How The Last Ice Age Shaped Canada

What Were The Ice Ages? The Ice Ages began 2.4 million years ago and lasted until 12,500 years ago. Glacials: cold periods during which glaciers covered large parts of the world Interglacials: very warm periods during which many of the glaciers melted.

Ice Ages Cycle

Why were there Ice Ages? Many causes have been suggested for the ice ages including: changes in solar flux changes in the shape of Earth’s orbit & the tilt of its axis Probably it was a combination of several such influences.

The Pleistocene Epoch The Pleistocene Epoch is the actual name for the time period This period is the first in which Homo sapiens evolved, and by the end of the epoch humans could be found in nearly every part of the planet.

The Last Ice Age The world's most recent glacial period began about 110,000 years ago and ended around 12,500 years ago.

Laurentide Ice Sheet A massive ice sheet that covered most of Canada and a large portion of the northern US It covered most of northern North America between 95,000 and 20,000 years ago. It created much of the surface geology of the area, leaving behind many glacial landforms

Retreat of the Laurentide Ice Sheet As the ice sheet retreated, it left behind many large glacial lakes

How Do Glaciers Form Landscapes? By scratching the surface like sandpaper Glaciers can pick up rocks and sand Then the ice sheet acts like sandpaper and scratches the land underneath Striation: a scratch mark on a rock It can also polish the rock smooth

How Do Glaciers Form Landscapes 2) The glacier will dump rocks along the way Glaciers will leave rocks and sediment as it moves It will leave little mounds and hills along its edges

Glacial Landforms Till: the sediments in a glacier Moraines, Eskers, Drumlins: hills created from the deposit of till from a glacier Kettle Hole: the hole or lake created from a leftover chunk of glacial ice

Toronto’s Ice Age

Great Lakes and Lowlands Most of the Great Lakes’ basins were carved out by the moving ice. Soil and rocks were scooped off the Canadian Shield and deposited over southern parts such as Toronto.

Formation of the Great Lakes

Toronto Drumlins Toronto has several drumlins, ridges created by glaciers. https://www.youtube.com/watch?v=677PQitX7Fk

Don Valley The deep wide lower Don valley was formed after the draining of Lake Iroquois (a huge glacial lake) Many streams, including The Don, cut deep U-shapes ravines through the previously V-shaped valley

Toronto’s Lakeshore Modern Lake Ontario is within the bed of ancient Lake Iroquois, a meltwater lake that rose while Ice Age glaciers blocked the outlet of the Saint Lawrence River to the sea.

Old Toronto

Oak Ridges Moraine North of the city The moraine's spongy wetlands and soil were deposited 12,000 years ago from the retreating glacier Now dozens of streams spring from there and 35 of them pass through the Greater Toronto Area.

The Toronto Islands The Scarborough Bluffs, for instance, are a section of the Lake Iroquois shoreline. Toronto Islands were created from sand deposits eroded from the Scarborough Bluffs The sand collected near the mouth of the Don River, forming a long, sandy spit that would eventually be the Toronto Islands. They were only a peninsula until a severe storm washed out part of the peninsula in the 1850s

Ice Age Videos http://www.youtube.com/watch?v=dJ5GYQrkvxI 2:08 “What is an Ice Age?” https://www.youtube.com/watch?v=er9DqviC5XE 44:04 “North American Ice Age”