Whizz-bang hypothesis for the Younger Dryas bites the dust

Such has been the urge to leap on the impact theory of Earth system change, that virtually every drastic event recorded in the geological timescale has been linked by someone or other to the effects of bombardment by extraterrestrial objects. The most recent concerns the Younger Dryas and the extinction of the mammoths (see Whizz-bang view of Younger Dryas and Impact cause for Younger Dryas draws flak in EPN July 2007 and May 2008). The hypothesis stemmed from reports of an association of tiny magnetic spherules, soot and purported nanodiamonds and fullerenes (carbon molecules bonded into ‘geodesic’ spheres) with the onset of the Younger Dryas, the roughly coincident disappearance of Clovis tools and the demise of several large North American mammal species, including mammoths. Regular columnist for Science magazine, Richard Kerr,  reports that independent searches for all the evidential materials at the sites where they were said to occur have drawn unrelieved blanks (Kerr, R.A. 2010. Mammoth-killer impact flunks out , Science, v. 329, p. 1140-1141). Nonetheless, the core supporters of the hypothesis are clinging to their guns.