Lava erupts underwater
Bulbous pillow lavas at Isua show deep, standing oceans 3.7 billion years ago.
- When
- Known to
- ± 50 million years
- Era
- Eoarchean, Archean
Pillow basalts form only when lava is quenched by water, and their presence at Isua puts substantial standing water on Earth's surface at this date. Along with the sediments beside them they close the case that the Eoarchean planet had real oceans rather than transient pools. The rock chemistry also suggests the water was hotter and more acidic than today's seas.