Younger Dryas impact hypothesis

Hypothesis on what initiated the Younger Dryas climatic period (stadial)

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The Younger Dryas impact hypothesis (YDIH) proposes that the onset of the Younger Dryas (YD) cool period (stadial) at the end of the Last Glacial Period, around 12,900 years ago was the result of some kind of cosmic event with specific details varying between publications.[1]: Sec 1 The hypothesis is widely rejected by relevant experts.[2][1][3][4] It is influenced by creationism, and has been compared to cold fusion by its critics due to the lack of reproducibility of results.[5] It is an alternative to the long-standing and widely accepted explanation that the Younger Dryas was caused by a significant reduction in, or shutdown of the North Atlantic Conveyor due to a sudden influx of freshwater from Lake Agassiz and deglaciation in North America.[6][7][8]

In 2007, the first YDIH paper[9] speculated that an air burst caused by a comet hitting the atmosphere over North America created a Younger Dryas boundary (YDB) layer; however, inconsistencies have been identified in other published results.[1] Authors have not yet responded to requests for clarification and have never made their raw data available.[5] Some YDIH proponents have also proposed that this event triggered extensive biomass burning, a brief impact winter that destabilized the Atlantic Conveyor and triggered the Younger Dryas instance of abrupt climate change[9]: p. 16021 which contributed to extinctions of late Pleistocene megafauna, and resulted in the disappearance of the Clovis culture.[10][11]

## Comet research group

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The Comet research group (CRG), dedicated to investigating the YDIH, was established in 2016[2] by Allen West[a] (and others).[12][13] Their stated mission is to "find evidence about comet impacts and raise awareness about them before your city is next."[14]

The credibility and motivations of individual CRG researchers have been questioned by critics of the impact hypothesis, including their specific claims for evidence in support of the YDIH and the effects of meteor air bursts or impact events on ancient settlements, people, and environments.[2] Doubts have been raised about several of the CRG's other claims.;[15] for example a 2021 paper suggested that a Tunguska-sized or larger airburst destroyed Tall el-Hammam, a Middle Bronze Age city located in the Jordan Valley near the Dead Sea around 1650 BCE.[16] Image forensics expert Elisabeth Bik discovered evidence for digital alteration of images used as evidence for the claim that the village of Tall el-Hammam was engulfed by an airburst.[17][18] CRG members initially denied tampering with the photos but eventually published a correction in which they admitted to inappropriate image manipulation.[19] Five of the paper's 53 images received retouching to remove labels and arrows present in other published versions of the photos, which Bik believed to be a possible conflict with Scientific Reports' image submission guidelines but was not in itself a disproval of the Tall el-Hammam airburst theory.[20] Subsequent concerns that have been brought up in PubPeer have not yet been addressed by the CRG, including discrepancies between claimed blast wave direction compared to what the images show, unavailability of original image data to independent researchers, lack of supporting evidence for conclusions, inappropriate reliance on young Earth creationist literature, misinformation about the Tunguska explosion, and another uncorrected example of an inappropriately altered image.[21] On February 15, 2023, the following editor’s note was posted on this paper: "Readers are alerted that concerns raised about the data presented and the conclusions of this article are being considered by the Editors. A further editorial response will follow the resolution of these issues."[22] On August 30, 2023, a paper authored by a CRG member and leading YDIH advocate was retracted by Scientific Reports. The journal's Retraction Note cited a publication "indicating that the study does not provide data to support the claims of an airburst event or that such an event led to the decline of the Hopewell culture."[23]. On April 24, 2025, Nature issued another Retraction Note, this time for the Tall el-Hammam paper, citing concerns about methodology, analysis, and data interpretation.[24]

## Supposed evidence

[edit]

Proponents believe that certain microscopic debris is evidence of impact and that "black mats" of sediment are evidence of widespread fires. They contend that extinction of megafauna was synchronous with associated effects on prehistoric human societies. They say that their observations and interpretations cannot be adequately explained by volcanic, anthropogenic, or other natural processes.[25] They argue that there is a synchronous Younger Dryas boundary layer that should be used as a local,[26] or even global[27] stratigraphic marker. Archaeologist Stuart J Fiedel has remarked that "The bolide and its effects have been characterized inconsistently from one paper to the next, which makes this hypothesis difficult to refute."[28] In 2011, a review of the evidence led researchers to state "The YD impact hypothesis provides a cautionary tale for researchers, the scientific community, the press, and the broader public" as "none of the original YD impact signatures have been subsequently corroborated by independent tests. Of the 12 original lines of evidence, seven have so far proven to be non-reproducible. The remaining signatures instead seem to represent either (1) non-catastrophic mechanisms, or (2) terrestrial rather than extraterrestrial or impact-related sources. In all of these cases, sparse but ubiquitous materials seem to have been misreported and misinterpreted as singular peaks at the onset of the YD. Throughout the arc of this hypothesis, recognized and expected impact markers were not found, leading to proposed YD impactors and impact processes that were novel, self-contradictory, rapidly changing, and sometimes defying the laws of physics."[29] Additionally, a comprehensive refutation of the Younger Dryas Impact Hypothesis was published in 2023, stating "There is no support for the basic premise of the YDIH that human populations were diminished, and individual species of late Pleistocene megafauna became extinct or were diminished due to catastrophe."[1]: Sec 3.2 Another example is that of extensive wildfires claimed by some YDIH proponents[30] that has been refuted by experts.[31][1]: Sec. 9 "Evidence and arguments purported to support the YDIH involve flawed methodologies, inappropriate assumptions, questionable conclusions, misstatements of fact, misleading information, unsupported claims, irreproducible observations, logical fallacies, and selected omission of contrary information."[1]

### Hypothetical impact markers

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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.[6][32] One of the most widely publicized discoveries (nanodiamonds in Greenland) has never been verified and is disputed.[33]

