The Archean impact barrage
Eight layers of glass beads record asteroid strikes vastly larger than the one that killed the dinosaurs.
- When
- —
- Duration
- 240 million years
- Known to
- ± 30 million years
- Era
- Paleoarchean, Archean
Spherule beds through the Barberton succession record at least eight major impacts between 3.47 and 3.23 billion years ago. The beads are droplets of rock vapour that condensed and rained back down worldwide, and several beds show the graded layering left by impact tsunamis. Earth was still being hit on a scale with no counterpart in later history.