Younger Dryas Impact Research Articles

Rejection of Holliday et al.'s alleged refutation of the Younger Dryas impact hypothesis

Rejection of Holliday et al.'s alleged refutation of the Younger Dryas impact hypothesis

Rebuttal of Sweatman, Powell, and West's “Rejection of Holliday et al.'s alleged refutation of the Younger Dryas Impact Hypothesis”

Rebuttal of Sweatman, Powell, and West's “Rejection of Holliday et al.'s alleged refutation of the Younger Dryas Impact Hypothesis”

Representations of calendars and time at Göbekli Tepe and Karahan Tepe support an astronomical interpretation of their symbolism

ABSTRACT Göbekli Tepe, an archaeological site in southern Turkey, features several temple-like enclosures adorned with many intricately carved symbols. It is located centrally among a group of Taş Tepeler pre-pottery Neolithic sites which include Karahan Tepe and Sayburç. Here, an earlier astronomical interpretation for Gobekli Tepe’s symbolism is supported and extended by showing how V-symbols on Pillar 43 in Enclosure D can be interpreted in terms of a lunisolar calendar system with 11 epagomenal days, which would make it the oldest known example of its type. Furthermore, it is shown how Göbekli Tepe’s 11-pillar enclosures and a megalithic 11-pillar pool structure at nearby Karahan Tepe can also be interpreted in terms of the same lunisolar calendar system. Other V-symbols at Göbekli Tepe are also interpreted in astronomical terms, and it is shown how the Urfa Man statue, a wall carving at Sayburç and a statue at Karahan Tepe that display V-symbol necklaces can be interpreted as time-controlling or creator deities. Symbolic links with later cultures from the Fertile Crescent are explored. Throughout, links are made with the Younger Dryas impact and Cauvin’s theory for the origin of the Neolithic revolution in the Fertile Crescent.

The Encke comet impact/airburst and the Younger Dryas Boundary: Testing the impossible hypothesis (YDIH)

Many have tagged the Younger Dryas Impact Hypothesis (YDIH), a supposition, lacking convincing evidence in support. The core of criticism lies squarely on uniformitarianism, that is, uniform processes moving uniformly with no room for catastrophic events, specifically cosmic catastrophic forces. Beyond philosophically based aversion to the YDIH, specific criticism comes from megafauna and archaeologic corners, related to the near coeval disappearance of specific Late Pleistocene species on the one hand, and relation to disruption and temporary disappearance of the Clovis people et al. on the other. The Younger Dryas geologic paradigm, originally in place with meltwater release into the Atlantic in tow, attention slowly drifted to explanation of an innocuous looking, thin (~1-3 cm), black sediment bed found in lacustrine and fluvial deposits of the American southwest, and other intercontinental places. Thus, with thin dark beds of Gubbio in mind, the quest to explain black mat (BM) beds took on a cosmic aspect, one with growing, supporting evidence on several continents. The impossible hypothesis, now the probable explanation of the Younger Dryas climatic reversal, is at center stage, set at 12.8 ka, with a burgeoning corpus of evidence its cornerstone.

Rebuttal of Holliday et al.’s Comprehensive Gish Gallop of the Younger Dryas Impact Hypothesis

In an article comprising some 96,000 words, Holliday et al. (2023) (HEA) claim to have “comprehensively refuted” the Younger Dryas impact hypothesis (YDIH), even though it has been corroborated by scores of articles in dozens of peer-reviewed journals based on the discovery of some combination of synchronous nanodiamonds, exotic microspherules and platinum enrichment at more than 50 Younger Dryas boundary sites on five continents. No hypothesis or theory is immune from criticism, but to “comprehensively refute” one so well established should require dispositive falsifying evidence. However, HEA provide no new evidence of their own and many of their arguments are based on faulty reasoning. Their remaining differences of opinion do not lend themselves to the falsification of an active hypothesis supported by an abundance of reproducible evidence, which now includes shocked quartz which is generally accepted to be produced only by cosmic impacts. Their article can therefore be called a Gish gallop; a long series of weak or flawed arguments designed to overwhelm an opponent. Since HEA’s claims are too many to respond to individually, we instead have selected portions of their article for critical analysis. By providing strong line-by-line counterarguments to their text we crucially show that they demonstrate a poor understanding of the logic required to test the YDIH and a poor understanding of uncertainty in experimental data analysis, and these problems propagate through many parts of their review. We also show that they repeatedly distort the facts and make misleading claims or derisory remarks. In summary, their approach is a corruption of the scientific method. In fact, the YDIH remains in a very strong position and probably represents a second example to go along with the Alvarez Theory of an extraterrestrial event that affected life on Earth. A hypothesis with such potential should not be so casually dismissed and instead should continue to be the subject of research.

