The End of Eden: The Comet That Changed Civilization

Altair

Ambassador
Ambassador
FOTCM Member
#1
Recently finished this book written by Graham Phillips. It was mentioned here: Comets and Catastrophism Book List. And it's indeed a fascinating read. The book reads like a crime story. The author argues that in 1486 BC there was a huge comet which caused a mass epidemic of violence in previously peaceful nations like the megalithic culture of Britain, Olmec civilization, the Middle Eastern kingdoms of the Hittites, Mitanni, and Assyria as well as in China and Egypt. This mass violence and hysteria were very sudden and lasted only for two decades. It gave rise not only to new kingdoms, new social structures but also to new religions like Atenism, Zoroastrianism, and Hinduism, as the author suggests. He also says that there was no evidence of any climate change in this period which could have explained this massive spike of violence.


Impression of the spectacular ten-tailed comet recorded by the Ancient Egyptians in 1486 BC. (Illustration by Graham Phillips)


The Assyrian winged disk. One of the many similar glyphs that represented deities that appeared throughout the world after the comet’s appearance in 1486 BC. (Public Domain)

The symbol for the god Lao-Tien-Yeh glyph that first appeared in China during the early fifteenth century BC. (Photography by Graham Phillips)



The Egyptian Aten symbol that may originally have depicted the magnificent comet of 1486 BC. (Public domain)

He suggests it may have been caused by the release of vasopressin after breaking apart of the comet (like Tunguska):

Comets contain amino acids, and one such amino acid is a substance called vasopressin, which is deadly in high doses. In the lesser quantities that might be released into the atmosphere during a cometary collision, there could be nonfatal but nevertheless detrimental effects on human beings. It would make them decidedly more aggressive. In the body, small amounts of vasopressin are produced naturally to act as hormones to facilitate preparedness for fight or flight when an individual faces a threat. Usually, natural vasopressin produces a heightened state of readiness, but in abnormally high measures, the same substance causes belligerent, even violent behavior. Experimental studies have even suggested the disturbing possibility that mass homicidal behavior would result if a city’s water supply was ever contaminated with sufficient quantities of the chemical.

Could a substance like vasopressin have caused the global epidemic of violence following the comet of 1486 BC? Unfortunately, at present, there is no way to determine this scientifically one way or the other; any soil contamination would have been washed away into rivers and seas long ago. And although there is no evidence in ice-core samples suggesting vasopressin in the atmosphere during the period in question, this does not negate the possibility. If a cometary fragment exploded in the air, the blast would probably occur, as it did at Tunguska, between three and six miles high, well below the stratosphere. As there would have been no terrestrial impact, the amount of vaporized cometary material would probably remain primarily within the troposphere and not circulate globally by stratospheric conditions.

The inhabitants of the area closest to an airburst would be most affected by the vasopressin release; indeed, in two regions we know of, the violent behavior following 1486 BC was initially more intense and frantic. The Aryans from Afghanistan swept southeast into the Indus Valley, savagely massacring the Harappans and needlessly destroying their cities, while twenty-five hundred miles away in China, although a previously lenient society became abruptly cruel, oppressive, and tyrannical, and ultimately disintegrated in warfare and chaos, there is no evidence of the same kind of homicidal insanity. In the region of the northeast Mediterranean, we find the Mitannians of northern Syria initially fighting with mindless suicidal frenzy, while the Egyptians from northern Africa, although just as aggressive, wage more calculated warfare. One vivid account concerning the northeast Mediterranean demonstrates just how insane the violent behavior in that region appears to have been. The account is found among contemporary Hittite texts discovered at Hattusas. Part of the Hittite empire had included Cappadocia, in southern Turkey, and here the members of a peaceful community took to butchering one another in their own homes.
This vasopressin explanation sounds a bit a far-fetched to me, though. There is no evidence that comet fragments may contain it in any amounts and no traces of it were found in ice-cores from this period. As he describes the events after 1486 BC it looks like a power take-over by psychopaths. Some already mentioned that electromagnetic radiation from comets might have caused a mutation which led to psychopathy in some people. But that it happened so suddenly and had so far-reaching consequences?:huh: It's indeed very creepy if that was the case.
 

Pashalis

Ambassador
Ambassador
FOTCM Member
#2
Last edited:

c.a.

