North America almost splits
A rift tears 3,000 kilometres through the continent, floods it with lava — and then stops.
- When
- Known to
- ± 20 million years
- Era
- Mesoproterozoic, Proterozoic
Around 1.1 billion years ago a rift begins opening through what is now the Great Lakes region, erupting one of the largest volumes of lava in Earth's history over 15 to 22 million years. Then it fails, probably because the Grenville collision on the other side of the continent locked it shut. It is the biggest failed rift known. Lake Superior sits in its scar, and it hosts substantial copper deposits.