|
A GEOLOGICAL HISTORY
Last updated on Monday March 05, 2012
Ancient
Seas' of Niagara
Rocks
& Sedimentary Deposits
Geography of Niagara
A view of the rock strata along the Whirlpool Rapids section of the Niagara Gorge
The Niagara Region is located on a portion of a great plain which runs east to west from the northern Laurentian Highlands (Canadian Shield) approximately 161 kilometers north of Toronto, Ontario to the southern Allegheny Plateau which form the foothills of the Adirondack Mountains and the Appalachian Mountains. The Niagara table land mass extends 100 kilometers (62 miles), both east and west from the Niagara River. This plain is a small part of the Great Lakes low lands in which Lake Superior, Lake Michigan, Lake Huron, Lake Erie and Lake Ontario lie. The areas north and south of the Great Lakes low lands are the high lands. Climate in Niagara has been similar to the current weather patterns for the past 5,000 years. Today the Great Lakes hold twenty percent of the worlds fresh water supply. Ninety-nine (99%) percent of this water is of glacial origin. The Niagara Peninsula is actually an isthmus.
The Niagara Escarpment begins in Watertown New York, USA and continues westerly along the Manitoulin Island in the Province of Ontario, Canada. It continues through Wisconsin and Illinios. It is 1,609 kilometers in length and is the weathered edge of a very ancient sea bottom. Throughout its length from Hamilton, Ontario to Watertown, New York the escarpment ranges from 183 meters (600 feet) above sea level to 189 meters (620 feet) above sea level. The Niagara Escarpment is the ultimate reason the Falls of Niagara was born. Without the escarpment, Niagara Falls may never have materialized. After millions of years, the Niagara Escarpment continues to erode in a southward direction. The Niagara Escarpment was formed and existed before glaciations. The land that is now Southern Ontario emerged from the sea of the Paleozoic Era at least 245 million years ago or more. The Ordovician and the Silurian rocks of the Niagara Escarpment are of the oldest found in Niagara dating back to 430 - 415 million years ago. The escarpment is not a fault line or a rift line but was created through erosion. It is a "cuesta". To understand the age of the Niagara Escarpment consider the following time line:
Five kilometers west of Lewiston, New York, the escarpment is so steep that it rises 73meters ( 240 feet) in 0.4 kilometers (1/4 mile). The eastern portion of the Niagara Escarpment is higher than in the west. The escarpment at Watertown, New York is 147 meters (483 feet) above sea level. The ancient uplift and rising crust of the land in the eastern portion of North America is quite noticeable. Only in Niagara can one find a gravel beach 147 meters (483 feet) above the nearest body of water.
A smaller Onondaga Escarpment runs east - west is located along the northern shoreline of Lake Erie. Consisting of Onondaga limestone cap rock, this escarpment runs through Buffalo, New York and Fort Erie, Ontario. This escarpment is most noticeable east of Buffalo, however rarely rises more than 10 meters. Substantial breaks in the Onondaga Escarpment have allowed Lake Erie waters to flow into the low lands of the Wainfleet Marsh 10,500 - 11,000 years ago and again 4,000 - 5,000 years ago during periods of time when the water level in the Erie Basin was much higher from the influx of waters from glacial Lake Agassiz. Other physical breaks in this escarpment can be found at Lowbanks and Highway #58 in Port Colborne. Between the Niagara Escarpment and the Onondaga Escarpment is a relatively flat and poorly drained lowland called the Tonawanda plain.
A view of the rock strata along the Niagara Gorge
Eons ago, the Niagara area the bottom of an ancient tropical salt water sea. Ancient specimens are being found today deep under the soils of Niagara that are still today found at the bottom of our great oceans. Approximately 65 million years ago at the end of the Cretaceous and the beginning of the Tertiary periods, scientists claim that a giant asteroid collided with the Earth in the area of the Yucatan Peninsula of Mexico. This collision resulted in a massive amount of debris being propelled into the atmosphere on a world wide scale which caused a catastrophic change in the climate and led to the extinction of the dinosaur and many other life forms. This event continues to be re-examined and debated and will continue to be debated well into the future, however there is little doubt that the climate made a dramatic change to an era of the Ice Age.
A view of the rock strata along the Niagara Gorge
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:
As the late Wisconsin Glacier retreated northward, it created several outlets: An outlet from Lake Algonquin (Lake
Huron) to Lake Iroquois (Lake Ontario)
During the period of
glaciations and shortly afterwards,
the climate in Niagara was arctic. Vegetation was tundra and arctic fauna.
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.
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
A view of an infant gorge along
the face of the Niagara Gorge
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.
