A VIOLENT HURRICANE OF BOLIDES
WHAT KIND OF COSMIC IMPACT?
From quite early in the research, since the first strong impact-proxy evidence was analyzed, it’s been the consensus view of CRG members that the agent responsible for the Younger Dryas cataclysm was a comet. Wolbach’s study strengthens that position, noting:
Comets are a compositionally variable mix of volatile ices, meteoritic material, and presolar dust. … Wide ranges of elemental ratios confirm that cometary material is heterogeneous, similar to the YDB samples. Although the type of YDB impactor remains unclear, the current evidence does not support any specific meteoritic type as source. Instead, the broad extent of biomass burning at the YD onset is more consistent with Earth’s collision with a fragmented comet50 … [resulting in a] violent hurricane of bolides51 … [that] detonated above and/or collided with land, ice sheets, and oceans across at least four continents in the Northern and Southern Hemispheres.52
This scenario, the study argues, explains all the anomalous and synchronous evidence:
Vaporization of cometary materials, and platinum-group-element–rich target rocks, injected Pt, Ir, Os, and other heavy metals into the stratosphere, accompanied by impact-related nanodiamonds, meltglass, and microspherules.53
Airburst fireballs and the ejection of molten rocks … triggered many individual wildfires over wide areas, producing one of the largest concentrations of combustion aerosols deposited in the Greenland ice sheet during the past 120,000–368,000 years. In the higher midlatitudes, atmospheric and oceanic temperatures abruptly decreased from warm interglacial to near-glacial conditions within a few months to a year. Atmospheric and cometary dust, along with AC/soot, triggered the rapid onset of an impact winter. This blocking of sunlight led to a die-off of vegetation. Damage to the ozone layer likely led to an increase in ultraviolet-B radiation reaching Earth’s surface, damaging flora and fauna. Increases in nitrogen compounds, sulfates, dust, soot, and other toxic chemicals from the impact and widespread wildfires likely led to an increase in acid rain. Increased production of organic matter and burn products from environmental degradation and biomass burning contributed to algal blooms and the subsequent formation of widespread black mats.54
In my view, however, by far the most significant finding of the study, fitting perfectly with the scenario of a disintegrating comet, is:
The impact event destabilized the ice-sheet margins, causing extensive iceberg calving into the Arctic and North Atlantic Oceans. The airburst/impacts collapsed multiple ice dams of proglacial lakes along the ice-sheet margins, producing extensive meltwater flooding into the Arctic and North Atlantic Oceans. Destabilization of the ice sheet also may have triggered extensive subglacial ice-sheet flooding, leaving widespread, flood-related landforms across large parts of Canada. The massive outflow of proglacial lake waters, ice-sheet meltwater, and icebergs into the Arctic and North Atlantic Oceans caused rerouting of oceanic thermohaline circulation. Through climatic feedbacks, this, in turn, led to the YD cool episode.55
In other words, the long-established and widely accepted evidence linking the onset of the Younger Dryas cold interval to a freshwater flood off the North American ice cap and consequent changes in oceanic circulation is fully accepted by Wolbach. What she and her coauthors add, however, is:
an additional key element … suggesting that these climate-changing mechanisms did not occur randomly but rather were triggered by the YDB impact event. After shutdown of the ocean conveyor, the YD episode persisted … not because of continued airburst/impacts but because, once circulation stopped, feedback loops and inertia within the ocean system maintained the changed state of circulation until it reverted to its previous state.56
Indeed so. No one is suggesting that impacts and airbursts continued throughout the entire 1,200 years of the Younger Dryas cold interval. Wolbach and her colleagues leave us in no doubt that their study is focused on the beginning of that interval and specifically on the sudden and mysterious climatic reversal from warm to cold around 12,800 years ago that they attribute to an “impact event.” They remind us at several points in their Journal of Geology paper, however, that when they speak of an “event” they do not mean to imply a one-off “hurricane of bolides” striking the earth over a single day or two in a single year. What the evidence points to, instead, is a series of such brief but deadly encounters recurring biannually over the full period of 21 years of platinum enrichment identified in the Greenland ice cores.57
Many of the individual impactors would have been Tunguska-meteor-size or smaller, but they would have come in vast swarms capable of doing enormous damage, and there is evidence that at least once during these 21 years the biannual “hurricane of bolides” may have contained comet fragments with diameters of a kilometer or more.
