The Toronto Story

This has been updated and seventeen satellite images have been added. This posting contains street descriptions of the Toronto area. Readers unfamiliar with the area can just skim over the street names. It is not necessary to know locational details to understand this.

ALL SATELLITE IMAGES IN THIS POSTING ARE FROM GOOGLE EARTH

We know the Toronto story. In the Eighteenth Century, Fort York was built on the northern shore of Lake Ontario. Settlements around the fort continued to grow until today it is a world-class city to which people from all corners of the globe come to live.

But that is only the most recent chapter of The Toronto Story. The story goes back 12,000 years to the melting of the last glacier. The ice may have been two km thick in some places and when the climate warmed and it melted, a veritable ocean of water was released. This water and bergs of ice formed the physical geography of Toronto that we see today.

Lake Iroquois, the larger predecessor to Lake Ontario began to drain faster through the St. Lawrence and Hudson Rivers due to shifting land levels caused by the release of the pressure of the ice so that the level of what is now Lake Ontario was getting lower and the shoreline receding even as this ocean of meltwater poured into it. The former shore of the lake is visible in some places in the Toronto area.

This task was made somewhat easier by the fact that Toronto tends to establish parks in many of it's ravine areas and I could see trails of green on a map and satellite images. This is the general image that we will be using. We can see the former water and ice drainage channels, in dark green, because Toronto has put parks in the ravines that were thus formed.

West of Toronto a natural gap between two areas of higher ground formed a vast temporary river to drain the central area of southern Ontario. This was called the "Dundas River" by natural historians and it flowed through where the Town of Dundas is now located. Both ice and water would be deflected here by the Niagara Escarpment. This wide gap can be seen while driving the 403 west from the QEW to Ancaster Heights. The flow of water eroded a low area that we now call Hamilton Harbour. It is also known as Burlington Bay. This is well to the west of Toronto.

In several locations across southern Ontario, pooling areas formed in low areas that the rushing waters flowed into, as the last ice age was ending. The lowest parts of these pooling areas remain filled with water today. Lakes Nipissing, Simcoe and, St. Clair all display multiple arms that are the remains of channels for inflowing waters following the glacial melting. All of these are the results of underlying intersections of lines of magma emergence, as described in the posting on the geology blog, "The Story Of Planet Earth", in the supporting document, "The Emergence Geology Of Ontario".

Notice the "arms" of Lake Simcoe, directly north of Toronto,

 The "arms" of Lake Nipissing.

 And the "arms" of Lake St. Clair.

On Lake Simcoe, to the north of Toronto, Cook's Bay took in water from the south. Kempenfelt Bay, around which Barrie is built, took in the flow from the west and, the elongated Lake Conchiching from the north. 

It is known that, for a while, the route for flowing water from the upper Great Lakes to Lake Ontario went through Lake Simcoe and the Trent River rather than through Lake St. Clair, Lake Erie and, Niagara Falls. This is why the section of the Niagara River Gorge around the power plants and the Lewiston-Queenston Bridge is so narrow.

Notice how narrow the Niagara Gorge is, from the Whirlpool to the Escarpment, compared to the Gorge further south, between the Falls and the Whirlpool. This is because most of the water from the Great Lakes, except Lake Erie, took a detour across southern Ontario during the time that this part of the Gorge was forming.

During the time that the falls were eroding their way southward through this section, the Niagara River was only draining Lake Erie, which was isolated from the other upper lakes. But eventually, the waters from the upper lakes established a new route through Lake St. Clair into Lake Erie and over the falls. This gave the falls much more erosive power and we can see where the gorge gets wider further south because of this.

THE ORIGINAL CHANNEL

The Toronto area is shaped roughly like a half of a bowl on the northern shore of Lake Ontario. The lowest point of this bowl is about where High Park is today. This represents the Humber Valley. From directly out of the north, a flow of water from the melting ice crossed the area on it's way to the lake, which was then at a considerably higher level than it is now so that all of what is now downtown Toronto was under water.

This was a powerful flow of water that eroded a channel on it's way down to the lake. Yonge Street is on the east side of this channel and Avenue Road is on the west side of it. We will call this simply "The Original Channel" and it can easily be seen by crossing it on Lawrence, Eglinton or, St. Clair Avenues.

