Great Lakes

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The Great Lakes and their drainage basin

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Great Lakes summary

Great Lakes

Q: What lakes comprise the Great Lakes of North America?

The Great Lakes are a chain of deep freshwater lakes in east-central North America comprising the lakes Superior, Michigan, Huron, Erie, and Ontario.

Q: How were the Great Lakes of North America formed?

The present configuration of the Great Lakes basin is the result of the movement of massive glaciers through North America, a process that began about one million years ago during the Pleistocene Epoch. The glaciers undoubtedly scoured existing valleys, widening and deepening them and radically changing the drainage of the area.

Q: Which of the Great Lakes is the largest?

Lake Superior is the largest of the five Great Lakes of North America. It is also one of the world’s largest bodies of fresh water. It is 350 miles (563 km) long (east to west), and at its greatest width it is 160 miles (258 km) from north to south.

Q: Where does water in the Great Lakes originate?

The Great Lakes receive their water supply from precipitation, which increases from west to east and from north to south. The average annual rainfall in the Lake Superior basin is 30 inches (760 millimeters), 31 inches in Lakes Huron and Michigan, and 34 and 36 inches in Lakes Erie and Ontario, respectively.

Q: How do the Great Lakes influence the regional climate?

The Great Lakes modify the climate of the surrounding region by absorbing a large quantity of heat in the warmer months, which is then lost to the atmosphere during the colder months. This causes cooler summers and warmer winters than would otherwise occur in the region.

lake system, North America

Written by Alfred M. Beeton

Fact-checked by The Editors of Encyclopaedia Britannica

Last Updated: Jan 8, 2025 • Article History

What lakes comprise the Great Lakes of North America?

How were the Great Lakes of North America formed?

Which of the Great Lakes is the largest?

Where does water in the Great Lakes originate?

How do the Great Lakes influence the regional climate?

News •

Scientists find hidden 'hotspot' that helped create the Great Lakes before North America even existed • Jan. 7, 2025, 4:31 AM ET (Live Science)

Warming Great Lakes could lead to stronger snow storms, climate scientists say • Jan. 3, 2025, 11:52 PM ET (CBC)

Arctic blast set to bring snow, cold temps to U.S. • Jan. 2, 2025, 1:40 PM ET (CBS)

Great Lakes ice forecast: Forecasters predict turnaround from 2024 record low season • Dec. 26, 2024, 10:40 AM ET (USA Today)

More snow expected in Northeast and Great Lakes region ahead of Christmas • Dec. 22, 2024, 9:45 PM ET (NBC)

Great Lakes, chain of deep freshwater lakes in east-central North America comprising Lakes Superior, Michigan, Huron, Erie, and Ontario. They are one of the great natural features of the continent and of the Earth. Although Lake Baikal in Russia has a larger volume of water, the combined area of the Great Lakes—some 94,250 square miles (244,106 square kilometres)—represents the largest surface of fresh water in the world, covering an area exceeding that of the United Kingdom. Their drainage basin of about 295,710 square miles (which includes the areas of the lakes themselves and their connecting waterways) extends approximately 690 miles ...(100 of 4048 words)

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