How did glaciers shape the landforms of Southern Ontario?

The landforms of Southern Ontario were extensively shaped by glacial action, resulting in a landscape primarily composed of gently rolling plains and various glacial deposits. During the last glacial period, the region was covered by massive ice sheets that scoured the land and deposited significant amounts of geologic debris.123

The region’s topography is defined by several distinct glacial features:

• Depositional Landforms: The landscape is characterized by till plains, moraines, and drumlins, which are streamlined hills aligned with the direction of former ice movement. Eskers—sinuous ridges formed in pressurized tunnels at the base of melting ice sheets—are also well displayed throughout the region.42
• Glacial Lakes: As the ice retreated, meltwaters created vast, flat lake plains and shorelines. These areas, such as those found in the western part of the Ontario peninsula, are notably flat and contribute to the region's high agricultural productivity.451
• Drainage and Erosion: Glacial streams carved giant spillways, and the movement of ice radically altered the area's drainage patterns. In eastern Ontario, the region was once inundated by the Champlain Sea, which left behind a very flat plain.43

While most of Southern Ontario consists of these glacial landforms, the Niagara Escarpment remains a significant exposed bedrock structure that interrupts the otherwise rolling terrain.41