Niagara Natural History Summary

Many people go on vacation to Niagara Falls during the summer and I would like to make the natural history that I hope to have added there easier to understand. It would be helpful to have some familiarity with the Niagara area to understand this.

There is a blog about insights into the natural history of the Niagara Falls area, on www.markmeekniagara.blogspot.com , but I would like to write a single posting encompassing everything in chronological order.

EARLY LIMESTONE FORMATION

Eons ago, in warm shallow seas, microscopic creatures lived and died. Their bodies piled up on the bottom to eventually form layers of limestone (calcium carbonate). These layers can be seen today in the gorge of Niagara Falls. Even before that, waves pulverized rocks into sand which then formed layers on the bottom of the sea. The land was later forced upward by tectonic activity, and this forms the geological foundation of the area.

You can see the layers of limestone rock strata in the walls of the Niagara Gorge at the falls. Touch the image in the upper left to enlarge it.

 
THE FORMATION OF THE NIAGARA ESCARPMENT

Most likely, a meteor composed of magnesium landed in the sea at some point. This led to a layer of limestone composed of magnesium carbonate, instead of the usual calcium carbonate. Ordinary limestone is dissolved by water and erosion over long periods of time. But the layer of magnesium carbonate was much more resistant to erosion.

This top layer of highly resistant limestone resulted in what we see today as the Niagara Escarpment. It may appear to be some type of fault line, but it is actually formed by uneven erosion due to shielding by this erosion-resistant top layer of limestone. The actual name of this type of limestone is Lockport Dolostone, named for the nearby city on the edge of the escarpment. The Niagara Escarpment is believed to be at least two hundred million years old.

The Niagara Escarpment, which appears as a cliff, can be seen across the following satellite image in Niagara County. South is above the escarpment and north is below it. The escarpment shows as the concentration of dark green tree growth on it.

This hard top layer of rock is actually why the falls at Niagara exist. The falls were originally where Lewiston-Queenston is today. But the falling water dissolves the softer limestone below until the top layer has nothing supporting it from beneath, and pieces of it break off and fall away. This is how the falls have worked their way northward, to where they are now, over the past ten thousand years, or so.

In the center of the following satellite image, notice how narrow the Niagara River is in the bottom half of the image. The narrowing point is the Niagara Escarpment at Lewiston-Queenston. This is where the falls began, at the end of the last ice age about 12,000 years ago. The falls have been steadily cutting their way through the rock strata, and moving backward to where they are now. 

The bulge in the lower Niagara River is the Niagara Glen. It is basically a pile of rock that formed thousands of years ago when the river split in two while eroding it's way through the underlying limestone. This formed an island with high limestone cliffs. But the island collapsed, leaving the pile of rock that we see today.

 THE APPALACHIAN COLLISION

The next major event after the formation of the Niagara Escarpment by gradual uneven erosion is the sliding tectonic collision, between what is now Africa and what is now North America, that formed the ridges and mountains across the eastern United States known as the Appalachians. This exerted extreme northward pressure on the area.

Across Pennsylvania, to the south, the collision front of the Appalachians underwent a major change in direction due to the Canadian Shield to the north, the dense layer of rock underlying the eastern half of Canada. This forms a line, which I named The Humber Line because it passes through Toronto and forms the change in elevation seen in east-west streets west of downtown , that forms the eastern side of the Humber Valley. It also forms Georgian Bay as it goes right along it's main axis.

The Humber Line also passes directly through the Niagara Area. The pressure against the Niagara Escarpment increased as the point of collision moved eastward, across Pennsylvania, and the direction of tectonic pressure shifted from northwestward to northward.

The Appalachians curve across Pennsylvania. The "focal point" of the curve is around the city of Harrisburg. This change in direction changed the direction of the northward tectonic pressure. Notice how the straight line easternmost shore of Lake Erie south of downtown Buffalo forms a straight line along the Humber Line.

Following this same line to the northwest, it forms the straight line southwestern shore of Navy Island, in the Niagara River above the falls.

This line, due to the change in direction of the pressure of the Appalachian collision, continues to the northwest, crosses Lake Ontario, to form Humber Bay and the Humber Valley in Toronto, hence the name of the line as the Humber Line.