The Living Force
FOTCM Member
#3
I am thinking we could also toss in (the possibility's), that the increase of Cosmic Rays, additionally poisoning peoples metal instability.
Coupled with the world drug trade that by my estimates adds a significant inclusion with the mental decline.
As well as many other components.

Atmospheric Radiation Increasing from Coast to Coast in the USA
October 24, 2018
/ Dr.Tony Phillips

Cosmic rays activity and monthly number of deaths: a correlative study. - PubMed - NCBI
J Basic Clin Physiol Pharmacol.
2002;13(1):23-32.
Cosmic rays activity revealed significant negative correlation with solar/geomagnetic activity indices and related physical phenomena levels. This activity strongly correlated with flux of protons with the energies >90 MeV proton flux and did not exhibit significant correlation with 60 MeV proton fluxes. Cosmic rays intensity correlation with monthly numbers of deaths was strong for noncardiovascular deaths, suicides, and traffic accidents. The correlation was much weaker for deaths caused by ishemic heart disease and strokes.
Health threat from cosmic rays - Wikipedia
Central nervous system
Snip:
See also: Central nervous system effects from radiation exposure during spaceflight
Hypothetical early and late effects on the central nervous system are of great concern to NASA and an area of active current research interest.
It is postulated short- and long-term effects of CNS exposure to galactic cosmic radiation are likely to pose significant neurological health risks to human long-term space travel.[34][35] Estimates suggest considerable exposure to high energy heavy (HZE) ions as well as protons and secondary radiation during Mars or prolonged Lunar missions with estimates of whole body effective doses ranging from 0.17 to greater than 1.0 Sv.[36] Given the high linear energy transfer potential of such particles, a considerable proportion of those cells exposed to HZE radiation are likely to die.
Based on calculations of heavy ion fluences during space flight as well as various experimental cell models, as many as 5% of an astronaut’s cells might be killed during such missions.[37][38]
With respect to cells in critical brain regions, as many as 13% of such cells may be traversed at least once by an iron ion during a three-year Mars mission.[3][39] Several Apollo astronauts reported seeing light flashes, although the precise biological mechanisms responsible are unclear.
Likely pathways include heavy ion interactions with retinal photoreceptors[40] and Cherenkov radiation resulting from particle interactions within the vitreous humor.[41] This phenomenon has been replicated on Earth by scientists at various institutions.[42][43] As the duration of the longest Apollo flights was less than two weeks, the astronauts had limited cumulative exposures and a corresponding low risk for radiation carcinogenesis. In addition, there were only 24 such astronauts, making statistical analysis of any potential health effects problematic.

Cosmic radiation exposure and persistent cognitive dysfunction. - PubMed - NCBI
Sci Rep. 2016 Oct 10 ;6:34774. doi: 10.1038/srep34774.
Abstract
The Mars mission will result in an inevitable exposure to cosmic radiation that has been shown to cause cognitive impairments in rodent models, and possibly in astronauts engaged in deep space travel. Of particular concern is the potential for cosmic radiation exposure to compromise critical decision making during normal operations or under emergency conditions in deep space. Rodents exposed to cosmic radiation exhibit persistent hippocampal and cortical based performance decrements using six independent behavioral tasks administered between separate cohorts 12 and 24 weeks after irradiation. Radiation-induced impairments in spatial, episodic and recognition memory were temporally coincident with deficits in executive function and reduced rates of fear extinction and elevated anxiety. Irradiation caused significant reductions in dendritic complexity, spine density and altered spine morphology along medial prefrontal cortical neurons known to mediate neurotransmission interrogated by our behavioral tasks. Cosmic radiation also disrupted synaptic integrity and increased neuroinflammation that persisted more than 6 months after exposure. Behavioral deficits for individual animals correlated significantly with reduced spine density and increased synaptic puncta, providing quantitative measures of risk for developing cognitive impairment. Our data provide additional evidence that deep space travel poses a real and unique threat to the integrity of neural circuits in the brain.

Assessing cosmic radiation impacts on commercial airline crew | Result In Brief | CORDIS | European Commission
 

c.a.

The Living Force
FOTCM Member
#4
Take a trip down to the bottom of the best-preserved impact crater on Earth.
by David J. Eicher

With the start of the 50th anniversary of the legendary Apollo missions, you might be dreaming about what it would have been like to explore lunar craters up close. Well, there’s a pretty good way to live that dream, right here on Earth. Meteor Crater, the world’s best impact scar, lies on the Arizona plain about 18 miles west of Winslow — you know, that town from the Eagles song.

