Whirlpool Rapids.
The Falls then re-established at about the area of the Whirlpool Rapids Bridge upriver to our right, and resumed carving its way through solid rock to its present location.
Straddling the Canadian-United States International Border and both in the Province of Ontario
and the State of New York, Niagara Falls attracts some 12 Million tourists to her majestic
awesome beauty each year.
The Niagara is a fairly young river, only 12,000 years old!, a microsecond in geological time. The
Niagara Escarpment, which was created by erosion is much older. The glaciers pressed down on
the land during the last ice age and laid down layers of sediment, then the slow process of erosion
of ice and water ate at the surface of the escarpment
.
The mighty river plunges over a cliff of dolostone and shale. Niagara Falls is the second largest
falls on the globe next to Victoria Falls in southern Africa.
One fifth of all the fresh water in the world lies in the four Upper Great Lakes-Michigan, Huron,
Superior and Erie. All the outflow empties into the Niagara river and eventually cascades over
the falls.
At the bottom of the falls, the water travels 15 miles over many gorges until it reaches the fifth
Great Lake-Ontario. The land between the lakes does not slope at an even grade, but forms a
spectacular drop approximately the same height as a 20 story building and this is known as the
"Niagara Escarpment" Two billion years ago it was buried under a blanket of ice.
As the years past, the process of erosion took place, (and still does) five distinct 'gorges' were
formed-Lewiston Brange Gorge, Old Narrow Gorge, Upper & Lower Great Gorges and the
Whirlpool Narrow Gorge.
Approximately 500 years ago the river encountered an obstacle that caused it to 'split into two
death in the winter of 1780). This was the original sediment left from a vanished Lake Tonawanda
(an Indian name).
On the eastern part of the island, the American Falls took shape, the Horseshoe Falls, is on the
western side, where the river angles some 90 degrees.
The water flow on the American side of the falls is much less in strength because of Goat Island,
whereas Horseshoe Falls has no obstruction to divert it.
It should be noted that a third much narrower falls exists. Over the years these falls have been
called at different times; Luna Falls, Iris Falls and is currently named Bridal Veil Falls.
Man has not been able to completely control the flow of the water over the falls, even modern
engineers have tried. Much of the water today is fed through underground channels and pipes to
nearby hydro electric power stations.