On a large scale, we can see again that the long axis of Georgian Bay, in Ontario, points in a straight line to Harrisburg and the line passes right along the straight line of the easternmost shore of Lake Erie south of downtown Buffalo, as described above. The Bruce Peninsula, which separates Georgian Bay from Lake Huron, as well as Manitoulin Island, is actually formed by the Niagara Escarpment, which also forms Northern Michigan and continues all the way to Wisconsin.

THE "BREAKING POINT" OF THE NIAGARA ESCARPMENT

At first, the pressure was not enough to actually move the escarpment but it raised the rocky ridge along Route 65, to the west of the Ontario towns of Fonthill, Ridgeville and, Pelham. As the collision front moved eastward, the pressure reached a point where the entire escarpment broke and shifted. This is at Short Hills Provincial Park, to the southwest of St. Catharines, and is directly opposite the point at which the rocky ridge terminates. This is because, from this point eastward, the tectonic pressure went into moving the escarpment rather than raising the ridge.

The pressure also went into fracturing the limestone layers to the south of the escarpment to form a broad valley in the rock strata. This is what I pointed out, and named "The Niagara Valley". On the Canadian side of Niagara Falls, at least that portion which is not covered by the Niagara Falls Moraine today, the land gets lower as we go eastward. This can be readily seen on Thorold Stone Road. But on the American side, by the falls, the ground generally gets lower as we go westward.

The lower Niagara River, below the falls, as well as the falls themselves, are at the bottom of this valley. The strata on the American side is actually tilted to the southwest because the escarpment is shaped like a saw tooth, rather than a level plateau. On the map, it can be seen that the lower Niagara River, which flows though the nadir of the Niagara Valley, is roughly parallel to the segment of the escarpment just east of the "breaking point" at Short Hills Provincial Park.

Short Hills Provincial Park is where the Niagara Escarpment changes direction. The Park, in the center of the following image, is like the bottom of a "V" with the escarpment in different directions on each side.

 THE END OF THE LAST ICE AGE

This concludes the geological portion of the Niagara story. Far in the distant future, ice ages began. The most recent of these concluded about 12,000 years ago. The rest of the story involves the glaciers that came with these ice ages.

A glacier is a vast sheet of ice, about one or two kilometers in height. Glaciers begin to form when the temperature gets cold enough that the snow from one winter has not melted when the following winter begins. Snow piles up year after year, decade after decade, and century after century. The weight of the snow above compresses it into ice.

When an object is large enough, such as this vast sheet of ice, it is affected by the rotation of the earth. The glacial ice is thus pulled southward, toward the equator, and somewhat eastward by the earth's eastward rotation. This towering mountain of ice pushes tremendous amounts of dirt and rock in front of it, where it remains when the ice age ends and the glaciers melt.

One such mass, deposited by a glacier in a previous ice age, is the Niagara Falls Moraine. This covers much of the city of Niagara Falls, Canada, and is best seen as the high ground on the Canadian side by the falls. The Niagara Valley can be seen on Thorold Stone Road only because that area was not covered by the moraine.

More soil and loose rock was deposited against the Niagara Escarpment by the moving glacial ice. The reason that Ridge Road, around Lewiston, is so-named is that it is built upon a ridge along the bottom of the escarpment that was put there by the glacier.

The glaciers of each ice age obliterates the drainage pattern of the rivers over the land, and at the conclusion of the ice age the pattern forms anew. There was a predecessor of the Niagara River in the warm period before the last ice age. This warm period ended maybe 20,000 years ago.

This predecessor river is known as the St. David's River for the Ontario town where it met the escarpment. The St. David's River was filled in by the soil and loose rock pushed into it by the glacier of the ice age. But when the present Niagara River, working it's way northward, met the looser fill of the former St. David's River in the midst of the solid rock layers, it caused the Niagara River to change direction and for the river to have to form a whirlpool to accommodate the change of direction. This is seen today in the whirlpool of the lower river.

