What Is the Niagara Escarpment? Ontario's Long Rocky Ridge

A ridge you may have driven past

If you have driven from Toronto toward Hamilton or Niagara Falls, you may have seen it: a long, steep, rocky edge rising above the flat land near Lake Ontario. In some places it looks like a wall of grey stone with trees growing along the top. This is the Niagara Escarpment.

An escarpment is a long cliff or steep slope that separates higher land from lower land. The Niagara Escarpment Commission, an agency of the Ontario government, says the escarpment spans 725 kilometres from the tip of the Niagara Region to the top of the Bruce Peninsula. It also describes the escarpment as more than 450 million years old.^[2]

Hard rock on top, soft rock below

How does a cliff that long form? An archived article from the University of Waterloo's Earth sciences publication, Wat On Earth, explains that the escarpment was made by differential erosion. That means weather and streams wore away rocks of different hardness at different speeds.

On top of the escarpment sits a caprock of dolostone, a hard rock that resists wearing away. Underneath are weaker shale rocks that erode more easily. Streams removed the softer shale and undercut the hard caprock, until the hard layer was left standing as a cliff. The article says this took millions of years.

Here is a simple way to picture it, with an invented model. Put a hard cracker on top of a stack of soft cake, then drip water on the side. The cake washes away first, and the cracker edge sticks out. Rock is much slower, but the idea is similar: the hard layer on top protects the soft layer under it until the soft layer is worn away from the side.^[1]

Not a crack in the Earth

Some people guess that a long cliff must mark a place where the ground cracked and one side slid down. The Wat On Earth article says the Niagara Escarpment is not formed by faulting. The rock layers were not pushed up or dropped down. Erosion did the work.

The article says the erosion is most easily seen at Niagara Falls, where the fast-moving river speeds up the process. The Niagara River pours over the hard caprock and wears away the soft rock underneath. In the Daily Read on the Great Lakes, you learned how the lakes are connected. The Niagara River is one of those connections, carrying water from Lake Erie toward Lake Ontario, and it crosses the escarpment at the falls.^[1]

From Niagara to the Bruce and beyond

In Ontario, the escarpment runs north from the Niagara River, curves past Hamilton and up through the hills west of Toronto, and then forms the spine of the Bruce Peninsula, which separates Georgian Bay from the main part of Lake Huron.

The Wat On Earth article explains that the escarpment does not stop in Ontario. It continues through Manitoulin Island and other islands in northern Lake Huron, and it can be traced into northern Michigan. It also stretches into New York State and Wisconsin, roughly circling a large bowl of rock under the state of Michigan.^[1]

People and the land

At the northern end of the escarpment is Bruce Peninsula National Park. Parks Canada describes towering cliffs of the Niagara Escarpment plunging into the blue waters of Georgian Bay. Parks Canada also says the park is in the traditional territory of the Saugeen Ojibway Nation, the traditional keepers of the Saugeen (Bruce) Peninsula.

On another page about the park, Parks Canada calls it the traditional home of the Saugeen Ojibway Nation and says the Nation has long depended on the land for food and spiritual life. The same page lists cliffside cedars and limestone coasts among the park's natural features.^[3]

Protecting a long, narrow place

Because the escarpment is so long and passes through cities, farms and forests, Ontario created a special agency for it. The Niagara Escarpment Commission says the Ontario government established it in June 1973. It is a regulatory agency that manages development on the escarpment and applies the policies of the Niagara Escarpment Plan. For example, people who want to build in the plan area may need a permit from the Commission.

The Commission describes the escarpment as a UNESCO World Biosphere. A biosphere reserve is a place recognized for protecting nature while people continue to live and work there. Parks Canada also says Bruce Peninsula National Park is part of a UNESCO World Biosphere Reserve.

The escarpment is also a place to explore. The Commission says it is home to Canada's longest footpath, the Bruce Trail. Many families walk short sections of the trail to see the cliffs, the views and the forest along the top of the ridge.^[2]