"Scientists say rocks on the English coast contain clues of the processes that drove the end-Triassic event that killed as much as a quarter of all life on Earth."
"Some 200 million years ago, the rocks that became the Palisades cliffs just across the Hudson River from Manhattan formed during volcanic activity that helped rip apart the ancient supercontinent Pangea. That volcanism helped lead to the birth of the Atlantic Ocean while it also contributed to killing off as much as a quarter of all life on Earth during the event known as the end-Triassic mass extinction.
Marine animals like ammonites, ichthyosaurs and corals took huge hits during the extinction, and scientists have long suspected that the Atlantic-forming volcanism had something to do with it because of its effects on the climate and oceans. But evidence of what exactly killed life has been scant, making it one of the least understood of the so-called Big Five mass extinctions that punctuate the history of life on Earth.
Research published in January in the journal Geology, though, is starting to fill in the gaps of this prehistoric murder mystery.
By studying rocks in the southwest of England, a team of scientists found evidence of two triggers. One is that as oceans absorbed carbon dioxide emissions from the volcanic activity, they became so acidic that animals with shells dissolved in the water and died. The other is that the oceans lost their oxygen and became toxic to all but the most hardy ocean creatures."