Younger Dryas impact hypothesis
The Younger Dryas impact hypothesis (YDIH) or Clovis comet hypothesis posits that fragments of a large (more than 4 kilometers in diameter), disintegrating asteroid or comet struck North America, South America, Europe, and western Asia around 12,850 years ago, coinciding with the beginning of the Younger Dryas cooling event. Multiple meteor air bursts and/or impacts are claimed to have produced the Younger Dryas (YD) boundary layer (YDB), depositing peak concentrations of platinum, high-temperature spherules, meltglass, and nanodiamonds, forming an isochronous datum at more than 50 sites across about 50 million km2 of Earth's surface. Some scientists have proposed that this event triggered extensive biomass burning, a brief impact winter and the Younger Dryas abrupt climate change, contributed to extinctions of late Pleistocene megafauna, and resulted in the end of the Clovis culture. The view is a minority, with the prevailing view being that the Younger Dryas was generated by an influx of glacial meltwater into the North Atlantic.
The evidence given by proponents of a bolide or meteorite impact event includes "black mats", or strata of organic-rich soil that have been identified at over 50 archaeological sites across four continents, primarily in North America and Greenland.[a] Proponents have reported materials including nanodiamonds, metallic microspherules, carbon spherules, magnetic spherules, iridium, platinum, platinum/palladium ratios, charcoal, soot, and fullerenes enriched with helium-3 that they interpret as evidence for an impact event that marks the beginning of the Younger Dryas. Proponents of the hypothesis claim that these data cannot be adequately explained by volcanic, anthropogenic, or other natural processes. It has been suggested that this boundary layer should be used as a local stratigraphic marker.
It is hypothesized that the impact event brought about the extinction of many species of North American Pleistocene megafauna. The animals included camels, mammoths, the giant short-faced bear, and numerous other species that the proponents suggest died out at the time. The proposed markers for the impact event are claimed to have contributed to the transition from Clovis culture to subsequent patterns. The supposed event is claimed to have triggered extensive biomass burning, a brief impact winter, and an abrupt climate change.
Early speculative hypotheses 
The Younger Dryas was first recognized in Denmark in 1901 by Nikolaj Hartz and Vilhelm Milthers, and the term was coined in 1912. However, there were several speculative hypotheses connecting comets with climatic events over the last 12,000 years that predate its discovery.
The earliest known hypothesis about a comet that had a widespread effect on human populations can be attributed to Edmond Halley, who in 1694 suggested that a worldwide flood had been the result of a near-miss by a comet. The issue was taken up in more detail by William Whiston, a protégé of and popularizer of the theories of Isaac Newton, who argued in his book A New Theory of the Earth (1696) that a comet encounter was the probable cause of the Biblical Flood of Noah in 2342 BCE. Whiston also attributed the origins of the atmosphere and other significant changes in the Earth to the effects of comets.
[T]he greater part of men and animals drowned in a universal deluge, or destroyed by the violence of the shock given to the terrestrial globe; whole species destroyed; all the monuments of human industry reversed: such are the disasters which a shock of a comet would produce.
A similar hypothesis was popularized by Minnesota congressman and pseudoarchaeology writer Ignatius L. Donnelly in his book Ragnarok: The Age of Fire and Gravel (1883), which followed his better-known book Atlantis: The Antediluvian World (1882). In Ragnarok, Donnelly argued that an enormous comet struck the Earth around 6,000 BCE to 9,000 BCE,[b] destroying an advanced civilization on the "lost continent" of Atlantis. Donnelly, following others before him, attributed the Biblical Flood to this event, which he hypothesized had also resulted in catastrophic fires and climate change. Shortly after the publication of Ragnarok, one commenter noted, "Whiston ascertained that the deluge of Noah came from a comet's tail; but Donnelly has outdone Whiston, for he has shown that our planet has suffered not only from a cometary flood, but from cometary fire, and a cometary rain of stones."
The Younger Dryas impact hypothesis 
In 2006, The Cycle of Cosmic Catastrophes: How a Stone-Age Comet Changed the Course of World Culture, a trade book by Richard Firestone, Allen West and Simon Warwick-Smith, was published by Inner Traditions – Bear & Company and marketed in the category of Earth Changes. It proposed that a large meteor air burst or impact of one or more comets initiated the Younger Dryas cold period about 12,900 BP calibrated (10,900 14C uncalibrated) years ago.
In May 2007, at a meeting of the American Geophysical Union in Acapulco, Firestone, West, and around twenty other scientists made their first formal presentation of the hypothesis. Later that year, the group published a paper in the Proceedings of the National Academy of Sciences (PNAS) that suggested the impact event may have led to an immediate decline in human populations in North America.
In 2008, C. Vance Haynes Jr. published data to support the synchronous nature of the black mats,[a] emphasizing that independent analysis of other Clovis sites was required to support the hypothesis. He was skeptical of the bolide impact as the cause of the Younger Dryas and associated megafauna extinction but concluded "... something major happened at 10,900 YBP (14C uncalibrated) that we have yet to understand." The first debate between proponents and skeptics was held at the 2008 Pecos Conference in Flagstaff, Arizona.
In 2009, a paper in the journal Science asserted that nanodiamonds were evidence for a swarm of carbonaceous chondrites or comet fragments from air burst(s) or impact(s) that set parts of North America on fire, caused the extinction of most of the megafauna in North America, and led to the demise of the Clovis culture. A special debate-style session was convened at the 2009 AGU Fall Meeting in which skeptics and supporters alternated in giving presentations.
In 2010, astronomer William Napier published a model suggesting that fragments of a comet—initially 50 to 100 kilometers in diameter—could have been responsible for such an impact, and that the Taurid complex is formed of the remaining debris. Napier refined this model and published further research in 2019. An independent study carried out in 2021 by Ignacio Ferrín and Vincenzo Orofino added support for these ideas.
In 2011, a group of scientists challenged the Younger Dryas impact hypothesis on the basis of claims that most of the conclusions could not be reproduced and were a misinterpretation of data. Skepticism increased when it was reported that one of the lead authors of the original paper had practiced geophysics without a license.[c] Around that time, other articles claimed that no nanodiamonds were found and that the supposed carbon spherules could be fungus or insect feces and included modern contaminants. In response, in June 2013 some of the original proponents published a re-evaluation of spherules from eighteen sites worldwide that they interpret as supporting their hypothesis.
In 2012, another paper in PNAS offered evidence of impact glass that resulted from the impact of a meteorite. Another group of scientists reported evidence supporting a modified version of the hypothesis—involving a fragmented comet or asteroid—was found in lake bed cores dating to 12,900 YBP from Lake Cuitzeo in Guanajuato, Mexico. It included nanodiamonds (including the hexagonal form called lonsdaleite), carbon spherules, and magnetic spherules. Multiple hypotheses were examined to account for these observations, though none were believed to be terrestrial. Lonsdaleite occurs naturally in asteroids and cosmic dust and as a result of extraterrestrial impacts on Earth. Lonsdaleite has also been made artificially in laboratories.[relevance questioned]
In 2013, scientists reported a hundredfold spike in the concentration of platinum in Greenland ice cores that are dated to 12,890 YBP with 5 year accuracy. They attribute this platinum anomaly to the likely impact of a large (~0.8 km) iron-rich meteorite locally onto Greenland's ice, which would have been "unlikely to result in an airburst or trigger wide wildfires proposed by the YDB impact hypothesis." But they write that the large Pt anomaly "hints for an extraterrestrial source of Pt". An alternative suggestion is that the Greenland Pt anomaly was caused by a small local iron meteorite fall without any widespread consequences, but this is disputed by the paper's authors who claim that a global platinum anomaly is expected due to the ~ 20 year lifetime of the platinum signal.
In 2016, a report on further analysis of Younger Dryas boundary sediments at nine sites found no evidence of an extraterrestrial impact at the Younger Dryas boundary. Also that year, an analysis of nanodiamond evidence failed to uncover lonsdaleite or a spike in nanodiamond concentration at the YDB.
In 2018, two papers were published dealing with an "extraordinary biomass-burning episode" associated with the Younger Dryas Impact. The claims of extraordinary fires are disputed.
In 2019, scientists reported evidence in sediment layers with charcoal and pollen assemblages both indicating major disturbances at Pilauco Bajo, Chile in sediments dated to 12,800 BP. This included rare metallic spherules, melt glass and nanodiamonds thought to have been produced during airbursts or impacts. Pilauco Bajo is the southernmost site where evidence of the Younger Dryas impacts has been reported. This has been interpreted as evidence that a strewn field from the Younger Dryas impact event may have affected at least 30% of Earth's radius. Also in 2019, analysis of age-dated sediments from a long-lived pond in South Carolina showed not just an overabundance of platinum but a platinum/palladium ratio inconsistent with a terrestrial origin, as well as an overabundance of soot and a decrease in fungal spores associated with the dung of large herbivores, suggesting large-scale regional wildfires and at least a local decrease in ice age megafauna.
In 2019, a South African team consisting of Francis Thackeray, Louis Scott and Philip Pieterse announced the discovery of a platinum (Pt) spike in peat deposits at Wonderkrater, an artesian spring site in South Africa in the Limpopo Province, near the town of Mookgophong (formerly Naboomspruit) situated between Pretoria and Polokwane. The spike in platinum was documented in a sample dated at 12,744 years BP (calibrated) preceding a decline in a paleo-temperature index based on multivariate analysis of pollen spectra. This drop in temperature is associated with the Younger Dryas. The Wonderkrater platinum spike is in marked contrast to the almost constant low Pt concentrations in adjacent levels. It is consistent with the Younger Dryas Impact Hypothesis and is the first of its kind in Africa, supplementing evidence for platinum anomalies at more than 25 other sites in the world.