This summer I had the chance to travel to Meteor Crater along with its owner, Drew Barringer, whose family has owned Meteor Crater since 1903 — that’s right, the crater is privately owned — and a small group led by planetary scientist David Kring of the Lunar and Planetary Institute in Houston. One of the natural wonders of the world, the crater attracts some 270,000 visitors per year. The site contains a beautiful, expansive visitor center and educational museum with spectacular scientific displays, and normally the visit includes walking around a portion of the 2.4-mile circumference around the crater’s rim. Rarely do visitors get the chance to climb down to the crater’s floor and explore the whole thing. But this year, that’s exactly what we did, and it afforded a unique view of what a small asteroid can do to our planet.

The best crater on the planet

Long ago the inner solar system was bombarded repeatedly with asteroids, planetesimals, and comets. All you need to do to see the evidence of the so-called Late Heavy Bombardment, when much of this frenzy of impacts occurred, is to look at the Moon or Mercury. These worlds have a nearly complete record of ancient scars dating to the early days of the solar system, more than 4 billion years ago. Earth has not been exempted from this aerial attack, but our planet has a widespread system of resurfacing. It comes from plate tectonics, mountain building, volcanism, wind, water, continental drift, and the slumping of craters, mountains, and volcanoes. The record of impacts on our planet gets covered up pretty quickly.

And yet we know many impacts have taken place on Earth in its past. Famous among them is the K-Pg Impact in the Yucatán Peninsula, which among other things wiped out the dinosaurs 66 million years ago. More recently, impacts such as the Tunguska event, an airburst explosion of an asteroid over Siberia in 1908, and the Chelyabinsk impact in 2013, come to mind.

And then there’s Meteor Crater, the first proven and best preserved of all Earth impact craters, gouged into the Arizona desert. Because we know of past impacts and what caused them doesn’t mean they will stop. At some point in the future, humans will have to do something to prevent another such impact, and so Meteor Crater has a great deal to teach us.

Meteor Crater is unlike any other spot on Earth. Perched at an elevation of 5,710 feet (1,740 m) above sea level, the impact scar stretches 3,900 feet (1,200 m) across — three-quarters of a mile — and the floor is 560 feet (170 m) deep. The crater’s rim rises 148 feet (45 m) above the surrounding desert plain.

The story of understanding Meteor Crater begins in 1891, with the Philadelphia physician, mineralogist, and mineral dealer A. E. Foote (1846–1895), who heard of the crater from a railroad executive who sent him a sample of iron from the crater. Foote analyzed the iron and deduced the sample came from a meteorite. He immediately traveled to the location with a team of assistants, to a point “185 miles due north of Tucson,” and collected masses and fragments of meteoritic iron. Foote found that the meteorites contained signature minerals and elements such as troilite, daubréelite, carbon, and diamonds, of extraterrestrial origin.

Foote wrote a scientific paper about his find and presented it at a meeting of the American Association for the Advancement of Science in Washington, D.C. In it he described the meteorites, wrote about “Crater Mountain,” but he did not connect the crater with a meteorite impact, despite writing that he could not locate lava, obsidian, or “other volcanic products.” He believed that a large iron meteorite of 500 to 600 pounds impacted near the site, but as unconnected with the crater. The pieces of meteorite were linked with the surrounding plain, and at one point the crater was called Coon Mountain. Meteorites found near the site were shipped from a small town nearby called Canyon Diablo, and so the meteorite fragments found were called Canyon Diablo meteorites.

In the audience at Foote’s Washington lecture was none other than Grove Karl Gilbert (1843–1918), chief geologist of the U.S. Geological Survey. He was immediately entranced by the story of the crater and the meteoritic iron. He believed that perhaps the crater was the result of the impact of a large iron mass, or that the crater was produced by a large steam explosion and had nothing to do with the meteorites. He conducted measurements in late 1891 to detect meteoritic material underneath the base of the crater. He carefully measured the crater’s volume and the volume of material ejected into the crater’s rim. If the two were equal, he would reason that no mass lay beneath the crater floor. He also measured the crater’s magnetic field. He found the same volume and also detected no magnetic anomaly. So Gilbert figured the crater had formed from a steam explosion, unrelated to the meteorites.

