It’s an extraordinary sight that’s so big it’s visible from space. The Manicouagan Reservoir is around 40 miles long and covers an area of 750 square miles, dwarfing anything you would find in the UK.
But in the reservoir is another extraordinary geographical feature: an island that is in fact bigger than the lake it sits in. The island is called René-Levasseur Island and it’s in Quebec, Canada.
Scientists believe it was created 215 million years ago by the impact of a three-mile-long meteorite. They say it is the fifth most powerful known impact the Earth has ever seen. The fascinating sight of the lake and island from above have led some to call it “the eye of Quebec”. British astronaut Tim Peake is among those who have photographed it from space.
The reservoir is 350 metres deep at its deepest point and holds 34 cubic miles of water, making it one of the biggest freshwater reservoirs in the world. Meanwhile, the island’s highest point is Mount Babel, rising 600 meters (1,970 feet) above the lake level .
Although the crater’s age means it is one of the world’s oldest impact craters, the events that caused the lake are much more recent. Nasa’s Earth Observatory explains: “In the 1960s, Hydro-Québec constructed the Daniel Johnson Dam — the largest multiple arch-and-buttress concrete dam in the world — on the Manicouagan River.
“Prior to the dam’s completion in 1968, two separate crescent-shaped lakes flanked the sides of the impact crater: Manicouagan Lake on the east and Mouchalagane (Mushalagan) Lake on the west. As the water levels rose over the next few years, the previously isolated water bodies joined to form the Manicouagan Reservoir, which finished filling in 1977.”
The dam took 11 years to build and was named after Daniel Johnson Sr, the 20th Premier of Quebec, who kickstarted the project.
The five largest known impact craters in the Earth’s history
- Vredefort, Free State, South Africa: 2,000 million years ago, 160km diameter
- Chicxulub, Yucatan, Mexico: 66 million years ago, 150km diameter
- Sudbury, Ontario, Canada: 1,800 million years ago, 130km diameter
- Popigai, Siberia, Russia: 35 million years ago, 100km diameter
- Manicouagan, Quebec, Canada: 215 million years ago, 100km diameter