Thackeray and his colleagues recognise that Terminal Pleistocene megafaunal extinctions in southern Africa (Megalotragus priscus, Syncerus antiquus and Equus capensis) may be attributed to both environmental change and human predation within a period of time before and after 12,800 cal yr BP. However, on the basis of data presented in their study, they state that the consequences of a hypothesised YD cosmic impact (including the dispersal of atmospheric dust) may have contributed to some extent to the process of extinctions not only in southern Africa, but also to that which occurred in North and South America as well as Europe, recognising synchroneity of Pt anomalies that has been cited in support the Younger Dryas Impact Hypothesis. It is noted that in parts of South Africa, the Robberg stone tool technology terminates at about 12,800 cal yr BP, co-terminus with the termination of the Clovis technocomplex in North America, but further work is required to assess this coincidence.
In 2019 research at White Pond near Elgin, South Carolina, conducted by Christopher Moore from the University of South Carolina and 16 colleagues, used a core to extract sediment samples from underneath the pond. The samples, dated by radiocarbon to the beginning of the Younger Dryas, were found to contain a large platinum anomaly, consistent with findings from other sites, A large soot anomaly was also found in cores from the site.
In 2020, a group led by Andrew M. T. Moore found high concentrations of iridium, platinum, nickel, and cobalt at the Younger Dryas boundary in material from Tell Abu Hureyra. They concluded that the evidence supports the impact hypothesis.
In 2021, chemical engineer Martin B. Sweatman authored a paper published in Earth-Science Reviews, entitled "The Younger Dryas impact hypothesis: Review of the impact evidence". After reviewing the abundant platinum, microspherule, nanodiamond, melt-glass, and soot/charcoal evidence at the Younger Dryas boundary, including its reproducibility and synchroneity on several continents and the cometary scenario for its production, he suggests that the impact hypothesis should now be referred to as a 'theory'. Notably, he concludes "... arguments by a small cohort of researchers against their claims of a major impact are, in general, poorly constructed, and under close scrutiny most of their evidence can actually be interpreted as supporting the impact hypothesis."
In January 2022, James L. Powell compared the hesitancy in accepting the hypothesis to other initially controversial ideas such as continental drift, lunar impact cratering, and anthropogenic global warming. He also echoed Sweatman's remarks and suggested that a kind of groupthink had set in amongst critics.
Chronology and age-dating
A study of Paleoindian demography found no evidence of a population decline among the Paleoindians at 12,900 ± 100 BP, which was inconsistent with predictions of an impact event. They suggested that the hypothesis would probably need to be revised.[text–source integrity?] A critique of the Buchanan paper concluded that these results were an insensitive, low-fidelity population proxy incapable of detecting demographic change. The authors of a subsequent paper described three approaches to population dynamics in the Younger Dryas in North America, and concluded that there had been a significant decline and/or reorganisation in human population early in this period. The same paper also shows an apparent resurgence in population and/or settlements in the later Younger Dryas.
There is evidence that the megafaunal extinctions that occurred across northern Eurasia, North America, and South America at the end of the Pleistocene were not synchronous. The extinctions in South America appear to have occurred at least 400 years after the extinctions in North America. The extinction of woolly mammoths in Siberia also appears to have occurred later than in North America. A greater disparity in extinction timings is apparent in island megafaunal extinctions that lagged nearby continental extinctions by thousands of years; examples include the survival of woolly mammoths on Wrangel Island, Russia, until 3700 BP, and the survival of ground sloths in the Antilles, the Caribbean, until 4700 cal BP. The Australian megafaunal extinctions occurred approximately 30,000 years earlier than the hypothetical Younger Dryas event.
The megafaunal extinction pattern observed in North America poses a problem for the bolide impact scenario, since it raises the question why large mammals should be preferentially exterminated over small mammals or other vertebrates. Additionally, some extant megafaunal species such as bison and brown bear seem to have been little affected by the extinction event, while the environmental devastation caused by a bolide impact would not be expected to discriminate. Also, it appears that there was collapse in North American megafaunal population from 14,800 to 13,700 BP, well before the date of the hypothetical extraterrestrial impact, possibly from anthropogenic activities, including hunting.
A group in the Netherlands examined carbon-14 dates for charcoal particles that showed wildfires occurred well after the proposed impact date, and the glass-like carbon was produced by wildfires and no lonsdaleite was found. Research at the Atacama Desert in Chile showed that silicate surface glasses were formed during at least two distinct periods at the end of the Pleistocene, separated by several hundred years.[needs update]
Claims for impact debris
Scientists have asserted that the carbon spherules originated as fungal structures and/or insect fecal pellets, and contained modern contaminants and that the claimed nanodiamonds are actually misidentified graphene and graphene/graphane oxide aggregates. Iridium, magnetic minerals, microspherules, carbon, and nanodiamonds are all subject to differing interpretations as to their nature and origin, and may be explained in many cases by purely terrestrial or non-catastrophic factors. An analysis of a similar Younger Dryas boundary layer in Belgium yielded carbon crystalline structures such as nanodiamonds, but the authors concluded that they also did not show unique evidence for a bolide impact. Researchers have also found no extraterrestrial platinum group metals in the boundary layer, which is inconsistent with the hypothesized impact event.[d] Further independent analysis was unable to confirm prior claims of magnetic particles and microspherules.
Evidence for widespread fires
Marlon et al. suggest that wildfires were a consequence of rapid climate change. Radiocarbon dating, microscopy of paleobotanical samples, and analytical pyrolysis of fluvial sediments in Arlington Canyon on Santa Rosa Island by another group found no evidence of lonsdaleite or impact-induced fires. Research published in 2012 has shown that the so-called "black mats" are easily explained by typical earth processes in wetland environments.[e] The study of black mats, that are common in prehistorical wetland deposits which represent shallow marshlands, that were from 6000 to 40,000 years ago in the southwestern USA and Atacama Desert in Chile, showed elevated concentrations of iridium and magnetic sediments, magnetic spherules and titanomagnetite grains. It was suggested that because these markers are found within or at the base of black mats, irrespective of age or location, that these markers arise from processes common to wetland systems, and probably not as a result of catastrophic bolide impacts.[e]
Researchers have also criticized the conclusions of various studies for incorrect age-dating of the sediments, contamination by modern carbon, inconsistent hypothesis that made it difficult to predict the type and size of bolide, lack of proper identification of lonsdaleite, confusing an extraterrestrial impact with other causes such as fire, and for inconsistent use of the carbon spherule "proxy". Naturally occurring lonsdaleite has also been identified in non-bolide diamond placer deposits in the Sakha Republic.
Dating of boundary layers
Using statistical analysis and modeling, James P. Kennett and others concluded that widely separated organic-rich layers, including black mats, were deposited synchronously across multiple continents as an identifiable Younger Dryas boundary layer. In 2019, Jorgeson and others tested this conclusion with the simulation of radiocarbon ages. They accounted for measurement error, calibration uncertainty, "old wood" effects, and laboratory measurement biases, and compared against the dataset of radiocarbon ages for the Laacher See eruption. They found the Laacher See 14C dataset to be consistent with expectations of synchroneity. They found the Younger Dryas boundary layer 14C dataset to be inconsistent with the expectations for its synchroneity, and the synchronous global deposition of the hypothesized Younger Dryas boundary layer to be extremely unlikely.
Reproducibility of results
Proponents of the hypothesis have responded to defend their findings, disputing the accusation of irreproducibility or replicating their findings, and have published further research. Critics of the hypothesis have addressed the claims, and have published counterarguments.[excessive citations]
Impact crater in Greenland
A 2018 paper presented evidence for a possible impact crater of unknown age (then thought to be some point during the Pleistocene) under the Hiawatha Glacier in Greenland. Kurt Kjær, the lead author of the paper, mentioned that in early drafts, a possible connection between the Hiawatha impact and the Younger Dryas had been explicitly called out by the team. Other scientists also speculated about such a link in news reports. Skeptics rejected this connection because it would have required an improbably recent impact—an impact of this size should occur only once every few million years—and it would have left evidence such as a young ejecta blanket.
Christian Koeberl, an impact crater expert from the University of Vienna, disagreed entirely with the assessment of the site.[f] He was quoted in Popular Science saying: "[Kjær et al.] report on some interesting phenomena, but the 'definitive' interpretation and conclusion that a large impact crater underneath the ice has been discovered is a severe over-interpretation of the existing data." In 2021, Elizabeth Silber et al. modeled the propsed impact and found that it was consistent with the present morphology of the structure. In an interview with Global News, Silber joined others in suggesting that the impact could have occurred as recently as the onset of the Younger Dryas.
In 2022, Argon–argon dating combined with uranium–lead dating of shocked zircon crystals found in impact melt rocks in outwash downstream of the glacier pushed the estimate back to around 58 million years ago, during the late Paleocene.[g] Confirmation would require drilling almost one km (3,300 ft) through the ice sheet above the crater.
Critiques of air burst claims
Physicist Mark Boslough, a specialist in planetary impact hazards and asteroid impact avoidance, has undertaken a sustained critique in social media and in print of the hypothesis that an impact event or air burst was responsible for either a mass extinction of Late Pleistocene fauna in North America, abrupt climate change at the onset of the Younger Dryas, or the destruction of human settlements at Tall el-Hammam.[h] He has been especially critical of a group of investigators called the Comet Research Group (CRG) that includes several individuals who have published papers supporting the Younger Dryas impact hypothesis.
Other hypotheses have been proposed to explain the onset of the Younger Dryas, with the most accepted one being that it was caused by a significant reduction or shutdown of the North Atlantic "Conveyor" in response to a sudden influx of fresh water from Lake Agassiz and deglaciation in North America. Although initially sceptical, Wallace Broecker—the scientist who proposed the conveyor shutdown hypothesis—eventually agreed with the idea of an extraterrestrial impact at the Younger Dryas boundary, and thought that it had acted as a trigger on top of a system that was already approaching instability.[i]
Another proposed cause has been volcanic activity. However, this has been challenged recently due to improved dating of the most likely suspect, the Laacher See volcano. In 2021, research by Frederick Reinig et al. precisely dated the eruption to 200 ± 21 years before the onset of the Younger Dryas, therefore ruling it out as a culprit. The same study also concluded that the onset took place synchronously over the entire North Atlantic and Central European region. A press release from the University of Mainz stated, "Due to the new dating, the European archives now have to be temporally adapted. At the same time, a previously existing temporal difference to the data from the Greenland ice cores was closed."