Platinum, shock-fractured quartz, microspherules, and meltglass widely distributed in Eastern USA at the Younger Dryas onset (12.8 ka)

Sediment sequences spanning the 12,800-year-old lower Younger Dryas boundary (YDB) were investigated at three widely separated sites in eastern North America (Parsons Island, Maryland, a Newtonville sandpit in southern New Jersey, and Flamingo Bay, South Carolina). All sequences examined exhibit peak abundances in platinum (Pt), microspherules, and meltglass representing the YDB cosmic impact layer resulting from the airbursts/impacts of a fragmented comet ∼12,800 years ago. The evidence is consistent with the Younger Dryas impact hypothesis (YDIH) recorded at ∼50 other sites across North and South America, Europe, Asia, and the Greenland ice sheet. These sequences were also examined for shock-fractured quartz, based on a recent study suggesting that low-shock metamorphism may result from low-altitude bolide airbursts similar to that observed during near-surface atomic detonations. Now, for the first time in a suite of well-separated sites in North America, we report in the YDB the presence of quartz grains exhibiting shock fractures containing amorphous silica. We also find in the YDB high-temperature melted chromferide, zircon, quartz, titanomagnetite, ulvöspinel, magnetite, native iron, and PGEs with equilibrium melting points (∼1,250° to 3,053°C) that rule out anthropogenic origins for YDB microspherules. The collective evidence meets the criteria for classification as an “impact spherule datum.”

An Extraterrestrial Pt Anomaly during the Late Glacial-Younger Dryas: Viso Massif (Italy and France)

Paleosol evidence supporting the Younger Dryas Impact Hypothesis (YDIH) on the Viso Massif of France and Italy is expanded by a Pt anomaly at all sites investigated, accompanied by elevated Os, Ir, Ru, and Rh concentrations at several sites, thus affirming a cosmic driver to the YD climatic shift at 12.8 ka. Original, thin Allerød soils prevalent at the end of the Late Glacial comprise sediments affected by an airburst from a hypothesized secondary daughter fragment or fragments of the main 2P/Encke progenitor comet train that intersected Earth’s land surface and its alpine-continental ice sheets. This event has been previously postulated to have breached Lake Agassiz and other proglacial lakes in North America, released meltwater into the Atlantic Ocean through the St. Lawrence and into the Arctic through the Mackenzie River system, after which cold surface water shut down the thermohaline circulation of the Gulf Stream in the North Atlantic. This thermohaline event is the traditional explanation for YD cooling, but was it fast enough to match the pollen evidence, which confirms rapid temperature reversal? Or was an “impact winter” involved? Cosmic signatures reported here include elevated Pt/Pd ratios, Os, Ir, Ru, and Rh concentrations with orders of magnitude (OM) for Ir used to establish the main center of conflagrations that helped trigger an impact winter. While most sections show variable distributions of PGEs, some are fully affected by concentrations entirely through the unweathered substrate or parent material horizons (called “Cu” horizons). Peak distributions of platinum group elements (PGEs) provide new information on the dispersal patterns of grains that add the Western European Alps to the intercontinental array of sites containing the Younger Dryas boundary (YDB) layer, also sometimes called the black mat (BM). Previously, most age determinations for the Alps were derived from relative dating determinations (RD), but here, we report an AMS C14 date from one LG paleosol (G11-Bw) yielding an age of 12,816 ±44 cal yr BP age, coeval with the average 12.8 ka age of the BM.

Premature rejection in science: The case of the Younger Dryas Impact Hypothesis.