The yellow line in this image shows the route of what I believe was the "Original Channel" that began flowing when the glaciers of the last ice age began melting. It forms a shallow ravine but is not visible in the satellite imagery. The line does not go all the way to the lake because the level of the lake was much higher than it is today, with all the water from melting glaciers. The former shoreline can still be seen in some places in the Toronto area.

FROM THE WEST TO THE DON VALLEY

In time, the flow of water from directly north of Toronto into the Original Channel diminished. We can see that there is a lesser dip at St. Clair Ave. to the south than there is at Eglinton Ave. because by the time the lake had retreated to the line at St. Clair Ave., the flow had diminished in this channel.

There was more highland area in the central part of southern Ontario and from there flowed two mightly channels of water eastward. As the two channels crossed the Toronto area, the bowl shape of the terrain brought the two closer together until they had nearly merged.

If you go north on Yonge St. from Steeles Ave., you will cross the first great dip, which we will call the "Steeles Channel" and then the second one, which we will call the "Thornhill Channel". If you go east on Steeles Ave. from Yonge St., you will see that the two channels have changed direction and are flowing southward.

The Steeles Channel has it's lowest point at Bayview Ave. and the Thornhill Channel at Leslie St. Not far south of Steeles Ave. The two channels merge to join the Don Valley. These channels would have cut off the flow of water from the north of Toronto to the original channel.

Inside the box we see two channels merging to form the Don Valley, which is the most important feature of Toronto's geography. Remember that ice and water is flowing southward, toward Lake Ontario.

The Don Valley is the most prominent natural feature of the Toronto area and can be observed, of course, from the Don Valley Parkway. Going north on the parkway from downtown, it forms a kind of an S-curve, going from one side of the valley to the other and then back across the broad valley again.

To the west of the Don Valley, ravines carved by the flowing waters after the ice age come together to form what we will call the "York Channel". The large dip on Eglinton Ave. at Leslie St. is where the York Channel joins the Don Valley. 

The dark green "V" on the satellite image of Toronto is what I call the "York Channel", after the original name of Toronto, on the left merging with the Don Valley, on the right. Smaller channels join both of these channels, before they merge with each other.

The York Channel can be seen at Lawrence Ave. and Bayview Ave. On Lawrence Ave. can be seen dips in the road at Bathurst St. and Saguenay Ave., these small channels also merged with the York Channel.

The Valley in the road on Eglinton Ave. at Bayview Ave. is what we will call the "Leaside Channel". This also joins the Don Valley at Leaside. Like the numbers on a clock, channels of fast-flowing water come from all directions except south to join the Don Valley. It is easy to see how the Don Valley has "arms" or inlets coming in from all directions much like Lakes Simcoe and Nipissing.

If the ground had not been so sloped toward Lake Ontario, the Don Valley would be a lake instead of a vast ravine. We can see on a map the inlets coming into lakes like Simcoe and Nipissing. If the ground here had been flat, this is what the Don Valley would be like today.

The Moore Channel, as I will call it, joins the Don Valley at the Moore Park Ravine. The valley on Eglinton Ave. at Mount Pleasant Road is this channel.

The Chaplin Channel was an important route for rushing water heading for the Don Valley from the melting glaciers. On Eglinton Ave., the channel's east bank is at Heddington Ave., it's low point is at Chaplin Crescent and it's west bank is at Old Forest Road. On Dufferin St., north of Eglinton Ave.

The dips in the road at Glencairn Ave. and Dane Ave. merge to form the Chaplin Channel. The small dips on Lawrence Ave. at Varna Dr. and Brookview Dr. are also channels that merged with this channel. The vast dip on Yonge St. north of Lawton Blvd. is the Chaplin Channel. It cut right across the then-obsolete Original Channel and it joins the Don Valley at Rosedale.

The Rosedale Channel joins the Don Valley at Rosedale Ravine. There is a wide dip in the road on St. Clair with a ravine just east of Bathurst St. This channel can also be seen in the dip on Dufferin St. at Castlefield Ave.

These channels approaching the Don Valley from the west display the deepest valleys on Eglinton Ave. in comparison with other east-west roads further north such as Lawrence Ave. This is because the smaller channels were still merging at the Lawrence Ave. level.