Some scientists have asserted that the carbon spherules originated as fungal structures or insect fecal pellets, and contained modern contaminants[34][35] and that the claimed nanodiamonds are actually misidentified graphene and graphene/graphane oxide aggregates.[36][37] A patent application by Allen West and James Kennett in 2009 for methods of forming nanodiamonds based on research in support of the impact hypothesis also likely misidentified copper and copper oxides and appears to have since been abandoned.[1]: Sec. 12.5 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.[38][39] An analysis of a similar Younger Dryas boundary layer in Belgium yielded carbon crystalline structures such as nanodiamonds, but the authors concluded that they did not show unique evidence for a bolide impact.[40] An independent group of researchers reported much lower concentrations of platinum group metals in the purported boundary layer (by a factor of 30 for iridium).[b][41][43] The original authors argued that these concentrations were still >300% (a factor of 3) above background in 2 of their samples.[44] Another group was unable to confirm prior claims of magnetic particles and microspherules in 2009.[45] Other studies involving YDIH proponents found concentrations of magnetic spherules but not all were associated with the YDB and not all were attributed to an ET event.[46][47][48][49][50]

### "Black mats"

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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 about 50 archaeological sites across North America.[c] 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.[53] In 2019, Jorgeson and others tested this conclusion with the simulation of radiocarbon ages.[54] 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.[54]

Marlon et al. suggest that wildfires were a consequence of rapid climate change.[55] "The changes in woody biomass, fire frequency, and biomass burning are not coincident with changes in CO2, although increasing CO2 may have contributed to woody biomass production during the early part of the Bølling–Allerød. Clovis people appeared in North America between 13.4 and 12.8 ka, broadly coincident with the sharp increase in biomass burning at 13.2 ka, and then rapidly spread out across the continent."

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.[56] Research published in 2012 has shown that the so-called "black mats" are easily explained by typical earth processes in wetland environments.[d][57] This 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, they likely arise from processes common to arid-climate wetland systems and not as a result of catastrophic bolide impacts.[d][57]

Researchers have also criticized the conclusions of various studies for incorrect age-dating of the sediments,[58] contamination by modern carbon, inconsistent hypothesis that made it difficult to predict the type and size of bolide,[59] lack of proper identification of lonsdaleite,[60] confusing an extraterrestrial impact with other causes such as fire,[61] and for inconsistent use of the carbon spherule "proxy".[62] Naturally occurring lonsdaleite has also been identified in non-bolide diamond placer deposits in the Sakha Republic.[63]

### Extinction of megafauna

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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.[64][65][66] The extinction of woolly mammoths in Siberia also appears to have occurred later than in North America.[64] 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,[64][65][67] and the survival of ground sloths in the Antilles,[68] the Caribbean, until 4700 cal BP.[64] The Australian megafaunal extinctions occurred approximately 30,000 years earlier than the hypothetical Younger Dryas event.[69]

The megafaunal extinction pattern observed in North America poses a problem for the bolide impact scenario since it raises the question of why large mammals should be preferentially exterminated over small mammals or other vertebrates.[70] 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.[64] Also, it appears that there was a collapse in North American megafaunal population from 14,800 to 13,700 BP, well before the date of the hypothetical extraterrestrial impact,[71] possibly from anthropogenic activities, including hunting.[72]

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.[73] 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.[74][needs update]

### Impact on human societies

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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,[75] suggesting that the hypothesis would probably need to be revised.[76][77][text–source integrity?] A critique of this paper[76] concluded that these results were an insensitive, low-fidelity population proxy incapable of detecting demographic change.[78] 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 reorganisation in human population early in this period. The same paper also shows an apparent resurgence in population and settlements in the later Younger Dryas.[79] A 2022 study by an independent group presents genomic evidence that a previously unidentified pre-18,000 BP South American population suffered a major disruption at the Younger Dryas onset, resulting in a significant loss of lineages and a Y chromosome bottleneck.[80]

### Hiawatha crater

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NASA digital elevation model with the ice sheet removed to show the surface of bedrock in the region around the Hiawatha Glacier

A 2018 paper reported the discovery of an impact crater under the Hiawatha Glacier in Greenland of unknown age.[81] Kurt Kjær, the lead author of the paper, speculated that it might date to the Pleistocene (2.58 million to 11,700 years ago), and mentioned a possible connection to the Younger Dryas.[82]

However, in 2022 the crater was dated to around 58 million years ago, the late Paleocene, using Argon–argon dating combined with uranium–lead dating of shocked zircon crystals.[e][83][84]

## Other explanations

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Main article: Younger Dryas § Causes

A number of other hypotheses have been put forward about the cause of the Younger Dryas climate event.

### Mainstream explanation

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The most widely accepted explanation is that it began because of a significant reduction or shutdown of the North Atlantic "Conveyor" – which circulates warm tropical waters northward – as the consequence of deglaciation in North America. Geological evidence for such an event is not fully secure,[85] but recent work has identified a pathway along the Mackenzie River that would have spilled fresh water from Lake Agassiz into the Arctic and thence into the Atlantic.[86][87] The global climate would then have become locked into the new state until freezing removed the fresh water "lid" from the North Atlantic.

### Other alternatives

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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.[f][88]

Another hypothesis suggests instead that the jet stream shifted northward in response to the melting of the North American ice sheet, which brought more rain to the North Atlantic, which freshened the ocean surface enough to slow the thermohaline circulation.[89]

Another proposed cause has been volcanic activity.[90][91] 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.[92] 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."[93]

## History

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Find sources: "Younger Dryas impact hypothesis" – news · newspapers · books · scholar · JSTOR (October 2022) (Learn how and when to remove this message)

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The idea that a comet struck North America at the end of the last ice age was first proposed as a speculative premise by the American congressman and pseudohistorian Ignatius Donnelly in 1883, who suggested it formed the Great Lakes and caused a sudden extreme cold period, which devastated animal and human populations.[1]

In 2001, Richard Firestone and William Topping published their first version of the YDIH, "Terrestrial Evidence of a Nuclear Catastrophe in Paleoindian Times" in Mammoth Trumpet, a newsletter of the Center for the Study of the First Americans.[94] They proposed that "the entire Great Lakes region (and beyond) was subjected to a particle bombardment and a catastrophic nuclear radiation..." They argue that this cataclysm generated a shock wave that gouged out the Carolina Bays and reset the radiocarbon clock. Most geologists today interpret the Carolina bays as relict geomorphological features that developed via various eolian and lacustrine processes. Multiple lines of evidence, e.g. radiocarbon dating, optically stimulated luminescence dating, and palynology, indicate that the Carolina bays predate the start of the Holocene. Fossil pollen recovered from cores of undisturbed sediment taken from various Carolina bays in North Carolina by Frey,[95][96] Watts,[97] and Whitehead[98][99] document the presence of full glacial pollen zones within the sediments filling some Carolina bays. The range of dates can be interpreted that Carolina bays were either created episodically over the last tens of thousands of years or were created at time over a hundred thousand years ago and have since been episodically modified.[100][101][102] Recent work by the U.S. Geological Survey[103] has interpreted the Carolina bays as relict thermokarst lakes that have been modified by eolian and lacustrine processes. Modern thermokarst lakes are common today around Barrow (Alaska), and the long axes of these lakes are oblique to the prevailing wind direction.

