Manicouagan
A ring-shaped lake visible from space.
Key facts
- When
- about 214 million years ago
- Where
- Quebec, Canada
- What hit
- an asteroid about 5 km across
- Era
- Deep time
- Location
- 51.38° N, 68.70° W
Probably several million megatons of TNT.
Thousands of times all the nuclear weapons in the world, but only a few per cent of Chicxulub.
What happened
Manicouagan in Quebec is one of the best preserved large impact structures on Earth. Its most famous feature is a ring of water about 70 km across, now a reservoir, that surrounds a central plateau of impact melt rock. The whole structure is thought to have been about 100 km wide when it formed.
The impact happened in the Late Triassic, when the first dinosaurs and mammals were living alongside many other kinds of reptile.
Effects
For a time, Manicouagan was suggested as the cause of the great extinction at the end of the Triassic. More accurate dating showed it is about 13 million years too old, so it was not responsible. It is now a useful example that a large impact does not always cause a mass extinction.
The evidence
Shocked minerals, shatter cones and a thick sheet of impact melt rock, which has been dated precisely using crystals of zircon.
Did you know?
Astronauts often photograph Manicouagan from orbit, especially in winter when its ring of ice stands out.
Its central island, René-Levasseur Island, is larger than the lake around it.
Related pages
How is impact energy measured? See energy explained, or try the impact calculator.