Glassy melt products requiring formation temperatures above roughly 1,500–2,200 °C occur in strata near the Younger Dryas onset at several sites.

Proponent-laboratory mineralogy without blinded confirmation; temperature, even if right, does not identify the heat source, and the Abu Hureyra extension carries an unreviewed correction.

The high-temperature melt glass claim is mixed. Proponents identify interesting mineralogy suggesting temperatures above 2,200 °C, but these findings lack broad independent replication and definitive in situ context. The strongest opposing consideration is that extreme heat alone does not identify a cosmic source; anthropogenic fires, lightning, and industrial contamination can produce similar phases, requiring strict chronostratigraphic and chemical exclusion that has not been met.

Bunch et al. and later proponent work report meltglass and related phases whose mineralogy suggests formation at very high temperatures (1,700–>2,200 °C) in strata dated near the Younger Dryas onset (YDIH‑E012, E013), which is clearly non‑trivial. However, these materials come from proponent laboratories, lack blinded independent re‑analysis, and have not been shown in securely dated in situ contexts to be uniquely associated with the onset rather than with other high‑temperature processes (e.g., lightning, anthropogenic fires, industrial contamination). The strongest opposing consideration is that such high temperatures are achievable by known terrestrial processes, so without better contextual control and geochemical discrimination the melts’ existence does not strongly implicate impacts.

Bunch and colleagues and the Abu Hureyra study report meltglass whose mineralogy is interpreted to require formation temperatures of roughly 1,730 to more than 2,200 °C, which would narrow the field of heat sources if independently confirmed. Temperature does not name a cause: lightning, settlement fires, and industrial slag also reach these regimes, and depositional age, in-situ context, and analogue exclusion remain unmet. The strongest opposing consideration is that confirmed high-temperature phases in securely dated boundary strata at Carolina bays and a Syrian tell would be genuinely interesting mineralogy. The materials are largely unreplicated, Abu Hureyra carries a 2025 correction, and no blinded confirmation is in the evidence records.

The melt materials exist and proponent mineralogy reports formation temperatures of roughly 1,500 to >2,200 °C, but that is the whole of the affirmative case: no independent replication, no blinded phase identification, insecure depositional context at the archaeologically complex Abu Hureyra tell, and a 2025 correction to that paper whose content was not reviewed for this case. High formation temperature narrows the field of causes but cannot name one — lightning fulgurites, settlement fires, and industrial slag reach the same regimes. Strongest opposing consideration: the temperature estimates may yet prove correct and the mineralogy is genuinely interesting — this is unverified rather than contradicted — but as impact evidence it currently carries an attribution the observation alone cannot support.

The melt-glass reports come exclusively from proponent laboratories, have no independent replication in either direction, and two of the relevant papers carry corrections whose content was not reviewed for this case. The phase interpretations underlying the temperature estimates have never had blinded confirmation, and at a complex tell site such as Abu Hureyra the mundane high-temperature analogues — settlement fires, later occupation, lightning — are exactly the hardest to exclude. The strongest opposing consideration is that no study in this evidence base has looked for these materials and failed to find them, so this line is under-tested rather than refuted; genuinely verified >2,000 °C phases in dated in-situ context would be a substantial finding. Note also that temperature alone identifies a heat regime, not a heat source.

Proponent-laboratory mineralogy (YDIH-E012) without blinded confirmation; extreme temperature, even if right, does not name the heat source, and the Abu Hureyra extension (YDIH-E013) carries an unreviewed 2025 correction.

Proponent-laboratory mineralogy reports very high formation temperatures (YDIH-E012), unreplicated and unblinded, and extreme temperature does not name the heat source. The Abu Hureyra extension (YDIH-E013) sits at a tell where anthropogenic high-temperature analogues are hardest to exclude and carries an unreviewed 2025 correction.

Proponent-laboratory mineralogy reports very high formation temperatures (YDIH-E012), unreplicated and unblinded, and extreme temperature does not name the heat source. The Abu Hureyra extension (YDIH-E013) sits at a tell where anthropogenic high-temperature analogues are hardest to exclude and carries an unreviewed 2025 correction.