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.[104]

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.[6][105] 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.[9] Since this paper was considered too controversial for standard peer review, it was handled by a specially selected 'personal editor' who was friendly to the hypothesis.[8]

In 2008, C. Vance Haynes Jr. published data to support the synchronous nature of the black mats,[c] 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."[106] The first debate between proponents and skeptics was held at the 2008 Pecos Conference in Flagstaff, Arizona.[107][108]

In 2009, papers by Kerr[109] and Kennett[110] 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.[111]

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.

In 2011, Pinter and others challenged the Younger Dryas impact hypothesis on the basis that most of the conclusions could not be reproduced and were a misinterpretation of data.[29] Skepticism increased when it was reported that one of the lead authors of the original paper had practiced geophysics without a license.[g][112][12] Around that time, Daulton stated that no nanodiamonds were found[36] and that the supposed carbon spherules could be fungus or insect feces and included modern contaminants as stated by Boslough and others[34] and Roach.[35] In response, in June 2013 Wittke and others published a re-evaluation of spherules from eighteen sites worldwide that they interpret as supporting their hypothesis.[32]

In 2012, a paper by Bunch and others reported the discovery of scoria like objects (SLO) and stated that they were consistent with an extraterrestrial impact or airburst.[25] Post-publication review of this paper suggests that at least some of these SLOs are anthropogenic.[113] 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.[114] Lonsdaleite has also been made artificially in laboratories.[115][63][relevant?]

In 2013, Petaev and others reported a hundredfold spike in the concentration of platinum in Greenland ice cores roughly dated to 12,890 YBP.[116] This anomaly was attributed to a small local iron meteorite fall without any widespread consequences.[117] A refutation of the YDIH,[1] by Holliday and others (including Petaev), showed that the Pt spike was not evidence to support the YDIH because it occurred 20 years after the YDB.

In 2016, Holiday and others reported on further analysis of Younger Dryas boundary sediments at nine sites found no evidence of an extraterrestrial impact at the Younger Dryas boundary.[118] Also that year, Daulton and others reported an analysis of nanodiamond evidence failed to uncover lonsdaleite or a spike in nanodiamond concentration at the YDB.[119]

In 2017, C R Moore and others reported a Pt anomaly at eleven continental sites dated to the Younger Dryas, which is linked with the Greenland Platinum anomaly.[120]

In 2018, dealing with an "extraordinary biomass-burning episode" associated with the Younger Dryas Impact were reported by Wolbach and others[121][122] and Lynch.[123] However, these claims of extraordinary fires are disputed by Holliday and others[124] with a response by Wolbach.[125]

A map from Mario Pino et al. 2019 [126] showing 53 Younger Dryas boundary sites. Orange dots represent 28 sites with peaks in both platinum (Pt) and other impact proxies such as high-temperature Fe-rich spherules. Red dots represent 24 sites with impact proxies but lacking Pt measurements.

In 2019, Pino and others 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.[126] This included rare metallic spherules, melt glass and nanodiamonds thought to have been produced during airbursts or impacts.[126] 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.[126] Also in 2019, CR Moore and others reported 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.[127]

In 2019, Thackery and others reported that a ~10 ppb platinum (Pt) enrichment in peat deposits at Wonderkrater in South Africa was associated with the YDB, although the age uncertainty range of the anomaly exceeded 2 thousand years.[128]

In 2019 research at White Pond near Elgin, South Carolina, conducted by CR 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.[129][130]

Examples of meltglass from Tell Abu Hureyra [131]

In 2020, a group led by Allen West reported 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,[131][132] but this was quickly contradicted by another study calling the YDIH into question because the samples were extremely unlikely to have been deposited at the same time.[133] Since all samples from the site were expended, the findings cannot be confirmed.[134]

In 2022, a paper by geologist James L. Powell, a YDIH proponent, claimed that opponents had prematurely rejected YDIH,[3] detailing the example of research published by Firestone and others in 2001[94] and the inability of a later study by Surovell and others in 2009[45] that was unable to reproduce these results leading a number of other scientists to reject YDIH.[3]: Table 4 Powell argues that since then, many independent studies have reproduced that evidence at dozens of YD sites.[3]

A March 2023 article by planetary impact physicist Mark Boslough and YDIH opponent stated that "...the YDIH has never been accepted by experts in any related field" because it is "plagued by self contradictions, logical fallacies, basic misunderstandings, misidentified impact evidence, abandoned claims, irreproducible results, questionable protocols, lack of disclosure, secretiveness, failed predictions, contaminated samples, pseudoscientific arguments, physically impossible mechanisms, and misrepresentations".[2]

This article may contain inappropriate self-references to the Wikipedia project or to itself. Please address the problem by removing references to Wikipedia or to the article as a document. (March 2024)

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In July 2023 Holliday and others published a comprehensive refutation of the YDIH[1] that collected and summarized many of the positions from opponents to YDIH publications mentioned in the above history. Sections in this article refute the areas of evidence regarding Hypothetical impact markers,[1]: Sec. 8-12 "Black mats,"[1]: Sec. 6 Extinction of megafauna,[1]: Sec. 3.2 Impact on human societies,[1]: Sec. 3.1 the Hiawatha crater.[1]: Sec. 7 Also criticized were fundamental assumptions,[1]: Sec. 3 flawed sampling,[1]: Sec. 4 inadequate dating,[1]: Sec. 5 Pseudoarchaeological divined date of the impact event,[1]: Sec. 5.2 pseudoscience (fringe) evidence and conjecture,[1]: Sec. 14 issues with other YDIH claims, such as the Carolina bays,[1]: Sec. 13.1 contradictory results when different groups have examined the same sample specimens,[1]: Sec. 14 and unparalleled promotion of YDIH outside of scientific literature.[1]: Sec. 14 The paper also responded to and critiqued assertions from Powell.[10] The paper concludes that since "YDIH evolved directly from pseudoscience, the initial publication in scientific literature was seriously plagued by poorly documented interpretations and baseless assertions." and lists 11 serious flaws that persist in YDIH.[1]: Sec. 17