In popular culture
The impact hypothesis has been the subject of documentaries, including Mammoth Mystery on National Geographic Explorer (2007), Journey to 10,000 BC on the History Channel (2008), Survival Earth on Channel 4 (2008), and Megabeasts' Sudden Death on PBS Nova (2009).
Graham Hancock's 2015 book Magicians of the Gods argued that the Younger Dryas comet destroys the earth in a time cycle and that it was responsible for the Noahide flood myth, then universalizes the myth by comparing it with that of other peoples. These claims were criticized for their inaccuracy by various independent reviewers, including Jason Colavito, Michael Shermer, and Marc J. Defant.[j] Hancock expanded upon his claims in his subsequent book, America Before: The Key to Earth's Lost Civilization (2019), in which he claimed that the Younger Dryas catastrophe had wiped out all traces of a sophisticated Ice Age civilization in North America.
In 2017, a debate was held on the Joe Rogan Experience between proponents Graham Hancock, Randall Carlson, and Malcolm A LeCompte, and opponents Michael Shermer, and Marc J. Defant.[j] The week that the podcast was released, the network was reportedly averaging over 120 million downloads a month.
A 2021 episode of the Science Channel series Ancient Unexplained Files had a segment on the evidence from Abu Hureyra; geoscientist Sian Proctor also described the impact hypothesis as a whole.
- Carolina bays
- Coherent catastrophism
- Murray Springs Clovis Site
- Pleistocene megafauna
- Tollmann's bolide hypothesis
- Tunguska event
- The darkened stratum was first identified at the Lehner Mammoth-Kill Site by Emil Haury who named it "Lehner swamp soil"; it was later renamed by Vance Haynes as the "black mat".
- In Ragnarok: The Age of Fire and Gravel (1883) Donnelly suggested that the flood of Noah "probably occurred somewhere from eight to eleven thousand years ago" (6,117 BCE to 9,117 BCE); in his previous book Atlantis: The Antediluvian World (1882) Donnelly followed Plato's timeline and gave a date of 9,600 BCE (11,550 BP) for the destruction of Atlantis.
- Allen West had the conviction expunged after the matter was reported on by Rex Dalton. West (originally Allen Whitt until he changed his name legally in 2006) is described as having no formal academic affiliation and a degree from a Bible college which he wouldn't name.
- One of the authors of this study, Matthew Boyd, later published a paper that argued in favour of the impact hypothesis.
- Pigati has noted that his 2012 paper  does not disprove the impact hypothesis.
- Koeberl was a co-author of the "requiem" paper which argued against the YDIH seven years earlier.
- This paper's co-authors include Kurt Kjær and Elizabeth Silber
- Boslough closed out his most recent critique by recommending a paper by Peter H. Schultz et al. that provided evidence for "nearly simultaneous (seconds to minutes) intense airbursts close to Earth's surface near the end of the Pleistocene" in the Atacama Desert. Schultz was a co-author of the paper that originally proposed the Younger Dryas impact hypothesis.
- Broecker did not believe that the impact caused extinctions.
- Both Michael Shermer and Marc J. Defant have since indicated that they accept the impact hypothesis.
- Powell JL (5 January 2022). "Premature rejection in science: The case of the Younger Dryas Impact Hypothesis". Science Progress: a review journal of current scientific advance. 105 (1): 1–43. doi:10.1177/00368504211064272. ISSN 0036-8504. PMID 34986034. S2CID 245771840. Wikidata Q110444998.
- Pino M, Abarzúa AM, Astorga G, Martel-Cea A, Cossio-Montecinos N, Navarro RX, Lira MP, Labarca R, et al. (13 March 2019). "Sedimentary record from Patagonia, southern Chile supports cosmic-impact triggering of biomass burning, climate change, and megafaunal extinctions at 12.8 ka". Scientific Reports. 9 (1): 4413. Bibcode:2019NatSR...9.4413P. doi:10.1038/s41598-018-38089-y. PMC 6416299. PMID 30867437.
- Sun N, Brandon AD, Forman SL, Waters MR, Befus KS (1 July 2020). "Volcanic origin for Younger Dryas geochemical anomalies ca. 12,900 cal B.P." Science Advances. 6 (31): eaax8587. Bibcode:2020SciA....6.8587S. doi:10.1126/sciadv.aax8587. ISSN 2375-2548. PMC 7399481. PMID 32789166.
- Moore AM, Kennett JP, Napier WM, Bunch TE, Weaver JC, LeCompte M, Adedeji AV, Hackley P, et al. (6 March 2020). "Evidence of Cosmic Impact at Abu Hureyra, Syria at the Younger Dryas Onset (~12.8 ka): High-temperature melting at >2200 °C" (PDF). Scientific Reports. 10 (1): 4185. Bibcode:2020NatSR..10.4185M. doi:10.1038/S41598-020-60867-W. ISSN 2045-2322. PMC 7060197. PMID 32144395. Wikidata Q90119243.
The wide range of evidence supports the hypothesis that a cosmic event occurred at Abu Hureyra ~12,800 years ago, coeval with impacts that deposited high-temperature meltglass, melted microspherules, and/or platinum at other YDB sites on four continents.
- Haury EW, Sayles EB, Wasley WW (July 1959). "The Lehner Mammoth Site, Southeastern Arizona". American Antiquity. 25 (01): 2–30. doi:10.2307/276674. ISSN 0002-7316. JSTOR 276674. Wikidata Q59224169.
- "Paleoindian Studies and Geoarchaeology at the University of Arizona". University of Arizona. Archived from the original on 23 July 2018.
Vance Haynes later renamed it the 'black mat'
- Firestone RB, West A, Kennett JP, Becker L, Bunch TE, Revay ZS, Schultz PH, Belgya T, et al. (9 October 2007). "Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling". Proceedings of the National Academy of Sciences of the United States of America. 104 (41): 16016–21. Bibcode:2007PNAS..10416016F. doi:10.1073/pnas.0706977104. PMC 1994902. PMID 17901202.
- Sweatman MB (19 May 2021). "The Younger Dryas impact hypothesis: Review of the impact evidence" (PDF). Earth-Science Reviews. 218: 103677. Bibcode:2021ESRv..21803677S. doi:10.1016/J.EARSCIREV.2021.103677. ISSN 0012-8252. S2CID 236231169. Wikidata Q106977355.
Evidence is mainly in the form of geochemical signals at what is known as the YD boundary found across at least four continents, especially North America and Greenland, such as excess platinum, quench-melted materials, and nanodiamonds.
- Dalton R (16 May 2007). "Blast in the past?". Nature. 447 (7142): 256–257. Bibcode:2007Natur.447..256D. doi:10.1038/447256a. PMID 17507957. S2CID 11927411.
- Wittke JH, Weaver JC, Bunch TE, Kennett JP, Kennett DJ, Moore AM, Hillman GC, Tankersley KB, et al. (June 2013). "Evidence for deposition of 10 million tonnes of impact spherules across four continents 12,800 y ago". Proceedings of the National Academy of Sciences of the United States of America. 110 (23): E2088–97. Bibcode:2013PNAS..110E2088W. doi:10.1073/pnas.1301760110. PMC 3677428. PMID 23690611.
- Bunch TE, Hermes RE, Moore AM, Kennett DJ, Weaver JC, Wittke JH, DeCarli PS, Bischoff JL, et al. (July 2012). "Very high-temperature impact melt products as evidence for cosmic airbursts and impacts 12,900 years ago". Proceedings of the National Academy of Sciences of the United States of America. 109 (28): E1903–E1912. Bibcode:2012PNAS..109E1903B. doi:10.1073/pnas.1204453109. PMC 3396500. PMID 22711809.
- Andronikov AV, Andronikova IE, Loehn CW, Lafuente B, Ballenger JA, Crawford GT, Lauretta DS (March 2016). "Implications from chemical, structural and mineralogical studies of magnetic microspherules from around the lower younger dryas boundary (new mexico, usa)". Geografiska Annaler. Series A, Physical Geography. 98 (1): 39–59. doi:10.1111/GEOA.12122. ISSN 0435-3676. Wikidata Q106891675.
The presence of the high number of such microspherules in the sediments can serve as a local stratigraphic marker in identification of the [lower Younger Dryas boundary] there where dark variety of the black mat is absent.
- Sweatman MB (19 May 2021). "The Younger Dryas impact hypothesis: Review of the impact evidence" (PDF). Earth-Science Reviews. 218: 103677. Bibcode:2021ESRv..21803677S. doi:10.1016/J.EARSCIREV.2021.103677. ISSN 0012-8252. S2CID 236231169. Wikidata Q106977355.
- Haynes G (5 November 2010). "The catastrophic extinction of North American mammoths and mastodonts". World Archaeology. 33 (3): 391–416. doi:10.1080/00438240120107440. S2CID 26671638.
- Carrasco MA, Barnosky AD, Graham RW (December 2009). "Quantifying the extent of North American mammal extinction relative to the pre-anthropogenic baseline". PLOS ONE. 4 (12): e8331. Bibcode:2009PLoSO...4.8331C. doi:10.1371/journal.pone.0008331. PMC 2789409. PMID 20016820.
- "John Martin (1789-1854) - The Eve of the Deluge". Royal Collection Trust. Archived from the original on 29 April 2021. Retrieved 15 July 2021.
