EARTH

Lava Too Hot to Exist Today

~3.5 to 2.7 billion years ago

Archean · Paleoarchean

These lavas erupted so hot that they flowed like water rather than creeping like modern lava, and they crystallised into blades of olivine as long as a hand. Nothing like them has erupted since: the Earth's interior has cooled too far to produce them again.

Why it matters

These flows are a thermometer for the young Earth: they show, more directly than any other rock, how far the planet had cooled from its violent beginnings. They are also why most of the nickel we mine comes from rocks of this age.

Dating & uncertaintyDisputed

They erupted near 1,600 degrees, some three hundred degrees hotter than any lava today. Whether that requires a mantle hundreds of degrees hotter, or only wet rock melting at ordinary temperatures above a sinking plate, has been argued for fifty years. Water measured inside the crystals now favours the hot mantle.

Sources

1. Grove & Parman (2004), Earth and Planetary Science Letters · Thermal evolution of the Earth as recorded by komatiites
2. Sobolev et al. (2016), Nature · Komatiites reveal a hydrous Archaean deep-mantle reservoir
3. Grosch & Viljoen (2023), Journal of African Earth Sciences · The discovery and petrogenetic significance of komatiites

Earth history as one day

05:29:5218 h 30 min before midnight

if Earth’s 4.54 billion years were compressed into a single day