Mass Extinctions – end of Permian
Saturday, December 3, 2005 5:00:37 PM
The world's largest mass extinction occurred however at the end of Permian about 250 million years ago. The cause (or combination of causes as I am more inclined to believe) of the different mass extinctions has been controversial. I have no doubt that environmental change played a major role, but what triggered this change? An asteroid/meteor/bolide hitting the earth (now the most popular suspected dinosaur murderer), a deep-sea methane release, outpouring of basalt lava (known as Lava Plateaus, Flood Basalts or Large Igneous Provinces (LIP), or what?
The Deccan Traps in India are one of the largest volcanic provinces in the world, and many scientists think or thought that they caused the extinction at the K/T boundary.
The world's largest ever lava plateau was however created in todays Siberia about 248 or say 250 million years ago (who cares about a few million years). Within a couple of hundred thousand years the lava flows had covered more than 25 million square kilometres (that is about 3 times the size of the United States). If the lava had been evenly spread all over the globe, it would have had a thickness of about 3 meters to give you an idea of what the 3 million square kilometres erupted lava is worth. There can be no doubt that this had an enormous environmental effect, but did it cause the Permian mass extinction?
Research, published in the journal Geology, reveals vital clues about the mass extinction at the end of the Permian period.
See http://www.imperial.ac.uk/P7101.htm (Imperial College London News Release of 1 December 2005)
The researchers believe that the volcanic gases from the eruption of the Siberian flood basalt would have depleted earth's protective ozone layer and acidified the land and sea causing massive soil erosion with not only disastrous effect for life on land, but soil materials washed into the oceans would have blocked out light and soaked up oxygen with catastrophic effects for oceanic life.
As an afterthought: soil erosion has caused the loss of a third of arable land over the last forty years (at least partly due to human activity).