More evidence that volcanoes killed the dinosaurs

Geologists and paleontologists have been kicking around an idea for the past several decades which threatens to overturn the scientific canon surrounding the demise of the dinosaurs. Rather than an asteroid impact, say a growing number of researchers, it was extreme volcanic activity that drove the dinosaurs to extinction. Critics complain that there isn’t enough evidence to support such a wild hypothesis — but new data is emerging in support of the claim.

The going theory, of course, is that a giant asteroid struck the Yucatan region of Mexico during the late Cretaceous period — a cataclysmic event that instigated a mass extinction across the entire globe. This theory, which gained popular acceptance several decades ago, supplanted the pre-existing notion that it was an ice age that drove the dinosaurs to extinction. It also cast aside the theory that volcanism might have been responsible.

But now, the idea is resurfacing — and new evidence is shedding light on the possibility. 

Back in 2008, Princeton geoscientist Gerta Keller rekindled the discussion by hypothesizing that dinosaurs died out gradually from climate change — what was caused by a series of severe volcanic eruptions in India at the end of the Cretaceous period.

Interestingly, this happened about 300,000 years after the Chicxulub impact in the Yucatan. Keller claims that the asteroid was too small, and that it had little to no effect on life. The real extinction action, argues Keller, didn’t happen until a vast mountain range in India unleashed its pent-up fury.

Called the Deccan Traps, it’s a rocky area that still covers much of India today. During the time of its eruptions — a phase that lasted tens of thousands of years — it spewed lava over an area the size of France, if not larger.

And indeed, the geological evidence points to a staggering geological event. According to Keller, these massive volcanic mountains poured out a relentless stream of lava that started to layer upon itself. Keller suggests that the total volume in cubic miles was greater than the Rockies and the Sierras combined. During the eruptions, the volcanoes would have shot sulphur dioxide and carbon dioxide into the atmosphere, while the lava would have encroached on an area up to 650 miles (1,045 km) across. So in addition to local destruction, the gasses would have caused climate cooling and eventual ocean acidification.

Keller’s research also suggests that it took the Earth about half a million years to recover, mostly on of account of at least four additional Deccan eruptions, which occurred about 280,000 years after the initial mass extinction.

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