FROM THE EAST TO THE DON VALLEY

The roughly half bowl shape of the Toronto area continues east of the Don Valley. As in the west there were inflowing channels that merged and joined the Don Valley but not until the lake had retreated far enough. The flow from the eastern part of Toronto merged into a powerful channel that actually took over the Don Valley inflow and caused it to flow westward instead of southward toward the lake for about three kilometres.

On Warden Ave. going southward from Eglinton Ave., you will see the land getting lower toward the lake. There are two great dips in the road not far apart. The one closest to Eglinton Ave., we will call the "Eglinton Channel", the other we will call the "Danforth Channel".

These two merged to form what I will call the "Woodbine Channel" that takes over the Don Valley. In fact, it is a kind of comparable valley itself that can be said to merge with the Don Valley.

In the box is what I call the "Woodbine Channel". It merges with the Don Valley from the east and changes it's direction of flow. This causes the Don Valley to flow westward, instead of southward, for about 3 km, as can be seen in the imagery.

Not all channels east of the Don Valley flow into the Valley or the Woodbine Channel. There is the Scarborough Channel further east that can be seen in the great dip on Lawrence Ave. from Mc Cowan Rd. to Burnview Cr. Another vast valley can be seen south of Lawrence Ave. on Scarborough Golf Club Rd.

These eastern channels form an outlet at Bluffer's Park. But many of the broad, shallow dips on East Lawrence Ave. ultimately contributed their waters to the Woodbine Channel.

Morningside Park was also a vast pooling area that emptied it's waters into the lake via the ravine through which Highland Creek now flows. A more local drainage took place at what is now Sylvan Park through the same route that Bellamy Ravine Creek now flows. Rouge Park was a drainage channel, the Rouge Channel, that could have rivalled the Don Valley if it had had the time to develop.

Closer to the Don Valley, Danforth Ave. gets lower in elevation west of Woodbine Ave. and a low valley can be seen going to the south. This formed the outlest at Ashbridge Bay, just east of the Don Valley outlet. There is a shallow dip on Danforth Ave. at Linsmore Cres. and Greenwood Ave. that also goes here.

THE HUMBER SYSTEM

It is easy to see whether on a map or through actual observation that the Don Valley becomes much narrower as it approaches Lake Ontario. The reason for this is obvious. As the lakeshore withdrew to within a couple of kilometres of where it is today, the flow of water through the Don Valley had drastically diminished. The vast channels that supplied water to it were running dry except for small creeks and that is the way they remain today.

After the Don Valley System had had it's day, another player came on the scene. As the lakeshore withdrew southward, more land was exposed that had previously been under water. As you drive west on Eglinton Ave. west of the Chaplin Channel, you will notice that the ground gets progressively lower and as the flow through the Don Valley began to diminish, another great drainage system formed here in what is now the western part of the city.

The Humber Channel was a mighty flow from the northwest that came down toward what is now Humber Bay. The Humber River that we have today is but a ghost of that channel of long ago. We notice today, two vast dips in the road on Jane St., one at Eglinton Ave. and one at Alliance Ave. The dip at Alliance Ave. is the route of the former Black Creek Channel, through which Black Creek now flows. The Black Creek Channel can also be observed in the valley on Weston Rd. at Black Creek Dr.

The valley on Jane St. at Eglinton Ave. is what is known today as the "Eglinton Flats". The reason for this flat area is the course of the Humber Channel. The great flow of water through this channel from the melting glacier underwent a curve in it's flow that is bypassed by the modern Humber River.

Water flowed from the higher area of Toronto to the lower western part of the city, the Humber System. North and south of Eglinton Ave. around Keele St. you can see the channels that drained water into the Black Creek Channel.

There are two great channels that, unlike the Black Creek Channel, never joined the Humber Channel before emptying into the lake. The elongated Grenadier Pond in High Park is the remains of one such channel, the Grenadier Channel. Parallel to it on the other side of High Park is another vast channel that we will name the Parkside Channel.

The elongated Grenadier Pond, which appears to be a continuation of Humber Bay, is the remnants of a great drainage channel west of downtown Toronto.