The progress of science has sometimes been unjustifiably delayed by the premature rejection of a hypothesis for which substantial evidence existed and which later achieved consensus. Continental drift, meteorite impact cratering, and anthropogenic global warming are examples from the first half of the twentieth century. This article presents evidence that the Younger Dryas Impact Hypothesis (YDIH) is a twenty-first century case.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 Paleo-Indian culture. Soon after publication, a few scientists reported that they were unable to replicate the critical evidence and the scientific community at large came to reject the hypothesis. By today, however, many independent studies have reproduced that evidence at dozens of YD sites. This article examines why scientists so readily accepted the early false claims of irreproducibility and what lessons the premature rejection of the YDIH holds for science.

The Correlation Between Impact Crater Ages and Chronostratigraphic Boundary Dates

Abstract The accurately measured ages of 89 large impact craters and layers were compared with the boundary dates for Periods, Epochs and Ages of the Geological Time Scale by a weighted least squares fit. They are highly correlated with a χ2/f=0.63. A Monte Carlo simulation of randomly chosen crater ages gives a >99.8% probability that this result is not random. No craters are found in the oceans or, until recently, in ice which collectively cover 80% of Earth’s surface indicating that far more impacts have occurred than are known. Multiple impacts cluster near the times of boundary dates so, based on the observed cluster sizes assuming a binomial distribution, it was determined that the average cluster multiplicity is five. Comparison of the impact ages with the dates of the great extinctions revealed a strong correlation with χ2/f=0.36 and a multiplicity of 8-9 impacts. It is shown that volcanism, although correlated with boundary dates, is a continuous process unrelated to sudden extinctions. During the past 125 Ma the rate of global change and the impact rate have increased dramatically as the Earth passes near the OB star association. Multiple impacts 12.9 ka ago ended the Pleistocene epoch at the onset of the Younger Dryas (YD) causing worldwide extinctions. The date and extent of the YD impact may be consistent with a 62 Ma cycle of major impact events. During the Holocene 20 crater, airburst, and impact tsunami chevron ages correspond to dates of global cooling with a χ2/f=0.75 and >99% probability. Future impacts could reverse global warming or even induce next ice age.

Radiocarbon simulation fails to support the temporal synchroneity requirement of the Younger Dryas impact hypothesis

AbstractFine-scale temporal processes, such as the synchronous deposition of organic materials, can be challenging to identify using 14C datasets. While some events, such as volcanic eruptions, leave clear evidence for synchronous deposition, synchroneity is more difficult to establish for other types of events. This has been a source of controversy regarding 14C dates associated with a hypothesized extraterrestrial impact at the Younger Dryas Boundary (YDB). To address this controversy, we first aggregate 14C measurements from Northern Hemisphere YDB sites. We also aggregate 14C measurements associated with a known synchronous event, the Laacher See volcanic eruption. We then use a Monte Carlo simulation to evaluate the magnitude of variability expected in a 14C dataset associated with a synchronous event. The simulation accounts for measurement error, calibration uncertainty, “old wood” effects, and laboratory measurement biases. The Laacher See 14C dataset is consistent with expectations of synchroneity generated by the simulation. However, the YDB 14C dataset is inconsistent with the simulated expectations for synchroneity. These results suggest that a central requirement of the Younger Dryas Impact Hypothesis, synchronous global deposition of a YDB layer, is extremely unlikely, calling into question the Younger Dryas Impact Hypothesis more generally.

Sediment Cores from White Pond, South Carolina, contain a Platinum Anomaly, Pyrogenic Carbon Peak, and Coprophilous Spore Decline at 12.8 ka

A widespread platinum (Pt) anomaly was recently documented in Greenland ice and 11 North American sedimentary sequences at the onset of the Younger Dryas (YD) event (~12,800 cal yr BP), consistent with the YD Impact Hypothesis. We report high-resolution analyses of a 1-meter section of a lake core from White Pond, South Carolina, USA. After developing a Bayesian age-depth model that brackets the late Pleistocene through early Holocene, we analyzed and quantified the following: (1) Pt and palladium (Pd) abundance, (2) geochemistry of 58 elements, (3) coprophilous spores, (4) sedimentary organic matter (OC and sedaDNA), (5) stable isotopes of C (δ13C) and N (δ15N), (6) soot, (7) aciniform carbon, (8) cryptotephra, (9) mercury (Hg), and (10) magnetic susceptibility. We identified large Pt and Pt/Pd anomalies within a 2-cm section dated to the YD onset (12,785 ± 58 cal yr BP). These anomalies precede a decline in coprophilous spores and correlate with an abrupt peak in soot and C/OC ratios, indicative of large-scale regional biomass burning. We also observed a relatively large excursion in δ15N values, indicating rapid climatic and environmental/hydrological changes at the YD onset. Our results are consistent with the YD Impact Hypothesis and impact-related environmental and ecological changes.

