[X] My Assistant

[Guest_BruceMoomaw_*]

...in Antarctica. This was the biggest mass extinction event in the history of multicellular life -- it wiped out something like 95% of all existing marine species as opposed to only about 50% for the impact that ended the dinosaurs -- and it has been one of the biggest remaining geological mystery stories. An even bigger giant impact has always been a serious suspect -- but because no crater could be found, other suspects have also been high on the list, ranging from the titanic flood volcanic outburst of the "Siberian Traps" region to a huge buildup of CO2 in the deep sea that was then suddenly released due to geological events (a planet-wide version of the Lake Nyos CO2 eruption that smothered hundreds of people in a matter of seconds in Cameroon). Indeed, there has been a recent comprehensive book on the mystery which ended by concluding that the mystery is still utterly unsolved.

Well, we seem finally to have found a crater that is both gigantic enough, and of just the right age, to be the culprit -- in the only place on Earth it could have hidden for so long: beneath the Antarctic ice layer.

http://www.space.com/scienceastronomy/060601_big_crater.html

It isn't quite settled yet, but this looks like an impact crater fully 500 km wide -- more than twice as wide as Chiczulub -- and thus quite big enough to have done the job, if it really IS an impact crater.

[NMRguy]

My position was not to be overly pessimistic, but I find it misleading when the headline of a news story is "Antarctic crater linked to big die-off". Blame it on media sensationalism, I guess. But these scientists now have a great hypothesis, and they must now go dig up evidence (literally) to prove their position. Greenland and Antarctica are areas of the Earth that still have secrets locked away under all of that ice.

[Guest_Richard Trigaux_*]

My position was not to be overly pessimistic, but I find it misleading when the headline of a news story is "Antarctic crater linked to big die-off". Blame it on media sensationalism, I guess. But these scientists now have a great hypothesis, and they must now go dig up evidence (literally) to prove their position. Greenland and Antarctica are areas of the Earth that still have secrets locked away under all of that ice.

I somewhat agree. If we look at the images in the article, we' see that the structure is VERY ROUGHLY circular. Many other circles of similar diametre also appear on the gravimetric map, as the poor resolution create a blur of this size around any punctual object. So it is a bit fast to claim that it is the big new hypothesis. With such a aproximate identification, the Hudson bay in Canada, or the northern plain of Italy, would be candidates too.