In a December 2023 article by CR Moore and others[135] stated that "anomalous peak abundances of platinum and Fe-rich microspherules with high-temperature minerals have previously been demonstrated to be a chronostratigraphic marker for the lower Younger Dryas Boundary (YDB) dating to 12.8 ka," was found in sediments at Wakulla Springs, Florida. "The study confirms the utility of this YDB datum layer for intersequence correlation and for assessing relative ages of Paleoamerican artifacts, including those of likely Clovis, pre-Clovis, and post-Clovis age and their possible responses to environmental changes known to have occurred during the Younger Dryas cool climatic episode."

## In popular culture

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The impact hypothesis has been the subject of documentaries,[136] including Mammoth Mystery on National Geographic Explorer (2007),[137] Journey to 10,000 BC on the History Channel (2008),[138] Survival Earth on Channel 4 (2008), and Megabeasts' Sudden Death on PBS Nova (2009).[h][139][140][141]

Graham Hancock argued in his 2015 book Magicians of the Gods that the Younger Dryas comet destroyed the earth in a time cycle and that it was responsible for the Noahide flood myth. He inferred that this myth was widespread elsewhere on earth by comparing it with the flood mythology of other peoples.[142][143] These claims were criticized as inaccurate by independent reviewers, including Jason Colavito, Michael Shermer, and Marc J. Defant.[i][144][145][146] Hancock expanded on his claims in a 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.[147]

In 2017, a debate was held on the Joe Rogan Experience between proponents[clarification needed] Graham Hancock, Randall Carlson, and Malcolm A. LeCompte and opponents Michael Shermer and Marc J. Defant.[i][150] The week that the podcast was released, the network was reportedly averaging over 120 million downloads a month.[151]

A 2021 episode of the Science Channel series Ancient Unexplained Files had a segment on the evidence from Abu Hureyra;[131] geoscientist Sian Proctor also described the impact hypothesis as a whole.[152]

In 2022 Graham Hancock presented in a Netflix series titled Ancient Apocalypse, with episode 8 specifically covering the YDIH. In March 2023 Mark Boslough published a commentary in Skeptic magazine with the conclusion that many attributes of the series are pseudoscience.[2]

## See also

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* Carolina bays – Elliptical depressions concentrated along the Atlantic seaboard of North America
* Murray Springs Clovis Site – Archaeological site in Arizona, United States
* Shiva hypothesis – Scientific theory concerning impact events
* Taurids – Annual meteor shower
* Tollmann's bolide hypothesis – Hypothetical impact event
* Tunguska event and Chelyabinsk meteor \- two examples of meteors exploding in the atmosphere

## Footnotes

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1. ^ Allen 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.[12]
2. ^ One of the authors of this study, Matthew Boyd,[41] later published a paper that argued in favour of the impact hypothesis.[42]
3. ^ a b The darkened stratum was first identified at the Lehner Mammoth-Kill Site by Emil Haury who named it "Lehner swamp soil";[51] it was later renamed by Vance Haynes as the "black mat".[52][9]
4. ^ a b Pigati has noted that his 2012 paper [57] does not disprove the impact hypothesis.[39]
5. ^ This paper's co-authors include Kurt Kjær and Elizabeth Silber
6. ^ Broecker did not believe that the impact caused extinctions.[88]
7. ^ Allen West had the conviction expunged after the matter was reported on by Rex Dalton.[112][12]
8. ^ Megabeasts Sudden Death was removed from online streaming after NOVA WGBH learned about problems with the hypothesis and data discrancies.[1]
9. ^ a b Both Michael Shermer and Marc J. Defant have since indicated that they accept the impact hypothesis.[148][149]

