WASHINGTON — The most extensive extinction in history, the dying-out of about 90% of all species 250 million years ago, may have been caused by a massive flow of molten rock that covered an area half the size of Australia to a depth of more than a mile.
A study appearing today in the journal Science suggests the flood of molten rock that created a plateau known as the Siberian Traps in Russia was almost twice as big as previously believed and could have continued for thousands of years, changing the climate of the entire planet.
A group of United Kingdom and Russian scientists says in Science that such an eruption of flood basalt would have filled the planet's atmosphere with a choking concentration of sulfur dioxide, carbon dioxide and other gases.
Samples from the lava flow have been age-dated at about 250 million years. Other studies have shown that during this period the Earth experienced its most extensive extinction crisis--which killed at least 90% of ocean species and more than 70% of land creatures.