Unaware of this primitive geological work, geologist Daniel Moreau Barringer (1860–1929, and pronounced Bear-in-GER, with a hard G) learned of the crater while talking to a friend on the veranda of a Tucson hotel. The son of Daniel Moreau Barringer, U.S. Congressman from North Carolina, and nephew of Confederate Brig. Gen. Rufus Barringer, Daniel was astonished by the site and dreamed of a lucrative find of iron and nickel from the meteorite mass. He was already an experienced silver miner and was well financed, and so in 1903 he acquired the crater through a series of mining claims. The site is more commonly known as Meteor Crater, but its proper scientific name is the Barringer Meteorite Crater. After making 10 trips to study the crater, Barringer produced an analytical paper of his own, aided by his business partner, Benjamin Chew Tilghman.

Unlike Gilbert, Barringer carefully studied the distribution of the meteoritic iron and found that pieces were scattered concentrically around the crater. He described strata in the crater walls, and suggested they were uplifted by a forceful impact. He examined and correctly described the inverted layers of material upturned by the impact. He found that the largest ejected blocks were oriented in an east-west line, suggested the trajectory of an impacting body. He found that silicate minerals were crushed so finely that “grittiness” could not be detected. Barringer also noted the absence of any volcanic material to a depth of 1,400 feet below the surrounding desert plain. A steam explosion seemed out of the question. Barringer concluded correctly that the crater must have been the result of an impact from space.

The earlier work of Foote and especially Gilbert, with his reputation, continued to color the interpretation of the site for many years. In an age when catastrophic events seemed too unusual, and geologists adhered to belief in slow, continuous, uniform processes, Barringer’s conclusions — correct as they were — were largely ignored well beyond his lifetime.

And then came a renaissance for the ideas of Daniel Barringer. The mountain of additional confirming evidence came from the work of Gene Shoemaker (1928–1997), geologist and one of the founders of planetary science. Reexamining the problem and studying Meteor Crater for his PhD. work at Princeton, in 1960, Shoemaker incorporated new studies of nuclear blast explosions and developed a new model for understanding high-speed, energetic impacts. He conducted immensely detailed studies of the geology of the crater and correlated them with features found in the nuclear-bomb crater Teapot Ess in Nevada.

Along with geologist Edward Chao (1919–2008), Shoemaker discovered telltale shocked quartz from impact energy in the form of the minerals coesite and stishovite. Shoemaker‘s studies confirmed what Barringer believed: the crater was definitely an impact from a meteorite. Shoemaker went on to train Apollo astronauts at Meteor Crater (and nearby Sunset Crater, a volcanic cinder cone), and pioneered the field of astrogeology with the founding of the U.S. Geological Survey Astrogeology Branch in Flagstaff.



A trip down into the crater

Gene Shoemaker was very much on my mind when I arrived at Meteor Crater in June 2018 for our journey down to the crater floor. Gene died tragically in an auto accident in Australia, far before his time, and I had gotten to know he and his wife Carolyn, the world’s leading discoverer of comets, when I was hanging around Flagstaff in the 1980s. Also on my mind was David Kring, the leading expert on Meteor Crater, and my new friend Drew Barringer, Chairman and CEO of The Barringer Crater Company and my fellow Lowell Observatory Advisory Board member.

Our group began our hike into the crater on a sweltering day. Indeed the humidity was low, but the temperature tipped the scales at 95° F (35° C), so we brought plentiful supplies of water with us. We expected the adventure to last at least three to four hours. Members of our group were all well acclimated; I was not, having come from an elevation of 800 feet in Wisconsin two days beforehand. The difference in altitude and heat would come back to haunt me later in the journey.

After getting our stuff together and assembling our group, we traversed through the beautiful visitor center and headed west along the crater rim trail. This would take us several hundred feet to a century-old trail leading downward into the crater. As we walked along, we had to be extraordinarily careful, led and at times warned by David Kring, who is certainly the world’s leading expert on Meteor Crater as a planetary scientist. Great care must be taken about where to step so as not to disturb the placement of rocks, damage water-needy plants, or leave impressions and prints here and there. The crater is very much an active research laboratory in which many factors are studied, the disturbing the positions of artifacts can disrupt the knowledge to be gained.