Sedimentary record from Patagonia, southern Chile supports cosmic-impact triggering of biomass burning, climate change, and megafaunal extinctions at 12.8\u2009ka

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. In the most extensive investigation south of the equator, we report on a ~12,800-year-old sequence at Pilauco, Chile (~40°S), that exhibits peak YD boundary concentrations of platinum, gold, high-temperature iron- and chromium-rich spherules, and native iron particles rarely found in nature. A major peak in charcoal abundance marks an intense biomass-burning episode, synchronous with dramatic changes in vegetation, including a high-disturbance regime, seasonality in precipitation, and warmer conditions. This is anti-phased with northern-hemispheric cooling at the YD onset, whose rapidity suggests atmospheric linkage. The sudden disappearance of megafaunal remains and dung fungi in the YDB layer at Pilauco correlates with megafaunal extinctions across the Americas. The Pilauco record appears consistent with YDB impact evidence found at sites on four continents.

The putative Saginaw impact structure, Michigan, Lake Huron, in the light of gravity aspects derived from recent EIGEN 6C4 gravity field model

Abstract The hypothetical impact structure in the Saginaw Bay (Michigan, USA, Lake Huron) has been tested by the gravity data derived from the recent gravity field model EIGEN 6C4 (expanded to degree and order 2190, with ground resolution of ~9 km). The following gravity field aspects were used: the gravity disturbances/anomalies, second derivatives of the disturbing potential (Marussi tensor), two of three gravity invariants, their specific ratio (known as 2D factor), the strike angles, and the virtual deformations. These gravity aspects are sensitive in various ways to the underground density contrasts. For the Saginaw Bay area, we confirm that we do not see any typical impact crater in terms of gravity disturbance or the radial second order derivative, possibly because of the thick layer of the ice located at the place and time of the impact. But the “combed” strike angles (one type of the gravity aspects we use) disclose a trace of high pressure to the SE/S/SW of the Bay and may be due to an impacting body. Thus, we provide circumstantial evidence of the Younger Dryas impact hypothesis.

Comprehensive analysis of nanodiamond evidence relating to the Younger Dryas Impact Hypothesis

ABSTRACTDuring the end of the last glacial period in the Northern Hemisphere near 12.9k cal a BP, deglacial warming of the Bølling–Ållerod interstadial ceased abruptly and the climate returned to glacial conditions for an interval of about 1300 years known as the Younger Dryas stadial. The Younger Dryas Impact Hypothesis proposes that the onset of the Younger Dryas climate reversal, Pleistocene megafaunal extinctions and disappearance of the Clovis paleoindian lithic technology were coeval and caused by continent‐wide catastrophic effects of impact/bolide events in North America. While there are no known impact structures dated to the Younger Dryas onset, physical evidence of the impact/bolide events is argued to be present in sediments spanning several continents at stratigraphic levels inferred to date to the Bølling‐Ållerod/Younger Dryas boundary (YDB). Reports of nanometer to submicron‐sized diamonds in YDB sediments, in particular the rare 2H hexagonal polytype of diamond, lonsdaleite, have been presented as strong evidence for shock processing of crustal materials. We review the available data on diamonds in sediments and provide new data. We find no evidence for lonsdaleite in YDB sediments and find no evidence of a spike in nanodiamond concentration at the YDB layer to support the impact hypothesis.