I found the sources of these two channels. Just off Old Weston/Rogers Rd. on higher ground, there is a valley at Kane Ave. This is the route of the Grenadier Channel. There is another valley just off Old Weston Rd. at Chambers Ave. This is the route of the Parkside Channel. The two parallel channels curve toward Humber Bay and end up on opposite sides of High Park.

There is also a broad, shallow dip noticable on St. Clair Ave. at Batavia Ave. This is a local drainage channel that drained waters south of where the Black Creek Channel joined the Humber Channel. The remains of this channel can be seen in West Pond in Rennie Park, near High Park. We will call this the West Channel. It flowed between the Humber and Grenadier Channels and emptied into Humber Bay.

On Bloor St., there is a mild dip in the road west of Christie and Grace Sts. near Christie Park. There is also a dip on St. Clair Ave. at Lauder Ave. This is the remains of what we will call the Lauder Channel. This was a small drainage channel that caught the water flowing down from the higher ground in the west of the Chaplin Channel and south of the Black Creek Channel.

There is a very wide valley in Dundas St. around Islington Ave. This tells us that Mimico Creek was once far more than just a creek. In fact, it was a very mighty river that emtied water from melting glaciers into Humber Bay.

The Humber System was a vast and elaborate drainage system just as was the Don Valley System. The reason that there is no great Humber Valley can easily be seen by looking at a map. Except for the Black Creek Channel joining the Humber Channel, the channels of the Humber System empty into Humber Bay before they have the chance to join together to create a Humber Valley as great as the Don Valley. If the shore of the lake would have receded five kilometres more, we may have today a Humber Valley Parkway as well as a Don Valley Parkway.

The Humber Valley is, of course, the result of the Humber Line that I noticed. This line is the result of pressure on the land from the Appalachian collision, which took place between what is now Africa and what is now North America.

The line in the following image is the Humber Line, formed when the collision front of the sliding tectonic collision changed direction. This line runs from the "focal point" of the curve of the Appalachians, around Harrisburg PA, to the long axis of Georgian Bay. It passes right through the Toronto area, west of downtown, and forms the gradual drop in elevation going westward on east-west streets, such as Blood Street.

The Humber Line that I found meets the shore of Lake Ontario at Humber Bay, and is what formed Humber Bay.

 THE CREDIT SYSTEM

West of the Humber System around Mississauga, we have the third major drainage system in the Toronto area. I will name it the "Credit System" after the Credit River. This system is less developed than the Humber System simply because it had less low hinterland to collect water from melting glaciers. This system is on the western side of the vast half-bowl that is the Toronto area.

The wide, shallow dip on Lakeshore Rd. in front of Humber College seems to be an isolated, local drainage area. The wide dip on Lakeshore Rd. at Etobicoke Creek shows that, like Mimico Creek, it was once far more than merely a creek. It was a great drainage channel, the Etobicoke Channel. This Etobicoke Channel can be seen to have formed from two merging channels.

On Burmanthorpe Rd., a great valley can be observed with Fieldgate Dr. on one side, Ponytail Dr. and Etobicoke Creek on the bottom and Mill Rd. on the other side. A little further eastward, another, smaller, dip can be seen just west of Saturn Rd. This formed a peninsula, now known as Markland Wood in the same way that Don Mills was formed in the Don Valley System.

Along Burmanthorpe Rd., there is a very wide but relatively shallow valley with Westminster Pl. on one side, Tomken Rd. and Little Etobicoke Creek in the valley and Dixie Rd. on the other side. This "Applewood Channel", as we will call it, was a vast but short-lived river that did not have time to develop the V-shape of mature rivers.

On Lakeshore Rd. there is a dip in the road at Cawthra Rd. There is also a dip on Dundas St. just east of Cawthra Rd. That means that this "Cawthra Channel" extends in a relatively straight line perpendicular with the shore of Lake Ontario. This is unlike most other channels in any of the three drainage systems.

The channels in the Credit System to both the east and west of the Cawthra Channel point toward it at various angles so that even the Cawthra Channel is nowhere near as large as the channel that now houses the Credit River, it can be considered as the focal point of the Credit System.

