Built by a geologist

Glacial Landforms

Glacial Landforms Canada is a living textbook of glacial geology . The Laurentide Ice Sheet left behind an extraordinary variety of landforms that geologists use to reconstruct ice sheet behaviour. Learning to recognise these features is essential for any geologist working in Canada. Erosional Landforms These features were carved by the ice: Glacial Striations - Scratches and grooves carved into bedrock by rocks embedded in the base of the glacier - Show the direction of ice flow - Found throughout the Canadian Shield on exposed bedrock surfaces Roches Moutonnées - Asymmetric bedrock hills shaped by glacial erosion - Smooth, streamlined side facing the direction the ice came from stoss - Rough, plucked side facing the direction the ice moved toward lee U-Shaped Valleys - River valleys reshaped by glacial erosion into a broad, U-shaped cross-section - Common in the Rocky Mountains and Laurentian Highlands Depositional Landforms These features were built from material deposited by the ice: Moraines - Ridges of till unsorted sediment deposited at the margins of a glacier - Terminal moraines mark the farthest advance of the ice - Lateral moraines form along the sides - The Oak Ridges Moraine north of Toronto is one of Canada's most prominent examples Drumlins - Elongated, teardrop-shaped hills of till, moulded by moving ice - The long axis is parallel to the direction of ice flow - Found in drumlin fields containing hundreds or thousands of drumlins - The Peterborough Drumlin Field in Ontario contains over 3,000 drumlins Eskers - Long, winding ridges of sand and gravel deposited by meltwater streams flowing in tunnels beneath the ice - Can extend for tens or even hundreds of kilometres - Often used as natural transportation routes and sources of aggregate Kettle Lakes - Formed when blocks of ice buried in glacial sediment melted, leaving a depression - The depression fills with water to create a kettle lake - Common throughout Manitoba, Saskatchewan, and Ontario Erratics - Large boulders transported by glaciers and deposited far from their source - The Big Rock near Okotoks, Alberta is one of the world's largest glacial erratics 16,500 tonnes - By tracing erratics back to their source rock, geologists can determine ice flow directions Reading the Landscape When you look at the Canadian landscape with geological eyes, you can read the story of the ice sheet: - Th