Interpreting palaeofire evidence from fluvial sediments: a case study from Santa Rosa Island, California, with implications for the Younger Dryas Impact Hypothesis

ABSTRACTFluvial sequences from the late Pleistocene to the Holocene are exposed in Arlington Canyon, Santa Rosa Island, Northern Channel Islands, California, USA, including one outcrop that features centrally in the controversial hypothesis of an extra‐terrestrial impact at the onset of the Younger Dryas. The fluvial sequence in Arlington Canyon contains a significant quantity and range of organic material, much of which has been charred. The purpose of this study was to systematically describe the key outcrop of the Arlington sequence, provide new radiocarbon age control and analyse organic material in the Arlington sediments within a rigorous palaeobotanical and palaeo‐charcoal context. These analyses provide a test of previous claims for catastrophic impact‐induced fire in Arlington Canyon. Carbonaceous spherular materials were identified as predominantly fungal sclerotia; ‘carbon elongates’ are predominantly arthropod coprolites, including termite frass. ‘Glassy carbon’ formed from the precipitation of tars during charcoalification. None of these materials indicate high‐temperature formation or combustion. Charcoal and other materials in Arlington Canyon document widespread and frequent fires both before and after the onset of the Younger Dryas, recording predominantly low‐temperature surface fires. In summary, we find no evidence in Arlington Canyon for an extra‐terrestrial impact or catastrophic impact‐induced fire.

A Blind Test of the Younger Dryas Impact Hypothesis.

The Younger Dryas Impact Hypothesis (YDIH) states that North America was devastated by some sort of extraterrestrial event ~12,800 calendar years before present. Two fundamental questions persist in the debate over the YDIH: Can the results of analyses for purported impact indicators be reproduced? And are the indicators unique to the lower YD boundary (YDB), i.e., ~12.8k cal yrs BP? A test reported here presents the results of analyses that address these questions. Two different labs analyzed identical splits of samples collected at, above, and below the ~12.8ka zone at the Lubbock Lake archaeological site (LL) in northwest Texas. Both labs reported similar variation in levels of magnetic micrograins (>300 mg/kg >12.8ka and <11.5ka, but <150 mg/kg 12.8ka to 11.5ka). Analysis for magnetic microspheres in one split, reported elsewhere, produced very low to nonexistent levels throughout the section. In the other split, reported here, the levels of magnetic microspherules and nanodiamonds are low or nonexistent at, below, and above the YDB with the notable exception of a sample <11,500 cal years old. In that sample the claimed impact proxies were recovered at abundances two to four orders of magnitude above that from the other samples. Reproducibility of at least some analyses are problematic. In particular, no standard criteria exist for identification of magnetic spheres. Moreover, the purported impact proxies are not unique to the YDB.

Bayesian chronological analyses consistent with synchronous age of 12,835–12,735 Cal B.P. for Younger Dryas boundary on four continents

The Younger Dryas impact hypothesis posits that a cosmic impact across much of the Northern Hemisphere deposited the Younger Dryas boundary (YDB) layer, containing peak abundances in a variable assemblage of proxies, including magnetic and glassy impact-related spherules, high-temperature minerals and melt glass, nanodiamonds, carbon spherules, aciniform carbon, platinum, and osmium. Bayesian chronological modeling was applied to 354 dates from 23 stratigraphic sections in 12 countries on four continents to establish a modeled YDB age range for this event of 12,835-12,735 Cal B.P. at 95% probability. This range overlaps that of a peak in extraterrestrial platinum in the Greenland Ice Sheet and of the earliest age of the Younger Dryas climate episode in six proxy records, suggesting a causal connection between the YDB impact event and the Younger Dryas. Two statistical tests indicate that both modeled and unmodeled ages in the 30 records are consistent with synchronous deposition of the YDB layer within the limits of dating uncertainty (∼ 100 y). The widespread distribution of the YDB layer suggests that it may serve as a datum layer.

