Mark Boslough, sometimes known as the Bos, claimed comets make up only one per cent of the population of earth crossing objects – and exist only for short periods of time (see http://cosmictusk.com/william-napier-to-mark-boslough/). This view echoes the mainstream consensus that comets are little more than dirty snowballs and disappear as quickly as they appear – and the Clube and Napier hypothesis has never been accepted. In fact, there is a fair bit of virulent objection to the hypothesis – not wanted. Opens too many cans of worms.
Bill Napier was invited by George Howard to make a response to Boslough and he does just that by describing what it might have been like to pass through a stream of debris from a disintegrating comet (gravel, pebbles, larger objects) and ends up by saying the Boslough cometary model was irrelevant as it had nothing to do with the actual circumstances that prevailed in our environment during the Holocene and earlier. He takes no account of, shows no awareness of modern developments in cometary dynamics.
The post below the above one has a two page print out of a new article by Petaev, Sichun Huang, Jacobsen and Zindler, on a large anomaly in the GISP 2 ice core, that apparently shows evidence for a cataclysm at the Younger Dryas Boundary – making the Boslough et al effort immediately out of date. While it notes carbon spherules have been found on the ground they concentrate on what was in the atmosphere and fell as snow over Greenland – a platinum anomaly. It was aired first at the 44th Lunar and Planetary Science Conference (2013). See also http://cosmictusk.com/rise-of-the-zombie-harvard-confirms-major-impact-a…
Meanwhile, at http://phys.org/print279878907.html … we learn that an Ice Age extinction event reshaped Australia's plant diversity.