A view of Roy Terrace - the birth
site of Niagara Falls
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. 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. 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.
When the Falls of Niagara eroded the gorge back to the present day Thompson Point (where the Spanish Aero Car and the Whirlpool is located), the river found erosion of the rock much easier. The Niagara River broke through a rock barrier which held back glacial debris which had been previously filled into what was the ancient gorge of the St. David's River. The waters of the Niagara River quickly flushed this area of all the glacial debris (what is today the Whirlpool) and changed direction to follow the ancient gorge a short distance in a southward direction. It is believed that the Whirlpool Rapids Gorge which extended southward to the present Michigan Central Railroad Bridge, had also been carved from the rock from the ancient St. David's River which was also responsible for the carving out of the now filled in St. David's buried gorge. The ancient Whirlpool Rapids gorge was 38 meters (125 feet) wide. During the advance of the late Wisconsin Glacier the ancient Whirlpool gorge and the St. David's gorge were filled with glacial debris. At one moment in time, the ancient river did not make a dog leg turn at the Whirlpool but rather followed a relative straight line via the St. David's Gorge through the present Village of St. David's to the shore of Lake Iroquois (Lake Ontario). The St. David's buried gorge existed 22,800 years ago. It was a small portion of an ancient drainage system which extended the width of the Niagara Peninsula from Low Banks at Lake Warren (Lake Erie) to St. Catharines at Lake Iroquois (Lake Ontario). The St. David's Buried Gorge was found to be 1219 meters (4000 feet) long and 305 meters (1000 feet ) wide at the Whirlpool. The gorge was 91 meters (300 feet) deep. This gorge was 200 feet (60 meters) deeper that the current floor of Lake Ontario. The gorge extends into Lake Ontario 2.4 kilometers (1.5 miles) west of the present Niagara River. When Ontario Hydro was building the intake water tunnels to feed the Sir Adam Beck Hydro-Electric power plant, it was forced to bring the tunnels to the surface while crossing the St. David's Buried Gorge because they could not bore into the glacial debris. Instead they had to build concrete flumes on each side of this crossing to prevent water from being siphoned away through the buried gorge. In 1998, the Niagara Parks Commission remodeled a portion of the Niagara Parks Golf Course nearest Whirlpool Road. This project consisted of the removal of the second hole and the installation of a large pond. This area of the golf course was built on top of an area of the St. David's Buried Gorge known as Bowman's Ravine. The ravine had previously been used by the Canadian Niagara Power Company as a dumping area for rock debris taken from the wheel-pit excavation. When the unlined pond which when filled with water, the
water immediately leached away into the glacial debris of the buried gorge. This pond
needed to be fitted with a liner to hold the water within the confines of the pond.
This is the site of the Falls of Niagara 6,000 - 7,000 years ago. The water falls at this point was 37 meters (120 feet) to the water pool below. Here also existed an ancient island similar in size to the present Goat Island. Water flowed around both sides of this island before falling over the edge of the Wintergreen Flats to the water below resulting in two separate water falls. The dual falls continued until the main gorge to the east eroded back far enough past the beginning of the island effectively cutting off the secondary flow to the west of the island. The Falls of Niagara became a single Falls once again. Today the remnants of the ancient island lay below the Wintergreen Flats in two identifiable terraces. They are: Fosters Flats is the portion
of the Niagara Glen closest to the river. The word "glen" is a Scottish word for a steep sided narrow valley. Read more about the Niagara Glen
After the Niagara River eroded the Niagara Gorge beyond Devils Hole, the waters of Lake Tonawanda was still draining. One of the secondary outlets was at Devils Hole where a water falls created a ravine perpendicular to the wall of the Niagara Gorge. The flow of Lake Tonawanda diminished before this
infant gorge could establish itself. Read more about
Devil's Hole.
In 1841, Charles Lyell, a British scientist and a father of modern geology came to Niagara Falls. From observations of the rocks at the Falls and along the Niagara River, Lyell was able to demonstrate beyond a doubt that the cascading waters had eroded the gorge from the edge of the escarpment at Queenston - Lewiston to its present location. Lyell's conclusions were supported by an equally
distinguished pioneer American geologist, James Hall. His independent studies for the
State of New York included the first accurate survey of the rim of the falls to establish
a basis for measuring the rate of recession. The slowing of the erosion rate is caused by two major factors:
There was a single water falls 800 - 600 years ago. The
separation of the water falls into the two current water falls: the American &
Horseshoe Falls is remarkably new in terms of its 12,000 year history. The crest line of water falls was relatively straight until after 1775 when the Horseshoe shape began to form. Two thousand (2,000) years ago, the crest line of the Falls was located north of the current Rainbow Bridge. Four thousand - five hundred (4,500) years ago, the crest line of the Falls was located north of the current Whirlpool Bridge. The shape of the crest line determines its stability. The uniform Horseshoe shape of the crest line of the Falls provides greater stability. The deepest plunge pools are carved out when the crest line of the Falls is relatively stable. The American Falls has no regular mode of collapse. The present amount of water flowing over the American Falls is insufficient to erode the Irondequoit Dolostone (limestone) talus at the base of the Falls. The rock surface reaches its maximum at Hubbard Point (along Canadian side of gorge). This point is known as the Lyell / Johnson Ridge.
