» Home > In the News

Landscape fires and asteroids

28 March 2013

No, this is not out of a catastrophist book or part of the Younger Dryas debate but comes straight from the horses mouth at the AGU, the geological and geophysical mainstream in the US – see http://wattsupwiththat.com/2013/03/27/asteroid-likely-caused-global-fire… … revisits the idea an asteroid struck the Yucatan and seems to suggest it coincided with the Cretaceous-Palaeogene (or K/Pg rather than K/T boundary, for some reason) (T being Tertiary which includes the Palaeogene). The theory is that the asteroid would have created enough heat to ignite fires across the globe and kill everything except those animals that were able to find shelter (under the ground or under water). Other scientists have challenged the theory of a global landscape fire as there is an absence of a charcoal rich layer, and soot observed in the debris layer itself originated from the impact site itself and not from landscape fires, as such.

This new paper by Robertson et al, 'K/Pg Extinction:Re-evaluation of the heat/fire hypothesis' in the Journal of Geophysical Research doi:10.1002/jgrg.20018, 2013 (http://onlinelibrary.wiley.com/doi/10.1002/jgrg.20018/abstract), associates the supposed lack of charcoal to changes in the sedimentation rate. When sediment rates are increased, accumulating faster, they display evidence of an excess of charcoal – not a deficiency. Wow. Does this mean they may have been laid down quickly – as in the Mount St Helens volcanic eruption?

I don't suppose for one moment this is what is being suggested, but it would allow the dots to be joined up. They haven't been joined up before as too many geologists do not accept fast sedimentation rates – even though it was observed in real life when the top was blown off Mount St Helens. The uniformitarian explanation for sedimentation rates has in a way crippled the K/T boundary discussion and we have a situation now where they will seriously tell you that it involved not just an asteroid, that was a minor bit of the extinction event, but other things such as the huge magma that spilled out of the Deccan Traps on the opposite side of the globe. Have Robertson et al let the cat out of the bag. Will the geology big guns be about to smoke them out – and can we expect an avalanche of papers explaining exactly why the sedimentation rates blow a hole in the Robertson et al theory.

The comments at Watts Up With That were surprisingly mainstream in character. Nothing like the reception displayed when it comes to climate. Funny, that.

A layer rich in carbon was also found in Denmark (some years ago) and was dubbed the 'grey chalk' and this has been used by some researchers as the post impact fire storm layer. We have grey chalk here in the UK, found beneath the escarpment and sought out by cement companies. This appears to be wash created by water, and represents chalk mixed with clay that has denuded over time, but of course that assumes the water action took place over a uniformitarian time scale. As such, it has no connection to the K/T boundary and is probably much later in date, whereas the grey chalk in Denmark appears to have evidence of micro graphite spherules or volcanic/impact glasses. The problem here is that the grey chalk is assigned a period of around 600,000 years (the time it is estimated it took to be laid down) so it is not exactly regarded as instantaneous – by mainstream.

For the K/Pg boundary event to be seen in proper context it is probably necessary to have at least some of these sedimentary layers as rapid formations – but here is the point of most resistance. Sedimentary rates are a main plank of geochronology. Robertson et al will meet an awful lot of resistance in even suggesting a minor contraction of the sedimentary rates – but they are at least placing their heads above the parapet, and that is to be highly commended.

Skip to content