Interesting terrain that forms this circle. I happened on it when I was looking at Google Earth.
Anyone have any ideas? Answer below:
René-Levasseur Island is a large island in the centre of Lake Manicouagan in Quebec, Canada. Its highest peak is Mount Babel, at 952 m (3,123 feet). With a total area of 2,020 km² (and a diameter of 72 km), the island is larger in area than the annular lake in which it is situated. René-Levasseur Island is the world's second largest lake island (the largest is Manitoulin Island in Lake Huron).
The geological structure was formed by the impact of a meteorite 214 million years ago. The meteorite is believed to have been about 5 km in diameter, and would have hit the earth at a speed of 17 km/s, the fourth most powerful known impact the earth has seen. The impact of the meteorite formed a crater roughly 100 km in diameter, the centre of which forms the island known today. It became an artificial island when the Manicouagan reservoir was flooded in 1970, merging two crescent-shaped lakes: Mouchalagane Lake on the western side and Manicouagan Lake on the eastern side. It is the largest artificial island in the world.
The Manicouagan Reservoir, and René-Levasseur Island are sometimes called the "eye of Quebec".