Scarborough Bluffs, Limestone cliffs along Lake Ontario in Toronto, Canada.

Scarborough Bluffs is a limestone escarpment along Lake Ontario in Toronto, running 15 kilometres from Victoria Park Avenue to Highland Creek and rising up to 90 metres. Its pale grey and white face is cut by vertical gullies, with darker streaks and patches of exposed earth, and a thin soil layer with trees at the top.

The landform developed twelve thousand years ago when a large glacial lake accumulated sediment and later drained away. The walls began forming as the waters of Lake Ontario eroded the soft ground.

Elizabeth Simcoe named the bluffs after Scarborough, North Yorkshire, in 1793 because the escarpment reminded her of the limestone cliffs near her hometown; her diary noted the shore looked like chalk cliffs. The name passed to the whole township in 1796, and a stylized version of the bluffs later appeared on the flag of the former city of Scarborough.

Several parks along the cliffs offer lookout points, paths down to the shore and access to narrow beaches at the base of the walls. Some sections are closed due to landslide risk, so watch for warning signs and stay on marked trails.

Fossils of extinct plants and animals that lived thousands of years ago sometimes appear in the layers. Geologists also find remnants of trees pressed down by the ice of the last glacial period.