It will soon be tourist season in the Niagara Region and I would like to post a brochure about my tourist attractions in the city of Niagara Falls, Canada.
The landscape of the city is, in itself, a tourist attraction to anyone interested in the natural history events which came with the end of the last ice age, about 12.000 years ago. What I am writing here is explained in more detail in the posting "Secondary Glaciation And The Niagara Impact Craters" on the Niagara natural history blog, www.markmeekniagara.blogspot.com . However, that posting is complex and I think it would be valuable to have a simplified version here.
The falls formed as the Niagara River flowed over the escarpment at what is now Lewiston-Queenston, and began gradually cutting it's way through the limestone strata to form the gorge that we see today. The whirlpool formed where the river underwent a sharp turn as it cut it's way to the buried river which ran this course from the previous warm era before the last ice age, which ended about 20,000 years ago. That river was known as the St. David's River because it met the escarpment, to form a falls which may have been much like the falls of today, near the Ontario village of St. Davids.
When driving on the QEW (Queen Elizabeth Way) west of the Stanley Avenue Exit, you will cross a broad dip in the level of the highway. This is the remnant of the St. Davids River. It was filled in by the massive amounts of soil and loose rock moved along by the encroaching glacier of the last ice age.
What is known as the Niagara Glen, with the massive limestone pieces in the gorge, was formed when the river split in two to form an island in the middle before the two branches of the river reunited, but which later collapsed.
Here is a summary of what I have added to the story of Niagara Falls, Canada. My Niagara blog also described a lot on the American side, but the discoveries on the Canadian side are more concentrated and easy to see for someone not familiar with the area. In fact, the features on the Canadian side of Niagara Falls make up virtually the entire landscape of the city.
The Niagara Escarpment is basically a cliff, but it also has a gradual southward slope. As the temperature warmed and the last ice age ended, the glacier broke apart and a wall of massive bergs of ice slid down the slope of the escarpment. These sliding bergs plowed up the soil and loose rock in front of them until the ice had melted to the point where it could not push the debris any more. The soil and loose rock formed a ridge that we see today. It is the ridge upon which the western section of Lundy's Lane is built, within the city, from around the intersection with Drummond Road westward as far as the hydraulic canal.
There are two other ridges in the area that I can think of. One is the much smaller ridge upon which Center Street in Lewiston was built. That was formed in a similar way, but by ice sliding toward the base of the Niagara Escarpment.
The other is what we could call "The Medical Ridge" in downtown Buffalo because Buffalo General Hospital and Roswell Park Cancer Hospital is built upon this glacial ridge. I described it in the section "The Very Special Escarpments Of Buffalo And Fort Erie" in the posting on the geology blog, "All About The Appalachians".
The glacier of the ice age was up to 2 km in height. As the ice age ended, a large section slid across the westward slope of the rock strata around the falls and in the upper Niagara River, above the falls. It is this slope which produces the fast current and the rapids above the falls. This large section of glacier pressed up against what is known as the Niagara Falls Moraine, which is the high ground seen on the Canadian side adjacent to the falls and on which the towering hotels are built. (Remember that neither the falls nor the gorge was there at this time, and the present Niagara River had not yet formed).A moraine means that this land is not solid rock, but soul and loose rock deposited by a long-ago glacier during an ice age. The sliding section of glacier pressed up against the moraine, creating Clifton Hill, the bluff in Queen Victoria Park and, the high ground above the falls.
As the temperature warmed further, the ice near the bottom of the section of glacier melted faster than the ice on top until the glacier became top heavy. A massive slab of ice, weighing millions of tons, broke free and crashed to the ground below. The result is the change in elevation on Lundy's Lane / Ferry Street, at the intersection with Sylvia Place, and the corresponding changes in elevation seen on nearby Grey Avenue and Allendale Avenue.
The impact pushed back a section of what was the Lundy's Lane Ridge and created another ridge, upon which Main Street / Portage Road is built. The place where this new ridge intersects with the remaining section of the Lundy's Lane ridge, around the intersection of Lundy's Lane and Drummond Road, forms the highest point in the city. In the posting, I named this high point "Mount Niagara".
You can easily see on a map how Main Street / Portage Road forms a curve to the south of the intersection with Lundy's Lane because this is the ridge formed by the impact.
Here is the map link with the satellite imagery and Google Street View that I use: www.maps.google.com .
One thing that caught my attention is that Main Street / Portage Road, on the ridge that was formed by the impact, forms a curve with a street called Valley Way, to the north. There is a section of Valley Way that, sure enough, is a valley, on the street between Fourth and Sixth Avenues. That is because this was formed by another glacial impact from the same source. The ground slopes to the north along the numbered avenues because of this impact. just as Kitchener Street, a short distance to the south, has a westward sloping surface due to the impact of the Lundy's Lane Crater.
The meltwater from the Lundy's Lane glacial slab formed a temporary lake, which was approximately bisected from north to south by Stanley Avenue and extended from approximately where Stanley Avenue meets Main Street / Portage Road in the south to around Arthur Street in the north. In the Niagara Blog, I named this "Lake Niagara".
Notice that, if we follow the curve of the Main Street/Portage Road ridge to the southeast, back to the area of Queen Victoria Park, it brings us to Murray Street which appears to be built in a cut in the bluff above the park. This cut is in just the right place to have been formed by a torrent of meltwater, guided along the curve of the ridge and flowing to the low area which is now the falls and lower river just below the falls.
Meanwhile, the Valley Way Crater formed a temporary river, which I named the "Valley Way River", through which the meltwater of the first glacial slab as well as a lot of other water from the melting glaciers, drained away. (Remember that the falls nor the gorge was here at this time and the Niagara River was only just forming). Evidence of the Valley Way River can easily be seen in the valley along Valley Way, at the intersection of Portage Road in the minor drop in elevation of the road surface.
What about the whirlpools of Niagara? There is the famous whirlpool in the gorge, but if you bring up two windows of www.maps.google.com , it is easy to see why I established that the so-called "embayment" at Dufferin Islands is almost exactly the same size and shape as the whirlpool in the gorge, thus showing that it originated as a whirlpool also. Such a whirlpool will form by carving away the rock layers where a fast flowing river must make a sudden change of direction, usually due to the slope of the rock strata.
The embayment at Dufferin Islands is the whirlpool left over from the St. Davids River, from the previous warm era between ice ages. From there, the St. Davids River flowed across what is now Goat Island, and this can be seen in the drop in elevation on the island, adjacent to the Three Sisters Islands, and in the adjacent waterfall stretching across the river, about 2 meters high, and known as the Green Cascade.
If you are familiar with the area and wonder why the St. Davids River flowed some distance east of where the river turns toward the lower river, over the falls as dictated by the slope of the rock strata, as it does today, the answer is simple. Remember that we saw above how a sliding section of the melting glacier plowed the Niagara Falls Moraine back to where it is today, in the line of Clifton Hill-the bluff in Queen Victoria Park-the high ground above the falls, and this was before that happened. The moraine must have extended eastward near to where Dufferin Islands now is.
I find still another whirlpool in this "city of whirlpools", but this was only a temporary one.formed by the great volume of meltwater at the end of the ice age. This is in Leslie Park, adjacent to Valley Way, and was formed by the volume of water flowing in from the north after flowing down eastward slopes such as that seen to the east of Stanley Avenue between Morrison and Bridge Streets.
For more information about the natural history of the Niagara area, see "The Summary of Niagara Natural History", on this blog.