On the QEW (Queen Elizabeth Way), west of Stanley Avenue, there is a broad dip in the level of the roadway opposite the village of St. David's. That is the remains of the St. David's River from before the last ice age. This forms a break in the Niagara Escarpment which is visible in the following satellite imagery. In the center of the following image you can see, by the dark green line of the trees, the break in the Niagara Escarpment at the Ontario village of St. David's. 

The remains of this former river can also be seen on Goat Island, on the American side at the falls. There is a low waterfalls that stretches across the upper Niagara River, not far above the main falls, that is known as "The Green Cascade". This was cut by the flowing waters of the St. David's River. On a line with the Green Cascade there is a low area on Goat Island, around where the Three Sisters Islands are, that is also the result of this former river.

This is the beginning of the Green Cascade, a low waterfall stretching above the Niagara River some distance above the main waterfall. This is a remnant of the St. David's River from the warm period before the last ice age. Image from Google Street View.

 
The line of the Green Cascade, across the upper Niagara River, leads straight to the embayment at Dufferin Islands, on the Canadian side above the falls. This is because this was once a whirlpool. The embayment at Dufferin Islands is almost exactly the same size and shape as the whirlpool in the lower river.

This is the whirlpool in the Niagara River, in the lower river below the falls where the river changes direction.

Now look at the embayment at Dufferin Islands, right in the center of the image, seen from the same altitude.

That is because the embayment at Dufferin Islands was a whirlpool in the warm period before the last ice age, where the St. David's River changed direction.

But why did the former St. David's River follow this particular course? The answer appears to be fairly obvious. The Humber Line, described above, passes right through this gap in the Niagara Escarpment which marks the route of the former St. David's River. It was following this Humber Line.

Look at how a continuation of the line of flow into the Niagara Whirlpool leads directly to the gap in the escarpment at St. Davids. This line is a segment of the Humber Line.

 LAKE TONAWANDA

The drainage flow pattern in the Niagara area was not always as it is now. There was once a lake, named Lake Tonawanda, which existed for most of the time since the end of the last ice age. There is a high point in the rock layers alongside the lower river, known as the Lyell-Johnson Ridge, that can be seen as peaking at Cedar Avenue on the American side and Eastwood Street, on the Canadian side. This point is not far north of the Rainbow Bridge.

When the falls, cutting it's way northward from it's beginning on the Niagara Escarpment, cut through this ridge then Lake Tonawanda drained. All that remains of it today is the broad upper Niagara River above the falls. The former shores of this lake can still be seen in many places on the U.S. side. North of the former K-Mart, on Military Road in the Town of Niagara, if you look southward it seems as if you might be looking out over a lake, and 3500 years ago you would have been.

The slope up to higher ground in the city of Tonawanda used to be the southern shore of the lake, which continues eastward toward Rochester. The deepest part of this lake was where the falls are now located, my guess is that the depth there was about 9 meters.

The so-called Alabama Swamps, east of the Niagara area, are all that remain of the former Lake Tonawanda which existed for about 7,000 years after the end of the last ice age.

OTHER COULD-HAVE-BEEN ROUTES OF THE NIAGARA RIVER

In Lockport NY, we can see traces of the natural history also. The Niagara River was not the only route by which the former lake Tonawanda drained into Lake Ontario. State Street is built upon an old river bed that once was another drainage route, the legacy of this route is Eighteen Mile Creek. If not for the Niagara Valley that I described, the Niagara River might be there today.

Evidence that there was such a drainage route in the warm period prior to the last ice age can also be seen in the gap in the escarpment adjacent to Upper Mountain Road and Sunset Drive. The flow of water through here not only carved this gap but weakened the rock layers, causing part of the escarpment to collapse and form a hill called Gothic Hill.

The V-shaped area of dark green trees in the following image is a gap in the Niagara Escarpment at Lockport, New York. This was formed by the flow of water along another route by which the former Lake Tonawanda drained. This is to the east of the present Niagara River. The Niagara River might have been here except for the Niagara Valley, described above, through which the river like the St. David's River before it, ended up flowing.