- Mangerud J (4 November 2020). "The discovery of the Younger Dryas, and comments on the current meaning and usage of the term". Boreas. 50 (1): 1–5. doi:10.1111/BOR.12481. hdl:11250/2766487. ISSN 0300-9483. S2CID 228909393. Wikidata Q109955604.
- Levitin D (4 September 2013). "Halley and the eternity of the world revisited". Notes and Records. 67 (4): 315–329. doi:10.1098/RSNR.2013.0019. ISSN 0035-9149. PMC 3826193. Wikidata Q94018436.
However, [Edmond Halley] returned to the subject a year later in a lecture 'About the Cause of the Universal Deluge' read to the Society on 12 December 1694. Halley advanced a theory of periodic catastrophism; specifically, he suggested—two years before a similar idea was put forward by William Whiston—that the Flood was caused by a comet.
- Halley E (31 December 1724). "VII. Some cosiderations about the cause of the universal Deluge, laid before the Royal Society, on the 12th of December 1694". Philosophical Transactions of the Royal Society. 33 (383): 118–123. Bibcode:1724RSPT...33..118H. doi:10.1098/RSTL.1724.0023. ISSN 0261-0523. Wikidata Q108458886.
- Strauss M (30 December 2016). "Why Newton Believed a Comet Caused Noah's Flood". National Geographic. Archived from the original on 20 September 2021. Retrieved 14 November 2021.
Working backward, Whiston noted that one such cosmic encounter occurred in 2342 B.C., which, at the time, was believed to be the date of the great Deluge.
- Meehan RL (1999). "Whiston's Flood". Archived from the original on 25 January 2021. Retrieved 7 June 2019.
- May A (2019). Cosmic impact: understanding the threat to Earth from asteroids and comets. London. p. 8. ISBN 978-1-78578-493-4. OCLC 1091996674.
In his book The System of the World, first published in 1796, Laplace speculated that cometary impacts might result in global extinctions.
- Laplace PS (1796). Exposition Du Systême Du Monde (in French). Paris, France: Cercle social. pp. 61–62.
[U]ne grande partie des hommes et des animaux, noyée dans ce déluge universel, ou détruite par la violente secousse imprimée au globe terrestre; des espèces entières anéanties; tous les monumens de l’industrie humaine, renversés; tels sont les désastres que le choc d’une comète a dû produire.
- Laplace PS (1809). The System of the World. Translated by Pond J. p. 64.
[T]he greater part of men and animals drowned in a universal deluge, or destroyed by the violence of the shock given to the terrestrial globe; whole species destroyed; all the monuments of human industry reversed: such are the disasters which a shock of a comet would produce.
- Donnelly IL (1883). Ragnarok: The Age of Fire and Gravel. p. 404.
The Deluge of Noah probably occurred somewhere from eight to eleven thousand years ago. Hence, about twenty thousand years probably intervened between the Drift and the Deluge. These were the 'myriads of years' referred to by Plato, during which mankind dwelt on the great plain of Atlantis.
- Donnelly IL (1882). Atlantis: The Antediluvian World. p. 29.
Plato states that the Egyptians told Solon that the destruction of Atlantis occurred 9000 years before that date, to wit, about 9600 years before the Christian era.
- Winchell A (1887). "Ignatius Donnelly's Comet". The Forum. IV: 115.
- Firestone R, West A, Warwick-Smith S (4 June 2006). The Cycle of Cosmic Catastrophes: How a Stone-Age comet changed the course of world culture. Bear & Company. ISBN 978-1591430612.
- Gramling C (26 June 2018). "Why won't this debate about an ancient cold snap die?". Science News. Archived from the original on 5 August 2021. Retrieved 21 August 2021.
The first formal description of the Younger Dryas impact hypothesis came in 2007, when four researchers sat in front of a gaggle of reporters at the American Geophysical Union’s spring meeting in Acapulco, Mexico.
- Haynes CV (May 2008). "Younger Dryas "black mats" and the Rancholabrean termination in North America". Proceedings of the National Academy of Sciences of the United States of America. 105 (18): 6520–6525. Bibcode:2008PNAS..105.6520H. doi:10.1073/pnas.0800560105. PMC 2373324. PMID 18436643.
- "2008 Pecos Conference". swanet.org. Archived from the original on 3 August 2019. Retrieved 3 August 2019.
- Kerr RA (January 2009). "Planetary impacts. Did the mammoth slayer leave a diamond calling card?". Science. 323 (5910): 26. doi:10.1126/science.323.5910.26. PMID 19119192. S2CID 29639618.
- Kennett DJ, Kennett JP, West A, Mercer C, Hee SS, Bement L, Bunch TE, Sellers M, et al. (January 2009). "Nanodiamonds in the Younger Dryas boundary sediment layer". Science. 323 (5910): 94. Bibcode:2009Sci...323...94K. doi:10.1126/science.1162819. PMID 19119227. S2CID 206514910.
- "Younger Dryas Boundary: Extraterrestrial Impact or Not? I Posters". abstractsearch.agu.org. 2009 AGU Fall Meeting. PP31D. Archived from the original on 3 August 2019. Retrieved 9 June 2021.
"Younger Dryas Boundary: Extraterrestrial Impact or Not? II". abstractsearch.agu.org. 2009 AGU Fall Meeting. PP33B. Archived from the original on 29 April 2021. Retrieved 9 June 2021.
- Napier WM (23 June 2010). "Palaeolithic extinctions and the Taurid Complex" (PDF). Monthly Notices of the Royal Astronomical Society. 405 (3): 1901–1906. arXiv:1003.0744. Bibcode:2010MNRAS.405.1901N. doi:10.1111/J.1365-2966.2010.16579.X. ISSN 0035-8711. Wikidata Q56883287.
- Napier WM (28 June 2019). "The hazard from fragmenting comets". Monthly Notices of the Royal Astronomical Society. 488 (2): 1822–1827. arXiv:2004.01870. Bibcode:2019MNRAS.488.1822N. doi:10.1093/MNRAS/STZ1769. ISSN 0035-8711. Wikidata Q106920086.
- Gough E (13 April 2020). "When Comets Break Up, the Fragments Can Be Devastating If They Hit the Earth". Universe Today. Archived from the original on 14 March 2021. Retrieved 29 June 2021.
- Ferrín I, Orofino V (November 2021). "Taurid complex smoking gun: Detection of cometary activity". Planetary and Space Science. 207: 105306. arXiv:2011.13078. Bibcode:2021P&SS..20705306F. doi:10.1016/J.PSS.2021.105306. ISSN 0032-0633. S2CID 227210565. Wikidata Q108888402.
This high percentage of active asteroids gives support to the hypothesis of a catastrophe that took place during the Upper Paleolithic (Clube and Napier, 1984).
- Romero J (30 September 2021). "Swarm of Near-Earth Comets Linked to Recent Ice Giant Breakup". Discover. Archived from the original on 14 October 2021. Retrieved 14 October 2021.
The findings are welcomed by those who believe Comet Encke and the other products of this astronomical event are responsible for many of Earth's most violent and consequential impacts over the last 20,000 years.
- "Shootout YDB hypothesis at Laramie American Quaternary Association conference". cosmictusk.com. 31 July 2010. Archived from the original on 7 August 2020. Retrieved 3 August 2019.
- Pinter N, Scott AC, Daulton TL, Podoll A, Koeberl C, Anderson RS, Ishman SE (22 February 2011). "The Younger Dryas impact hypothesis: A requiem". Earth-Science Reviews. 106 (3–4): 247. Bibcode:2011ESRv..106..247P. doi:10.1016/j.earscirev.2011.02.005.
- "Enforcement Action". California Department of Consumer Affairs - Board for Professional Engineers, Land Surveyors, and Geologists. 6 June 2002. Archived from the original on 8 April 2012.
The Board's inquiry concluded that Kevin Lee Jonker and Allen Whitt had practiced geophysics without a license.
- Dalton R (14 May 2011). "Comet Theory Comes Crashing to Earth". Pacific Standard. Archived from the original on 11 February 2021. Retrieved 24 July 2019.
- Daulton TL, Pinter N, Scott AC (September 2010). "No evidence of nanodiamonds in Younger-Dryas sediments to support an impact event". Proceedings of the National Academy of Sciences of the United States of America. 107 (37): 16043–7. Bibcode:2010PNAS..10716043D. doi:10.1073/pnas.1003904107. PMC 2941276. PMID 20805511.
- Boslough M, Nicoll K, Holliday V, Daulton TL, Meltzer D, Pinter N, Scott AC, Surovell T, et al. (2013). "Arguments and Evidence Against a Younger Dryas Impact Event". In Giosan L, Fuller DQ, Nicoll K, Flad RK, Clift PD (eds.). Climates, Landscapes, and Civilizations. Geophysical Monograph Series. pp. 13–26. doi:10.1029/2012GM001209. ISBN 9781118704325.
- Roach J (22 June 2010). "Fungi, Feces Show Comet Didn't Kill Ice Age Mammals?". National Geographic. Archived from the original on 17 July 2021. Retrieved 17 July 2021.
- Israde-Alcántara I, Bischoff JL, Domínguez-Vázquez G, Li HC, DeCarli PS, Bunch TE, Wittke JH, Weaver JC, et al. (March 2012). "Evidence from central Mexico supporting the Younger Dryas extraterrestrial impact hypothesis". Proceedings of the National Academy of Sciences of the United States of America. 109 (13): E738–E747. Bibcode:2012PNAS..109E.738I. doi:10.1073/pnas.1110614109. PMC 3324006. PMID 22392980.
- Bundy FP (1967). "Hexagonal Diamond—A New Form of Carbon". The Journal of Chemical Physics. 46 (9): 3437–3446. Bibcode:1967JChPh..46.3437B. doi:10.1063/1.1841236.
