© Neily Trappman Studio
A few years ago, as a hobby, and pass-time, I set out to see if I could work out a better way of identifying potential sites to go meteorite hunting. I had learned to do battle damage assessment from aerial reconnaissance photos a long time ago in the Army. And the blast damage, and ground effects from an explosive event, are pretty much the same, no matter what the source of the explosion might be. It's only a question of scale, and explosive force. Visually, there is very little difference in the appearance of a bomb crater, and an impact crater of the same size. So a forensic technique of reading the patterns of movement in the emplacement of blast effected materials on the ground applies well in the search for potential impact related geology. The quality of the image data now commonly available to anyone with a good PC, an internet connection, and a copy of Google Earth, is excellent. In the past five years, the publically available image data has really come into its own. And today's 21st century satellite imagery allows us to study the surface of the Earth at a level of detail our fathers could never have imagined.
Back in the 1920's, using aerial photography, a geologist named J. Harlan Bretz noticed evidence for the mega-floods that sculpted the Grande Coulee, and the 'Channeled Scablands' of eastern Washington. Bretz was the first to use Aerial photographs to detect, and map, catastrophic mass movement of the Earth's surface materials when he described the scarring of a catastrophic glacial flood event at the end of the last ice age, in an event he called The Spokane Flood
Aerial photography allowed him a perspective from which patterns of fluid flow, and catastrophic mass movement of terrain materials, could be perceived on a scale that had been unimaginable until he described them. What he had found, were the patterns of fluid flow, like the ripples you see in the sedimentary deposits of a stream bed, but these 'ripples' are hundreds of feet high. Bretz saw them as empirical evidence of a major catastrophic flood event, on a scale that the standard theorists of his day thought was inconceivable.
Today we know that all of the water came from a glacial lake now referred to as Lake Missoula. The huge lake formed in western Montana during the ice age, when a part of the Cordilleran Ice Sheet called the Purcell Trench lobe extended far enough south that it blocked the Clark Fork River in Northern Idaho. In a repeating cycle during the last ice age, when the lake level would get high enough, the ice damn would fail releasing a catastrophic flood downstream. Then the glacier would continue to advance, blocking the river again, and the cycle would repeat.
More 600 cubic miles of water was released each time that ice dam on the Clark Fork River would fail. And the volume of the resulting flood torrents has been calculated at 8 to 10 cubic miles per hour. Or flow a rate that amounts to 10 times the combined flows of all the rivers on the planet Earth. It turned out J.Harlan Bretz was exactly right. Although most of the academic community of his time thought he had a screw loose, or two.
Almost a hundred years before him, most geologists had already decided to agree without question that sudden, catastrophic, geologic changes just didn't happen anymore. And that all geomorphology on the surface of the Earth is the result of slow processes we see going on around us today, and requiring millions of years. They were naively mistaken.
One of the biggest mysteries I've ever confronted lies in the question of how theoretical geology could be so far removed from the empirical reality now clearly visible, and legible, in modern 21st century satellite images.
It didn't take much digging in the history books to figure out where the Earth sciences went wrong.
The root problem with the thinking in the Earth sciences goes all the way back to Gottfried Leibniz, in the early 18th century, and his slogan of 'Natura Non Facit Saltus', (Nature does not jump).
Leibniz may have been a mathematical genius. But he wouldn't even pass a 5th grade geology test of today. Yet he had the full backing of governments, big business, and the big churches. Because he believed, and taught, that the Great God of the Universe had created planet Earth, with all its flora, and fauna, just for us, and to do with as we pleased.
The old clichés like 'buying a pig in poke', 'don't let the cat out of the bag', and 'empty sack of lies' all have their roots in the same old con. It went something like this: At an old country fair, a con artist would approach a likely looking mark to sell him a piglet in a 'poke' bag. But it's not really a pig in the bag; it's a cat. The cat wiggles, and squirms, just like a little pig when you poke him through the bag. And as long as the bag stays closed, the con works just fine. But as soon as the bag is opened, the cat escapes. And the victim is left holding nothing but an empty sack of lies.
