At www.cosmictusk.com April 9th … there is an article on the YD boundary event and it’s impact on Arizona, published in Proceedings of the National Academy of Sciences. Many sites in Arizona have evidence of the Clovis culture which apparently thrived in the centuries immediately before the Younger Dryas period. A raft of large animals became extinct at the boundary, the dividing line being a thin black layer in the geology (they are below but not above the black layer). Basically, that is the argument but this research is a trifle sceptical and still seems to be thinking in terms of Clovis people wiping out all those mammals (including a lot of small species). It is noted that nano-diamonds are a common ingredient of cosmic dust and they rain down on earth on a regular basis. The Firestone and West et al argument is that the black layer contained a lot of nano-diamonds and other extra-terrestrial material and this argument is a kind of rearguard action.
Likewise, over at www.springer.com April 12th (see also www.sciencedaily.com/releases/2010/04/100412084527.htm )there is a piece that argues that Palaeo-Indians thrived in North America during the Younger Dryas cool event (that lasted over a 1000 years) and this is taken as evidence that nothing out of the ordinary occurred at the start of the Younger Dryas – especially nothing catastrophic in nature (or cosmic). The piece is quoting a paper in Journal of World Prehistory and the evidence appears to hinge on dating Palaeo-Indian remains at what was a C14 plateau. We can expect the arguments to spin back and forth between the two sides for some time to come, but certainly by the early Holocene Palaeo-Indians appear to be spread across the Plains and Rockies, dispersed across diverse habitats – which could not have happened suddenly. The argument is that the global cooling event was not as serious in North America, especially in mid-West and West, than it was in Europe, and there has been a lot of geological evidence to support this position over quite a number of years (see the Mammoth Trumpet at www.centerfirstamericans.org ). Why it should have been cold, particularly during the winter months, in the North Atlantic and NW Europe, and not in North America is something that requires an explanation.
Meanwhile, www.cosmictusk.com April 12th provides a swathe of papers by the likes of Clube and Napier, Steel and Asher, and Izumi, that are all available to download in pdf format to add to your collection, everything from the Origin of Comet Encke, the Microstructure of Terrestrial Catastrophism, Asteroids in the Taurid Complex, and a piece with a Japanese angle.