Following the last glacial maximum, at the end of the Pleistocene, there was a period of rapid change in the earth system (Björck, S. (2007)). This included; the onset of the younger Dryas cold reversal, which saw the return of glacial like conditions across the northern hemisphere and megafaunal extinction, where 35 genera of large mammals became extinct across North America (Firestone et al., 2007). One possible explanation for this change is the Younger Dryas Impact Hypothesis (YDIH), which proposes that an extra terrestrial (ET) object hit the earth 12,900 years ago (Firestone et al., 2007), which would have killed the megafauna near the impact zone, weakened the Laurentide ice sheet, which was covering the majority of North America, discharging
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Nanodiamonds are formed by a dynamic shock process, and have been found in sediments of the K-T boundary, and other impact craters (Korberl et al (1997)). Therefore nanodiamonds in the YDB must result from ET sediments and shock processes, both of which can be explained by an ET impact (Kennett et al (2009)). Firestone et al., 2009, also suggests formation through wildfires, that were ignited through the impact (see below) These nanodiamonds have been found to peak in YDB sediments ~10 to 3700 ppb (REWU) (Firestone et al., 2009), with extremely low levels above and …show more content…
DNA testing shows contrasting evidence to the apparent abrupt extinction. There appears to be a staggered effect, where different species have gone extinct at different times, in different areas. (Haynes 2010). This is directly contradicts the impact hypothesis, and the remains found beneath the black mat and not above it. It is possible that it can be explained with local scale extinction occurring instantaneously, while global scale extinction takes longer. This still is evidence against the impact hypothesis.
Survol?, revisited the original sites attempted to reproduce the results, while they were focused on a subset of the sites, they were unable to reproduce any of the original results of the markers. However there have been repeated analysis’s since surovell et al, which were able to replicate some of the results. This could be because of surovell et al neglected touse scanning electron microscopy and energy dispersive x ray spectroscopy, which were used by Firestone et al., 2007. (WITKEI) it has also been reported that they failed to visit the exact locations that the markers were
Nanodiamonds are formed by a dynamic shock process, and have been found in sediments of the K-T boundary, and other impact craters (Korberl et al (1997)). Therefore nanodiamonds in the YDB must result from ET sediments and shock processes, both of which can be explained by an ET impact (Kennett et al (2009)). Firestone et al., 2009, also suggests formation through wildfires, that were ignited through the impact (see below) These nanodiamonds have been found to peak in YDB sediments ~10 to 3700 ppb (REWU) (Firestone et al., 2009), with extremely low levels above and …show more content…
DNA testing shows contrasting evidence to the apparent abrupt extinction. There appears to be a staggered effect, where different species have gone extinct at different times, in different areas. (Haynes 2010). This is directly contradicts the impact hypothesis, and the remains found beneath the black mat and not above it. It is possible that it can be explained with local scale extinction occurring instantaneously, while global scale extinction takes longer. This still is evidence against the impact hypothesis.
Survol?, revisited the original sites attempted to reproduce the results, while they were focused on a subset of the sites, they were unable to reproduce any of the original results of the markers. However there have been repeated analysis’s since surovell et al, which were able to replicate some of the results. This could be because of surovell et al neglected touse scanning electron microscopy and energy dispersive x ray spectroscopy, which were used by Firestone et al., 2007. (WITKEI) it has also been reported that they failed to visit the exact locations that the markers were