On Lakeshore Rd. in Port Credit, we find a dip in the road at Helene St. at Harbour Marina. There is a corresponding wide dip on Dundas St. at Confederation Pkwy and Mason Heights. That means that this "Helene Channel" is fairly perpendicular to the lake shore, entering from slightly westward. We can see that, like the Don Valley System, channels converge from every direction except south like the hands on a clock.

On Burmanthorpe Rd., near Square One, there is a wide dip with a low point at Robert Speck Pkwy. This is the Mississauga Valley. On Dundas St., there is a broad valley with a low point at Constitution Blvd. and Tomken Rd. Both are the "Mississauga Channel" and it joins the Etobicoke Channel.

We can see that Cooksville Creek occupies the vast Mississauga Valley at Burmanthorpe Rd., but no valley where it reaches the lake at Port Credit. This demonstrates not only that the Mississauga Valley Channel went off and merged with another channel before the lakeshore retreated to it's present position but that Cooksville Creek is a latecomer to the Credit System and never carried much more water, from melted glaciers, than it carries today.

The Credit River, the center of the Credit System, displays what a vast amount of water it once carried at the valley around it on Dundas St. It can also be viewed very well on Burmanthorpe Rd. near Credit Woodlands. East of the Credit River Valley on Burmanthorpe Rd., there is a vast, wide valley with the eastern side at Perivale Rd. This we will call the "Perivale Channel" and it merged with the Credit Channel.

The Credit River Valley shows why rivers have valleys. Because they once carried much more water than they do today and if the same volume of water is flowing through a river, it will erode the ground faster in the middle of the river, where it is moving fastest, and form a V-shaped valley with the river at the bottom.

West of the Credit River, there is a significant dip in Lakeshore Rd. at Richards Park. There is a corresponding dip on Dundas St. at Erin Mills Pkwy. Let's call this the "Erin Mills Channel".

West of the Erin Mills Channel, we have a dip in the road on Lakeshore Rd. at Jack Darling Park and a corresponding dip in Dundas St. and Winston Churchill Blvd. We will call this the "Churchill Channel".

In this Credit System, we can see that the channels come in from all directions, except south, like the hands on a clock to empty into the lake in the area of the Credit River mouth and the Lakeview Generating Plant. This system is clearly less developed than the Humber System and certainly the Don Valley System simply because the lake shore stopped retreating before the channels merged and created one vast valley like the Don Valley.

DELTAS

There is more to the natural history of the Toronto area since the last glacier than the three drainage systems. We can see that the Don Valley is messy. The reason being that it did not have time to be smoothed out by millennia of flowing water. It's source of water ended when the water from the melting glacier stopped flowing through it.

But where did all the soil and loose rock go that comprised the area excavated by the vast Don Valley and the channels that joined it? It is easy to notice that the Toronto Islands are where the Don Valley meets the lake. Those islands are actually a river delta deposited by a great but messy and temporary river. Silt was deposited when the lake was at a higher level and when it lowered, the islands emerged as dry land.

Have you ever wondered how the Toronto Islands formed? This scenario explains it. The first of the following images shows the location of the Toronto Islands, the second is a close-up.

 

The thing that I notice about river deltas is that they usually occur when the river has it's source in a body of water instead of being only the drainage of a watershed. The two most famous deltas in the world are the Nile and the Mississippi. Both have as their source a body of water rather than a watershed. The Nile emerges from Lake Victoria and the Mississippi from the lakes of Minnesota. The Amazon River is bigger than either but has no delta because it is solely a watershed river.

The Niagara and St. Lawrence Rivers also emerge from bodies of water yet these two have no deltas. But these two rivers are of high volume relative to their length and there is quite a sandbar in Lake Ontario at the end of the Niagara River. The former Dundas River described earlier has no delta either, in fact it carved out the low area that we now call Hamilton Harbour or Burlington Bay. But this was a pre-existing channel that the waters from the melting glacier simply flowed through.

It seems certain that deltas, or delta islands, as we will call the Toronto Islands, form when a flow of water forces it's way from one body of water to another and plows along silt with it. The long piece of land at Long Point on the Ontario shore of Lake Erie was almost certainly formed in the same way. Has anyone ever noticed the similarity in shape and size between Presque Isle in Erie, Pennsylvania and the Toronto Islands? It is because both are the result of the same process.

This is the Long Point Peninsula.

