Checked · The Younger Dryas
There is no Younger Dryas crater. What that costs both sides
The claim
The absence of an impact crater at 12,900 years ago disproves the Younger Dryas impact hypothesis.
Our verdict
Under reviewNo crater of the right date has been identified, and that is a real cost to the impact case. It is not a disproof. An airburst leaves no crater, and airbursts are real. But an explanation for why the evidence is missing is not itself evidence, and the impact case has to carry that.
Start with the fact, because it is not in dispute. No impact crater has been identified dating to the onset of the Younger Dryas.
For a hypothesis whose name contains the word impact, that is a conspicuous hole, and how each side handles it tells you a lot about how each side argues.
The airburst answer
Proponents propose an airburst: an object that detonates in the atmosphere rather than reaching the ground. That produces heat, pressure and a debris field without excavating a hole.
This is not special pleading invented for the occasion. Airbursts happen. Tunguska in 1908 flattened a large area of Siberian forest and left no crater, and Chelyabinsk in 2013 was recorded in high definition by a country full of dashcams. The mechanism is real and well characterised.
Why it is still a cost
An airburst hypothesis is unfalsifiable in exactly the place a crater would have been decisive. If the theory predicts no crater, then finding no crater confirms nothing and refutes nothing. The theory has bought consistency with the evidence by giving up the strongest test it could have passed.
Structural point about evidence, applied to the Earth-Science Reviews exchange of 2021 to 2024.
That is not an accusation of bad faith. It is a description of what the move costs. A hypothesis that survives every observation because it predicts none of them in particular is harder to believe, not easier, and the proponents know this, which is why the case rests on the geochemical markers instead.
Where the sceptics overreach
The sceptical version, put carelessly, is: no crater, no impact. That does not follow, and it is refuted by Tunguska, which is an impact event nobody disputes and which left no crater.
The careful sceptical position is different and much stronger. It is that removing the crater removes the single piece of evidence that would have settled the question in one direction, and that what remains is a set of geochemical markers with a poor reproduction record. That is an argument about the strength of the remaining evidence, not a syllogism about holes in the ground.
Why this belongs in the case FOR, too
Book 4 puts the missing crater in the chapter arguing for the hypothesis, as well as in the chapter arguing against it. That is deliberate.
A strongman version of a case includes the strongest objection to it. If the pro chapter leaves out the crater and the counter chapter introduces it, the reader has been managed rather than informed, and the sequencing has done the arguing.
Where this leaves things
The five labels, applied to this question. Nothing is left unlabelled.
No crater dating to the onset of the Younger Dryas has been identified.
Airbursts occur and leave no crater. Tunguska 1908 is the standard example.
Whether an airburst occurred at the Younger Dryas boundary. The airburst explanation is coherent and it is not evidence.
The claim that the absence of a crater by itself disproves the hypothesis.
The claim that the absence costs the hypothesis nothing.
Sources
- Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling. Firestone, R. B. et al., PNAS 104(41), pages 16016 to 16021, 2007.
- The Younger Dryas impact hypothesis: Review of the impact evidence. Sweatman, M. B., Earth-Science Reviews 218, article 103677, 2021.
- Comprehensive refutation of the Younger Dryas Impact Hypothesis (YDIH). Holliday, V. T. et al., Earth-Science Reviews 247, article 104502, 2023.
- Rejection of Holliday et al.'s alleged refutation of the Younger Dryas impact hypothesis. Sweatman, M. B., Powell, J., West, A., Earth-Science Reviews 258, article 104960, 2024.
- Rebuttal of Sweatman, Powell, and West's rejection of Holliday et al.'s alleged refutation of the Younger Dryas Impact Hypothesis. Holliday, V. T. et al., Earth-Science Reviews 258, article 104961, 2024.
Related
Where this is argued in full
Answering the Architect Question
Both cases at the same length, measured and printed at the back. The argument runs across four papers in one journal and you can read all of it.
Both cases at the same length, measured and printed at the back. It is written and not on sale, and advance readers can read it first.