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Mount Toba and extinction
Eric Martichuski wrote:
>>From: Mickey Mortimer
>>Surely you meant much more recently, and the story itself looks suspect to
>More like 70,000 years ago (give or take). But it's not as suspect as you
>might believe. The estimated date for the genetic bottleneck in our
>ancestry coincides nicely with the super-volcanic explosion of Mount Toba,
>near Indonesia (71,000 years ago). And I'm using "supervolcano" in the
>sense that Yellowstone National Park is basically one _huuuuuge_ caldera.
>Mount Toba sent up around 800 cubic kilometers of ash. Tambora (largest
>historical eruption) only emitted 20 cubic kilometers. Mt. St. Helens was
>only a measly 0.2.
>Within the past 450 million years, we know of only one eruption that was
>Paleoclimatology studies say that Toba caused 6 years of near total winter,
>and the next millennia was the harshest period during that ice age.
>We know humanity went through a bottleneck. Such an eruption is going to
>_severely_ impact human populations (along with all other sorts of
>populations). Tiny, scattered populations facilitate the rapid divergence
>into "races" that we see occuring in the fossil record around 50,000 to
>75,000 years ago.
>It's all circumstantial evidence, to be sure...but extremely suggestive
>nonetheless. Googling for "human, genetic bottleneck and volcano" gives
>a lot more info on the subject.
>And, beyond all that, it _must_ be true because I saw it on the Discover
I red "volcano.und.nodak.edu/vwdocs/vw_hyperexchange/toba.html. The text is:
"...the Toba eruption, dated at 75,000 years ago, was the most recent
truely large eruption of the Earth. Bill Rose and Craig Chesner of Michigan
Technological University combining all of the information on the extent of
the Toba volcanic material to deduce that the total amount of erupted
material was about 2,800 cubic km. About 800 cubic km was ignimbrite...at
the remaining 2,000 cubic km fell as ash, with the wind blowing most of it
to the west."
(William I. Rose is a professor of mineralogy, petrology and meteorology of
Michigan Technological University.)
Mount Toba produced 2,000 and isn't 800 cubic km of ash. This volume is
four times greater then the K-T impact was. Since the four times greater
volume of matter carried in the air did not cause mass extinctions, the
smaller volume definitely could not.