We traversed down the antique path carefully, pausing occasionally to listen to David’s scientific explanations of various key points, positions, or vistas that would help to explain the crater’s history. One of the first things we noticed in climbing down was to turn our heads back up to see the raised rim, and the enormous blocks of uplifted rock above us that were thrown out of the crater. One could easily imagine what it would be like to climb down into a crater on the Moon and see such similar features; large boulders that had been blasted up and landed atop the rim, in an upheaval that turned the rock’s natural layering upside-down.

David then took us to a point and showed us close-up views of some white Coconino Sandstone, the plentiful rock that is made almost entirely of finely ground quartz, pulverized into small particles. This is sedimentary rock, the lowest layer of the upper portion of the native landscape, and preserves a cross-layered structure that formed from fossilized sand dunes, left from a time when Northern Arizona was dune field similar to the modern Sahara Desert.

Other types of rock are exposed in the crater walls, and include — rising above the Coconino — the Toroweap Formation, a thin layer of sandstone and dolomite, and above it, the Kaibab Formation, a thicker layer of dolomite, dolomitic limestone, and thin sandstone. The represents a time when the area was covered in a sea, and abundant fossils exist in these layers. They include trilobites, brachiopods, cephalopods, gastropods, and pelecypods, and date from the Permian, more than 250 million years ago. Lastly, there is the reddish siltstone Moenkopi Formation, closest to the surface.

As we kept winding our way downward, slowly, along the trail, the heat was astonishing. We stopped here and there to look at a wall of Coconino Sandstone, appreciating the finely pulverized quartz that makes it up, and to look at the reddish Moenkopi, and to gaze at fossils in the Kaibab. The march downward lasted much longer than an hour, and as we rested and regrouped, carefully climbing over rocks, sometimes scaling down small boulders, and making sure we didn’t cause any rockslides or smash native plants with our feet.

Meteor Crater’s geology

As we stopped to rest, David continued his narrative of the structure of the crater for us. The crater has a simple bowl-shape, typical for impact craters that are less than roughly 2 km in diameter in sedimentary rock and smaller than 4 km in crystalline targets. The crater has no features of large craters visible on the Moon such as central peaks, rings, modification zones of collapsed walls, or deformational rings surrounding the impact. Meteor Crater does have so-called tear faults that cross-cut the terrain in four areas, giving the crater a squarish appearance. Joints in the landscape are thought to have existed before the impact, and the creation of the crater fractured these faults.

In 1960, Gene Shoemaker produced the definitive geological map of Meteor Crater. His work demonstrated that the upper crater walls and uplifted crater rim are composed of Coconino, Toroweap, Kaibab, and Moenkopi formation rocks. Debris is scattered around the crater’s perimeter and within it, too, of course: Shoemaker mapped the impact debris within the crater in a careful way.

Geologists have a special term for rock that has been smashed and mixed up and fused back together — breccia. Shoemaker mapped several types of brecciated rock from the impact within the crater. Some of them contain fragments of rock from more than one of the geological formations. Some of them contain shock-melted rock along with debris from the meteorite. The crater has changed dramatically since it formed. Erosion and the accumulation of sediments have played major roles in remaking Meteor Crater. Debris has collected at the base of the crater’s walls. This has reduced the steepness of the walls. The apparent size of the crater has changed due to erosion of the rim’s height, shallowing of the wall slope, and large quantities of sediment filling in the crater’s floor. As the rim shrank in height and the upper walls eroded, the apparent diameter grew.

Atop the debris from the impact on the crater’s floor, the brecciated rock, lie ancient lake sediments to a level of about 100 feet (30m). The ancient lake sediments have comingled with material shedding downward from the crater walls. Following the impact, the environment in this area became far more arid, and the lake evaporated. So standing on the floor of the crater is now standing well over 100 feet higher than one would have stood just after the impact.

As we continued to wind our way down, it was stunning to look up and see how large the walls are as viewed from within. It‘s clear why astronauts were routinely brought here for training, first by Shoemaker and now by Kring. The landscape certainly offers a lunar-like world to climb into, and exposes explorers to a variety of mesmerizing geological features. It’s also a challenging environment, well suited for testing astronaut durability. The 95° F heat on our day was starting to wear on me, the easterner. After the better part of an hour, we reached a point where the downward climb tapered off a bit and we could see we were approaching the horizontal trek across the crater’s floor. It strikes you as almost incredible that you start by thinking, “sure, we can walk right down there!” And then the amazingly large scale of the place hits you. It takes a long time to make your way down toward the floor.

