An independent evaluation of the Younger Dryas extraterrestrial impact hypothesis (SRC-SUROVELL-2009)

An independent evaluation of the Younger Dryas extraterrestrial impact hypothesis

Surovell, T. A.; Holliday, V. T.; Gingerich, J. A. M.; et al. (9 authors total) · 2009

AI-verified citationSRC-SUROVELL-2009

identifier / locator

Proceedings of the National Academy of Sciences 106(43): 18155–18158. DOI: 10.1073/pnas.0907857106

verification note

Confirmed via Crossref (2026-08-22 batch): title, first author, journal, volume, issue, and pages match.

reliability notes

The first major independent replication attempt (seven sites); its protocol was in turn criticized by LeCompte et al. 2012 — the exchange, not either paper alone, is the state of the microspherule dispute.

Evidence drawn from this source

Undermines· strongYDIH-E007

what the source states: An independent seven-site study — including two sites from the original Firestone sample — attempted to reproduce the reported boundary peaks in magnetic grains and magnetic microspherules and did not find spherule enrichment at the Younger Dryas boundary at any site.
what we infer: The first serious outside test of the founding observation, and it failed cleanly. The proponents' answer (LeCompte et al., carried below) is that the protocol differed in ways that lose spherules — a live methodological dispute rather than a settled verdict, but the burden it creates is real: the signature proxy appears only under proponent protocols.
limitations: LeCompte et al. 2012 documented concrete protocol deviations (size-fraction handling, magnetic separation) that could plausibly cause real spherules to be missed.