GLACIAL IMPACT CRATERS IN NIAGARA FALLS, CANADA

Around where the falls are now located, massive bergs of ice slid along the slope of the strata to the southwest to compact the edge of the Niagara Falls Moraine to form the higher ground above the falls and Queen Victoria Park. As temperatures gradually warmed, this massive glacier fractured laterally. A vast slab of ice, weighing millions of tons, slid off the top and crashed to the ground below.

The result can be seen today in the sudden rise in elevation on Lundy's Lane/Ferry Street, just east of Portage Road/Main Street. The same rise can be seen on Allendale Avenue and Grey Avenue. This is an impact crater formed by the falling ice. The melting slab produced a rush of water, and the channel that it carved can be seen on McRae Street just east of Stanley Avenue.

A similar impact crater can be seen along Victoria Avenue, and streets to the west, and in the "valley" portion of Valley Way, between Sixth and Fourth Avenues. The slab of ice that formed this crater also came from the mountain of ice pressed against the higher ground at Queen Victoria Park.

Notice how Main Street, at the far left of the map, forms an arc with Valley Way, at the top of the map. That is because Main Street / Portage Road is built along the crest of one glacial impact crater and Valley Way, illustrated by the yellow line, is built along the bottom of another. The Niagara River is the blue color on the map.

The "valley" in Valley Way must have continued westward, over where the school is now located. But the tremendous amount of water from the melting ice seems to have washed it away. Water would have been raging down the slope around Thorold Stone Road, and it must have appeared as do the upper rapids above the falls today. From Stanley Avenue, there is a drop in elevation looking eastward along streets from Elm to Cedar. Water would have rushed down this, until reaching level ground where it would have flowed southward.

Such was the force of this flowing water that it not only washed away a portion of the valley along Valley Way, but it carved away at the opposite side of the valley. Notice the curved drop in elevation that can be seen in Leslie Park, at Sixth Avenue and Valley Way, and also notice that this curve is located just adjacent to where the "valley" portion ends. I only noticed this because I used to sled down that curved slope as a boy, and go to the school across the street.

Notice the curve in the center of the following image of Leslie Park. This curve, just south of Valley Way, is the crest of a cut that was made in the side of the glacial impact crater by water flowing down the north side of the valley formed by the crater as the glacial ice melted at the end of the last ice age.

This formed a temporary river, in my writing I though it logical to name it the Valley Way River, draining the water from the melted glaciers. The river flowed along the nadir of the impact crater, but once it got beyond the crater it shifted northward to a more logical place between the southward slope above the escarpment and the northward slope of the impact crater, along Park Street.

Such sliding bergs of ice created many ridges in Niagara County, particularly in the southwestern quadrant of the county because the escarpment gets lower going eastward and this has the effect of sloping the rock strata.

WHY ARE THERE TWO FALLS AT NIAGARA?

Have you ever thought about how illogical it is that there are two falls at Niagara? The American Falls is higher in elevation, and carries less then 10% of the total water flow, so why does it even exist? Why doesn't all of the water just go over the Horseshoe Falls? There is a simple answer.

One berg of ice slid down the southward slope that can be seen along the numbered streets in the 70s, in Niagara Falls, NY. It kept sliding southward until the slope of the rock strata became more westward, so that it changed direction, carving away the ground beneath it all the way. We can see it's trail today as Burnt Ship Creek, across northern Grand Island and than in the gap between Goat Island and the U.S. mainland. This berg is why the American Falls are there.

Has anyone noticed the similarity between the wide marsh area at the northern end of Grand Island, NY, and the branch of the upper Niagara River that flows to the American Falls? The span of both is illustrated by a yellow line.

 

The reason is that the two channels were formed by the same sliding berg of ice as the glacial ice melted and broke up at the end of the last ice age. The wide marsh area separates Grand Island from Buckhorn Island. The berg continued sliding downstream and carved the channel leading to the American Falls.

That explains the apparently illogical fact that the American Falls even exists when all of the water could flow over the main falls, which is lower in elevation. Less than 10% of the total water flows over the American Falls.

Again, this is the Humber Line that I discovered.

This is only a brief summary of the natural history of the Niagara area, in chronological order. You can read in detail about this, and much more, on my Niagara natural history blog, www.markmeekniagara.blogspot.com .