The Isua supracrustal belt
A strip of Greenland rock 3.8 billion years old preserves the oldest surface Earth still has.
- When
- Known to
- ± 50 million years
- Era
- Eoarchean, Archean
Unlike the gneisses around it, the Isua belt formed at the surface — lavas, muds and chemical sediments laid down in water and only lightly cooked since. It is the oldest sequence in which the actual environment of early Earth can be read rather than inferred. Nearly every claim about the Eoarchean world, from ocean chemistry to the earliest life, traces back to these few square kilometres.