Reply to Bunch et al.: Younger Dryas impact proponents challenge new platinum group elements and osmium data unsupportive of their hypothesis

Abstract

Bunch et al. (1) attempt to distort the significance of our results by referring to percentage variations rather than absolute concentrations in platinum group elements (PGE). Table 1 shows that the highest Ir concentrations we measured within the intervals highlighted by Bunch et al. (1) are roughly 30 times lower than those they previously reported (2). Readers should note that Ir data from the University of Hawaii and Belgian laboratories compare well with those from other laboratories using different analytic methods, and that our data from the Younger Dryas (YD) sections do not remotely resemble analyses of sediments from known impact horizons. Bunch et al. (1) implicitly acknowledge that the original data (2) are erroneous by selectively replotting our data to argue that …