Wisconsin Glacier in NiagaraThe Niagara Escarpment was covered with a sheet of ice 2 – 3 kilometers thick (Wisconsin Glacier) 23,000 – 12,000 years ago.
The last glacial ice age occurred during three distinct periods of time during the past 65,000 years. The glacier originated east of Hudson Bay in northern Quebec and Labrador. This great glacier was known as “the Wisconsin Glacier”.
The early Wisconsin Glacier covered the Niagara District and most of the northern North America 65,000 years ago. This glacier remained for a period of approximately 15,000 years before retreating 50,000 years ago.
The middle Wisconsin Glacier advanced again over the Niagara District 40,000 years ago. It remained for approximately 8,000 years before retreating 32,000 years ago.
The late Wisconsin Glacier advanced again 20,000 years ago. It remained for approximately 8,000 years before beginning its final retreat 12,000 years ago.
The plain of the lowest beach was 122 – 153 meters (400 – 500 feet) above present Lake Ontario (Lake Iroquois).
As the Glacier retreated, the water levels slowly lowered forming four lakes:
Glacial Lake Algonquin – ( area including Lake Superior, Lake Michigan and Lake Huron)
Glacial Lake Warren – small (Lake Erie)
Glacial Lake Iroquois – small (Lake Ontario)
Glacial Lake Tonawanda – area western New York
Glaciers ranged up to 4.8 kilometers (3 miles) thick. Ice at 1.2 kilometers (1 mile) thick would exert a pressure of 150 tons per square foot. It is estimated that the weight of the glacier depressed the earth 61 meters ( 200 feet). When the glacier retreated the land began to rise in what is referred to as glacial rebound.
As the late Wisconsin Glacier retreated northward, it created several outlets:
An outlet from Lake Algonquin (Lake Huron) to Lake Iroquois (Lake Ontario)
An outlet from Lake Algonquin (Lake Huron) through Lake Nippissing to the Ottawa Valley
An outlet from Lake Iroquois (Lake Ontario) through the Mohawk Valley (Rochester) to the Hudson River
The rising of the lands from glacier rebound finally cut off these outlets with the exception of the Niagara River.
During the period of glaciations and shortly afterwards, the climate in Niagara was arctic. Vegetation was tundra and arctic fauna.
Glacial Lake IroquoisLake Iroquois (Lake Ontario) was nearly the same depth as Lake Warren (Lake Erie). Following the retreat of the middle Wisconsin Glacier and ancient lake which occupied the present Lake Ontario basin was created. This Lake was called Lake Lundy. After the waters of Lake Lundy fell due to the reflex action of the land, it became a smaller lake named Lake Iroquois.
The depth of Lake Iroquois was much lower initially when Iroquois beach was created. The shoreline of Lake Iroquois was carbon dated at 12,000 years old with a degree of accuracy of plus or minus 450 years.
During the life of Lake Iroquois the northern shore rebounded at a greater amount than the southern shore. This resulted in the water levels continually rising along the southern shore causing increased erosion along the edge of the Niagara Peninsula.
Lake Iroquois was a pro-glacial lake. The northern shore of this lake was the southern edge of the retreating glacier.
The waters of glacial Lake Iroquois were held back by the ice of the giant glacier which lay across the St. Lawrence valley to the east. The only outlet for this lake was at Rome and Utica, New York where the water exited to the ocean through the Mohawk and Hudson River Valley.
Later this route shifted to a route north of the Adirondacks through the Champlain Valley. When this happened, the water level in Lake Iroquois dropped 15 meters (50 feet). When the Wisconsin Glacier had retreated north of the St. Lawrence Valley, Lake Iroquois’s water level dropped to within several years to sea level.
Over the past ten thousand years, the lake water level has risen to its present level as the eastern end of current Lake Ontario continues its post glacial rebound uplift.
During the past 100 years, the post glacial rebound at the eastern end of Lake Ontario has resulted in the water level at the western end of this lake to rise 0.3 meters.
Glacial Lake LundyFifty thousand years ago, a broad glacier pressed over the Niagara Escarpment holding back the melt waters to the South. This formed a large glacial lake named Lake Lundy.
As the glacier retreated northward, a lower water outlet was created at Rome, New York which resulted in the rapid draining of Lake Lundy. For a very long time after the glacier retreated, it held back the melt waters to such a great level that the Niagara Peninsula and Escarpment were covered by a large lake (Lake Ontario, Lake Huron and Lake Erie were one).