Carl Linnaeus, and Charles Darwin, loved Leibniz. And they both quoted him verbatim. He managed to almost completely eliminate any academic consideration of episodic worldwide catastrophes from western thinking. And by the time James Hutton, and Charles Lyell, came along, most geologists were well-conditioned followers of his way of thinking. Hutten gets the credit for the origin of Uniformitarianism. Charles Lyell just popularized his ideas in 1830, when he published his book 'Principles of Geology'. But Hutten, and Lyell, just picked up on Leibniz's thinking, and ran with it.
They weren't brilliant geological thinkers either. But their unquestioned uniformitarian/gradualist assumptions, based on the idea that the earth was shaped only by slow-moving forces still going on around us today, and expressed in the slogan of "The present is the key to understanding the past", has become the foundation postulate of the Earth Sciences ever since. Governments, and big institutions, loved it. And they bought it like a pig in a poke with generous funding packages that came with rules that shut the door to any consideration, or publication, of theories of sudden catastrophic events, as a possible driving force in the geo-morphology of this world for more than 150 years. That's a cruelly long time time to leave the poor kitty in a bag.
But the questions of just what the hell happened around 13,000 years ago that caused the extinctions of the mega fauna in North America, the disappearance of the Clovis culture, and a return to Ice age conditions that lasted more than a thousand years, has caused us to take a closer look, and I'm afraid we've let the cat out of the bag.
The trouble we face today, Just as Mr. Bretz did back in the 1920s, is that through the same 19th century process of mutual-inter-assumptive reasoning, and confabulation, instead of sound, experiment-driven, science, the Earth sciences are still founded on that unquestioned 'Gradualist' assumption. But gradualism only works until something sudden happens. And Harlan Bretz showed us that if you want to understand, or predict, the nature of the planetary scarring of a geologically recent catastrophic event, especially one that's different from anything that's ever been studied before, Sir Charles Lyell's 19th century, gradualist-assumptive, reasoning just won't get you there.
Apparently, being able to see the truth is no guarantee that anyone's going to bother to look where you're pointing anytime soon. It wasn't until 1965 that a report from an independent geologist's tour concluded that Harlan Bretz was right. And finally, in 1976, at the age of 96, hewas awarded the Penrose Medal of the Geological Society of America. Which is just about the most prestigious award a person can get in the field of geology. Upon receiving the award, Mr. Bretz is said to have complained to his son that he couldn't gloat properly, because all of his enemies were dead.
The satellites of today have raised the ante. Using aerial photography from blimps, and airplanes, Bretz could see evidence of catastrophic material movement on a statewide scale. With the imagery now available through Google Earth, we can detect, and read, patterns of catastrophic mass movement of terrains on a continental scale. The event Bretz perceived was only implausible from a standard theory viewpoint because of its size. And yet, by comparison, and in the final analysis, someday it may be seen that his glacial mega flood in the Pacific Northwest was only a minor little footnote in the events of the early Holocene. And some of those events were far more terrible then a glacial flood.
In June 1908, an explosion rocked a remote, swampy area in central Siberia, in Russia; it came to be known as the "Tunguska event." And a later expedition to the site found that 20 miles of trees had been knocked down and set alight by the blast. Today, it's understood that Tunguska's devastation was caused by a 100-foot asteroid that had entered Earth's atmosphere, causing an airburst.
Some 13,000 years earlier, just after the end of the last ice age, the Earth's climate had begun to warm up to temperatures much like what we enjoy today, when an occurrence thought by many researchers to be some kind extraterrestrial impact set off an "impact winter", and a return to ice age conditions that lasted another 1,300 years, or so. And the event coincided with the end of the prehistoric Clovis culture. And the mass extinction of almost all of the giant animals that lived on North America at the time.
Perhaps the single most important paper on the subject of the Younger Dryas Cooling, is the 2007 paper by R.B. Firestone et al, and titled: Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling
The 2007 Firestone paper caused a pretty good stir in the academic community. And it has become the 'Flagship', so to speak, of the Younger Dryas impact hypothesis.
