EARTH × EXTINCTIONS

The Lava That Shares the Blame

~66 million years ago

Phanerozoic · Mesozoic · Cretaceous

More than a million cubic kilometres of lava erupted in India across the Cretaceous boundary, in four high-volume pulses, and at least one of them began tens of thousands of years before the asteroid arrived. Reading the carbon cycle instead of the rock gives a different order: the major outgassing starts and finishes distinctly before the impact, and only the impact lands on the extinction itself.

Why it matters

Two plausible causes acting within the same few tens of thousands of years, and separating them is the closest palaeontology comes to a murder trial. The strangest finding is that they may have worked against each other: with so much life gone, the ocean could absorb far more carbon dioxide than usual, which would have muffled the warming the eruptions should have produced.

Dating & uncertainty

Uranium-lead and argon-argon dating agree that the eruptions straddled the Cretaceous-Paleogene boundary but disagree on which pulses came before the asteroid. How much of the extinction volcanism owns remains openly contested.

Sources

1. Schoene et al. (2019), Science · U-Pb constraints on pulsed eruption of the Deccan Traps across the end-Cretaceous mass extinction
2. Sprain et al. (2019), Science · The eruptive tempo of Deccan volcanism in relation to the Cretaceous-Paleogene boundary
3. Hull et al. (2020), Science · On impact and volcanism across the Cretaceous-Paleogene boundary
4. Kale et al. (2025), Geological Society of America Bulletin · Spatio-temporal volume recalibration shows Deccan volcanism caused Terminal Cretaceous Mass Extinction

Earth history as one day

23:38:5821 min 2 s before midnight

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