It is amazing to me that many archaeologists continue to resist the evidence that the younger dryas cold period was caused by a comet impact on the Laurentide ice sheet, 12,800 years ago. The comet research group have produced extensive evidence, the clincher being the hexagonal nano-diamonds found in the Greenland ice sheet. If this were fully accepted it would cause a radical rethink of many aspects of world history at this period and beyond.
The main thing that deniers of the hypothesis point to is the lack of a crater as evidence of the impact. The first reason for this is that it hit several thousand feet depth of ice. You can calculate how much of the energy of a comet might be dissipated by melting of the ice, as I have done in my book Gods, Genes and Climate. But in addition to this a possible crater has been identified. This is Lake Nipigon just to the North of Lake Superior. This video explains the hypothesis and presents the evidence.
The evidence for the impact hypothesis can of course be challenged, as some scientists are doing. All archaelogical evidence is open to errors and is a matter of judgement. It comes down to a judgement as to what is the best way of explaining the several things that happened at this time, that are very likely interlinked.
Do you believe:
- A sudden release of water from Lake Aggassiz going North instead of South changed the North Atlantic currents? The Appalachian mountains are in the way of Eastern flooding from the Southern fringe of the Laurentide ice sheet and the ice sheet itself was blocking the way the great lakes now drain to the North West.
- The 38 species of animal that went extinct at this time were wiped out by humans? Slow-moving giant sloths maybe but 6 species of horse? Anyone who has tried to catch a horse that doesn’t want to be caught knows that idea is for the fairies. And horses could move south quickly to escape cold.
- That sudden decline in the highly successful Clovis people was driven by climate change? They were very sophisticated hunters who had probably lived through previous severe changes in climate. There is now a mound of evidence that humans had been in North America for thousands of years before the clovis culture.
- That black mats found all over America and in Europe were from localised fires or volcanism? This may well be a cause of some of them, but all?
- That spikes in platinum and nano-particles were from relatively steady-state phenomena, despite measurable spikes having been associated with the start of the younger dryas? The spikes are not as large as the impact that killed the dinosaurs, but they are there, and comets and meteorites can have different compositions.
Or should you choose to believe in a single main cause to explain all these?
- One or more impacts from the Taurid meteor stream.