Proponent-laboratory mineralogy reports very high formation temperatures (YDIH-E012), unreplicated and unblinded, and extreme temperature does not name the heat source. The Abu Hureyra extension (YDIH-E013) sits at a tell where anthropogenic high-temperature analogues are hardest to exclude and carries an unreviewed 2025 correction.

Proponent-laboratory mineralogy reports very high formation temperatures (YDIH-E012), unreplicated and unblinded, and extreme temperature does not name the heat source. The Abu Hureyra extension (YDIH-E013) sits at a tell where anthropogenic high-temperature analogues are hardest to exclude and carries an unreviewed 2025 correction.

Proponent-laboratory mineralogy reports very high formation temperatures (YDIH-E012), unreplicated and unblinded, and extreme temperature does not name the heat source. The Abu Hureyra extension (YDIH-E013) sits at a tell where anthropogenic high-temperature analogues are hardest to exclude and carries an unreviewed 2025 correction.

Potentially interesting mineralogy from proponent laboratories, largely unreplicated independently. The evidentiary burden — secure depositional age, in-situ context, exclusion of anthropogenic and geological analogues (lightning fulgurites, historical fires, industrial slag), and impact-specific chemistry — has not been met; the Abu Hureyra paper also carries a 2025 correction.

Melt glass exhibiting mineral phases suggestive of temperatures above 1,730 to 2,200 °C has been documented at multiple sites by proponent investigators. However, these mineralogical interpretations have not undergone independent blinded replication, and terrestrial alternatives such as lightning fulgurites, anthropogenic burning at tell settlements, and industrial contamination have not been rigorously excluded. The strongest opposing consideration is the analytical identification of melted titanomagnetite and lechatelierite in Abu Hureyra and North American sediments, which require extreme thermal regimes.

The claim rests entirely on proponent-team studies (Bunch 2012; Moore AH 2020) that are largely unreplicated independently, depend on phase interpretations without blinded confirmation, and — at Abu Hureyra — sit on a tell site where anthropogenic high-temperature contexts are the hardest analogues to exclude, with a 2025 correction of unreviewed content. The strongest opposing consideration is that mineralogy requiring 1,730–2,200 °C genuinely narrows the heat-source space; but narrowing is not identifying, and provenance, in-situ context, and dating remain the unmet burden.

YDIH-E012 reports high-temperature meltglass and phases from several sites with inferred formation temperatures in the claimed range, and YDIH-E013 extends a weaker version of the observation to Abu Hureyra. These are predominantly proponent-team identifications without blinded independent confirmation, and the Abu Hureyra paper has a correction whose content was not assessed in the packet. The strongest opposing consideration is that phase interpretation, depositional context, and terrestrial high-temperature analogues have not been adequately excluded, although those concerns bear more strongly on provenance than on whether glassy material was observed.

Mineralogical assemblages interpreted as requiring 1,500–2,200 °C formation temperatures are reported from several boundary-age strata, yet the studies are unreplicated independently, temperature estimates rest on contested phase interpretations, and mundane high-temperature analogues (lightning, fires, industrial) are not excluded. Strongest opposing consideration is the extreme temperature itself, which narrows but does not identify the heat source.

Bunch et al. 2012 report meltglass from boundary-age strata in the Carolinas, Pennsylvania and Venezuela, with phases interpreted as requiring roughly 1,730 to above 2,200 °C (E012). Moore et al. 2020 extend the claim to Abu Hureyra (E013); that paper carries a 2025 correction whose content was not reviewed. Both are proponent-network studies with no independent replication, no blinded confirmation of the phase interpretations, and unmet burdens on in-situ context and boundary dating, the latter inheriting C010's weaknesses. Confidence is low because the ledger contains no independent test in either direction: the observation is untested rather than failed. Strongest opposing consideration: if the phase identifications hold, the inferred temperatures exceed those of ordinary biomass fires (a background point, not a ledger record), and no record demonstrates a fulgurite, anthropogenic or industrial origin for these specimens.

Potentially interesting mineralogy from proponent laboratories, largely unreplicated independently. The evidentiary burden — secure depositional age, in-situ context, exclusion of anthropogenic and geological analogues (lightning fulgurites, historical fires, industrial slag), and impact-specific chemistry — has not been met; the Abu Hureyra paper also carries a 2025 correction.