As I mentioned, Daniel Barringer, Drew’s grandfather, was a geologist who was interested in the potential for finding iron that could be mined. With a pair of binoculars atop the rim, you can spy down to the center of the crater’s floor to see the remnants of mining operations from the past. You can also spy a life-sized cutout figure of an astronaut placed there for scale. That brings home the enormous distances involved with the crater. As we made our way down to the floor, starting to carefully walk across it, Kring described some of the history of the elder Barringer’s mining activities.

In 1892 Barringer had purchased a gold and silver mine near Cochise, Arizona, east of Tucson. A few years later he discovered a silver mine near Pearce, Arizona, a short distance south of Cochise. Funded by these ventures, excited over the crater near Winslow, he founded the Standard Iron Company and commenced drilling operations on the crater’s floor in 1903. He believed of course that the main mass of the meteoritic iron must be buried below the surface of the crater’s center. Over the next five years, Barringer and his colleagues drilled 28 holes into the crater’s floor, searching for the iron. The deepest of these reached 1,085 feet (323m). The team excavated seven shafts on the floor, the deepest of which reached 222 feet (68m), and sank several other shafts in other locations, as well as digging trenches.
The mining team extracted core samples along with chips and sand. None of the core sample material survives in the present day. The drilling suggested that the broken rock from the impact bottoms out at about 700 feet (210m), and amazingly, drilling detected a huge (5-acre) chunk of Coconino sandstone that was reported to have slumped off and landed in the middle of the zone of broken rock, some 200 feet (60m) deep.

Following the first mining explorations, which failed to find meteoritic iron, the United States Refining, Smelting, and Mining Company drilled more explorative holes between 1920 and 1922, on the south rim. This hole reached a depth of 1,376 feet (419m), more than 800 feet (240m) below the crater floor. That effort, too, failed to find significant amounts of iron.

A coherent picture of what happened, exactly, when a small asteroid slammed into the desert, began to emerge after Gene Shoemaker’s work in 1960. Geologists still don’t know such details as the asteroid’s trajectory, the exact energy unleashed, and so on, but over the last few years they’ve assembled a good general picture of what happened. The impactor, an iron-nickel object, slammed into what‘s now the Arizona desert and penetrated the Moenkopi formation to a depth of about its own diameter, exploding and releasing tremendous energy, generating a downward and radial shock wave. The flow of rock moved downward and outward before moving upward and outward. This made the crater and ejected debris into the surrounding landscape. Material along the walls slumped inward, forming a breccia lens. The total timeframe in making the crater was only a few seconds. The iron-nickel material, by the way, did not come from the core of an asteroid, as is often stated. Rather, type IAB irons appear to be metal from the differentiated base of an impact melt sheet on an asteroid — the result of an ancient collision.

Marching toward the crater’s center

Now our group was close to the floor of the crater. We climbed down a small vertical distance further, and made our objective the relics of the mining equipment we could see at the floor’s center. Remnants of the mining attempts of the early 20th century, surrounding the main central shaft, include a boiler and relics of a hoist, among other large iron pieces. Again, the scale of the crater fools you. You say to yourself, “Ah, I’ll just walk right over there.” And you find out that it is a very long walk.

As we traversed the crater floor, Kring continued his geological explanation of the crater. One of the key pieces of evidence to prove the crater was an impact came from analysis of what geologists call shock metamorphism. By finding shocked crystals of quartz, for example, they can tell a walloping force was unleashed there. Back in the first decade of the 20th century, Barringer and Tilghman discovered “rock flour,” pulverized Coconino sandstone. Barringer also found that much of the Coconino had been shocked. Later, geologists identified a mineral, coesite, in the crater, which is a high-pressure form of quartz. Soon after that find, they identified stishovite, another high-stress form of quartz, clearly indicated the great pressure that was unleashed with the impact. Other associated rocks showed indications of melting and resolidification.

We walked along, being careful not to squash plants, mindful of possible critters on the ground such as snakes and insects, and with an eye toward the center, as Kring continued his talk. He described how the impact uplifted the crater rim, and how uplift is visible in the layers of the crater walls. Fracturing within the crater walls bulked up the rock, preserving the uplifted rim. Broken rock fragments and ejecta filled parts of the walls, helping to preserve them. And the walls consist of blocks of rock that are in their normal strata, pushed up to vertical orientation, and even overturned as one looks up to the top of the rim.