- Kaminskii FV, Blinova GK, Galimov EM, Gurkina GA, Klyuev YA, Kodina LA, Koptil VI, Krivonos VF, et al. (1985). "Polycrystalline aggregates of diamond with lonsdaleite from Yakutian [Sakhan] placers". Mineral Zhurnal. 7: 27–36. Archived from the original on 23 October 2018. Retrieved 1 July 2017.
- Petaev MI, Huang S, Jacobsen SB, Zindler A (August 2013). "Large Pt [platinum] anomaly in the Greenland ice core points to a cataclysm at the onset of Younger Dryas". Proceedings of the National Academy of Sciences of the United States of America. 110 (32): 12917–12920. Bibcode:2013PNAS..11012917P. doi:10.1073/pnas.1303924110. PMC 3740870. PMID 23878232.
- Boslough M (December 2013). "Greenland Pt [platinum] anomaly may point to non-cataclysmic Cape York meteorite entry". Proceedings of the National Academy of Sciences of the United States of America. 110 (52): E5035. Bibcode:2013PNAS..110E5035B. doi:10.1073/pnas.1320328111. PMC 3876257. PMID 24347646.
- Petaev MI, Huang S, Jacobsen SB, Zindler A (24 December 2013). "Reply to Boslough: Is Greenland Pt anomaly global or local?" (PDF). Proceedings of the National Academy of Sciences of the United States of America. 110 (52): E5036. doi:10.1073/pnas.1320772111. PMC 3876271. PMID 24511625. Archived (PDF) from the original on 3 May 2019. Retrieved 9 August 2021.
- Holliday V, Surovell T, Johnson E (8 July 2016). "A Blind Test of the Younger Dryas Impact Hypothesis". PLOS ONE. 11 (7): e0155470. Bibcode:2016PLoSO..1155470H. doi:10.1371/journal.pone.0155470. PMC 4938604. PMID 27391147.
- Daulton TL, Amari S, Scott AC, Hardiman M, Pinter N, Anderson RS (19 December 2016). "Comprehensive analysis of nanodiamond evidence relating to the Younger Dryas Impact Hypothesis". Journal of Quaternary Science. 32 (1): 7–34. Bibcode:2017JQS....32....7D. doi:10.1002/jqs.2892. Archived from the original on 5 February 2020. Retrieved 5 February 2020.
- Moore CR, West A, LeCompte MA, Brooks MJ, Daniel IR, Goodyear AC, Ferguson TA, Ivester AH, et al. (March 2017). "Widespread platinum anomaly documented at the Younger Dryas onset in North American sedimentary sequences". Scientific Reports. 7 (1): 44031. Bibcode:2017NatSR...744031M. doi:10.1038/srep44031. PMC 5343653. PMID 28276513.
- Wolbach WS, Ballard JP, Mayewski PA, Adedeji V, Bunch TE, Firestone RB, French TA, Howard GA, et al. (March 2018). "Extraordinary biomass-burning episode and impact winter triggered by the Younger Dryas cosmic impact ∼12,800 years ago. Part 1. Ice Cores and Glaciers". Journal of Geology. 126 (2): 165–184. Bibcode:2018JG....126..165W. doi:10.1086/695703. S2CID 53021110.
- Wolbach WS, Ballard JP, Mayewski PA, Parnell AC, Cahill N, Adedeji V, Bunch TE, Domínguez-Vázquez G, et al. (March 2018). "Extraordinary biomass-burning episode and impact winter triggered by the Younger Dryas cosmic impact ∼12,800 years ago. Part 2. Lake, Marine, and Terrestrial Sediments" (PDF). Journal of Geology. 126 (2): 185–205. Bibcode:2018JG....126..185W. doi:10.1086/695704. S2CID 53494648. Archived (PDF) from the original on 4 November 2020. Retrieved 10 November 2020.
- Lynch BM (1 February 2018). "New research suggests toward end of Ice Age, human beings witnessed fires larger than dinosaur killer, thanks to a cosmic impact". University of Kansas (Press release). Archived from the original on 26 May 2021. Retrieved 14 December 2021.
- Holliday VT, Bartlein PJ, Scott AC, Marlon JR (5 December 2019). "Extraordinary Biomass-Burning Episode and Impact Winter Triggered by the Younger Dryas Cosmic Impact ∼12,800 Years Ago, Parts 1 and 2: A Discussion". The Journal of Geology. 128 (1): 69–94. Bibcode:2020JG....128...69H. doi:10.1086/706264. ISSN 0022-1376. Wikidata Q91978737.
- Wolbach WS, Ballard JP, Mayewski PA, Kurbatov A, Bunch TE, LeCompte MA, Adedeji V, Israde-Alcántara I, et al. (5 December 2019). "Extraordinary Biomass-Burning Episode and Impact Winter Triggered by the Younger Dryas Cosmic Impact ∼12,800 Years Ago: A Reply". The Journal of Geology. 128 (1): 95–107. Bibcode:2020JG....128...95W. doi:10.1086/706265. ISSN 0022-1376. Wikidata Q91978742.
- Moore CR (22 October 2019). "New evidence that an extraterrestrial collision 12,800 years ago triggered an abrupt climate change for Earth". The Conversation. Archived from the original on 23 October 2019. Retrieved 22 June 2021.
- Thackeray J, Scott L, Pieterse P (2 October 2019). "The Younger Dryas interval at Wonderkrater (South Africa) in the context of a platinum anomaly" (PDF). Palaeontologia Africana. 54. hdl:10539/28129. ISSN 0078-8554. Wikidata Q106978252.
- Ward CJ (22 October 2019). "UofSC archaeologist finds evidence of extinction theory" (Press release). University of South Carolina. Archived from the original on 3 March 2021. Retrieved 7 August 2021.
- Moore CR, Brooks MJ, Goodyear AC, Ferguson TA, Perrotti AG, Mitra S, Listecki AM, King BC, et al. (22 October 2019). "Sediment Cores from White Pond, South Carolina, contain a Platinum Anomaly, Pyrogenic Carbon Peak, and Coprophilous Spore Decline at 12.8 ka". Scientific Reports. 9 (15121 (2019)): 15121. Bibcode:2019NatSR...915121M. doi:10.1038/s41598-019-51552-8. PMC 6805854. PMID 31641142.
- Fernandez S (6 March 2020). "Fire from the Sky" (Press release). University of California, Santa Barbara. Archived from the original on 6 July 2021. Retrieved 7 August 2021.
Based on materials collected before the site was flooded, Kennett and his colleagues contend Abu Hureyra is the first site to document the direct effects of a fragmented comet on a human settlement.
- Taylor I (28 June 2021). "Did a huge comet impact ignite civilisation on Earth as we know it?". BBC Science Focus. Archived from the original on 28 June 2021. Retrieved 30 June 2021.
Sweatman argues that it should now be considered a consensus theory and calls for further research on its far-reaching consequences.
- Powell (2022, pp. 1–2) harvtxt error: no target: CITEREFPowell2022 (help): "Scientists have initially rejected many theories that later achieved widespread consensus..."
- Powell (2022, p. 37) harvtxt error: no target: CITEREFPowell2022 (help): "Instead of critically examining and rejecting these false claims, many geologists and impact specialists embraced them, thereby allowing an alleged absence of evidence to trump abundant, peer-reviewed evidence, even photographic evidence. Then a kind of 'groupthink' seems to have set in, rendering the YDIH beneath further consideration."
- Holliday VT, Meltzer DJ (October 2010). "The 12.9-ka ET Impact Hypothesis and North American Paleoindians". Current Anthropology. 51 (5): 575–606. doi:10.1086/656015. S2CID 17823479.
- Buchanan B, Collard M, Edinborough K (August 2008). "Paleoindian demography and the extraterrestrial impact hypothesis". Proceedings of the National Academy of Sciences of the United States of America. 105 (33): 11651–4. Bibcode:2008PNAS..10511651B. doi:10.1073/pnas.0803762105. PMC 2575318. PMID 18697936.
- Haynes G (2009). American megafaunal extinctions at the end of the Pleistocene. Springer Netherlands. p. 125. ISBN 978-1-4020-8792-9. Archived from the original on 6 May 2020. Retrieved 20 April 2012.
- Culleton BJ (16 December 2008). "Crude demographic proxy reveals nothing about Paleoindian population". Proceedings of the National Academy of Sciences of the United States of America. 105 (50): E111, author reply E112–4. Bibcode:2008PNAS..105E.111C. doi:10.1073/pnas.0809092106. PMC 2604924. PMID 19073929.
- Anderson DG, Goodyear A, Kennett JP, West A (2011). "Multiple lines of evidence for possible Human population decline/settlement reorganization during the early Younger Dryas". Quaternary International. 242 (2): 570–583. Bibcode:2011QuInt.242..570A. doi:10.1016/j.quaint.2011.04.020.
- Haynes G (2009). "Introduction to the Volume". American Megafaunal Extinctions at the End of the Pleistocene. Vertebrate Paleobiology and Paleoanthropology. pp. 1–20. doi:10.1007/978-1-4020-8793-6_1. ISBN 978-1-4020-8792-9.
- Fiedel S (2009). "Sudden Deaths: The Chronology of Terminal Pleistocene Megafaunal Extinction". American Megafaunal Extinctions at the End of the Pleistocene. Vertebrate Paleobiology and Paleoanthropology. pp. 21–37. doi:10.1007/978-1-4020-8793-6_2. ISBN 978-1-4020-8792-9.
- Hubbe A, Hubbe M, Neves W (September 2007). "Early Holocene survival of megafauna in South America". Journal of Biogeography. 34 (9): 1642–1646. doi:10.1111/j.1365-2699.2007.01744.x.
- Stuart AJ, Kosintsev PA, Higham TF, Lister AM (October 2004). "Pleistocene to Holocene extinction dynamics in giant deer and woolly mammoth". Nature. 431 (7009): 684–9. Bibcode:2004Natur.431..684S. doi:10.1038/nature02890. PMID 15470427. S2CID 4415073. Archived from the original on 20 June 2021. Retrieved 5 February 2020.