In 1972, remedial work was conducted at the Bridal Veil
Falls and Luna Island. This included the installation of steel dowel bolts and cable
tendons. In addition a series of holes were drilled to relieve hydrostatic pressure.
m/yr. = meters per year (average)
Accurate surveys of erosion of the Falls of Niagara began in 1842. From 1842 to 1905, the average rate of erosion of the Horseshoe Falls was 1.16 meters (3.8 feet) per year. From 1906 to 1927, this rate of erosion was reduced to .70 meters (2.3 feet) per year. This reduction coincided with the large quantity of water being diverted for hydro-electric generation. In 1896, Thomas Martin wrote that the annual recession of the American Falls was 7½ inches per year and the Horseshoe Falls was 2.18 feet per year. From 1842 to 1905, the average rate of erosion of the Horseshoe Falls was 1.16 meters (3.8 feet) per year. From 1906 to 1927, this rate of erosion was reduced to .70 meters (2.3 feet) per year. This reduction coincided with the large quantity of water being diverted for hydro-electric generation. The mean rate of erosion was 3.5 meters (5 feet) per year. Since 1942 the rate has been much slower. Today, through increased water diversion and anti-erosion remedial steps, the rate of recession at the Horseshoe Falls has been reduced to a fraction of what it used to be. Today it is estimated that erosion of the Horseshoe Falls is less than one foot per year. In the future, through remedial efforts and further water diversion that the amount of erosion at the Horseshoe Falls has been projected to be reduced to approximately 1 foot every 10 years. Today, erosion of the American Falls is estimated at 3 - 4 inches every 10 years. The water flow which is regulated at a minimum level of 10% of the estimated 100,000 cubic feet per second during the summer (50,000 cubic feet per second during winter) is insufficient to cause major erosion.
Niagara River Drainage
The Niagara River drains an area of 254,708 square miles (409,901.5 square kilometers) including the Upper Great Lakes. The surface area of Lake Erie is 9,910 square miles (25,655 square kilometers). It is the shallowest of all the Great Lakes, averaging 60 feet (18.29m) in depth. The levels of the Great Lakes vary on an annual basis in relation to season, rainfall, evaporation and runoff. The highest water levels are found in mid-summer and the lowest water levels are found in mid-winter. The internal time required for an increase supply of water to show its effect upon the level of Lake Erie is approximately 76 days. The internal time required for a decrease in the supply of water to show its effect upon the level of Lake Erie is approximately 132 days.
The extreme variation of water levels in Lake Erie: greatest variation between 1860 and
1907 was 3.89 feet
A variation in the level of Lake Erie of one foot at Buffalo, New York equates to a difference in the rate of water flow discharge from Lake Erie into the Niagara River of 20,000 to 25,000 cubic feet per second. During storms, the water level of Lake Erie at each end may vary as much as fifteen feet. The average annual rainfall in the Great Lakes equals 36 inches. The average annual evaporation rate in the Great Lakes equals 24 inches. The water discharge of the Niagara River has been determined by measurements taken at the International Railway Bridge at Buffalo/Ft. Erie (1,800 feet south of Lake Erie). Measurements began in 1897 the engineering staff of the U.S. Great Lakes Survey. The maximum monthly mean discharge of 257,000 cubic feet of water per second from Lake Erie occurred in March of 1896. This was equivalent to the entire surface of Lake Erie to a depth of 2.44 feet. The average discharge of the Niagara River between 1860 and 1907 equaled 212,000 cubic feet of water per second. Between 1860 and 1907, the greatest excess average for any month occurred in June of 1876 at 45,000 cubic feet of water per second or an increase in water flow of 21% (refer to maximum mean discharge). The greatest average in excess water flow in any one year occurred in 1876 at 26,000 cubic feet of water per second or an increase of 12%. The greatest water flow deficiency