A billion years without ice
No glaciation anywhere in the record for almost a billion years — the longest such gap in Earth's history.
- When
- Known to
- ± 200 million years
- Era
- Mesoproterozoic, Proterozoic
Between the Huronian glaciations and the Cryogenian, roughly 2.2 to 0.72 billion years ago, the geological record contains no evidence of continental ice sheets. Carbon isotopes stay unusually flat, oxygen stays low and stable, and sea level and ocean chemistry vary little. Whether this reflects a genuinely quiescent Earth or gaps in the record is debated, but the contrast with what came before and after is striking.