- Martin P (2005). "4 Ground Sloths at Home Cryptozoology, Ground Sloths, and Mapinguari National Park". Twilight of the mammoths: ice age extinctions and the rewilding of America. Berkeley: University of California Press. ISBN 978-0-520-23141-2.
- Barnosky AD (12 August 2008). "Colloquium paper: Megafauna biomass tradeoff as a driver of Quaternary and future extinctions" (PDF). Proceedings of the National Academy of Sciences of the United States of America. 105 (Supplement 1): 11543–11548. Bibcode:2008PNAS..10511543B. doi:10.1073/pnas.0801918105. PMC 2556404. PMID 18695222. Archived (PDF) from the original on 19 June 2021. Retrieved 6 July 2021.
- Scott E (2010). "Extinctions, scenarios, and assumptions: Changes in latest Pleistocene large herbivore abundance and distribution in western North America". Quaternary International. 217 (1–2): 225–239. Bibcode:2010QuInt.217..225S. doi:10.1016/j.quaint.2009.11.003.
- Gill JL, Williams JW, Jackson ST, Lininger KB, Robinson GS (November 2009). "Pleistocene megafaunal collapse, novel plant communities, and enhanced fire regimes in North America" (PDF). Science. 326 (5956): 1100–3. Bibcode:2009Sci...326.1100G. doi:10.1126/science.1179504. PMID 19965426. S2CID 206522597. Archived (PDF) from the original on 22 September 2017. Retrieved 14 January 2019.
- van Hoesel A, Hoek WZ, Braadbaart F, van der Plicht J, Pennock GM, Drury MR (May 2012). "Nanodiamonds and wildfire evidence in the Usselo horizon postdate the Allerod-Younger Dryas boundary". Proceedings of the National Academy of Sciences of the United States of America. 109 (20): 7648–53. Bibcode:2012PNAS..109.7648V. doi:10.1073/pnas.1120950109. PMC 3356666. PMID 22547791.
- Roperch P, Gattacceca J, Valenzuela M, Devouard B, Lorand JP, Arriagada C, Rochette P, Latorre C, et al. (2017). "Surface vitrification caused by natural fires in Late Pleistocene wetlands of the Atacama Desert". Earth and Planetary Science Letters. 469: 15–26. Bibcode:2017E&PSL.469...15R. doi:10.1016/j.epsl.2017.04.009. ISSN 0012-821X. Archived from the original on 17 April 2021. Retrieved 1 September 2020.
- Kerr RA (30 October 2010). "Mammoth-Killer Impact Rejected". Science NOW. AAAS. Archived from the original on 17 September 2018. Retrieved 17 September 2018.
- Pinter N, Ishman SE (2008). "Impacts, mega-tsunami, and other extraordinary claims". GSA Today. 18 (1): 37–38. doi:10.1130/GSAT01801GW.1.
- Perkins S (23 April 2012). "No Love for Comet Wipeout". Science. Archived from the original on 17 September 2018. Retrieved 17 September 2018.
- Tian H, Schryvers D, Claeys P (January 2011). "Nanodiamonds do not provide unique evidence for a Younger Dryas impact". Proceedings of the National Academy of Sciences of the United States of America. 108 (1): 40–4. Bibcode:2011PNAS..108...40T. doi:10.1073/pnas.1007695108. PMC 3017148. PMID 21173270.
- Paquay FS, Goderis S, Ravizza G, Vanhaeck F, Boyd M, Surovell TA, Holliday VT, Haynes CV, et al. (December 2009). "Absence of geochemical evidence for an impact event at the Bølling-Allerød/Younger Dryas transition". Proceedings of the National Academy of Sciences of the United States of America. 106 (51): 21505–10. Bibcode:2009PNAS..10621505P. doi:10.1073/pnas.0908874106. PMC 2799824. PMID 20007789.
- Teller J, Boyd M, LeCompte M, Kennett JP, West A, Telka A, Diaz A, Adedeji V, et al. (22 October 2019). "A multi-proxy study of changing environmental conditions in a Younger Dryas sequence in southwestern Manitoba, Canada, and evidence for an extraterrestrial event". Quaternary Research. 93: 60–87. Bibcode:2020QuRes..93...60T. doi:10.1017/QUA.2019.46. ISSN 0033-5894. Wikidata Q106863462.
We propose that this massive hydrological reorganization resulted from a cosmic impact event at the YD boundary.
- Surovell TA, Holliday VT, Gingerich JA, Ketron C, Haynes CV, Hilman I, Wagner DP, Johnson E, et al. (October 2009). "An independent evaluation of the Younger Dryas extraterrestrial impact hypothesis". Proceedings of the National Academy of Sciences of the United States of America. 106 (43): 18155–8. Bibcode:2009PNAS..10618155S. doi:10.1073/pnas.0907857106. PMC 2775309. PMID 19822748.
- Marlon JR, Bartlein PJ, Walsh MK, Harrison SP, Brown KJ, Edwards ME, Higuera PE, Power MJ, et al. (February 2009). "Wildfire responses to abrupt climate change in North America". Proceedings of the National Academy of Sciences of the United States of America. 106 (8): 2519–24. Bibcode:2009PNAS..106.2519M. doi:10.1073/pnas.0808212106. PMC 2650296. PMID 19190185.
...the charcoal data indicate an important role for climate, and particularly rapid climate change, in determining broad-scale levels of fire activity.
- Scott AC, Hardiman M, Pinter N, Anderson RS, Daulton TL, Ejarque A, Finch P, Carter-champion A (2017). "Interpreting palaeofire evidence from fluvial sediments: a case study from Santa Rosa Island, California, with implications for the Younger Dryas Impact Hypothesis". Journal of Quaternary Science. 32 (1): 35–47. Bibcode:2017JQS....32...35S. doi:10.1002/jqs.2914. ISSN 0267-8179. Archived from the original on 5 February 2020. Retrieved 5 February 2020.
- Pigati JS, Latorre C, Rech JA, Betancourt JL, Martínez KE, Budahn JR (May 2012). "Accumulation of impact markers in desert wetlands and implications for the Younger Dryas impact hypothesis". Proceedings of the National Academy of Sciences of the United States of America. 109 (19): 7208–12. Bibcode:2012PNAS..109.7208P. doi:10.1073/pnas.1200296109. PMC 3358914. PMID 22529347.
- Blaauw M, Holliday VT, Gill JL, Nicoll K (August 2012). "Age models and the Younger Dryas Impact Hypothesis". Proceedings of the National Academy of Sciences of the United States of America. 109 (34): E2240, author reply E2245–7. Bibcode:2012PNAS..109E2240B. doi:10.1073/pnas.1206143109. PMC 3427088. PMID 22829673.
- Boslough M (August 2012). "Inconsistent impact hypotheses for the Younger Dryas". Proceedings of the National Academy of Sciences of the United States of America. 109 (34): E2241, author reply E2245–7. Bibcode:2012PNAS..109E2241B. doi:10.1073/pnas.1206739109. PMC 3427067. PMID 22829675.
- Daulton TL (August 2012). "Suspect cubic diamond "impact" proxy and a suspect lonsdaleite identification". Proceedings of the National Academy of Sciences of the United States of America. 109 (34): E2242, author reply E2245–7. Bibcode:2012PNAS..109E2242D. doi:10.1073/pnas.1206253109. PMC 3427052. PMID 22829671.
- Gill JL, Blois JL, Goring S, Marlon JR, Bartlein PJ, Nicoll K, Scott AC, Whitlock C (August 2012). "Paleoecological changes at Lake Cuitzeo were not consistent with an extraterrestrial impact". Proceedings of the National Academy of Sciences of the United States of America. 109 (34): E2243, author reply E2245–7. Bibcode:2012PNAS..109E2243G. doi:10.1073/pnas.1206196109. PMC 3427112. PMID 22829674.
- Hardiman M, Scott AC, Collinson ME, Anderson RS (August 2012). "Inconsistent redefining of the carbon spherule "impact" proxy". Proceedings of the National Academy of Sciences of the United States of America. 109 (34): E2244, author reply E2245–7. Bibcode:2012PNAS..109E2244H. doi:10.1073/pnas.1206108109. PMC 3427080. PMID 22829672.
- Kennett JP, Kennett DJ, Culleton BJ, Tortosa JE, Bischoff JL, Bunch TE, Daniel IR, Erlandson JM, et al. (27 July 2015). "Bayesian chronological analyses consistent with synchronous age of 12,835-12,735 Cal B.P. for Younger Dryas boundary on four continents" (PDF). Proceedings of the National Academy of Sciences of the United States of America. 112 (32): E4344-53. Bibcode:2015PNAS..112E4344K. doi:10.1073/PNAS.1507146112. ISSN 0027-8424. PMC 4538614. PMID 26216981. Wikidata Q35718070.
- Jorgeson IA, Breslawski RP, Fisher AE (13 February 2020). "Radiocarbon simulation fails to support the temporal synchroneity requirement of the Younger Dryas impact hypothesis". Quaternary Research. 96: 123–139. Bibcode:2020QuRes..96..123J. doi:10.1017/qua.2019.83. ISSN 1096-0287. S2CID 213657406. Archived from the original on 20 June 2021.
- Israde-Alcántara I, Bischoff JL, DeCarli PS, Domínguez-Vázquez G, Bunch TE, Firestone RB, Kennett JP, West A (21 August 2012). "Reply to Blaauw et al., Boslough, Daulton, Gill et al., and Hardiman et al.: Younger Dryas impact proxies in Lake Cuitzeo, Mexico" (PDF). Proceedings of the National Academy of Sciences of the United States of America. 109 (34): E2245–E2247. Bibcode:2012PNAS..109E2245I. doi:10.1073/PNAS.1209463109. ISSN 0027-8424. PMC 3427057. Wikidata Q45746116.
