Scientists from Royal Holloway College (part of London University) in association with Sandia National Laboratory in the US, and 13 other universities in N America and Europe are down as contributing to the conclusions, are all unanimous in saying a large impact or airbursting comet or asteroid is out of context in explaining the sudden dip in climate at the Younger Dryas boundary and even less in respect of explaining the disappearance of Clovis points and their replacement by the similar Folsom points (which appear derivative).
The AD775/6 event was a Thunderbolts feature a week or so ago - go to www.thunderbolts.info/wp/2013.01/16/caught-in-the-crossfire/ ... and Rens Van Der Sluijs mentions both the entries of 776 (A/Sax Chron) and 793 (Roger of Wendover). Rens is however critical of the mainstream handling of the issue as they studiously ignored the work of a number of scientists he lists, including Paul LaViolette (2011). The latter has produced a wealth of geophysical and archaeological evidence in support of big solar flares (or stellar flares) and the next step will be to get hold of his paper.
Lawrence sent me a link on this and it has been around several blogs and web sites as well as mainstream sources. The full article is available in pdf format at http://mnras.oxfordjournals.org/content/early/2013/01/08/mnras.sts378.fu... ... and here we have a new theory to account for the spike in 775/6, previously attributed to a very big solar flare and then discounted as it was too big by far. We then had a dilution of the size of the solar flare, jiggery pokery or otherwise.
An article in the Observatory 125 (2005) pages 319-122, 'Earth in the Cosmic Shooting Gallery' by DJ Asher, Mark Bailey, V Emil'yanenkar abd Bill Napier (see www.arm.ac.uk/preprints/455.pdf) claims the terrestrial impact rate appears to be substantially higher than current NEO population models imply but is consistent with a significant unsee asteroid and cometary contribution to the hazard. A bit of doomsaying but interesting in how it might have impinged on the past.
At http://phys.org/print275575752.html ... we learn that climate see saws are not just a feature of the most recent Ice Age but were happening in earlier epochs, even as long ago as two million years. This is where the lake sediments extracted from the area of the Olduvai Gorge in Tanzania have taken scientists - in search of the roots of human beings. For a period of roughly 200,000 years the climate oscillated between closed woodland and open savannah grassland - on five or six occasions. Each change is said to have occurred abruptly - in a geological sense of abruptness.
At http://phys.org/print274439306.html ... is a story from a paper peddling scary doomsaying to the CAGW heartbeat. In the Eemian interglacial, 125,000 years or so ago, it claims, pulse racing, the global temperatures increased and this had a remarkable effect - corals in equatorial oceans declined but corals in some temperate regions thrived. The scary bit is that this is interpreted as corals vacating the equatorial zone as a result of global warming and migrating to regions that may now be somewhat cool but were then agreeable to corals.
One of the authors that wrote a paper debunking the Younger Dryas Boundary event has now switched attention to the Australian megafauna extinctions - see http://archaeologynewsnetwork.blogspot.com/2012/11/hunting-or-climate-ch.... This time, it is not the Younger Dryas he takes aim at but the period around 40,000 years ago. This is not sharply defined as noted in earlier posts but basically he is talking about mass die-offs, once again, in various parts of the world, but homing in on Australia in particular.
At www.sci-news.com/othersciences/paleoclimatology/article00384.html ... researchers in Pennsylvania and South Carolina, and now as far away as Syria, are said to have found a thin layer of sedimentary rock with melt glass material within it - formed at very high temperatures, over 1700 degrees Celsius. It is known as trinitite and forms at the surface from the melting of any sediments that may have been there, fused with rocks. Something very similar happened when a nuclear airburst occurred in New Mexico in 1945 (testing the bomb).
the media haven't seen fit to hardly mention the latest paper on the Clovis comet hypothesis, assuming it is a dud call, but apparently students and geologists have shot the paper to the 'most read' item in the journal Geology - so the experts, and the future experts, are interested, and pricking up their ears - see http://cosmictusk.com/clovis-comet-paper-1-read-article-in-geology/ One of the features of the paper (you can download a pdf at Cosmic Tusk) is that there was a large peak in ammonium ions in ice cores at the beginning of the Younger Dryas which has been
This story is at http://phys.org/print270934592.html ... a 660lb iron meteorite was found near Poznan in Poland. It is cone shaped, around 2m in diameter, and is thought to date from around 5000 years ago, or 3000BC. It seems it was one of several big ones closely accompanied by lots of little ones. They all landed in what is known as the 'Morasko Meteorite Reserve' and this one was dug out of the ground after being detected by a device designed to look for electromagnetic anomalies.