As I said before, the evidence remains thin. There is a layer of
ash-like material found at many sites. But the evidence for component
materials that are of likely extraterrestrial origin is lacking in most
sampled sites. Also, common dating of the layer in different areas is
not established.

Chris L Peterson
Cloudbait Observatoryhttp://www.cloudbait.com


Intreresting discussion, folks. However, the statement above is
incorrect. The black mat has been dated at 12,900 on most of the
known Clovis sites, by the dean of Clovis Archeaology, C. Vance
Haynes. He also makes some interesting comments regarding the comet
theory in general:

Vance Haynes on the Black mat:
http://georgehoward.net/Vance%20Haynes'%20Black%20Mat.htm

Also, some new info and a great deabte has been placed on YouTube
he
http://www.youtube.com/view_play_lis...566C328E999E76

Of the 97 geoarchaeological sites of this study that bridge the
Pleistocene-Holocene transition (last deglaciation), approximately
two thirds have a black organic-rich layer or ‘‘black mat’’ in the
form of mollic paleosols, aquolls, diatomites, or algal mats with
radiocarbon ages suggesting they are stratigraphic manifestations
of the Younger Dryas cooling episode 10,900 B.P. to 9,800 B.P.
(radiocarbon years). This layer or mat covers the Clovis-age landscape
or surface on which the last remnants of the terminal
Pleistocene megafauna are recorded. Stratigraphically and
chronologically
the extinction appears to have been catastrophic,
seemingly too sudden and extensive for either human predation or
climate change to have been the primary cause. This sudden
Rancholabrean termination at 10,900
50 B.P. appears to have
coincided with the sudden climatic switch from Allerød warming to
Younger Dryas cooling. Recent evidence for extraterrestrial impact,
although not yet compelling, needs further testing because a
remarkable major perturbation occurred at 10,900 B.P. that needs
to be explained.