- Napier WM, Bunch TE, Kennett JP, Wittke JH, Tankersley KB, Kletetschka G, Howard GA, West A (November 2013). "Reply to Boslough et al.: Decades of comet research counter their claims". Proceedings of the National Academy of Sciences of the United States of America. 110 (45): E4171. Bibcode:2013PNAS..110E4171N. doi:10.1073/pnas.1315467110. PMC 3831498. PMID 24350338.
- Wittke JH, Bunch TE, Kennett JP, Kennett DJ, Culleton BJ, Tankersley KB, Daniel IR, Kloosterman JB, et al. (October 2013). "Reply to van Hoesel et al.: Impact-related Younger Dryas boundary nanodiamonds from The Netherlands". Proceedings of the National Academy of Sciences of the United States of America. 110 (41): E3897-8. Bibcode:2013PNAS..110E3897W. doi:10.1073/pnas.1313207110. PMC 3799356. PMID 24244962.
- Kennett JP, Kennett DJ, Culleton BJ, Aura Tortosa JE, Bunch TE, Erlandson JM, Johnson JR, Jordá Pardo JF, et al. (December 2015). "Reply to Holliday and Boslough et al.: Synchroneity of widespread Bayesian-modeled ages supports Younger Dryas impact hypothesis". Proceedings of the National Academy of Sciences of the United States of America. 112 (49): E6723-4. Bibcode:2015PNAS..112E6723K. doi:10.1073/pnas.1520411112. PMC 4679043. PMID 26604309.
- Bement LC, Madden AS, Carter BJ, Simms AR, Swindle AL, Alexander HM, Fine S, Benamara M (February 2014). "Quantifying the distribution of nanodiamonds in pre-Younger Dryas to recent age deposits along Bull Creek, Oklahoma panhandle, USA". Proceedings of the National Academy of Sciences of the United States of America. 111 (5): 1726–31. Bibcode:2014PNAS..111.1726B. doi:10.1073/pnas.1309734111. PMC 3918833. PMID 24449875.
- LeCompte MA, Goodyear AC, Demitroff MN, Batchelor D, Vogel EK, Mooney C, Rock BN, Seidel AW (October 2012). "Independent evaluation of conflicting microspherule results from different investigations of the Younger Dryas impact hypothesis". Proceedings of the National Academy of Sciences of the United States of America. 109 (44): E2960-9. doi:10.1073/pnas.1208603109. PMC 3497834. PMID 22988071.
- Boslough M, Harris AW, Chapman C, Morrison D (November 2013). "Younger Dryas impact model confuses comet facts, defies airburst physics". Proceedings of the National Academy of Sciences of the United States of America. 110 (45): E4170. Bibcode:2013PNAS..110E4170B. doi:10.1073/pnas.1313495110. PMC 3831451. PMID 24170865.
- Boslough M (April 2013). "Faulty protocols yield contaminated samples, unconfirmed results". Proceedings of the National Academy of Sciences of the United States of America. 110 (18): E1651. Bibcode:2013PNAS..110E1651B. doi:10.1073/pnas.1220567110. PMC 3645552. PMID 23599285.
- Holliday VT (December 2015). "Problematic dating of claimed Younger Dryas boundary impact proxies". Proceedings of the National Academy of Sciences of the United States of America. 112 (49): E6721. Bibcode:2015PNAS..112E6721H. doi:10.1073/pnas.1518945112. PMC 4679064. PMID 26604317.
- Reimold WU, Ferrière L, Deutsch A, Koeberl C (2014). "Impact controversies: Impact recognition criteria and related issues". Meteoritics & Planetary Science. 49 (5): 723–731. Bibcode:2014M&PS...49..723R. doi:10.1111/maps.12284. ISSN 1086-9379.
- van Hoesel A, Hoek WZ, Pennock GM, Drury MR (2014). "The Younger Dryas impact hypothesis: a critical review". Quaternary Science Reviews. 83: 95–114. Bibcode:2014QSRv...83...95V. doi:10.1016/j.quascirev.2013.10.033.
- Meltzer DJ, Holliday VT, Cannon MD, Miller DS (May 2014). "Chronological evidence fails to support claim of an isochronous widespread layer of cosmic impact indicators dated to 12,800 years ago". Proceedings of the National Academy of Sciences of the United States of America. 111 (21): E2162-71. Bibcode:2014PNAS..111E2162M. doi:10.1073/pnas.1401150111. PMC 4040610. PMID 24821789.
- Thy P, Willcox G, Barfod GH, Fuller DQ (2015). "Anthropogenic origin of siliceous scoria droplets from Pleistocene and Holocene archaeological sites in northern Syria". Journal of Archaeological Science. 54: 193–209. doi:10.1016/j.jas.2014.11.027.
- van der Hammen T, van Geel B (2016). "Charcoal in soils of the Allerød-Younger Dryas transition were the result of natural fires and not necessarily the effect of an extra-terrestrial impact". Netherlands Journal of Geosciences. 87 (4): 359–361. doi:10.1017/S0016774600023416. ISSN 0016-7746.
- Kjær KH, Larsen NK, Binder T, Bjørk AA, Eisen O, Fahnestock MA, Funder S, Garde AA, et al. (November 2018). "A large impact crater beneath Hiawatha Glacier in northwest Greenland". Science Advances. 4 (11): eaar8173. Bibcode:2018SciA....4.8173K. doi:10.1126/sciadv.aar8173. PMC 6235527. PMID 30443592.
- Voosen P (14 November 2018). "Massive crater under Greenland's ice points to climate-altering impact in the time of humans". Sciencemag.org. Science. Archived from the original on 13 January 2019. Retrieved 13 January 2019.
- Amos J (14 November 2018). "Greenland ice sheet hides huge 'impact crater'". BBC News. BBC. Archived from the original on 13 January 2019. Retrieved 13 January 2019.
- Howard BC (14 November 2018). "City-size impact crater found under Greenland ice". National Geographic. Archived from the original on 4 June 2021. Retrieved 4 August 2021.
- Boslough M (March 2019). "Crater Discovery Story Flawed by Premature Link to Speculative Impact Hypothesis". Skeptical Inquirer. 43 (2): 6–7.
- Patel NV (15 November 2018). "There's a giant crater the size of a city hiding under Greenland But not everyone agrees it's from an asteroid impact". Popsci.com. Popular Science. Archived from the original on 13 January 2019. Retrieved 13 January 2019.
- Silber EA, Johnson BC, Bjonnes E, MacGregor JA, Larsen NK, Wiggins SE (July 2021). "Effect of ice sheet thickness on formation of the Hiawatha impact crater". Earth and Planetary Science Letters. 566: 116972. Bibcode:2021E&PSL.56616972S. doi:10.1016/J.EPSL.2021.116972. ISSN 0012-821X. Wikidata Q107085795.
Here we model crater formation using hydrocode simulations, varying pre-impact ice thickness and impactor composition over crystalline target rock. We find that an ice-sheet thickness of 1.5 or 2 km results in a crater morphology that is consistent with the present morphology of this structure.
- Bogdan, Sawyer (1 June 2021). "Western University scientist discovers possible age of massive impact crater in Greenland - London". Global News. Archived from the original on 2 June 2021. Retrieved 15 January 2022.
Because it is very well preserved, it points to a possibly very young age, as young as the onset of the Younger Dryas period (between 11,500 and 14,500 years ago).
- "Giant impact crater in Greenland occurred a few million years after dinosaurs went extinct" (Press release). University of Copenhagen. 9 March 2022. Archived from the original on 9 March 2022. Retrieved 10 March 2022.
- Kenny GG, Hyde WR, Storey M, Garde AA, Whitehouse MJ, Beck P, Johansson L, Søndergaard AS, et al. (11 March 2022). "A Late Paleocene age for Greenland's Hiawatha impact structure". Science Advances. 8 (10): eabm2434. doi:10.1126/SCIADV.ABM2434. ISSN 2375-2548. Wikidata Q111179348.
- Boslough M (January 2022). "Sodom Meteor Strike Claims Should Be Taken with a Pillar of Salt: A controversial, widely publicized paper claiming that a cosmic impact destroyed a biblical city has had key images photoshopped and rotated to fit the biblical hypothesis" (PDF). Skeptical Inquirer. 46 (1): 10–14. ISSN 0194-6730. Wikidata Q110293090.
- Schultz PH, Harris RS, Perroud S, Blanco N, Tomlinson AJ (2 November 2021). "Widespread glasses generated by cometary fireballs during the late Pleistocene in the Atacama Desert, Chile" (PDF). Geology. 50 (2): 205–209. Bibcode:2022Geo....50..205S. doi:10.1130/G49426.1. ISSN 0091-7613. Wikidata Q109378713.
- Broecker WS (2006). "Was the Younger Dryas Triggered by a Flood?". Science. 312 (5777): 1146–1148. doi:10.1126/science.1123253. PMID 16728622. S2CID 39544213.
- Broecker WS (12 June 2017), An extraterrestrial impact at the onset of the Younger Dryas? (PDF), Wikidata Q107575586, archived (PDF) from the original on 18 July 2021
- "Texas Cave Sediment Upends Meteorite Explanation for Global Cooling" (Press release). Waco, Texas: Baylor University. 31 July 2020. Archived from the original on 1 June 2021. Retrieved 3 August 2021.
- Reinig F, Wacker L, Jöris O, Oppenheimer C, Guidobaldi G, Nievergelt D, et al. (30 June 2021). "Precise date for the Laacher See eruption synchronizes the Younger Dryas". Nature. 595 (7865): 66–69. Bibcode:2021Natur.595...66R. doi:10.1038/S41586-021-03608-X. ISSN 1476-4687. Wikidata Q107389873.
[Measurements] firmly date the [Laacher See eruption] to 13,006 ± 9 calibrated years before present (BP; taken as AD 1950), which is more than a century earlier than previously accepted. ...thereby dating the onset of the Younger Dryas to 12,807 ± 12 calibrated years BP, which is around 130 years earlier than thought.
