As the weather gets colder and the snow starts to fall, many Ontarians eagerly await the opening of its ski hills. For those in the Greater Toronto Area there are many options to north, east and west to meet their needs in south-central Ontario (Figure 1). However, this area is not known for its towering mountain ranges so where, and why, do we get ski hills in this region. The answer, unsurprisingly, is the area’s Geology!

Figure 1- Location of notable ski hills in south-central Ontario and Toronto (star). Image courtesy of Google Earth.

On the moraine

Northeast of the GTA you can find two ski areas (Figure 1 sites A and G) nestled in the Oak Ridges Moraine (ORM). The Oak Ridges Moraine formed between converging ice lobes during past glaciations of the area and now forms a prominent topographic feature in the area. If you ever drove north from the GTA, and east of the Niagara Escarpment, you will likely recall driving up and over a large hill with the GTA in the rearview (Figure 2). This was likey the ORM which provides the necessary relief to create slopes to satisfy snow sport enthusiasts in the area (Figure 3).

Figure 2- View from atop the Oak Ridges Moraine demonstrating the change in elevation.

Figure 3- Ski Hill in Southern Ontario on the Oak Ridges Moraine.

On the escarpment

There are also several ski hills along the Niagara Escarpment(Figure 1 sites B,C, and D), another notable topographic feature in Southern Ontario which stretches from Lake Ontario in the south to Lake Huron in the north. For example, the famous Blue Mountain Ski area (Figure 1 site D) lies on an exposed part of the escarpment where it meets Georgian Bay.

On the outliers

Whereas other ski hills can be tied to significant topographic features on a regional scale (the Oak Ridges Moraine and Niagara Escarpment), there are two sites where this is not the case (Figure 1 sites E and F) located just northwest of Lake Simcoe. These ski hills exist due to the topographic imprint of till deposits which cover the Simcoe and adjacent areas north of the Oak Ridges Moraine. These deposits form more sporadic topographic highs relative to the regional scale topographic highs, such as the Oaks Ridges Moraine and Niagara Escarpment, responsible for other sites. Ironically, perhaps, many of the ski sites in Ontario (Figure 1 sites A, E,F, and G) were created during Ontario’s cold, glacial, periods and now grant enthusiasts an opportunity to enjoy Ontario’s geology during its cold winter months.

Want to learn more about Ontario’s Geology?

Check out the wealth of Geological sites on Planet Rocks site for you to explore!

Learn more about the Georgian Bay area which encompasses the northern most ski hills (Figure 1) and sites (for example sea stacks and caves along the Bruce Peninsula) you can explore when taking a break from skiing or in the off-season.

References

Google Earth 7.3.4, (2021) Ski Hills South-Central Ontario 41°11'30.80"N, 79°20'53.69"W, elevation 0M. Image NOAA, LandSat/Copernicus. Access 2021-12-09.