Geology of North America: the Ice Age

Throughout North America's history, glaciers have periodically covered large parts of the continent, known as ice ages. Over the past two million years, four major glaciation periods have been identified, linked to cooler global climates. These ice sheets, sometimes nearly two miles thick, last receded about 10,000 years ago. They shaped the landscape, creating features like the Great Lakes and Niagara Falls, and left behind glacial deposits.

What are the massive sheets of ice that have periodically covered North America called?

• Glaciers

• Snowcaps

• Icebergs

• Frost sheets

How many major glaciation periods have scientists identified in the past two million years?

• Four

• Three

• Two

• Five

What was the approximate thickness of ice sheets during extensive glaciations?

• 3,000 meters

• 2,000 meters

• 4,000 meters

• 1,000 meters

Which geographical feature is believed to have been carved out by the moving ice of glaciers?

• The Great Lakes

• The Rocky Mountains

• The Mississippi River

• The Grand Canyon

What role did glaciers play in the creation of Niagara Falls?

• They sculpted the landscape that led to its formation

• They formed the waterfall directly

• They had no impact on Niagara Falls

• They diverted a river to create the falls