This is Presque Isle. The reason delta Islands are more prominent in Lake Erie than in Lake Ontario might be that Lake Erie is shallower.

There are many small deltas formed by the outlets of former channels into Lake Ontario. To the east of the Don Valley there are Ashbridge Bay and Bluffer's Park. The islands at Ontario Place, I know are artificial. The Mimico Channel left quite a delta as did the broad, local drainage channel at Humber College. The Cawthra, Helene and, Credit Channels also left deltas in the lake.

SUMMARY

Hopefully, this has made some sense of Toronto's maze of ravines and the endless valleys and dips in the roads. We can only be awed by the volume of glacial water that it took to carve these channels. The ice must have melted relatively quickly or the process of carving these channels would have been too gradual to form deltas.

All documentation that I have seen concerning melting glaciers concerns the materials; tills, moraines and fluvoglacial deposits that the glacier leaves behind and pays little attention to the erosive power of the meltwater itself. I want to change that.

This area is a museum of river development. There is everything to be seen from wide, short-lived rivers that never lasted long enough to form the V-shaped cross-section to the small rivers of today in vast valleys that remind us of that wet world of long ago. There are so many of what we will call pre-rivers in various stages of formation. A place like the Eglinton Flats shows us how the small river of today took a "shortcut" in the valley of the curving Humber Channel.

The Humber and especially the Credit system never had the time or space to develop like the Don Valley System. If the shore of Lake Ontario would have receded another ten kilometres or so, the three systems would have merged into one big system that would have created a Grand Canyon of the north.

The time came when the ocean of water from melting glaciers had finished draining into the permanent bodies of water such as Lake Ontario and the oceans. The channels that had been carved by the rushing waters now hosted small rivers and creeks. Not much changed for more than ten thousand years. Then, Fort York was built here. The next thing we know, there is a great modern city built on these old channels and ravines. That is the Toronto story.

FORMATION OF THE DON VALLEY AND THE NIAGARA FALLS MORAINE

Here is an addendum to the Toronto Story that goes beyond the Toronto area and concerns the glacial formation of the Don Valley and it's relation to Niagara Falls.

The so-called Niagara Falls Moraine is a mass of land known to have been deposited by a glacier. Most of the city of Niagara Falls, Canada is built upon this moraine. It can be seen as the high ground on the Canadian side by the falls. I have found that the glacial thrust that deposited this moraine is the same one that initiated the formation of the Don Valley in Toronto.

If we look on a map of Toronto and Lake Simcoe to it's north, it is easy to trace this.
This lake has three "arms" extending from it. The northernmost arm, Lake Couchiching, is from the thrust of the glacier moving southward. The southward thrust was pushed westward by another glacial thrust that formed the arm on the western side of Lake Simcoe, Kempenfelt Bay, but it continued southward.

This formed the southern arm of Lake Simcoe, Cook's Bay. It is easy to see that the Don Valley is a direct continuation in a straight line with the southern arm of Lake Simcoe.

The Don Valley was largely dug by flowing water, but the reason it was a low-lying area to serve as a conduit for the glacial meltwater at the end of the last ice age in the first place is due to this glacial thrust.

Now, if we continue this straight line from the southern arm of Lake Simcoe through the Don Valley across Lake Ontario, we find that it comes straight to Niagara Falls. This has got to be the source of the Niagara Falls Moraine. Remember that the water level dropped during the ice ages because so much water was locked up in glaciers on land. Also any water that remained in Lake Ontario would be absolutely frozen solid so that a glacier, pulled by the rotation of the earth, could pass over it.

The powerful glacial thrust that created the southern arm of Lake Simcoe and began the Don Valley carried a vast amount of soil and rock with it which it dropped at Niagara Falls. Part of the moraine did not make it over the Niagara Escarpment at Lewiston-Queenston. This today forms the ridge upon which Ridge Road is built. The rest crossed the escarpment and today forms the high ground on the Canadian side by the falls. I believe that this happened not in the last ice age but the one before that, this means that some of the Don Valley was already there as the last ice age ended and was ready to act as a water and ice channel.

If you would like to continue this story in the Niagara area, here is a link:

www.markmeeksideas.blogspot.com/2019/06/niagara-natural-history-summary.html?m=0