But, Kring explained, the ejecta forming the crater walls was hardly the entirety of the material cast out from the crater. Rubble from the impact lies over a radial reach of more than a kilometer away from the crater’s center. The largest pieces of course lie near the crater rim, where blocks of limestone up to 60 feet across and sandstone to 100 feet in diameter were thrown. Some of these pieces weigh in at up to 5,000 tons. One of the largest blocks near the crater’s rim is called Monument Rock, or House Rock. It probably landed after about 2 seconds in the air and was traveling at about 30 mph (50 kph). Blocks of rock that landed half a kilometer beyond the rim, however, probably traveled at velocities of 225 mph (370 kph).

As we reached the central point of the crater floor, we stopped, rested, regrouped, and took some pictures of ourselves and of the mining equipment. So what, as we stood right where the colliding object landed, do we know of the asteroid itself?

Kring told us about the current thinking on the impactor. The current thinking is that it had a diameter of about 160 feet (50m). Of course what we know now, and what Barringer and his team of hopeful miners didn’t, is that the main mass was obliterated by the incredible energy released in the impact. Fragments of the iron-nickel meteorite, known as Canyon Diablo, have been picked up since prehistoric times. The estimated total mass recovered is something like 30 tons, but that’s a crude guess. A meteorites go, it is classified as a Group IAB iron. The composition of the meteorite is mostly iron, but with about 7 percent nickel and a small percentage of other elements. Many meteorites fall into Earth’s surface at relatively low velocities and survive in great numbers. The asteroid that produced Meteor Crater struck Earth when it was still traveling at a very high speed, which produced the explosive cratering event.

We gathered ourselves after the souvenir photo shoots at the floor’s center and got ready for the hike back up to the rim. The temperature was still blazingly hot, and we were tired, but imbibing plenty of water.

It’s an amazing thing to stand in the middle of the crater and look all around at the walls towering on all sides. I shot a couple of panoramas. Aside from the blue sky and desert terrain, you certainly got a taste of the psychology of what it would be like to be standing in the middle of a small crater on the Moon.

Looking upward, you could begin to imagine how the asteroid came in. It all would have happened in a flash, of course. Standing in the blast zone, you wouldn’t have known what hit you. The Hollywood business of seeing a blazing object coming in, trailing fire, with warning before the “bomb” goes off, is of course silly. That notwithstanding, the trajectory of the incoming asteroid is a tricky problem to solve that is still under debate. Early on, Barringer and others realized that an object coming in at a 45° angle would produce a round crater. Shoemaker and others since, most notably Kring, have noted that faults in the crater walls suggest a rough south-to-north direction of the incoming asteroid. But the opposite direction of motion could also be true. This is a question that can’t yet be answered with certainty.

We do know something of the immense energy released by the impact, however. Assuming a roughly 50m object, the object’s mass would be somewhere in the range of half a million metric tons. The incoming velocity of this asteroid? Somewhere in the range of 7 to 12 miles per second (11 to 20 km/s). That is really moving. As a rough estimate, physicists garner the impact energy released at approximately 10 megatons, or 700 times the energy of the bomb that exploded over Hiroshima.

The incredible force unleashed by this impact shook the immediate area and the region. The impact ejected debris from the site, produced a fireball, a radiating shock wave, and a related air blast. Plants and animals at the impact site would have been vaporized, as were portions of the asteroid and some of the underlying bedrock. The shock wave would have radiated across the surrounding landscape. The winds would have severely damaged any life forms to a diameter of some 20 miles (32 km). The destruction over this region would have killed or injured most animals and plants, and the air blast would have caused bleeding and fluid buildup in the lungs of creatures, suffocating them, and obstructing blood flow to the heart and brain. The blast wave would also have struck animals and plants over this region. On a scale far greater than a hurricane, winds would send rocks, tree branches, and other debris flying outward like missiles. The ballistic shock wave would have created injuries, perhaps many fatal, over a much larger area yet.

The climb back up

As he said several times when we began our long hike, Kring told us to take it easy and hydrate substantially. “There are two ways back out,” he told us. “You can climb, and so you need to take care of your body. Or you can be taken out by helicopter. That costs about $10,000, and I’m not going to pay for it.”

