The Cheltenham Badlands are a rock formation in Southern Ontario made of red-coloured ridges and gullies. They are located in the Town of Caledon within the Regional Municipality of Peel, Ontario, within a 36.6-hectare property of the same name owned by the Ontario Heritage Trust. The badlands are an exposed section of the Queenston Shale, a vast swath of shale rock that crosses Southern Ontario. Exposed through erosion caused by early farming practices, the badlands are a curious case of a natural wonder created through human activity.
The rocks that form the Cheltenham Badlands date back to the late Ordovician period (458.4–443.8 million years ago). At this time, the land of what is now Ontario was very different from today. The region’s climate was warm and dry, similar to the northwest coast of present-day Australia. To the west, the area bordered a sea along a shallow coast. To the east, near modern-day New York, the Taconic range of the Appalachian Mountains was rising steadily. Rivers flowed towards the sea’s shoreline, where they formed muddy deltas. Over time, this mud was buried by newer rocks and transformed into shale.
Today, these shales make up a group of rocks known as the Queenston Formation, named after the town in Ontario. They are about 61 to 244 m thick in Southern Ontario, and stretch west from the city of Niagara to Hamilton, then from Milton northwest to Nottawasaga Bay, gradually being overlain by the younger rocks of the Niagara Escarpment. The formation thins as it progresses north, reducing to just 61 m thick at the base of the Bruce Peninsula. At the Cheltenham Badlands, the rocks of the Queenston Formation are exposed to the surface.
Did you know?
The term badlands is derived from the French expression “mauvaises terres pour traverser,” roughly meaning “bad lands to cross.” It was used by 18th-century French explorers in what is now North and South Dakota to describe landscapes that were difficult to traverse, or were poorly suited for agriculture. Today, badlands means much the same thing: barely vegetated landscapes of soft rocks that have been deeply cut and shaped by erosion.
Indigenous Peoples and European Settlement
Indigenous peoples have lived in the region of the Cheltenham Badlands for thousands of years. The ancestors of the present-day Mississaugas of the Credit arrived in the area around 1700, setting up temporary villages on river flats and migrating according to the seasons. However, the badlands themselves were not created until European settlement, as their shales remained buried under soil and forest cover. The first record of European settlement in the area dates back to 1848, when the Crown granted Lot 34, Concession III to Joseph Wilkinson. It is unclear if Wilkinson farmed the land, but by 1861 much of its forest cover had been cleared for crops. By the early 1900s, the area was used for cattle pasturing.
Exposing the Rocks
Clearing of the area’s forest cover exposed the shallow soil overlying the shale, which, when exposed to the elements, began to erode, with water cutting deep valleys and hummocks into the soft clay. Arial photos show that the badlands had begun to develop by at least 1946, by which point much of the area had been cleared for agriculture or pastureland. When exposed to air, the shale clays oxidized, giving them their rich red colour. Groundwater seeping through the rocks has also led to the occasional green-grey stripe in the clay, resulting from red iron oxide changing to green iron oxide.
Did you know?
As Canada’s newest badlands, the Cheltenham site joined two other badlands sites in the country. Famous for its abundant fossils, the badlands in Alberta’s Dinosaur Provincial Park formed in a similar way as those in Cheltenham. Its rocks are composed of sediments that were laid down 75 million years ago, on a coastal plain with river deltas flowing into an ancient sea. However, unlike the Cheltenham Badlands, these rocks were exposed via natural processes. Twelve thousand years ago, during the ice age, runoff from nearby glaciers scoured the land, creating today’s badlands topography. Saskatchewan’s Big Muddy Valley, another badlands site, was created the same way.
After over a century of private ownership, the site became publicly owned in 2000, to both protect the badlands feature and secure a corridor for a portion of the Bruce Trail. With public access now available, the site began to receive many visitors, and foot traffic accelerated the ongoing erosion of the soft shale. In 2015, the Ontario Heritage Trust closed the property to public access. After undertaking a planning process with government agencies, First Nations and local communities, the Trust made several changes to the site. The changes include new boardwalks that allows access to the badlands without exposing them to foot traffic.