Posted on 07/08/2004 12:29:19 AM PDT by LibWhacker
According to new research led by a University of Colorado at Boulder geophysicist, a giant asteroid that hit the coast of Mexico 65 million years ago probably incinerated all the large dinosaurs that were alive at the time in only a few hours, and only those organisms already sheltered in burrows or in water were left alive.
The six-mile-in-diameter asteroid is thought to have hit Chicxulub in the Yucatan, striking with the energy of 100 million megatons of TNT, said chief author and Researcher Doug Robertson of the department of geological sciences and the Cooperative Institute for Research in Environmental Sciences. The "heat pulse" caused by re-entering ejected matter would have reached around the globe, igniting fires and burning up all terrestrial organisms not sheltered in burrows or in water, he said.
A paper on the subject was published by Robertson in the May-June issue of the Bulletin of the Geological Society of America. Co-authors include CU-Boulder Professor Owen Toon, University of Wyoming Professors Malcolm McKenna and Jason Lillegraven and California Academy of Sciences Researcher Sylvia Hope.
"The kinetic energy of the ejected matter would have dissipated as heat in the upper atmosphere during re-entry, enough heat to make the normally blue sky turn red-hot for hours," said Robertson. Scientists have speculated for more than a decade that the entire surface of the Earth below would have been baked by the equivalent of a global oven set on broil.
The evidence of terrestrial ruin is compelling, said Robertson, noting that tiny spheres of melted rock are found in the Cretaceous-Tertiary, or KT, boundary around the globe. The spheres in the clay are remnants of the rocky masses that were vaporized and ejected into sub-orbital trajectories by the impact.
A nearly worldwide clay layer laced with soot and extra-terrestrial iridium also records the impact and global firestorm that followed the impact.
The spheres, the heat pulse and the soot all have been known for some time, but their implications for survival of organisms on land have not been explained well, said Robertson. Many scientists have been curious about how any animal species such as primitive birds, mammals and amphibians managed to survive the global disaster that killed off all the existing dinosaurs.
Robertson and colleagues have provided a new hypothesis for the differential pattern of survival among land vertebrates at the end of the Cretaceous. They have focused on the question of which groups of vertebrates were likely to have been sheltered underground or underwater at the time of the impact.
Their answer closely matches the observed patterns of survival. Pterosaurs and non-avian dinosaurs had no obvious adaptations for burrowing or swimming and became extinct. In contrast, the vertebrates that could burrow in holes or shelter in water -- mammals, birds, crocodilians, snakes, lizards, turtles and amphibians -- for the most part survived.
Terrestrial vertebrates that survived also were exposed to the secondary effects of a radically altered, inhospitable environment. "Future studies of early Paleocene events on land may be illuminated by this new view of the KT catastrophe," said Robertson.
Though it appears at first that these energies are hard to imagine, it is very straightforward to do the calculations.
I don't have time to rebuild the calculations I've done several times in the past now, though.
Simply assume a mass 0.5-10 miles (1000-16000 meters) on a side and with a density about 3-5 times that of water for rock, 1-1.5 times water (which is 1000 kilograms/ cubic meter) for a water laden comet. It doesn't matter that much. It is easier to assume the mass is cubic instead of roundish, and again it doesn't matter much.
The huge energy factor is the velocity, which ranges from 20,000-80,000 mph (10-40 kilometers/ sec) for most comets/meteors/asteroids when they strike the earth's atmosphere.
For ease of your calculations, I provide that a single megaton of energy is equal to 4,186,000,000,000 joules (4.186 X 10^12) of energy (1,000,000,000 kilogram-meter^2/ sec^2) ... and I suggest you convert the masses and dimensions for your impact body to metric.
You will find that a moderate size asteroid striking the earth deposits many, many times the energy of the full arsenal of nuclear bombs on earth. Even the small 1ft diameter rocks end their life as spectacular fireballs seen noted for hundreds of miles. Fortunately, we don't get hit by anything bigger than a ten or twenty yards in diameter very often, but even those result in things like Crater Lake.
I though Crater Lake was volcanic in origin.
hehehehehe....
he said noodle-head
There is the whole T-Rex was a scavenger argument. Though there have been fossils of Stegs found with healed T-Rex teeth marks so it appears T-Rex went after live and moving thingys.
hehehehe noodle head......
Would that be hard, soft, cooked?
Indeed it is. It is a caldera.
Minority and female dinosaurs were hurt hardest.
Heehee...Who can say? But I will say that he is at the very least, entertaining.
He also adamantly poo poos the BADD (Birds Are Dinosaur Descendents) theory. I can't say one way or the other but the evidence does seem to be overwhelmingly in favor of it.
bump for later
Yup... it is the remnant of Mount Mazama which blew itself to pieces in a pyroclastic event (think Mt. St. Helens times 1,000) about 20,000 years ago.
This just proves that we really are not positive about the meteoric origin of the extra-terrestrial craters. We have yet to see a crater formed by such means. We may see one tomorrow... or we may never be looking at the right time to see one being formed.
