Searching for impact fragments across the Eifelian-Givetian boundary
by Philippe Claeys


Of impacts and of extinctions – some remarks of Dr. Tomasz Wrzołek

Ellwood et al. (2003) are OK in the first two points, but they are not OK at all in jumping to conclusions, against the third point – sadly, there is a very large group of geologists and geochemists who err in the same way, falling into vicious cycle, as correctly indicated by Hallam et Wignall (1997).
Circular reasoning: the main and fundamental point of disagreement in an otherwise interesting story of looking for mid-Devonian impact (Ellwood et al. 2003, with comments by Racki et Koeberl, 2004 and responses by Ellwood et al., 2004).


Ellwood B. B., Benoist S. L., El Hassani A., Wheeler C., Crick R. E., 2003. Impact ejecta layer from the Mid-Devonian: Possible Connection to Global Mass Extinctions. Science, Vol. 300, pp 1734–1737.
Ellwood B. B., Benoist S. L., El Hassani A., Wheeler C., Crick R. E., 2004. Response to Comment on "Impact ejecta layer [etc.]". Science, Vol. 303, p. 471.
Hallam A., Wignall P. B., 1997. Mass Extinctions and Their Aftermath. Oxford University Press, Oxford.
Racki G., Koeberl C., 2004. Comment on "Impact ejecta layer... [etc.]". Science, Vol. 303, p. 471.