Comets Over Canada: Part II

Ever since Geophysicist Allen West and others put it forward last year, I've been interested in the theory that a comet or other ET object exploding somewhere over Canada might have been the event that ended the Clovis Culture, triggered the Younger Dryas, and brought about the demise of the Mammoths.

Evidence seems to be mounting in support of the theory, but the latest brick in the wall

Samples of diamonds, gold and silver that have been found in the [Ohio] region have been conclusively sourced through X-ray diffractometry in the lab of UC Professor of Geology Warren Huff back to the diamond fields region of Canada.

The only plausible scenario available now for explaining their presence this far south is the kind of cataclysmic explosive event described by West’s theory. "We believe this is the strongest evidence yet indicating a comet impact in that time period," says Tankersley.

...raised a few problems for me. I wrote:

I cannot get this to jibe with earlier articulations of the theory. Specifically, geophysicist Allen West has previously suggested that the impactor exploded before touching ground (a la the Tunguska Event), this to explain the absence of a crater. But how could diamonds originating in the Canadian diamond fields have turned up so far South if not as ejecta from a (still undiscovered) crater?

I fired off an e-mail re these concerns to some of the theory's architects, and yesterday Mr. West himself was kind enough to respond and address this point:

The hypothesis is fairly complex. We believe the impact was a collision with a cloud of debris, much like Comet LINEAR [see above left]. The smaller objects would have detonated in the atmosphere, much like Tunguska. Depending on the angle of entry, the largest objects could have impacted the 3-km-thick ice sheet, creating ice-walled craters that left no lasting imprint on bedrock.

There are multiple processes that could account for the diamonds: 1) some diamonds appear to have condensed inside burning biomass due to the heat and pressure of the impacts/airbursts; 2) diamonds are known form from shock impact upon terrestrial materials, such as coal, peat, carbonate rock, which would have been entrained as detritus in the ice sheet or would have been near the surface under the ice; 3) diamonds may have been formed by carbon vapor deposition (CVD) in the plasma of the fireball; 4) pre-existing kimberlite diamonds could have been ejected into the air along with other detritus entrained in the ice sheet; and 5) the impacts/airbursts most likely created immense meltwater surges both from above and below the ice and which would have carried pre-existing diamonds and other debris along with the meltwater.

Thank you Mr. West.

While I still had his ear, I asked Mr. West about my favorite part of the theory, where several of his co-workers had produced evidence that, at around the time of the onset of the Younger Dryas

mammoth[s] and other great beasts from the last ice age were blasted with material that came from space.

Eight tusks [...] all show signs of having being peppered with meteorite fragments.

In other words, when the comet crashed over Canada, its as though every mammoth in proximity to the event took a shotgun blast full of metal tiny pellets to the head!

Back in December, I put this part of the theory to the lads and lasses of the Dinosaur Mailing list. Gregory S. Paul gave it a thumbs down:

Some in this discussion still seem to imagine that sand sized blast debris can be imbedded in bone surfaces or skin at substantial range from an meteoritic explosion. Tiny particles can travel at high velocities if they are being carried along by air that is itself an equally fast moving part of the supersonic shock wave (shock waves are shock waves because they move faster than sound) produced by the explosion, which are limited to the region immediately surrounding the point source. Anything hit by high velocity microdebris in this zone will be so severely damaged by even more obvious shock and heat that the sand impact will be incidental. The supposedly impacted tusks and bones should be shattered and scorched. Any living animal will be killed outright, the debris will not be the killing agent. Once the micro-debris hits stable air it slowsdown to harmless terminal velocity in well under a kilometer. Even pebble sized objects will slow down to a 100 mph in a few kilometers. That is why being hit by a round musket ball or grape shot at long range was not lethal.

Dr. West was kind enough to respond to this as well:

Most discussions cite the usual explanation for impacts, which is true in most cases. However, that theory fails to explain the Carancas impact (http://www.universetoday.com/2008/03/18/peruvian-meteorite-may-rewrite-impact-theories/) or the particles in mammoth tusks. New research hints at a "tunneling" effect for some impactors, particularly fragmented ones. In those cases, the leading objects tunnel into the atmosphere and explode, apparently opening the way for trailing objects to reach ever closer to the surface. Some bunker-buster bombs work on the same principle. The first bomb opens a crater, the 2nd digs deeper, and subsequent ones even deeper.

In simulations, the initial explosions of a highly fragmented comet appear to be able to push aside the atmosphere and allow the particles from subsequent explosions to travel with almost no atmospheric friction. This is all theoretical but explains some seemingly inexplicable phenomena.

So there you have it!!!