This is what was specifically proposed in the very first scientific paper to outline the Younger Dryas Impact Hypothesis. Coauthored by Wendy Wolbach, Richard Firestone, Allen West, and more than twenty others, and published in Proceedings of the National Academy of Sciences in October 2007, it raised the possibility that “multiple 2km objects struck the 2km thick Laurentide Ice Sheet.”58
Subsequently, in September 2013, Yingzhe Wu, Mukul Sharma et al. drew attention to the Gulf of St. Lawrence, Canada, where a submerged impact crater with a diameter of 4 kilometers—the Corossol Crater—has been dated to the Younger Dryas Boundary. Looking at a range of other evidence they concluded there had been multiple impacts in this region “that were closely associated in time.”59
Separately, Richard Firestone and Allen West reported evidence of an airburst at the Younger Dryas Boundary “near the Great Lakes of an object unusually enriched in titanium and other incompatible elements. Terrestrial-like ejecta fell close to an impact site near Gainey while projectile-rich ejecta fell farther away. High water content in the ejecta favors an airburst over the Laurentide Ice Sheet north of Gainey.”60
Now perhaps we are getting closer to an explanation of how a single cause could account both for plunging the earth into a 1,000-year “deep freeze” and for melting sufficient quantities of glacial ice to raise global sea level by up to 4 meters. The immense meltwater pulse that entered the North Atlantic and Arctic Oceans was of course not the result of anomalous global warming in an epoch of global cooling but a direct consequence of the “destabilization” of the ice sheet by impacts and airbursts of multiple comet fragments—indeed of a swarm of comets. The thermal energy and blast wave radiated out southward beyond the ice margin all across North America, accompanied by additional local airbursts and impacts that set immense areas of the continent’s primeval conifer forests ablaze,61 followed by “aerial detonations or ground impacts by numerous relatively small cometary fragments, widely dispersed across several continents.”62
Wolbach et al. looked into a series of seven episodes of meltwater release that occurred during the Ice Age, of which the Younger Dryas was the last. Named “Heinrich Events” (after Hartmut Heinrich, the marine geologist who first identified them), such episodes are distinguished by massive armadas of icebergs calving off the continental glaciers. These icebergs carry rocks, rubble, and other debris that as the bergs melt are deposited on the ocean floor where geologists can identify them, measure them, and derive estimates of scale and chronology.
It’s therefore notable that,
even though the YD is considered a Heinrich event (designated H0), the anomalously high peak in wildfire activity at the YD onset is completely opposite to that of six previous Heinrich events, which showed low levels of biomass burning. … This is a crucial observation: the presence of high peaks in biomass burning at the YD onset is completely contrary to very low levels of biomass burning observed at previous similar climatic transitions, making the YD climate episode highly anomalous and unexplainable by the natural processes that created previous warm-to-cold transitions.63
Again, the hypothesis of repeated encounters with the fragments of a disintegrating come
t over the 21 years from 12,836 to 12,815 years ago provides a straightforward explanation for this apparently anomalous state of affairs. The Younger Dryas Heinrich Event was not triggered by normal climatic changes but by the impacts of comet fragments on the North American ice cap.
We cannot say exactly when within that 21-year period the impact-related destabilization of the ice cap occurred. It might have been right at the beginning, or right at the end, or somewhere in the middle, and it might have happened more than once. What the data from the Greenland ice cores definitely do indicate, however, as we saw in the previous chapter, is that the ferocity and intensity of the bombardment, with its accompanying rain of platinum, increased year-on-year for the first 14 years, reached a peak around 12,822 years ago, and then declined over the next 7 years until ceasing as abruptly as it had begun.