This just proves that we really are not positive about the meteoric origin of the extra-terrestrial craters. We have yet to see a crater formed by such means.Actually, since 1994's SL-9 impacts on Jupiter (for those who needed more than the firsthand observations of the only scientist to visit the Moon -- Apollo 17), there aren't any credible scientists who attribute lunar craters to anything besides impact. In 1960 there was only a tiny minority (geologists mostly) who subscribed to the impact origin model. Now the alleged volcanic origin of Martian craters has been raised up (again), but with Martian proximity to the largest known asteroid belt, and the probable asteroidal capture origin for both of Mars' moons, plus the likelihood that most of the craters of the Hemisphere of Craters were formed from a single large impact event, it appears to be more foolishness from the impact opponents.
George W. Bush will be reelected by a margin of at least ten per cent
Here's an online facsimile of a paper rejected for publication in 1968. Have times changed? Or is it like Thoreau (or somebody) said -- "Times don't change. We change." ;')A Flash From the Past:On the Moon, material that is freshly exposed has a slight bluish tinge. Over time, because of the constant bomb ardment of cosmic rays, other high-energy particles and micrometeorites, the structure of the material changes and iron particles tend to predominate, making the material slightly red.
New Evidence Supports Moon Blast
by Henry Fountain
March 4, 2003
In the Clementine photos, Dr. Buratti and Mr. Johnson found o ne small crater that was "very, very blue and fresh appearing," Dr. Buratti said. It also happened to be in the exact center of the area they were looking. And it was the proper size — slightly less than a mile across, including the ejecta blanket. Dr. Bu ratti estimated the size of the asteroid at 20 yards in diameter.A Celestial CollisionEarly in the evening of June 18, 1178, a group of men near Canterbury, England, stood admiring the sliver of a new moon hanging low in the west. In terms they later described to a monk who recorded their sighting, "Suddenly a flaming torch sprang from the moon, spewing fire, hot coals and sparks." In continuing their description of the event, they reported that "The moon writhed like a wounded snake and finally took on a blackish appearance"... [P]lanetary scientist Jack Hartung of the State University of New York... gathered enough clues to suggest that a large asteroid... might have smacked into the moon just over the horizon on the back side. To test his suspicion, Hartung went to the Lunar and Planetary Institute in Houston, and inspected Russian and American photographs of the moon's back side. Sure enough, in just the right place, he found a remarkably fresh crater, 12 miles across and twice as deep as the Grand Canyon. From it radiated white splatter marks for hundreds of miles... Such an impact, reason astrophysicists, would set the moon to ringing like a gong for thousands of years... At Texas' McDonald Observatory, astronomers Odile Calame and J. Derral Mulholland of the University of Texas find that the surface of the moon moves back and forth fully 80 feet! Such an oscillation clearly implies a collision with something large, sometime within the not-too-distant past, probably within the memory of mankind. The problem is that there is no way to peg the date exactly at 1178.
by Larry Gedney
February 10, 1983Manicouagan CraterOriginally about 60 miles wide, this crater in Quebec, Canada, is one of the largest impact craters remaining on the planet. One of the distinguishing features of the more than 200 million-year-old crater is a ring lake. Popular with scientists, the crater has provided key insights about what exactly happens geologically when asteroids and comets slam into Earth.
by Dr David Whitehouse
Monday, February 15, 1999
Possible Formation of the Guatemala Basin by the Impact of an Extraterrestrial BodyThe earth must be as frequently cratered per unit area as the moon. By a relative cross section argument, more than 13 times the number of craters the size of the maria on the moon exist, or existed, on the earth. Whether such events occur with sufficient frequency in recent geologic time to provide tangible evidence today of such cratering is uncertain. From the arguments set forth, and the continuing discovery of meteorite craters on the continents (Short, 1966, Baldwin, 1963, Dietz, 1961, and Prouty, 1952) it seems likely that the importance of the effect of extraterrestrial bodies impacting the earth has been, at least, underestimated (the Alverez's hypothesis concerning the end of the dinosaurs by such a mechanism was more than a decade in the future). Certainly there is as much evidence at present to support our hypothesis for the formation of the Guatemala Basin as other hypotheses advanced to explain the low heat flow found in this basin.
by Charles E. Corry and Miller L. Bell
With the tests for shock processes advanced by Short (1966), our hypothesis should be capable of field verification or rejection.
George W. Bush will be reelected by a margin of at least ten per cent
Regardless of what was witnessed in 1178, or the observations of "blue" residue around an assumed "new" crater, we have yet to see a crater formed by an impact event... and therefore, the attribution of craters to impacts remains a theory, not a proven fact.
Is it the most logical theory? I would certainly think so.
ping to finish reading posts later.
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Talk about global warming!
Well anyway, this could be used as good justification to move forward on a space-based defense system. One that can hit incoming asteroids as well as outgoing ICBM's.
There was nothing sweeter than the subtle tang of desperation that hard-science students had when they came crawling to me to edit their lab reports.
Making them grovel was the real reward, the beer was just icing on the cake.
Didn't something similar happen with Vince Foster?
Try old Immanuel's "Worlds in Chaos" for another kick!
"Worlds in Chaos" = "Ages In Chaos"
This year Norway was hit by a meteoroid that by some reports may have caused a 20 Kiloton explosion. Imagine if something like that his some populated area.
We live in a shooting gallery!
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