## References

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### Citations

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1. ^ a b c d e f g h i j k l m n o p q r s t u v w x y Holliday, Vance T.; Daulton, Tyrone L.; Bartlein, Patrick J.; Boslough, Mark B.; Breslawski, Ryan P.; Fisher, Abigail E.; Jorgeson, Ian A.; Scott, Andrew C.; Koeberl, Christian; Marlon, Jennifer; Severinghaus, Jeffrey; Petaev, Michail I.; Claeys, Philippe (26 July 2023). "Comprehensive refutation of the Younger Dryas Impact Hypothesis (YDIH)". Earth-Science Reviews. 247 104502\. Bibcode:2023ESRv..24704502H. doi:10.1016/j.earscirev.2023.104502.
2. ^ a b c d e Boslough, Mark (March 2023). "Apocalypse! Why Graham Hancock's use of the Younger Dryas impact hypothesis in his Netflix series Ancient Apocalypse is all wet". Skeptic Magazine. 28 (1): 51–59.
3. ^ a b c d Powell, James Lawrence (January 2022). "Premature rejection in science: The case of the Younger Dryas Impact Hypothesis". Science Progress. 105 (1): 003685042110642. doi:10.1177/00368504211064272. ISSN 0036-8504. PMC 10450282. PMID 34986034.
4. ^ Chapman, Clark R.; Morrison, David; Harris, Alan W. (2025). "The Younger Dryas Impact: A Failed Hypothesis". Skeptical Inquirer. Vol. 49, no. 4\. pp. 59–62.
5. ^ a b Holliday, Vance T.; Daulton, Tyrone L.; Bartlein, Patrick J.; Boslough, Mark B.; Breslawski, Ryan P.; Fisher, Abigail E.; Jorgeson, Ian A.; Scott, Andrew C.; Koeberl, Christian; Marlon, Jennifer; Severinghaus, Jeffrey; Petaev, Michail I.; Claeys, Philippe (2024). "Rebuttal of Sweatman, Powell, and West's "Rejection of Holliday et al.'s alleged refutation of the Younger Dryas Impact Hypothesis"". Earth-Science Reviews. 258 104961: 3. Bibcode:2024ESRv..25804961H. doi:10.1016/j.earscirev.2024.104961.
6. ^ a b c 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.
7. ^ Sun et al. (2020), p. 1: "The prevailing hypothesis is that the cooling and stratification of the North Atlantic Ocean were a consequence of massive ice sheet discharge of meltwater and icebergs and resulted in reduction or cessation of the North Atlantic Conveyor."
8. ^ a b Jones, N (2 September 2013). "Evidence found for planet-cooling asteroid". Nature. doi:10.1038/nature.2013.13661. S2CID 131715496.
9. ^ a b c d 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.
10. ^ a b Powell (2022), p. 1: "The hypothesis proposes that the airburst or impact of a comet ~12,850 years ago caused the ensuing ~1200-year-long Younger Dryas (YD) cool period and contributed to the extinction of the Pleistocene megafauna in the Western Hemisphere and the disappearance of the Clovis PaleoIndian culture."
11. ^ Pino et al. (2019), p. 1: "The Younger Dryas (YD) impact hypothesis posits that fragments of a large, disintegrating asteroid/comet struck North America, South America, Europe, and western Asia ~12,800 years ago. Multiple airbursts/impacts produced the YD boundary layer (YDB), depositing peak concentrations of platinum, high-temperature spherules, meltglass, and nanodiamonds, forming an isochronous datum at >50 sites across ~50 million km² of Earth's surface. This proposed event triggered extensive biomass burning, brief impact winter, YD climate change, and contributed to extinctions of late Pleistocene megafauna."
12. ^ a b c d 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.
13. ^ George, Zach St (5 March 2024). "The Comet Strike Theory That Just Won't Die". The New York Times. Archived from the original on 13 December 2024. Retrieved 19 December 2024.
14. ^ "Comet Research Group". 14 July 2015. Retrieved 24 November 2024.
15. ^ Marcus, Adam (1 October 2021). "Criticism engulfs paper claiming an asteroid destroyed Biblical Sodom and Gomorrah". Retraction Watch. Retrieved 24 November 2021.
16. ^ Bunch, Ted E.; LeCompte, Malcolm A.; Adedeji, A. Victor; Wittke, James H.; Burleigh, T. David; Hermes, Robert E.; Mooney, Charles; Batchelor, Dale; Wolbach, Wendy S.; Kathan, Joel; Kletetschka, Gunther; Patterson, Mark C. L.; Swindel, Edward C.; Witwer, Timothy; Howard, George A. (20 September 2021). "RETRACTED ARTICLE: A Tunguska sized airburst destroyed Tall el-Hammam a Middle Bronze Age city in the Jordan Valley near the Dead Sea". Scientific Reports. 11 (1): 18632. Bibcode:2021NatSR..1118632B. doi:10.1038/s41598-021-97778-3. ISSN 2045-2322. PMC 8452666. PMID 34545151. (Retracted, see doi:10.1038/s41598-025-99265-5, PMID 40275027, Retraction Watch)
17. ^ "Paper That Claimed Asteroid Destroyed Biblical Sodom Comes Under Pall of Doubt". The Science Wire. 6 October 2021.
18. ^ Kincaid, Ellie (21 February 2023). "Journal investigating Sodom comet paper for data problems". Retraction Watch. Retrieved 23 November 2024.
19. ^ Bunch, Ted E.; LeCompte, Malcolm A.; Adedeji, A. Victor; Wittke, James H.; Burleigh, T. David; Hermes, Robert E.; Mooney, Charles; Batchelor, Dale; et al. (22 February 2022). "Author Correction: A Tunguska sized airburst destroyed Tall el-Hammam a Middle Bronze Age city in the Jordan Valley near the Dead Sea" (PDF). Scientific Reports. 12 (1): 3265. doi:10.1038/S41598-022-06266-9. ISSN 2045-2322. PMC 8864031. PMID 35194042. Wikidata Q111021706.
20. ^ Bik, Elisabeth (2 October 2021). "Blast in the Past: Image concerns in paper about comet that might have destroyed Tall el-Hammam". Science Integrity Digest. Retrieved 24 November 2021.
21. ^ Bunch, Ted E.; Lecompte, Malcolm A.; Adedeji, A. Victor; Wittke, James H.; Burleigh, T. David; Hermes, Robert E.; Mooney, Charles; Batchelor, Dale; Wolbach, Wendy S.; Kathan, Joel; Kletetschka, Gunther; Patterson, Mark C. L.; Swindel, Edward C.; Witwer, Timothy; Howard, George A.; Mitra, Siddhartha; Moore, Christopher R.; Langworthy, Kurt; Kennett, James P.; West, Allen; Silvia, Phillip J. (September 2021). "A Tunguska sized airburst destroyed Tall el-Hammam a Middle Bronze Age city in the Jordan Valley near the Dead Sea". Scientific Reports. 11 (1): 18632. Bibcode:2021NatSR..1118632B. doi:10.1038/s41598-021-97778-3. PMC 8452666. PMID 34545151. Retrieved 9 August 2022. (Retracted, see doi:10.1038/s41598-025-99265-5, PMID 40275027, Retraction Watch)
22. ^ Kincaid, Ellie (21 February 2023). "Journal investigating Sodom comet paper for data problems". Retraction Watch. Retrieved 27 February 2023.
23. ^ Tankersley, K.B.; Meyers, S.D.; Meyers, S.A.; Jordan, J.A.; Herzner, L.; Lentz, D.L.; Zedaker, D. (August 2023). "Retraction Note: The Hopewell airburst event, 1699–1567 years ago (252–383 CE)". Scientific Reports. 13 (1): 14201. Bibcode:2023NatSR..1314201T. doi:10.1038/s41598-023-41237-8. PMC 10468503. PMID 37648734.
