Palaeolithic Extinctions and the Taurid Complex, WM Napier, Cardiff Centre for Astrobiology, Cardiff University, available in PDF format for download to the general public but pending publication (which is agreed). George Howard was wondering, a few days ago, if the WISE space mission would find evidence of the Clube and Napier ‘remnants’ of a comet that broke up in the solar system during the Holocene period and gave rise to various meteor streams such as the Taurid complex. In this paper Bill Napier clearly ties their hypothesis onto the Firestone-West comet at the Younger Dryas boundary event 12,900 years ago. At that time it created a 1300 year period of cooling – but Napier does not address why that cooling came to a rapid end. As it stands at the moment the Younger Dryas is little different to a Heinrich/Dansgaard-Oeschger event and Napier does not delve into this – which is a disappointment.
In the introduction he outlines the Firestone/West discovery of nano-diamonds, melted plant resins, and lonsdaelite as well as soot, microspherules and magnetic grains etc. An alternative to a comet might be that the earth encountered a swarm of chondrites or small comets that led to multiple airbursts over a wide area. This idea might account for black mat formations as far away as Texas and the Andes. Napier goes on to suggest Comet Encke is a recently reactivated fragment of a progenitor comet that was much larger. Comet evolution commonly proceeds via fragmentation into smaller bodies (and he provides several examples of this process) and some of these bodies are dormant (quoting several papers by other researchers). He then adds, fireball outbursts from the Cygnid shower (the constellation of the Swan plays a prominent role in mythology I might add) support the hypothesis that the formation of the stream and dormant bodies within it proceeded from a cascade of disruptions of the progenitor comet (Trigo-Rodriguez et al 2009). The presence of substreams in the Taurid complex indicates the progenitor also took the path of multiple disintegration (and he lists research for substreams and NEOs that might have a connection). Napier points out there are 19 Near Earth Asteroids tightly bunched around Hephaistos (in relative terms) and form a distinct group (Steel and Asher 1994). Porubcan, Kornos and Williams (2006) found two such filaments originated between four and five thousand years ago (which ties in with both the research of Paul Dunbavin and that of Moe Mandelkehr as expressed in SIS articles and reviews), and another one somewhat earlier than 5000 years ago. The complex is much older than this, some 0.2 – 0.3 myr (Steel and Asher 1996) which is a surpisingly great age for a stream that may still be active (isolated events). This takes us back deep into the Pleistocene but Napier is only thinking in terms of the last 30,000 years, say from the last Glacial maximum. This means he is not thinking of a connection with the event that occurred around 35,000BP – which Firestone has not even integrated into the comet hypothesis. To do this would require a great deal of extra research – which clearly has not been done. It does however leave open a link to the Oldest and the Older Dryas events (also not mentioned).
Porubcan, Kornos and Williams (2006) and Babadzhanov, Williams and Kokhirova (2008) have found dynamical evidence of 9 small asteroids as well as 15 substreams within the Taurid complex and are associated with observable meteor showers and fireballs. Russian research stems initially from studies revolving around the Tunguska airburst in AD1908 and the most likely option that it involved a stray piece of cometary material possibly associated with the Taurid complex. There are of course various other avenues of research ongoing in Russia – and they apparently are also interested, and for a very long time, in the idea of electricity in space – even an electrical role in the Tunguska event. However, getting back to the Napier article, he says that in the course of the disintegration of the progenitor comet this would have given rise to concentrations of material along it’s orbital track and there may have been phases of enhanced fireball activity at certain points in time. Swarms of particles trapped in resonant orbits (Asher and Clube 1993) and (Dubieter and Arlt 2007) are one consequence, which leads to the Porubcan et al (2006) swarm between 3000 and 2000BC. Hence, Napier sees no problem in associating such a swarm with the 12,900BP event.
Napier then addresses geophysical expectations arising from an encounter with a swarm of cometary debris impinging on a hemisphere of the earth – and compares this to the evidence found at the YD boundary. In summary he puts the origin for the progenitor comet hypothesis as long ago as Whipple in 1967 and evidence has continued to accumulate since that time – first by Clube and Napier, and then by other astronomers. Radio and visual meteor data show that the zodiacal cloud is dominated by a broad stream of largely cometary material which incorporates an ancient dispersal system of related meteor streams. Embedded within this are significant numbers of large Near Earth Asteroids, including Comet Encke. He concludes by saying. ‘the object of this paper is not to claim that such encounters took place at 12,900BP – that is a matter for earth scientists – but to show that a convincing astronomical scenario can be constructed which seems to give a satisfactory match to the major geophysical features of YD boundary data.
Iwen Williams and David Asher are acknowledged for suggestions which materially improved the original version of this paper.
A link to this article is now available on George Howard’s website, www.cosmictusk.com