average for any month was March of 1896 at 43,500 cubic feet of water per seconds or a decrease of 21%. The greatest water flow deficiency in any year occurred in 1895 at 31,800 cubic feet of water per second or a decrease of 15%. In September 1999, Lake Erie's water level was at 571.19 feet (174.10m) above sea level. This was 4.3 inches (11 cm) below the long term average. Lake Erie's water level was the lowest that has been recorded since 1967. In February 2000, Lake Erie water level was at 570.08 feet (173.76 m) above sea level. This was 9 inches (23 cm) below the February long term average. Lake Erie's water level was the lowest that has been recorded since 1967. Summer of 1999 Great Lakes water levels were 16-24 inches (40-60 cm) below those levels recorded in 1998. In flow water rates from Lake Erie into the Niagara River have been recorded as follows: Sept. 1999 - Feb.2000 = average
173,400 cubic feet per second The water out flow rates of the Niagara River at Queenston are as follows: Sept.1999 - Feb.2000 = 184,000
cubic feet per second (greatest one month average = 188,930 cf/s) Lake Erie Precipitation Rates are as follows: Sept.1999 - Feb.2000 = 15.8 inches
(40.2 cm) of rain
Approximately ten thousand - five hundred (10,500) years ago, the water level of Lake Erie rose 3 - 4 meters above its present water level. At this time the Upper Great Lakes drained through North Bay and the Mattawa River, to the Ottawa River to the St Lawrence River Valley. This resulted in the water drainage through the Niagara River being reduced to only one tenth (1/10) of its present flow (representing only the drainage of Lake Erie). The reduction of water flow through the Niagara River continued for approximately six thousand - five hundred (6,500) years before the drainage route returned to its previous course through the Niagara River. This water reduction through the Niagara River correlates to the narrowness of the Niagara River Gorge. Isostatic rebound had lifted the land surrounding North Bay cutting off the out flow of water from the Nipissing Lakes (Upper Great Lakes). The rising waters on the southern shores of Lake Huron breached the Lake Huron moraine and discharged the entire flow into the Lake Erie basin. This new direction of flow was initially shared with an exit at the southern shore of current Lake Michigan. Over several hundred years, the water level of the Lake Erie Basin rose 3 - 4 meters increasing the flow through the Niagara River. This increased flow caused the rapid recession of the Falls of Niagara through the gorge south of the current Niagara Glen. Glacial Lake Agassiz had a great influence on the Lake Erie basin. Eleven thousand (11,000) years ago, pro-glacial Lake Aggassiz initially drained southward over a divide into the Mississippi River basin. As the divide rose from isostatic rebound, the entire flow of the Upper Great Lakes flowed into the Lake Erie basin through the Niagara River. The increased flow into Lake Erie caused water levels to rise in the basin up to five (5) meters. Water levels of Lake Tonawanda increased accordingly. Today, the winds can cause the water level in Lake Erie to rise 2 - 5 meters in several hours. Lake Erie is the shallowest of the Great Lakes with an average depth of sixty (60) feet.
The average flow of water through the Niagara River equals 212,000 cubic feet of water per second, falling a distance of 325 feet from Lake Erie to Lake Ontario would yield a potential 8 million horsepower or 5,965,600 kilowatts. The difference in elevation from Lake Erie to the base of the Falls of Niagara is a fall of approximately 226 feet. The difference in elevation from the head of the upper rapids to the base of the Falls is a fall of 212 feet. The difference in elevation from the Whirlpool Rapids to the mouth of the Niagara Gorge is a fall of 94.5 feet. The difference in elevation from the head of the gorge (base of Horseshoe Falls) to Fosters Flats at the Niagara Glen is a fall of 78.5 feet. The Ontario Hydro (Ontario Power Company) Generating Station at the base of the Horseshoe Falls operates under a normal head of 180 feet, utilizing only 85% of the available height of 212 feet.