24. ^ Bunch, Ted E.; LeCompte, Malcolm A.; Adedeji, A. Victor; Wittke, James H.; Burleigh, T. David; Hermes, Robert E.; Mooney, Charles; Batchelor, Dale; et al. (24 April 2025). "Retraction Note: A Tunguska sized airburst destroyed Tall el-Hammam a Middle Bronze Age city in the Jordan Valley near the Dead Sea". Scientific Reports. 15 (14291): 14291. Bibcode:2025NatSR..1514291B. doi:10.1038/s41598-025-99265-5. PMC 12022329. PMID 40275027.
25. ^ a b 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.
26. ^ 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."
27. ^ 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. "We expect the Pt anomaly to serve as a widely-distributed time marker horizon (datum) for identification and correlation of the onset of the YD climatic episode at 12,800 Cal B.P. This Pt datum will facilitate the dating and correlating of archaeological, paleontological, and paleoenvironmental data between sequences, especially those with limited age control."
28. ^ Fiedel, Stuart J (August 2022). "Initial Human Colonization of the Americas, Redux". Radiocarbon. 64 (4): 845–897\. Bibcode:2022Radcb..64..845F. doi:10.1017/RDC.2021.103. ISSN 0033-8222. S2CID 246024355.
29. ^ a b Pinter, Nicholas; Scott, Andrew C.; Daulton, Tyrone L.; Podoll, Andrew; Koeberl, Christian; Anderson, R. Scott; Ishman, Scott E. (1 June 2011). "The Younger Dryas impact hypothesis: A requiem". Earth-Science Reviews. 106 (3): 247–264\. Bibcode:2011ESRv..106..247P. doi:10.1016/j.earscirev.2011.02.005. ISSN 0012-8252.
30. ^ Wolbach, Wendy S.; Ballard, Joanne P.; Mayewski, Paul A.; Adedeji, Victor; Bunch, Ted E.; Firestone, Richard B.; French, Timothy A.; Howard, George A.; Israde-Alcántara, Isabel; Johnson, John R.; Kimbel, David; Kinzie, Charles R.; Kurbatov, Andrei; Kletetschka, Gunther; LeCompte, Malcolm A. (March 2018). "Extraordinary Biomass-Burning Episode and Impact Winter Triggered by the Younger Dryas Cosmic Impact ∼12,800 Years Ago. 1. Ice Cores and Glaciers". The Journal of Geology. 126 (2): 165–184\. Bibcode:2018JG....126..165W. doi:10.1086/695703. ISSN 0022-1376. S2CID 53021110.
31. ^ 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 23 February 2023.
32. ^ a b 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.
33. ^ Kurbatov, Andrei V.; Mayewski, Paul A.; Steffensen, Jorgen P.; West, Allen; Kennett, Douglas J.; Kennett, James P.; Bunch, Ted E.; Handley, Mike; Introne, Douglas S.; Hee, Shane S. Que; Mercer, Christopher; Sellers, Marilee; Shen, Feng; Sneed, Sharon B.; Weaver, James C.; Wittke, James H.; Stafford, Thomas W.; Donovan, John J.; Xie, Sujing; Razink, Joshua J.; Stich, Adrienne; Kinzie, Charles R.; Wolbach, Wendy S. (20 September 2022). "Discovery of a nanodiamond-rich layer in the Greenland ice sheet". PubPeer. Retrieved 28 September 2022.
34. ^ a b 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.
35. ^ a b 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.
36. ^ a b 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.
37. ^ Kerr RA (30 October 2010). "Mammoth-Killer Impact Rejected". Science NOW. AAAS. Archived from the original on 17 September 2018. Retrieved 17 September 2018.
38. ^ Pinter N, Ishman SE (2008). "Impacts, mega-tsunami, and other extraordinary claims". GSA Today. 18 (1): 37–38\. Bibcode:2008GSAT...18a..37P. doi:10.1130/GSAT01801GW.1.
39. ^ a b Perkins S (23 April 2012). "No Love for Comet Wipeout". Science. Archived from the original on 17 September 2018. Retrieved 17 September 2018.
40. ^ 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.
41. ^ a b 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.
42. ^ 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."
43. ^ Paquay FS, Goderis S, Ravizza G, Claeys P (December 2009). "Reply to Bunch et al.: Younger Dryas impact proponents challenge new platinum group elements and osmium data unsupportive of their hypothesis". Proceedings of the National Academy of Sciences of the United States of America. 107 (51): E59 – E60. doi:10.1073/pnas.1001828107. PMC 2872459.
44. ^ Bunch, TE, West, A, Firestone, RB, Kennett, JP, et al. (April 2010). "Geochemical data reported by Paquay et al. do not refute Younger Dryas impact event". Proceedings of the National Academy of Sciences of the United States of America. 107 (15): E58, author repliy E59-60. Bibcode:2010PNAS..107E..58B. doi:10.1073/pnas.1001156107. PMC 2872453. PMID 20388907.
45. ^ a b 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.
46. ^ Haynes, et al. (October 2010). "The Murray Springs Clovis site, Pleistocene extinction, and the question of extraterrestrial impact". Proceedings of the National Academy of Sciences of the United States of America. 107 (9): 4010–5\. Bibcode:2010PNAS..107.4010H. doi:10.1073/pnas.0908191107. PMC 2840150. PMID 20160115.
47. ^ LeCompte MA, Goodyear AC, Demitroff MN, Batchelor D, Vogel EK, Mooney C, Rock BN, et al. (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.
48. ^ Andronikov AV, Andronikova IE, Loehn CW, Lafuente B, Ballenger JA, Crawford GT, Lauretta DS (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\. Bibcode:2016GeAnA..98...39A. doi:10.1111/geoa.12122. S2CID 56032364.
49. ^ Kletetschka G, Vondrak D, Hruba J, Prochazka V, Nabelek L, Svitavska-Svoboda H, Bobek P, Horicka Z, et al. (October 2018). "Cosmic-impact event in lake sediments from central Europe postdates the Laacher See Eruption and marks onset of the Younger Dryas". The Journal of Geology. 126 (6): 561–575\. Bibcode:2018JG....126..561K. doi:10.1086/699869.
50. ^ Teller J, Boyd M, LeCompte MA, Kennett JP, West A, Telka A, Diaz A, Adedeji V, et al. (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\. doi:10.1017/qua.2019.46. S2CID 210614208.
51. ^ 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.
52. ^ "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'"
53. ^ 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. (erratum)
54. ^ a b 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.
55. ^ 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."
56. ^ 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. S2CID 46954364. Archived from the original on 5 February 2020. Retrieved 5 February 2020.
57. ^ a b c 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.
58. ^ 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.