A search for shocked quartz grains in the Allerød‐Younger Dryas boundary layer

AbstractThe Younger Dryas impact hypothesis suggests that multiple airbursts or extraterrestrial impacts occurring at the end of the Allerød interstadial resulted in the Younger Dryas cold period. So far, no reproducible, diagnostic evidence has, however, been reported. Quartz grains containing planar deformation features (known as shocked quartz grains), are considered a reliable indicator for the occurrence of an extraterrestrial impact when found in a geological setting. Although alleged shocked quartz grains have been reported at a possible Allerød‐Younger Dryas boundary layer in Venezuela, the identification of shocked quartz in this layer is ambiguous. To test whether shocked quartz is indeed present in the proposed impact layer, we investigated the quartz fraction of multiple Allerød‐Younger Dryas boundary layers from Europe and North America, where proposed impact markers have been reported. Grains were analyzed using a combination of light and electron microscopy techniques. All samples contained a variable amount of quartz grains with (sub)planar microstructures, often tectonic deformation lamellae. A total of one quartz grain containing planar deformation features was found in our samples. This shocked quartz grain comes from the Usselo palaeosol at Geldrop Aalsterhut, the Netherlands. Scanning electron microscopy cathodoluminescence imaging and transmission electron microscopy imaging, however, show that the planar deformation features in this grain are healed and thus likely to be older than the Allerød‐Younger Dryas boundary. We suggest that this grain was possibly eroded from an older crater or distal ejecta layer and later redeposited in the European sandbelt. The single shocked quartz grain at this moment thus cannot be used to support the Younger Dryas impact hypothesis.

South to north: Contrasting late-glacial and early-Holocene climate changes and vegetation responses between south and north Norway

Norway shows south–north climate and vegetation gradients today. Were there similar gradients during the late-glacial and early Holocene, 14,700–9000 years ago? A comparison was made along a south–north transect in Norway of plant-macrofossil reconstructions of past vegetation changes and independent summer temperature records derived from parallel chironomid data (C-Tjul). Three lake sites were selected with sediment cores with good chronological control. The importance of soil moisture is reflected by the reconstructed vegetation in relation to the temperature regime. Besides climate drivers, how important were intrinsic succession and competition in influencing vegetation patterns? Were migration delays significant, why and by how much? Oceanic climate in the late-glacial in south-west Norway resulted in snow-bed vegetation and glacier development in the Younger Dryas (YD). In contrast, the north was arid and continental, even into the early Holocene. Overall, temperatures were about 2°C colder than in the south. The YD impact differed markedly between south and north Norway. In the south, cooling at c. 12,700 cal. yr BP was swift and marked by strong responses. In the north, there was no impact at the chronological start of the YD, but cooling occurred later about 12,450 cal. yr BP together with increased aridity. During the early Holocene, temperature and oceanicity increased progressively northwards as the North Atlantic Current became established. Birch woodland developed in the south about 660 years after the start of the Holocene, after about 1000 years on Andøya, and after about 1450 years in northernmost Norway. However, the 590 year lag in the south after C-Tjul reached 11°C, the limiting temperature for tree-birch growth, decreased to 400 years in the north, as the birch tree-line kept pace with temperature rise. In the far north, a thermal maximum of 1°C above today’s mean July temperature and parallel vegetation development were recorded from 10,100 to 9370 cal. yr BP. On Andøya, temperatures exceeded present values by 1°C after 9700 cal. yr BP. There was no detectable period of above modern temperatures further south before 9000 cal. yr BP.

The Younger Dryas impact hypothesis: a cosmic catastrophe

ABSTRACTIn this paper we review the evidence for the Younger Dryas impact hypothesis (YDIH), which proposes that at ∼12.9k cal a BP North America, South America, Europe and the Middle East were subjected to some sort of extraterrestrial event. This purported event is proposed as a catastrophic process responsible for: terminal Pleistocene environmental changes (onset of YD cooling, continent‐scale wildfires); extinction of late Pleistocene mammals; and demise of the Clovis ‘culture’ in North America, the earliest well‐documented, continent‐scale settlement of the region. The basic physics in the YDIH is not in accord with the physics of impacts nor the basic laws of physics. No YD boundary (YDB) crater, craters or other direct indicators of an impact are known. Age control is weak to non‐existent at 26 of the 29 localities claimed to have evidence for the YDIH. Attempts to reproduce the results of physical and geochemical analyses used to support the YDIH have failed or show that many indicators are not unique to an impact nor to ∼12.9k cal a BP. The depositional environments of purported indicators at most sites tend to concentrate particulate matter and probably created many ‘YDB zones’. Geomorphic, stratigraphic and fire records show no evidence of any sort of catastrophic changes in the environment at or immediately following the YDB. Late Pleistocene extinctions varied in time and across space. Archeological data provide no indication of population decline, demographic collapse or major adaptive shifts at or just after ∼12.9 ka. The data and the hypotheses generated by YDIH proponents are contradictory, inconsistent and incoherent.