In it, a team of twenty six scientists studying sedimentary deposits from sites all over North America presented a whole suite of compelling evidence for a massive impact event of a comet that appears to have broken up, and scattered, fragments all across North America. The multiple, air bursts are thought to have triggered wide-spread bio mass burning on a continental scale. As well as causing a return to ice age conditions, and the extinction of many species. Including the mega fauna, like mastodons, wooly mammoths, and giant sloths. In all, I think something like 35 genera went extinct.
Its exact cause is by no means, a settled science though. And the biggest weakness in the YD impact hypothesis, as written,
is that it's impossible to construct a model with a four mile wide bolide that has enough time in the atmosphere to break up completely, and scatter fragments, and devastation over a continent sized area, without making a good sized crater somewhere. And "where's the crater?" became a rallying cry of opponents to the hypothesis.
The debate continues to go around, and around. Firestone, and friends, had found compelling evidence in the stratigraphic record that implied some kind of very large impact related catastrophe had occurred to trigger the Younger Dryas Cooling, and the megafaunal extinctions. But it was clear that the event was vastly different from anything that had been studied before. So they could only speculate on just exactly what the nature of the event was, or what had hit us, or where the actual impact zones were. Without an astronomical model that could confidently describe the the nature of the impactor/s, they were were at an impasse.
Meanwhile, astronomers Victor Clube, and William Napier, in their book The Cosmic Serpent
, had been talking about the giant comet they described as the progenitor of the Taurid Complex
since 1982. Their data is as solid as anything you can dig up with a trowel. But except for them, and a few others like Bob Kobres
, no one had connected the the dots, and put the Younger Dryas comet, and the Taurid Progenitor together. Except in private, speculative, emails, and letters. And to the best of my knowledge there was nothing in refereed literature.
Then, In early 2010, Professor Napier published a paper in the Journal Monthly Notices of the Royal Astronomical Society
titled, Paleolithic extinctions and the Taurid Complex
in it we read:
"The proposition that an exceptionally large comet has been undergoing disintegration in the inner planetary system goes back over 40 years (Whipple 1967), and the evidence for the hypothesis has accumulated to the point where it seems compelling. Radio and visual meteor data show that the zodiacal cloud is dominated by a broad stream of largely cometary material which incorporates an ancient, dispersed system of related meteor streams. Embedded within this system are significant numbers of large NEOs, including Comet Encke. Replenishment of the zodiacal cloud is sporadic, with the current cloud being substantially overmassive in relation to current sources. The system is most easily understood as due to the injection and continuing disintegration of a comet 50-100 km in diameter. The fragmentation of comets is now recognized as a major route of their disintegration, and this is consistent with the numerous sub-streams and co-moving observed in the Taurid complex. The probable epoch of injection of this large comet, ~20-30 kyr ago, comfortably straddles the 12.9 kyr date of the Younger Dryas Boundary.
The hypothesis that terrestrial catastrophes may happen on timescales ~0.1 Myr, due to the Earth running through swarms of debris from disintegrating large comets, is likewise not new (Clube & Napier, 1984). However the accumulation of observations has allowed us to build an astronomical model, closely based on the contemporary environment, which can plausibly yield the postulated YDB catastrophe. The interception of ~1015 gm of material during the course of disintegration is shown here to have been a reasonably probable event, capable of yielding destruction on a continental scale.
The object of this paper is not to claim that such an encounter took place at 12,900 BP - that is a matter for Earth scientists - but to show that a convincing astronomical scenario can be constructed which seems to give a satisfactory match to the major geophysical features of the Younger Dryas Boundary data.
If indeed the YDB event was an astronomical catastrophe, its occurrence bears little relation to current impact hazard assessments derived from NEO surveys."
With Professor Napier's work specifically proposing in refereed literature that the Taurid Progenitor was the Younger Dryas comet, he changed the game completely. Because he didn't just give us a convincing astronomical model of the event. We also have a pretty good picture of the physical properties of the thing that did the disastrous deed. And if you can describe a beast, you can predict it's footprints.