Searching for impact fragments across the Eifelian-Givetian boundary
by Philippe Claeys
Of impacts and of extinctions some remarks of Dr. Tomasz Wrzołek
- Refinement of stratigraphy and study of mass extinctions is OK!
- Looking for ancient bolide impacts is OK! And finding them is OK OK!!!
- There is a very, very long way between finding impact and proving that it had any measurable effect on biosphere.
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
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 17341737.
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.