With the retreat of the glacier, the rising land separated both Lake Ontario and Lake Erie.
Glacial Lake TonawandaGlacial Lake Tonawanda was created with the retreat of the last Wisconsin Glacier. The lake was located east of the Niagara River and covered most of the western New York area to Rochester.
Although large in area, it was shallow. The water along the eastern shore at Rochester, New York was only four feet deep.
At first Lake Tonawanda’s only water outlet was the same as Lake Lundy, at Rome New York. Rising land in the east cut off this outlet, forcing waters to seek other outlets.
Lake Tonawanda had five water outlets over the 644 kilometer (400 mile) Niagara Escarpment. These outlets were located in Holley New York, Medina New York, Gasport New York, Lockport New York and Lewiston New York.
Only the outlet to become the main spillway was at Queenston – Lewiston. Here the draining waters flowed over the Niagara Escarpment. It is here where the water falls of Niagara were born. This water course continues to be the main outlet which exists today.
Lake Erie was still very large and the width of the Niagara River was much wider than it is today. The entire area where the Falls are today was under water. The water depth was 9 – 12 meters (30 -40 feet). The slope (glacial moraine) on the west edge of Queen Victoria Park (on top of which the Skylon Tower and Minolta Tower are now situated) was a river bank about 12,000 years ago before the gorge was created.
The retreating glacier was the cause of the reduction in size of this much wider and much deeper glacial river known as the St. David’s River into what is now a smaller and shallower river known as the Niagara River.
As the glacier retreated north, the water followed to the much lower land recently uncovered. This caused the draining of the Lake Erie basin and Lake Tonawanda. As these waters drained, the river became much smaller resulting in the uncovering of land such as Niagara Falls, New York. Also uncovered was the present Grand Island and Three Sisters Islands and Queen Victoria Park in Niagara Falls, Ontario.
Birth of Niagara Falls
A view of Roy Terrace – the birth site of Niagara Falls at the Niagara Escarpment (Queenston-Lewiston)
As the Glacier retreated, the upper Lakes began draining into the lower lakes at five to six locations across the Niagara Escarpment. Twelve thousand years ago, the Niagara River ultimately became the main water outlet over the Niagara Escarpment. The waters of a much larger Lake Erie began to flow over the escarpment into a larger Lake Iroquois (Lake Ontario).
The Niagara River began to flow from the Lake Erie basin through Lake Tonawanda and down the present path of the river to the escarpment.
At this time, the lake plain from Queenston to Niagara on the Lake was covered with the waters of Lake Iroquois (Lake Ontario). The height of the lake was within 11 meters (35 feet) of the average level of the Niagara Escarpment at Queenston, Ontario.
The height of the initial Niagara Falls was only 11 meters (35 feet) as it flowed over the Niagara Escarpment at Queenston to the waters of Lake Iroquois below. As the water flowed over the escarpment to the water below, the water began eating through the glacial material and the limestone rock of the Niagara Escarpment to begin the formation of the Niagara Gorge.
The site of the birth of Niagara Falls was discovered by a geologist named Doctor Roy Spencer and today this site is known as “Roy Terrace”.
The flow rate of water back then was only twenty-five percent of the present flow rate. Scientists have calculated that the volume of water flowing over the Falls initially was 37,500 cubic feet per second.
As the Glacier continued receding further north, it opened silt barriers allowing waters to drain to the ocean resulting in the lowering of the water levels of Lake Iroquois (Lake Ontario).
The rising of the northern crust of the earth, a reflex action to the weight of a Glacier a half a mile or more thick, caused a faster outpouring of Lake Iroquois (Lake Ontario). The lower 11.2 kilometer (7 mile) stretch of the Niagara River to Lake Ontario was once 19 kilometers (12 miles) long.
Scientists have suggested that the eastern part of the North American continent is still in the process of tilting as part of the glacial reflex action. As the crust of the earth rises along the eastern seaboard the water flowing from the Great Lakes system will become slower.
The beginning of the last glacial retreat began 12,000 years ago. The third and last Wisconsin Glacier retreated east of Hudson Bay in Labrador. As the glacier retreated, the land began to rise. The crust of earth rocks are elastic when bent over large sections.
(This story is brought to you courtesy of Niagara Falls Thunder Alley)
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