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Re: The dinosaurs did not die in fire, from the latest Geology
Phil Bigelow wrote:
> And if
> there is a lack of both components in the boundary zone, then the data
> tells the researcher nothing.
Doesn't it tell you that atmospheric circulation patterns were such that
fine particulate matter associated with the impact and/or fires didn't
reach that site in any quantity? That's useful information re seasonal
flows and weather.
> Phrased another way: The researchers' premise is that soot and
> iridium-laden dust are both delicate atmospheric precipitates, and if
> both events occurred, and if one component is *preserved* at a particular
> K-T boundary layer site, then the other component *must* be preserved
> there as well. Any anomaly from the expected result can be used as
> evidence for falsification of the world-wide wildfire hypothesis. This
> is a reasonable premise.
This is not a reasonable premise. Original deposition of iridium from
impact detritus and de-orbiting of ejecta cannot be expected to be
associated with fire initiation in a 1 to 1 correlation.
> Unfortunately, control samples can bite you in the butt..........One
> stratigraphic inch of
> modern soil may represent 100 years of accumulation, and it may contain
> soot from 3 wildfires separated by 30 years.
Or more. The massive rains that likely persisted for some years washed
a heckuva lot of sediment from the upper portions of drainage basins and
redeposited them into lower downstream areas. Even today, west
Tennessee loses about 18 tons/acre/year of topsoil. So you can expect
to find areas where the surface layers of iridium (and soot) were
removed quickly and entirely and deposited well away from their origin
in 'layers' that might well be segregated somewhat differently than at
the origin (grain size differentiation). Rilling and gulleying would
result in even grosser distortions.
> Therefore, if the control samples from the Hell
> Creek formation paleosols usually record wildfires, then it makes sense
> that soot present in the K-T boundary layer would also be in "background"
> concentrations even though a fire might have occurred during the
> deposition of the K-T boundary layer.
Yup. Particularly if diffused by later events.
> The biggest problem encountered in sampling is that of preservation.
I should'uv read this sentence first. It can't be said any better than
> The corollary to this is
> that we are lucky to have ANY preserved K-T boundary air-fall impact
> deposits. To expect air-fall deposits to be found in all K-T boundary
> layers world-wide is naive.