Lake Connecticut facts for kids

Glacial Lake Connecticut was a huge lake that formed a long, long time ago, about 18,000 to 20,000 years ago. It covered the area where Long Island Sound and the coast of Connecticut are today. This amazing lake was created by meltwater from the front edge of a giant ice sheet during the last Ice Age.

The lake was held back by a natural dam made of rock and dirt, called a terminal moraine. This moraine is now the land that forms Long Island and Fishers Island.

What Was Glacial Lake Connecticut?

Glacial Lake Connecticut was a massive freshwater lake. It was formed by the melting ice from the Laurentide Ice Sheet, which was a huge glacier covering much of North America. As the glacier slowly started to melt and retreat, its water had nowhere to go, so it collected in front of the ice.

How the Lake Was Formed

The lake was created because the melting ice couldn't drain into the ocean right away. A big ridge of dirt and rocks, called a moraine, had been pushed up by the glacier. This moraine acted like a giant wall, holding back the meltwater and forming the lake.

• The moraine that dammed the lake is now the backbone of Long Island and Fishers Island.
• The lake was about the same size as the Long Island Sound we know today.

The Lake's Appearance

The water in Lake Connecticut was likely a beautiful turquoise blue-green color. This was because of tiny, super fine rock dust, called "rock flour," that was suspended in the water. This dust came from the glaciers grinding down rocks as they moved.

• The lake was fairly shallow, with an average depth similar to today's Long Island Sound, which is about 78 feet (24 meters).
• Fine sediments, like clay and silt, settled at the bottom of the lake as the meltwater slowed down.

The End of Lake Connecticut

Around 15,000 years ago, the natural dam holding back Lake Connecticut broke. This allowed the lake's water to rush out. The place where the water flowed out is now a narrow, fast-moving channel between the North Fork of Long Island and Fishers Island, known as The Race. It's famous for its strong rip currents.

What Happened After the Dam Broke?

After the dam failed, much of the lake bed was exposed to the wind. This caused a lot of erosion. Scientists can see evidence of this in the layers of dirt and rock at the bottom of Long Island Sound, where there are gaps in the sediment layers.

Saltwater Returns

The end of Lake Connecticut wasn't just one event. It was a process where saltwater from the ocean slowly started to flow in.

• This happened as sea levels around the world began to rise after the Ice Age.
• Also, the land that had been pressed down by the heavy ice sheets slowly started to rise up again, a process called isostatic rebound.
• There were times when saltwater came in, and then freshwater returned, until eventually, the area became the saltwater Long Island Sound we know today.