59. ^ 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.
60. ^ 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.
61. ^ 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.
62. ^ 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.
63. ^ a b 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.
64. ^ a b c d e 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.
65. ^ a b 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.
66. ^ Hubbe A, Hubbe M, Neves W (September 2007). "Early Holocene survival of megafauna in South America". Journal of Biogeography. 34 (9): 1642–1646\. Bibcode:2007JBiog..34.1642H. doi:10.1111/j.1365-2699.2007.01744.x.
67. ^ Stuart AJ, Kosintsev PA, Higham TF, Lister AM (October 2004). "Pleistocene to Holocene extinction dynamics in giant deer and woolly mammoth" (PDF). Nature. 431 (7009): 684–9\. Bibcode:2004Natur.431..684S. doi:10.1038/nature02890. PMID 15470427. S2CID 4415073.
68. ^ 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.
69. ^ 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.
70. ^ 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.2009.11.003.1–2&rft.pages=225-239&rft.date=2010&rft_id=info:doi/10.1016/j.quaint.2009.11.003&rft_id=info:bibcode/2010QuInt.217..225S&rft.aulast=Scott&rft.aufirst=E&rfr_id=info:sid/en.wikipedia.org:Younger+Dryas+impact+hypothesis" class="Z3988">
71. ^ 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.
72. ^ 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.
73. ^ 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.
74. ^ 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. S2CID 55581133. Archived from the original on 17 April 2021. Retrieved 1 September 2020.
75. ^ 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.
76. ^ a b 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.
77. ^ 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.
78. ^ 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.
79. ^ 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.
80. ^ Sepulveda PB, Mayordomo AC, Sala C, Sosa EJ, Zaiat JJ, Cuello M, Schwab M, Golpe DR, Aquilano E, Santos MR, Dipierri JE, Gomez EL, Bravi CM, Muzzio M, Bailliet G (2022). "Human Y chromosome sequences from Q Haplogroup reveal a South American settlement pre-18,000 years ago and a profound genomic impact during the Younger Dryas". PLOS ONE. 17 (8): e0271971. Bibcode:2022PLoSO..1771971P. doi:10.1371/journal.pone.0271971. PMC 9385064. PMID 35976870.
81. ^ 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.
82. ^ 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.
83. ^ "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.
84. ^ 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. Bibcode:2022SciA....8M2434K. doi:10.1126/SCIADV.ABM2434. ISSN 2375-2548. PMC 8906741. PMID 35263140. Wikidata Q111179348.
85. ^ Broecker, Wallace S. (2006). "Was the Younger Dryas triggered by a flood?". Science. 312 (5777): 1146–1148\. doi:10.1126/science.1123253. PMID 16728622. S2CID 39544213.
86. ^ Murton, Julian B.; Bateman, Mark D.; Dallimore, Scott R.; Teller, James T.; Yang, Zhirong (2010). "Identification of Younger Dryas outburst flood path from Lake Agassiz to the Arctic Ocean". Nature. 464 (7289): 740–743\. Bibcode:2010Natur.464..740M. doi:10.1038/nature08954. ISSN 0028-0836. PMID 20360738. S2CID 4425933.
87. ^ Keigwin, L.D.; Klotsko, S.; Zhao, N.; Reilly, B.; Giosan, L.; Driscoll, N.W. (2018). "Deglacial floods in the Beaufort Sea preceded Younger Dryas cooling". Nature Geoscience. 11 (8): 599–604\. Bibcode:2018NatGe..11..599K. doi:10.1038/s41561-018-0169-6. hdl:1912/10543. ISSN 1752-0894. S2CID 133852610.
88. ^ a b 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
89. ^ Eisenman, I.; Bitz, C.M.; Tziperman, E. (2009). "Rain driven by receding ice sheets as a cause of past climate change". Paleoceanography. 24 (4): PA4209. Bibcode:2009PalOc..24.4209E. doi:10.1029/2009PA001778. S2CID 6896108.
90. ^ "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.
91. ^ Sun et al. (2020).
92. ^ 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. PMID 34194020. 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."
93. ^ "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."
94. ^ a b Firestone, Richard B.; Topping, William (March 2001). "Terrestrial Evidence of a Nuclear Catastrophe in Paleoindian Times" (PDF). Mammoth Trumpit. 16 (2): 9–16. Retrieved 31 January 2023.
95. ^ Frey, David G. (1953). "Regional Aspects of the Late-Glacial and Post-Glacial Pollen Succession of Southeastern North Carolina". Ecological Monographs. 23 (3): 289–313\. Bibcode:1953EcoM...23..289F. doi:10.2307/1943595. JSTOR 1943595.
96. ^ Frey, David G. (1955). "A Time Revision of the Pleistocene Pollen Chronology of Southeastern North Carolina". Ecology. 36 (4): 762–763\. Bibcode:1955Ecol...36..762F. doi:10.2307/1931316. JSTOR 1931316.
97. ^ Watts, W. A. (1980). "Late-Quaternary Vegetation History at White Pond on the Inner Coastal Plain of South Carolina". Quaternary Research. 13 (2): 187–199\. Bibcode:1980QuRes..13..187W. doi:10.1016/0033-5894(80)90028-9. S2CID 140654499.
98. ^ Whitehead, Donald R. (1964). "Fossil Pine Pollen and Full-Glacial Vegetation in Southeastern North Carolina". Ecology. 45 (4): 767–777\. Bibcode:1964Ecol...45..767W. doi:10.2307/1934924. JSTOR 1934924.
99. ^ Whitehead, Donald R. (1981). "Late-Pleistocene Vegetational Changes in Northeastern North Carolina". Ecological Monographs. 51 (4): 451–471\. Bibcode:1981EcoM...51..451W. doi:10.2307/2937324. JSTOR 2937324.
100. ^ Brooks, Mark J.; Taylor, Barbara E.; Grant, John A. (1996). "Carolina Bay geoarchaeology and Holocene landscape evolution on the Upper Coastal Plain of South Carolina". Geoarchaeology. 11 (6): 481–504\. Bibcode:1996Gearc..11..481B. doi:10.1002/(SICI)1520-6548(199610)11:6<481::AID-GEA2>3.0.CO;2-4.
101. ^ Brooks, M. J. (2001). "Pleistocene encroachment of the Wateree River sand sheet into Big Bay on the Middle Coastal Plain of South Carolina". Southeastern Geology. 40: 241–257.
102. ^ Grant, John A.; Brooks, Mark J.; Taylor, Barbara E. (1998). "New constraints on the evolution of Carolina Bays from ground-penetrating radar". Geomorphology. 22 (3–4): 325–345\. Bibcode:1998Geomo..22..325G. doi:10.1016/S0169-555X(97)00074-3.3–4&rft.pages=325-345&rft.date=1998&rft_id=info:doi/10.1016/S0169-555X(97)00074-3&rft_id=info:bibcode/1998Geomo..22..325G&rft.aulast=Grant&rft.aufirst=John+A.&rft.au=Brooks,+Mark+J.&rft.au=Taylor,+Barbara+E.&rfr_id=info:sid/en.wikipedia.org:Younger+Dryas+impact+hypothesis" class="Z3988">
