Saturday, September 4, 2010
Mammoth Killing Space Blast Controversy
Not so fast Sherlock. As I have posted in the past, the impact was by a targeted comet that effectively struck the polar ice sheet slightly off center inducing a shift in the crust to end the Ice Age. The comet would have broken up sufficiently to spread the impact. That micro diamonds might have traveled with the comet is certainly plausible.
The impact induced a thirty degree crustal shift along an arc from the present pole through to thirty degrees south and centered in
Hudson Bay. This finished the Ice Age collapse already begun around 15,000 to 16,000 years BP by an earlier natural crustal shift. This last shift was most certainly induced in order to properly finish the job.
We have transported diamonds from the known diamond fields in the
North West Territories in the valley and we have impact craters formed by bodies of ice ejected from the impact. Ohio
More critically, we have a carbon rich layer to explain away. First of, it has nothing to do with forest fires. Otherwise every forest fire would have left its signature in the fossil record. It simply does not work that way. Hot carbon will ignite and burn to completion.
The carbon is and was a major constituent of the comet itself and during the impact it filled the atmosphere with carbon dust as did
Tunguska in 1908.
So far my conjecture is holding up quite well. It is noteworthy that a two thousand year gap lies between the two conjectured events. Obviously the first informed humanity that the possibility existed and the return of a full ice age encouraged a drastic response.
The precise repositioning of the crust then after two thousand years of serious melting, the present climatic regime we call the Holocene. The attached chart shows that the climate of the Holocene coincided with agriculture’s emergence and that it has nothing to do with the preceding climate regime.
Mammoth-killing space blast 'off the hook'
By Jonathan AmosScience correspondent, BBC News
31 August 2010
North American mystery: At least 17 groups of large animals die out in a very short space of time
The theory that the great beasts living in
North America 13,000 years ago were killed off by a space impact can now be discounted, a new study claims.
Mammoths, giant bears, big cats and the like disappeared rapidly from the fossil record, and a comet or asteroid strike was seen as a possible culprit.
But tiny diamonds said to have been created in the collision have been misinterpreted, a US-UK team says.
Without these diamonds, the theory falls, the group tells PNAS journal.
"This was really the last pillar for this theory and I think it's time now everyone moved on," said co-author Professor Andrew Scott, from Royal Holloway,
, told BBC News. University of London, UK
It has been one of the big palaeo-debates of recent years: what caused the extinction of the creatures and human settlers living across
North America at the start of a millennium-long climate cooling event known as the Younger Dryas?
The traditional theory had been that a sudden release of fresh water from a giant glacial lake into the
North Atlantic had upset the ocean's circulation and sent temperatures plummeting in just a few years.
But then a group of scientists started to challenge this position by pointing to what they said were tell-tale signs in the sediments at archaeological sites of an ancient impact from space.
These 12,900-year-old sediments were claimed to hold exotic materials: tiny carbon spheres, ultra-small specks of diamond - called nanodiamond - and amounts of the rare element iridium that are too high to have occurred naturally on Earth.
The sediments were also said to contain a layer of charcoal deposited by the colossal fire that would have swept the continent after the event.
No crater has ever been identified, but the proponents say the impactor may simply have broken up in the atmosphere as it came in; and as proof they have produced mammoth tusks that appear to have meteoritic shrapnel embedded in them.
But detractors believe they have now unpicked much of this evidence, and in the latest edition of the Proceedings of the National Academy of Sciences they say they have demolished the theory's best, last hope - the nanodiamonds.
The diamonds were said to have been found in discrete (black) layers at particular sites
These nano-sized, hexagonal bits of diamond, called lonsdaleite, can be good tracers for impacts; they're created in the intense pressure and heat of a space collision.
But having examined closely the carbon spherules purported to contain nanodiamonds in this case, Tyrone Daulton, Nicholas Pinter and Andrew Scott say there has been a misinterpretation.
"We looked for these diamonds and we couldn't find them," said Professor Scott. "But not only that, [the proponents of the theory] have misinterpreted what are really just aggregations of carbon.
"There were frequent low-temperature fires all through this period - this is no big deal. And what happens is that the carbon in molecules gets re-ordered and this happens in very small domains, less than micron-sized areas.
"It's not a high-temperature phenomenon; it happens at low temperatures. Obviously, what they've done is take that material and identified these domains as diamonds when they're not."
Even before this latest study, one of the world's leading experts on impacts - Dr Jay Melosh of
- had shown that an airburst was not capable of producing the shock pressures necessary to make nanodiamonds. Purdue University, US
The proponents of the impact theory are not prepared to let go of their ideas just yet, however.
Dr Douglas Kennett of the University of Oregon, Eugene, US, told Science Magazine that the research featured in PNAS had been looking in the wrong places.
"The Daulton et al claim that we have misidentified diamonds is false and misleading," he said.
And geoscience consultant Allen West added that Daulton and colleagues had not followed the same protocols and therefore it was no surprise they had came up with a blank.
"They looked at charcoal but we never mentioned that we ever found diamonds in the charcoal," he told BBC News.
"They did say that they looked in some carbon spherules but we looked at 10-15 per layer and specified that in our methodology, and they only looked at 'one to several' - that's their quote. They didn't understand what they were supposed to be looking for."
Allen West said further nanodiamond evidence in support of the impact theory would be published in the coming weeks.