It’s a good guess, therefore—nothing more scientific than that—that the peak of the comet’s interaction with the North American ice cap, and most likely the time when the really big fragments came in, would be around 12,822 years ago.
Allen West and fellow CRG scientist Richard Firestone think as many as eight such kilometer-scale fragments64 may have struck the ice cap, excavating their craters in the 2-kilometer-deep ice that subsequently melted away, leaving little or no permanent trace on the ground beneath, or leaving craters that are hard to find, for example, four suspiciously deep holes in lakes Superior, Michigan, Huron, and Ontario.65
Encounters with any fragments of this size, let alone multiple fragments, would already constitute a planetary disaster on an almost unimaginable scale, wherever they occurred. What we must keep in mind, however, although North America was the epicenter, is that the terrible impacts experienced there were only part of a much wider event that left a trail of devastation across at least three other continents.
WHAT WAS LOST
EXTINCTIONS OF ANIMAL SPECIES TOOK place all around the world at the onset of the Younger Dryas but were particularly fast, savage, and severe in North America, where thirty-five genera of large mammals were wiped out.66
Offering evidence from seventy-three sites across twenty-three US states, Wolbach et al. document the synchroneity of these megafaunal extinctions with the Younger Dryas impact.67 Three examples—one of which, Murray Springs, was the subject of the last chapter—can stand for the rest:
BLACKWATER DRAW, NEW MEXICO: At this site, a distinctive black-mat layer, dating to the onset of YD climate change, is in direct contact with peaks in magnetic spherules, Pt, Ir, and biomass-burning proxies, including charcoal, glass-like carbon, fullerenes, and PAHs [polycyclic aromatic hydrocarbons]. These proxies are draped conformably over the last known bones of mammoths killed by Clovis hunters, who then abandoned the site for hundreds of years. The evidence from Blackwater Draw suggests that the YDB impact event is coeval with the megafaunal extinctions and a human population decline, along with a peak in biomass burning and with YD climate change.
MURRAY SPRINGS, ARIZONA: Peaks in magnetic spherules, meltglass, nanodiamonds, Pt, and Ir [are located] immediately beneath a distinctive black mat that dates to the YD onset. Peaks in YDB biomass-burning proxies include charcoal, carbon spherules, glass-like carbon, AC/soot, fullerenes, and PAHs. At this site, several mammoths were killed by Clovis hunters, after which the black mat formed atop the bones and humans abandoned the site for ~1000 y. Thus, the evidence supports the synchroneity of the YDB impact event, increased biomass burning, YD climate change, megafaunal extinctions, and a major human population decline.
SHERIDEN CAVE, OHIO: There are YDB peaks in magnetic spherules, meltglass, nanodiamonds, Pt, and Ir. A charcoal-rich black mat dates to the YD onset and contains peak abundances of charcoal, AC/soot, carbon spherules, and nanodiamonds that are closely associated with the last known Clovis artifacts in the cave. The black-mat layer is in direct contact with the wildfire-charred bones of two mega-mammals, the flat-headed peccary (Platygonus compressus) and the giant beaver (Castoroidies ohioensis), that are the last known examples anywhere in the world of those extinct species.68
Horses, camels, mammoths, mastodons, giant ground sloths, saber-tooth tigers, short-faced bears, and dire wolves are among the other iconic creatures of the Ice Age that disappear from the record at this time. “This represents a major extinction,” James Kennett and Allen West remind us in a paper published in 2018 by the Florida Museum of Natural History:
Not only because so many large and well-known animals were lost, but also because many of the extinct taxa had resided for millions of years in North America. Horse evolution had continued without a break in North America since the Eocene (~55 million years ago) with the only known absence beginning at around ~12,800 years ago until their return from Europe ~500 years ago. Clearly such extinctions are highly anomalous.69
All in all, Kennett and West conclude:
Sufficient geologic and chronologic data now exists to support the hypothesis that megafaunal extinctions were caused by continental-scale ecosystem disruption, resulting from the cosmic impact at the onset of the YD. … The megafaunal extinction would not have occurred at or close to the YD onset without the YDB cosmic impact at ~12,800 years ago. Instead many of the now extinct animals would have survived much longer, even to modern times.70
The archaeological evidence is scarce, perhaps precisely because so much was swept away and covered over by the Younger Dryas earth changes. Nonetheless, it’s clear that along with the disruption of animal life in North America, the cataclysm also had severe consequences for human beings.