We started the climb back up thinking about the incredible blast, and how reality is far harsher than the movies make such things out to be. So when, when did all of this happen? That seemed to be one missing part of the story.

As we approached the edge of the floor and started our upward journey along the antique trail, over boulders, careful not to step on plants or displace rocks, Kring continued his lecture. It turns out that the thinking about the age of the impact has been changing relatively recently.

The earliest experts thought the crater so well preserved that it couldn’t be fantastically old. Barringer, in 1905, believed the crater to be between 2,000 and 3,000 years old. Finding the crater’s age is a tough process. The volumes of impact melt that could be analyzed via isotopic analysis are small, and the crater is young enough that some radiometric techniques for dating rocks are useless due to the half-lives of radioactive elements being too short in the crater samples.

In the 1930s, geologist Eliot Blackwelder of Stanford University examined the thickness of lake sediments on the floor, debris on the crater slopes, pitting of ejected limestone, and other factors, and estimated an age of 40,000 to 75,000 years. That turns out to be remarkably accurate in the more modern era.

For a time, scientists thought that Meteor Crater and the much smaller and more eroded Odessa Crater in West Texas might be linked. I asked Dave Kring about that as we climbed upward. The idea is that the ages of each were estimated to be in the range of 50,000 years for some time, and it seems strange that two craters in more or less the same region from more or less the same time period would be unrelated. But the trajectories for Meteor Crater and Odessa don’t seem to match up well. Any relationship seems hard to match up from an orbital point of view.

The business of directly measuring the age of the crater got underway in the 1980s. Using a specialized technique called thermoluminescence, which measures accumulated radiation, Stephen R. Sutton of the University of Chicago found an age of 49,000 years, plus or minus a few thousand. More recent studies have agreed with that figure. Now, however, Kring says studies in press may push the age of the crater — and of Odessa, by the way — to be somewhat older, possibly to 60,000 years or even somewhat older than that. Stay tuned.

A we climbed up, I felt more and more winded. And then a bit lightheaded. Over rocks, up the old trail we went, and I found myself having to pause more frequently. Yes, the guy from the Midwest had the heat getting to him. I didn’t really know it at the time, but I had heatstroke. I soldiered on, but as we neared the bottom of the rim, about to make our way out, I got sick. Yes, threw up in front of our group. It wasn’t my finest hour. I had learned a great deal updating my knowledge of the crater, but in one sense, the heat won the day.

Lessons for the future

As mentioned, the impactor that made Meteor Crater was a small asteroid in the range of 50 m diameter. It was material from an ancient planetesimal produced from an impact melt. Other impacts have frequently taken place on Earth and their scars have faded away. In the Arizona desert, with an impact just 60,000 or so years old, the scar is fresh.

Planetary scientists are frantically working on expanding their inventory of Near Earth Objects (NEOs), asteroids that could impact our planet in the future. Such impacts will happen. Fortunately, there are no very large objects in near Earth space, similar to the K-Pg impactor that struck the Yucatán 66 million years ago and killed a high percentage of species, including the dinosaurs. But what about small asteroids that could trike us and be city killers, or regionally devastating, like the asteroid that made Meteor Crater? Astronomers now know of about 18,500 NEOs, but the inventory of objects down to 50 meters in size is completely only to an estimated 1 percent. Yes, that’s 1 percent.

The Asteroid Day project aims to raise awareness for NEO research and discovery, and you can find out more about it here: asteroidday.org

For further details on Meteor Crater, its geology, and current science, you must read David Kring’s Guidebook to the Geology of Barringer Meteor Crater, Arizona, a.k.a. Meteor Crater, 2d ed., 270 pp., paper, Lunar and Planetary Institute, Houston, 2017. The complete publication is available online here: Lunar and Planetary Institute.
For information on visiting Meteor Crater, see the website at Meteor Crater Home Page.
For information about The Barringer Crater Company, visit www.barringercrater.com.

I encourage you to visit Meteor Crater. It is an incredible spectacle to see this amazing product of solar system interaction. The visitor center is fantastic, and a walk around a portion of the crater’s rim will show you an amazing overview of the site.

Thanks are due to Drew Barringer and to David Kring for their gracious hospitality and hosting during our visit, and for their expertise in assisting the production of this story.

Watch out for space rocks!


http://www.astronomy.com/~/media/Files/PDF/Magazine articles/Destination Moon.ashx


 
Last edited:
Top Bottom