The Portage Ridge

Keep in mind that there is also a Portage Ridge that I have named on the Canadian side in the posting on this blog, "Secondary Glaciation And The Niagara Impact Crater". Glacial Ridges are a product of the field that I developed and named "secondary glaciation". This concerns what happens at the end of an ice age when the glacier begins to melt and break apart.

Glacial ridges occur where there is a slope to the land, causing large bergs of ice breaking off the glacier to slide along the slope and push soil along with it. As the ice continues melting, eventually it "runs out of steam" and the soil remains, forming a glacial ridge. We could also call it a "secondary moraine", as opposed to a primary moraine which is deposited at the beginning of the ice age.

In the posting "Secondary Glaciation And The Niagara Impact Crater", I pointed out what may be the finest example of a glacial ridge anywhere, the one upon which Lundy's Lane in Niagara Falls, Canada is built. There is another upon which Center Street in Lewiston, NY is built.

Today, I would like to introduce a new secondary glacial moraine that were formed in the same way and around the same time as these two.

In downtown Niagara Falls, NY I have identified a secondary moraine that I will call "Portage Ridge" because Portage Road is built along it. If we drive north along this road beginning at Falls Street, we see that we are on a shallow ridge if we look eastward and westward along Falls Street and also on Welch Avenue.

Here is a map link http://www.maps.google.com/

By the time we get to Niagara Street and Fort Ave., the ridge has become bigger and rounded with the east side of the ridge steep in comparison with the western side. At Ferry Ave., Portage Ridge has become larger still and at Walnut and Pine Avenues it is very broad. The ridge begins to fade out as we go further north but from 11th st., it can still be detected if we look westward.

To see the reason for the formation of the Portage Ridge, all we have to do is look westward along the main streets of Pine Ave., Walnut Ave. and, Buffalo Ave. Look westward along Pine Ave. from the area of Hyde Park and you will see a long and gentle slope. The same can be seen parallel to this on Walnut Ave.

This westward slope, which is part of the underlying rock strata can also be seen on Buffalo Ave. by looking westward from around 63rd Street. It is, of course, this westward slope which forms the upper rapids in the river above the falls.

What happened about 12,000 years ago at the end of the last ice age is many large icebergs were breaking off the main glacier and sliding westward along this slope. These icebergs plowed up the soil in front of them so that a wall of soil was pushed forward. The weather was continually warming so that this wall of ice was melting.

Eventually, it melted to the point where it could not push the mound of soil any further and there it remained after the end of the ice age as the Portage Ridge. The moving wall of ice "ran out of steam" before it could push the ice along the slope around what is now the area of the falls.

Had this not happened, the soil in the Portage Ridge would have become part of the Niagara Falls Moraine, the high ground on the Canadian side around the falls and northward to Clifton Hill. Some of the soil did get pushed down the slope on Niagara Street to the west of Portage Road, this is why the ridge is narrower here. The ridge does not continue to the south of Falls Street because here the slope of the underlying rock strata there has more of a southward element.

As proof of my explanation of the origin of the Portage Ridge and the field of secondary glaciation in general, all we have to do is to look at a street map. It is well-known that the general slope to the underlying rock strata is to the southwest. We can see that Portage Road, which is built along the top of the Portage Ridge is exactly perpendicular to this, it runs southeast to northwest. This is just what we would expect if it's origin is due to a wall of ice sliding across the rock strata as I have described here.

So, if this is a glacial ridge like the one upon which Lundy's Lane is built, then why is it so low and rounded while the Lundy's Lane and Center Street Ridges are sharp and well-defined? The reason is simple. Unlike the other two ridges, which were formed in the same way, the Portage Ridge spent about 8,000 years under the waters of the former Lake Tonawanda. This lake formed after the end of the last ice age and drained probably 3500 hundred years ago.

Water was flowing toward the falls, which were then further north, through this part of the lake and the moving water eroded and rounded the Portage Ridge. As Lake Tonawanda drained, the steeper eastward side of the Portage Ridge formed part of the lake's shore.

Today, the northward extent of the former lake can easily be seen on Military Rd. in the Town of Niagara. The northern portion of the K-Mart parking lot is the former shore and from just north of K-Mart on Military Rd., it is easy to imagine looking out over a lake if you look southward and up until 3500 years ago, you would have been.

All that remains today of the former Lake Tonawanda is the broad upper Niagara River between North Tonawanda and the falls. At one time, in the deepest part of the lake around what is now the falls, the water was probably around 9 meters (about 30 feet) deep.