Did an extraterrestrial impact or airburst occur at the onset of the Younger Dryas, about 12,800 years ago?
Most likely: no impact or airburst occurred; the proposed markers are terrestrial or background cosmic material…Ahead on the evidence, not yet confirmed. It needs two reviews to be accepted.
Where it stands
Four answers have been proposed. No impact or airburst occurred; the proposed markers are terrestrial or background cosmic material… leads, with evidence 2 for, 1 against: supported by its tests. Three are still possible. Of the two narrower questions under it, none is answered yet.
Answers 4
History
- Firestone et al. puts forward: airbursts and impacts from a large fragmenting comet deposited a synchronous boundary layer with impact…
- Daulton et al.: electron microscopy identified claimed nanodiamonds as graphene and graphene-oxide aggregates.For: No impact or airburst occurred; the proposed markers are terrestrial or background cosmic material…
- Petaev et al. puts forward: a small or differentiated extraterrestrial body (such as an iridium-poor iron meteorite) left the Greenland…
- Wittke et al.: proponents report boundary-layer peaks at dozens of sites in North America, Europe, the Middle East and…For: Airbursts and impacts from a large fragmenting comet deposited a synchronous boundary layer with impact…
- Petaev et al.: the GISP2 spike has Pt/Ir ratios above all known terrestrial and chondritic materials and very high Pt/Al…For: A small or differentiated extraterrestrial body (such as an iridium-poor iron meteorite) left the Greenland…
- Meltzer et al.: only 3 of the 29 claimed sites have age control placing the layer at the onset.Against: Airbursts and impacts from a large fragmenting comet deposited a synchronous boundary layer with impact…
- Holliday et al.: the Lubbock Lake blind test found microspherules and nanodiamonds low or absent at the boundary and abundant…For: No impact or airburst occurred; the proposed markers are terrestrial or background cosmic material…
- Kenny et al.: no crater dates to the onset; the Hiawatha structure is about 58 million years old.Against: Airbursts and impacts from a large fragmenting comet deposited a synchronous boundary layer with impact…
- Holliday et al. puts forward: no impact or airburst occurred; the proposed markers are terrestrial or background cosmic material…
- Green et al.: the GISP2 platinum spike has no agreed terrestrial source.Against: No impact or airburst occurred; the proposed markers are terrestrial or background cosmic material…
- Green et al.: the spike lasts about 14 years, which fits a fissure eruption better than an instantaneous event.Against: A small or differentiated extraterrestrial body (such as an iridium-poor iron meteorite) left the Greenland…
- The PLOS One Editors: two 2025 papers adding Baffin Bay cores and shocked quartz were retracted for failures of age model and…Against: Airbursts and impacts from a large fragmenting comet deposited a synchronous boundary layer with impact…
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