.075 cubic feet of water per second = 1 horsepower 1 cubic foot of water dropping 170 feet = 25 horsepower 1 cubic foot of water dropping 1 foot = 0.147 horsepower 1 cubic foot of water = 59.5 pounds
A water discharge of 168,000 cubic feet per second falling 212 feet would yield 2,250,000 horsepower. A horsepower is equivalent to 33,000 foot/pounds per minute or 550 foot/pounds per second. In 1894 the average flow of water through the Niagara River was 270,000 cubic feet per second = 1,000,000,000 pounds per minute: 61.7 pounds per cubic foot of water X
60 seconds = Horsepower is a unit of power in the English system of units. It is equal to 33,000 foot pounds per minute or 550 foot pounds per second or approximately 746 watts. The term horsepower originated with James Watt, who determined by experiment that a horse could do 33,000 foot-pounds of work a minute in drawing coal from a coal pit. To convert horsepower to watts (multiply by 745.7)
During the daytime between April 1st and October 31st each year, 100,000 cubic feet of water flow over the Falls of Niagara. Water diversion for Hydro generation is maintained at 112,000 cubic feet of water per second. During the night between April 1st and October 31st of each year, 50,000 cubic feet of water flow over the Falls of Niagara. Water diversion for hydro generation is maintained at 162,000 cubic feet per second. From November 1st to March 31st of each year, 50,000 cubic feet of water flow over the Falls of Niagara. Water diversion for hydro generation is maintained at 162,000 cubic feet per second. Today hydro-electricity being generated at Niagara Falls as follows: 1) Sir Adam Beck Generating Station #1
= 403,900 kilowatts
A Total of 4,209,200 kilowatts are presently being generated
From September 1999 - February 2000, the average water diversion for hydro-electric power generation was as follows: Sir Adam Beck #1 & #2 = 57,630
cubic feet per second
From March 1999 - August 1999, the average water diversion for hydro-electric power generation was as follows: Sir Adam Beck #1 & #2 = 58,800
cubic feet per second
Where Rock and Power meet
STRATA OF THE NIAGARA GORGE CHART
Throughout the ages, nature has in conjunction with the wind, water & ice created stratified layers of rock and earth in Niagara. The Niagara Gorge provides a snapshot of those layers which would otherwise go unseen. Rock Layers from top to bottom are:
The base of the Whirlpool is at the base of the Medina group of rocks. The water level of Lake Ontario is at the rock strata of the Queenston Shale level. As the water falls reached an area just south of the present Michigan Central Railway Bridge erosion slowed when it encountered the highest limestone ridge in the Niagara District. This limestone ridge extended to just north of present day Eastwood Avenue. The water falls at this point was 15 meters (50 feet) higher than the current water falls. Because of the greater height of the falls the gorge is deeper. At this time Grand Island & Queen Victoria Park was submerged under 30 feet of water. Precambrian rocks record 80 -85 percent of the Earth's history. The Phanerozoic Age (the era of well developed life) is recorded in only 15 -20 percent of Earth's history.
The Village of Fonthill in the Town of Pelham (located approximately 20 miles west of Niagara Falls) is remarkable for what is known as a Kame - Delta . It was the pro-glacial delta of glacial Lake Warren. It was beach of this ancient glacial lake. Gravel's of this sea are found 242 meters (793 feet) above sea level. The steep northern slope marks point of contact with the ice field. The gentler southern slope is the lake ward slope of this glacial delta. This glacial lake was located east of the present day Great Lakes. It exited high over Lake Erie territory and exited into the Lake Ontario basin. Its beach was the last and highest of the gravel margins formed. During the retreat of the Lake Erie ice lobe of the Wisconsin Glacier which covered the Niagara Peninsula, the southern limit of the ice field remained nearly stationary at the Niagara Escarpment. Melt water from the glacier formed a series of glacial lakes. This melting water flowing from the glacier carried large amounts of debris, laying down a series of layers forming the kame - delta. The Fonthill Kame-Delta is the highest point of land in the Niagara area. Today this site is readily identified by the many transmission and microwave relay towers situated upon it.
Approximately 425 million years ago, Niagara was the bottom of an ancient tropical sea. Today fossils from that era can be found deep in the layers of rock of Niagara. Because of the depth of the Niagara Gorge, many of these fossils have been exposed along the walls of the gorge. Fossils found are:
The future of Niagara Falls is not easily predicted. The Falls of Niagara as we know it today will remain as it is for thousands of years to come. Erosion is the largest factor which will alter its appearance in the future. Some have estimated that the Falls would continue eroding southward for the next 8,000 years at which time it would reach the limits of Lake Erie. The eastern seaboard of North American is today still rising from the glacial rebound effect. It has been suggested that as the land rises on the eastern seaboard that water flow to the ocean will slow and reverse so that in the future the Falls would be much diminished or cease to exist entirely. Perhaps the most realistic outlook is that the Falls will continue to erode southward. There is no doubt that at some point in its future that the main Horseshoe Falls once it has eroded far enough south, will cut off the water flow to the American Falls. The Falls of Niagara will once again become one. The greatest threat to the integrity of the Horseshoe Falls and the American Falls is rock falls. The American Falls has been the victim of many rock falls in the past. As the rock talus collects at the base, it reduces the distance of the water fall and creates more of a cascade effect. In the future substantial rock falls may affect the
appearance and change the Falls of Niagara to mere water cascades and/or rapids.
THANK YOU FOR VISITING
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