103. ^ Swezey, C. S. (2020). "Quaternary Eolian Dunes and Sand Sheets in Inland Locations of the Atlantic Coastal Plain Province, USA". In Lancaster, N.; Hesp, P. (eds.). Inland Dunes of North America. Dunes of the World. Springer Publishing. pp. 11–63\. doi:10.1007/978-3-030-40498-7_2. ISBN 978-3-030-40498-7. S2CID 219502764.
104. ^ 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.
105. ^ 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."
106. ^ 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.
107. ^ Pecos Conference 2008 Comet Impact Debate. YouTube. 2008.
108. ^ "2008 Pecos Conference". swanet.org. Archived from the original on 3 August 2019. Retrieved 3 August 2019.
109. ^ Kerr RA (January 2009). "Planetary impacts. Did the mammoth slayer leave a diamond calling card?" (PDF). Science. 323 (5910): 26. doi:10.1126/science.323.5910.26. PMID 19119192. S2CID 29639618.
110. ^ 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" (PDF). Science. 323 (5910): 94. Bibcode:2009Sci...323...94K. doi:10.1126/science.1162819. PMID 19119227. S2CID 206514910.
111. ^ "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.
112. ^ a b "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."
113. ^ 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". PubPeer. Retrieved 15 August 2022.
114. ^ 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.
115. ^ 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.
116. ^ 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.
117. ^ 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.
118. ^ 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.
119. ^ 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.
120. ^ 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.
121. ^ 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.
122. ^ 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.
123. ^ 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.
124. ^ 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.
125. ^ 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.
126. ^ a b c d Pino et al. (2019).
127. ^ 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.
128. ^ 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: 30–35\. hdl:10539/28129. ISSN 0078-8554. S2CID 209443195. Wikidata Q106978252.
129. ^ 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.
130. ^ 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.
131. ^ a b c 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) (published 6 March 2020): 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 platinum at other YDB sites on four continents."
132. ^ 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."
133. ^ Hai Cheng; et al. (8 September 2020). "Timing and structure of the Younger Dryas event and its underlying climate dynamics". PNAS. 117 (38): 23408–23417\. Bibcode:2020PNAS..11723408C. doi:10.1073/pnas.2007869117. hdl:10261/240073. PMC 7519346. PMID 32900942.
134. ^ 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 theYounger Dryas Onset (~12.8 ka): High-temperature melting at >2200 °C". PubPeer. Retrieved 5 November 2023.
135. ^ Moore, Christopher R.; Brooks, Mark J.; Dunbar, James S.; Hemmings, C. Andrew; Langworthy, Kurt A.; West, Allen; LeCompte, Malcolm A.; Adedeji, Victor; Kennett, James P.; Feathers, James K. (20 December 2023). "Platinum and microspherule peaks as chronostratigraphic markers for onset of the Younger Dryas at Wakulla Springs, Florida". Scientific Reports. 13 (1): 22738. Bibcode:2023NatSR..1322738M. doi:10.1038/s41598-023-50074-8. ISSN 2045-2322. PMC 10733423. PMID 38123649.
136. ^ 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."
137. ^ "Mammoth Mystery". IMDb. 7 October 2007. Retrieved 20 August 2021.
138. ^ "Journey to 10,000 BC". IMDb. 2008. Retrieved 20 August 2021.
139. ^ Megabeasts Sudden Death, PBS NOVA 2009. YouTube. 2022.
140. ^ "Megabeasts' Sudden Death". IMDb. 31 March 2009. Retrieved 20 August 2021.
141. ^ "Megabeasts' Sudden Death". PBS Nova. 31 March 2009. Archived from the original on 12 June 2021. Retrieved 20 August 2021.
142. ^ 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.
143. ^ "MAGICIANS OF THE GODS by Graham Hancock". Kirkus Reviews. 3 September 2015. Archived from the original on 20 January 2021. Retrieved 14 January 2021.
144. ^ Colavito J. "Magicians of the Gods Review". Jason Colavito. Archived from the original on 5 December 2020. Retrieved 16 November 2017.
145. ^ 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.
146. ^ 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.
147. ^ 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.
148. ^ 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' https://doi.org/10.1038/s41598-020-60867-w" (Tweet) - via Twitter.
149. ^ 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."
150. ^ 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.
151. ^ Shermer M (23 April 2019). "Debating Science and Lost Civilizations". Skeptic. 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."
152. ^ 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.

### Bibliography

[edit]

* 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.

## Further reading

[edit]

* Bentley M (2 January 2009). "Diamond clues to beasts' demise". BBC News. Archived from the original on 3 September 2010. Retrieved 15 April 2012.
* 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.
* 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.
* 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.
* 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.
* Sweatman, Martin B. (July 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.

Presentations of the American Geophysical Union

* "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.
* "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.

Mammoth Trumpet

An extensive series of articles was published in Mammoth Trumpet, the magazine for Texas A&M University's Center for the Study of the First Americans, featuring conversations with many 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.

## External links

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Scholia has a profile for Younger Dryas impact hypothesis (Q1092095).

* Media related to Younger Dryas impact hypothesis at Wikimedia Commons

*[YDB]: Younger Dryas boundary
*[YDIH]: Younger Dryas impact hypothesis