Impact Extinctions: Dust Didn't Do It

Geological Society of America ^ | 01/23/02 | Kara LeBeau, GSA Staff Writer

[SunkenCiv]

Note: this topic is from January 24, 2002. Thanks Scully.

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[gleeaikin]

Some time ago I recall reading that the Iridium layer at Gubbio in Italy was several centimeters thick, not milimeters. I believe that other studies indicate that as study sites are farther from the Caribbean athe Iridium layers become thinner. Superheating, dust and soot would have been the seeds for heavy rain. Much destruction of vegetation even without a possible nuclear winter. Then add in thousands of years of sulfate arisols from the Deccan vulcanism, and there are lots of ways that life would have been severly damaged.

Then, we have the additional hypothesis about the Shiva Crater off Mumbai by Chattergee (sp?). It may be 4 to 6 times the size of the Yucatan crater, be of roughly the same age, and perhaps the cause of the Deccan activity. It has been more than a year since I last checked this one out.

[SunkenCiv]

The vulcanologists (some of ‘em) grasp at straws a *lot* because they miss being the only game in town. Lunar craters were incontrovertibly of volcanic origin until Apollo missions showed once and for all that they are impact structures. Now the volcanic crater nonsense is (or was, a few years back) being applied to Martian craters, which are clearly and obviously impact structures (other than Olympus Mons, or at least probably Olympus Mons).