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Re: The dinosaurs did not die in fire, from the latest Geology



An intriguing abstract.  I seem to remember an estimate of something
like 70 billion tons of soot contained in the boundary layer.  If my
memory is correct, it's an inconsequential amount at best.  More
comments inserted below.
JimC

Thomas R. Holtz, Jr. wrote:
> 
> The authors conclude ..... possibly increased rains, extensive cloud >cover 
> (again,...... would be more likely killing agents from the >extinction.

Well, let's see.  If you put an extra 8,000 to 30,000 cubic miles or so
of water vapor into the atmosphere, it might increase the immediate
rainfall.  And the floods from that immediate increase could be expected
to strip much of the vegetation from drainage basins worldwide (even if
unburnt).  And the bare soil would probably have raised the average CN
from something in the low to mid 70's to perhaps the low 90's, so more
of that precip would be converted to immediate runoff for decades to
come, and one could perhaps expect the hydrologic cycle to be biased
toward increased rainfall for a century or two after the event.....

> ABSTRACT
> 
> High soot contents have been reported in Cretaceous-Tertiary (K-T)
> sedimentary rocks, leading to the suggestion that the amount of thermal
> power delivered from the Chicxulub impact was sufficient to have ignited 
> wildfires. 

The impact energy is estimated to have been sufficient to break the
molecular bond of hundreds or thousands of cubic miles of water and then
to further strip the electrons from the outer shells of the seperated
oxygen and hydrogen atoms.  Would that have been enough energy to light
a wildfire?

> Soot cannot be used to indicate fire location, however, as soot
> from one large fire could spread globally.

Quite true.  Aren't there existing estimates of the worldwide variations
in distribution of soot following the event?


> Tertiary sedimentary rocks of six nonmarine sequences (Colorado to
> Saskatchewan) contain no charcoal or below-background levels of charcoal and
> a significant quantity of noncharred organic materials, revealing that there
> was no distinctive wildfire across the North American continent related to
> the K-T event.

Interesting.