Top of the list, of course, is the abrupt, mysterious disappearance of the entire successful, technically accomplished, and geographically widespread Clovis culture right around 12,800 years ago.71 Then, in the centuries following, if we take the case of the southeast as an example, we see a sudden anomalous 50 percent drop in the numbers of projectile points being made.72 A similar trend is seen in many other parts of North America at the same time,73 and in California there is evidence of a cessation of human activity between roughly 12,800 years ago and 12,200 years ago.74
A study of almost 700 cultural carbon-14 dates from across North America by David Anderson, Albert Goodyear, and others shows “a rapid decline” in human activities “at the beginning of the YD that reached its lowest level early in the YD … a 200-year-long 80 percent decline in the number of cultural carbon-14 dates, implying a major decrease in population … followed by a gradual rebound for ~900 years.”75
We do not possess a time machine. We cannot place ourselves physically in North America 12,800 years ago. But all the evidence suggests the continent passed through a tremendous, earthshaking cataclysm, and we know that at least one ancestral North American culture—Clovis—became every bit as extinct 12,800 years ago as the mammoths and the dire wolves.
What else went the way of Clovis in that time of burning darkness and icy floods?
CAPE FEAR
IMAGINE A WORLD WHERE GOOD, honest, hardworking, inquisitive scientists live in fear of ruining their careers, perhaps even of losing their jobs and incomes, if they investigate certain subjects that have been judged by a dominant elite to be “taboo.”
Is such a climate of fear-based conformity likely to result in good science that breaks new ground? Or is it likely to keep science stuck in a rut, endlessly refining and reconfirming established models while rejecting any evidence that suggests those models might be wrong or in need of fundamental revision?
These are not rhetorical questions, because it turns out that this “imaginary” world is the very world we live in today. Science in the twenty-first century does NOT encourage scientists to take risks in their pursuit of “the facts”—particularly when those facts call into question long-established notions about the human past.
The controversy surrounding the Younger Dryas Impact Hypothesis is an example. Since it was first proposed formally in 2007 the scientists behind it have endured an unrelenting barrage of deeply unpleasant and self-serving attacks
from a small but influential group of other scientists whose work and opinions are challenged by the notion of a comet-induced global cataclysm 12,800 years ago.
In my 2015 book, Magicians of the Gods, I give a detailed account of the major studies supporting the YDIH coupled with an equally detailed evaluation of the attacks made on the hypothesis up to that point.1 I will not repeat the same information here since it is on record and can easily be consulted. My conclusion at the time was that the attacks were generally unjustified, misleading, and propagandistic, and that the YDIH constitutes the best possible explanation for the earthshaking events of 12,800 years ago. Now, as I write these words in 2018, my desk is covered with papers published during the past 3 years presenting a great mass of new evidence that very strongly reinforces, extends, and develops the original Younger Dryas Impact Hypothesis. The biomass-burning and platinum studies mentioned in chapter 26 are the jewels in the crown, which is why I focused on them in the limited space available here. The other studies are referenced in the notes.2
I’m more confident than ever that the Comet Research Group scientists are on the right track, and I hold them in the highest regard for speaking truth to power and being willing to stick their necks out. I was therefore excited when George Howard, not a scientist but an environmental restoration specialist and a supporter of CRG who edits the online magazine Cosmic Tusk, contacted me to suggest a meet-up with some of the leading members of the group during my fall 2017 research trip across the United States. On the same trip I met Al Goodyear and Allen West, and now here was an opportunity to exchange views with some of their other colleagues.
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