Deccan Traps: Indian volcanoes that weakened dinosaurs
66 million years ago Indian lava covered 500000 square kilometres and stressed dinosaurs before the asteroid hit.
A million years of fire in India
About 66 million years ago fissures in western India poured basalt over 500000 square kilometres, stacking flows 2000 metres thick. Eruptions pulsed for nearly one million years, starting 400000 years before the Chicxulub impact and continuing after.
Sulfur first caused short volcanic winters with failed harvests of ferns and seeds, then carbon dioxide warmed Earth by four degrees. Oceans acidified, soils turned toxic with mercury, and dinosaur eggshells thinned in India, China and France before final extinction.
Volcanoes, asteroid or both
Scientists debated for decades whether Deccan gases or the asteroid killed dinosaurs, with mercury spikes and lava dates supporting volcanoes. The newest high-precision dates show 70 percent of Deccan volume erupted just before impact, then a second pulse after, suggesting a deadly one-two punch.
Today Deccan basalts form flat-topped hills across Maharashtra, with the Western Ghats exposing 1000 metre cliffs along roads and rails. Caves at Ajanta and Ellora are carved in this lava, letting visitors touch the very flows that darkened dinosaur skies.
- Place: western India, 500000 square km lava
- Time: 66 million years ago, before and after impact
- Effect: sulfur winters, then 4 degrees warming
- Evidence: mercury, thin eggshells, lava dates
- Today: basalts, Ghats cliffs, Ajanta caves