Geological periods are associated with fossils. After the fossils shift, that's a new period. The old life tended not to die quietly - there was a mass extinction event. One such period was the Devonian and its violent ending was 359 million years ago.
The press release states what's going on. East Greenland (and Titicaca) rocks on the 359 million year border were heated to see what was in the air at the time. That would be spores, consistent with Devonian flora: ferns and mosses. These spores weren't healthy. They had spines and were radiation-baked.
The Great Baking might be a Proxima-level flare, from our Sun or from some neighbour gone nova. Another model has that the ozone dissipated right here. (We got an ozone air-quality warning right here in Denver these last couple days.)
Before the Cretaceous rifting, Greenland was geologically part of the eastern North American Craton. (Which is why Trump wants it back.) Over the Devonian, this craton was in turn part of Euramerica, alias "Old Red Sandstone" - an equatorial continent. (Titicaca was, then, Gondwana, southern.) East Greenland in that continent had a big lake, which environs they say was like the Lake Chad region today. So the Euramerican ozone shifting was not because of some move to the Arctic.
It happens that the Devonian Earth was cold. This planet, at this time, heated rapidly. That heating knocked out the ozone-layer, planetwide.
No comments:
Post a Comment