- Michael Sigl [@THERA_4ever] (30 June 2021). "The study rules out a direct role of the Laacher See eruption in the inception of the Younger Dryas, but also highlights that this #climate anomaly (most commonly linked to a slowdown of the thermohaline circulation or ☄️) was preceded by a cluster of volcanic eruptions 🌋🌋🌋🌋" (Tweet) – via Twitter.
- "Eruption of the Laacher See volcano redated". University of Mainz (Press release). 1 July 2021. Archived from the original on 1 July 2021. Retrieved 26 August 2021.
That is 126 years earlier than the generally accepted dating based on sediments in the Meerfelder Maar from the Eifel region in Germany. ... This difference has far-reaching consequences for the synchronization of European climate archives and the understanding of North Atlantic and European climate history. ... This means that the [onset of the Younger Dryas] also occurred in Central Europe 130 years earlier, around 12,870 years ago respectively. This is in line with the onset of the cooling in the North Atlantic region identified in ice cores from Greenland. ... 'This strong cooling did not take place time transgressively, as previously thought, but rather synchronously over the entire North Atlantic and Central European region,' said Frederick Reinig.
- Balter M (12 May 2014). "What Caused a 1300-Year Deep Freeze?". Science. Archived from the original on 25 April 2022. Retrieved 21 August 2021.
The notion was popularized in television documentaries and other coverage on the National Geographic Channel, History Channel, and the PBS program NOVA.
- "Mammoth Mystery". IMDb. 7 October 2007. Retrieved 20 August 2021.
- "Journey to 10,000 BC". IMDb. 2008. Retrieved 20 August 2021.
- "Megabeasts' Sudden Death". IMDb. 31 March 2009. Retrieved 20 August 2021.
- "Megabeasts' Sudden Death". PBS Nova. 31 March 2009. Archived from the original on 12 June 2021. Retrieved 20 August 2021.
- Taube M (30 December 2015). "Book Review - Magicians of the Gods". The Washington Times. Archived from the original on 20 January 2021. Retrieved 14 January 2021.
- "MAGICIANS OF THE GODS by Graham Hancock". Kirkus Reviews. 3 September 2015. Archived from the original on 20 January 2021. Retrieved 14 January 2021.
- Colavito J. "Magicians of the Gods Review". Jason Colavito. Archived from the original on 5 December 2020. Retrieved 16 November 2017.
- Shermer M (1 June 2017). "No, There Wasn't an Advanced Civilization 12,000 Years Ago". Scientific American. Archived from the original on 20 February 2022. Retrieved 28 April 2022.
- Defant MJ (1 September 2017). "Conjuring Up a Lost Civilization: An Analysis of the Claims Made by Graham Hancock in Magicians of the Gods". Skeptic magazine. Archived from the original on 27 April 2021. Retrieved 27 April 2021.
- Casci M (29 March 2019). "Fresh clues in the hunt for a lost civilization - Graham Hancock interview". The Yorkshire Post. Archived from the original on 9 January 2022. Retrieved 29 April 2022.
- Michael Shermer [@michaelshermer] (11 March 2020). "Ok @Graham__Hancock I shall adjust my priors in light of more research like this, and modify my credence about your theory... "Evidence of Cosmic Impact at Abu Hureyra, Syria at the Younger Dryas Onset (~12.8 ka): High-temperature melting at >2200 °C" doi.org/10.1038/s41598-020-60867-w" (Tweet) – via Twitter.
- Defant MJ (5 June 2020). "The Younger Dryas Impact Hypothesis". Archived from the original on 26 January 2021. Retrieved 6 June 2021.
[Deadly Voyager] is a superb book and has absolutely convinced me there were comet airbursts at the Younger Dryas.
- Rogan J, Hancock G, Carlson R, Shermer M, Defant MJ, LeCompte MA (16 May 2017). Joe Rogan Experience #961 - Graham Hancock, Randall Carlson & Michael Shermer. Joe Rogan Experience. Event occurs at 2:06:55. Archived from the original on 21 December 2021.
- Shermer M (23 April 2019). "Debating Science and Lost Civilizations". Skeptic magazine. Archived from the original on 29 June 2021. Retrieved 20 August 2021.
According to Joe, as of that week he was averaging over 120 million downloads a month, putting him on a par with the biggest talk show hosts on television, either cable or broadcast.
- Bellinger K, Szulgit G, Wright JL, Proctor S (22 March 2021). "Gladiator Graveyard". Ancient Unexplained Files. Season 1. Episode 6. Science Channel. Event occurs at 12:40. Archived from the original on 21 December 2021. Wikidata Q109762970.
- Pringle H (23 May 2007). "Firestorm from space wiped out prehistoric Americans". New Scientist. 194 (2605): 8–9. doi:10.1016/S0262-4079(07)61277-9. Archived from the original on 14 September 2012. Retrieved 19 September 2017.
- Barlow J (23 May 2007). "UO researchers involved in Clovis impact theory" (Press release). Eugene, Oregon: University of Oregon. Wikidata Q110137681. Archived from the original on 20 March 2009. Retrieved 15 December 2021.
- Hoffman C (2 July 2008). "Exploding Asteroid Theory Strengthened by New Evidence Located in Ohio, Indiana". University of Cincinnati. Archived from the original on 31 July 2008. Retrieved 5 August 2008.
- Bentley M (2 January 2009). "Diamond clues to beasts' demise". BBC News. Archived from the original on 3 September 2010. Retrieved 15 April 2012.
- "Younger Dryas Boundary: Extraterrestrial Impact or Not I" (PDF). American Geophysical Union Fall Meeting, San Francisco, California. 16 December 2009. Archived from the original (PDF) on 23 April 2020. Retrieved 24 June 2021.
- "Younger Dryas Boundary: Extraterrestrial Impact or Not II" (PDF). American Geophysical Union Fall Meeting, San Francisco, California. 16 December 2009. Archived from the original (PDF) on 6 February 2012. Retrieved 15 April 2012.
- Holliday VT (2011). "A Cosmic Catastrophe: The Great Clovis Comet Debate: A personal perspective on an Outrageous Hypothesis". Argonaut Archaeological Research Fund. Tucson, Arizona: Department of Anthropology at the University of Arizona, University of Arizona. Archived from the original on 5 March 2016. Retrieved 14 July 2011.
- Bressan D (27 July 2011). "The Younger Dryas Impact Hypothesis". Scientific American Blog Network. Archived from the original on 15 March 2013. Retrieved 15 April 2012.
- Fernandez S (21 May 2013). "Comprehensive Analysis of Impact Spherules Supports Theory of Cosmic Impact 12,800 Years Ago". UC Santa Barbara. Archived from the original on 16 February 2021. Retrieved 24 June 2021.
- Firestone RB (24 July 2019). "Disappearance of Ice Age Megafauna and the Younger Dryas Impact". Capeia. Archived from the original on 10 April 2021. Retrieved 30 June 2021.
- Extensive series of articles published in Mammoth Trumpet, the magazine for Texas A&M University's Center for the Study of the First Americans, featuring conversations with many prominent YDIH proponents and opponents:
- Largent F (January 2008). "The Clovis Comet - Part I: Evidence for a Cosmic Collision 12,900 Years Ago" (PDF). Mammoth Trumpet. 23 (1): 1-3, 19-20. ISSN 8755-6898. Wikidata Q107225241.
- Largent F (April 2008). "The Clovis Comet - Part II: What the Data Tell Us" (PDF). Mammoth Trumpet. 23 (2): 15–18. ISSN 8755-6898. Wikidata Q107226201.
- Largent F (July 2008). "The Clovis Comet - Part III: The Implications" (PDF). Mammoth Trumpet. 23 (3): 18–20. ISSN 8755-6898. Wikidata Q107226305.
- Largent F (October 2008). "The Clovis Comet - Part IV: The Scientific Community Responds" (PDF). Mammoth Trumpet. 23 (4): 13–15. ISSN 8755-6898. Wikidata Q107226371.
- Lepper B (October 2009). "Fire Record Undercuts Clovis Comet Theory" (PDF). Mammoth Trumpet. 24 (4): 4–7. ISSN 8755-6898. Wikidata Q107228406.
- Largent F (April 2010). "The Clovis Comet Revisited - In the Crucible of Scientific Inquiry" (PDF). Mammoth Trumpet. 25 (2): 15–19. ISSN 8755-6898. Wikidata Q107228547.
- Largent F (July 2011). "The Clovis Comet Revisited - The Nanodiamond Controversy, Part I" (PDF). Mammoth Trumpet. 26 (3): 1-4, 8. ISSN 8755-6898. Wikidata Q107228612.
- Largent F (October 2011). "The Clovis Comet Revisited - The Nanodiamond Controversy, Part II: A Case of Mistaken Identity?" (PDF). Mammoth Trumpet. 26 (4): 1-3, 20. ISSN 8755-6898. Wikidata Q107228963.
- Largent F (July 2014). "The Clovis Comet - The Cratering Evidence" (PDF). Mammoth Trumpet. 29 (3): 1-5, 9. ISSN 8755-6898. Wikidata Q107229168.
- Largent F (January 2015). "The Clovis Comet - New Developments in the Proxy Evidence, Part I" (PDF). Mammoth Trumpet. 30 (1): 11–14. ISSN 8755-6898. Wikidata Q107229501.
- Largent F (April 2015). "The Clovis Comet - New Developments in the Proxy Evidence, Part II" (PDF). Mammoth Trumpet. 30 (2): 15–19. ISSN 8755-6898. Wikidata Q107230043.
- Largent F (October 2015). "The Clovis Comet - New Developments in the Proxy Evidence, Part III" (PDF). Mammoth Trumpet. 30 (4): 17–20. ISSN 8755-6898. Wikidata Q107230085.
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