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.
And wouldn't that have killed every land plant?
One of the clues is the size of the crater, which is still extant.
The first Hydrogen (Fusion) bomb was approx 10.4 Megatons.
It left a crater a mile wide..
The biggest H-bomb ever tested by the U.S. was 15 Megatons.
It left a crater 250 ft. deep and 6250 ft wide..
What's the size of the Yucatan Crater?
I would guess about 10 miles wide, and somewhere around 2000 to 2200 ft deep..
i.e., 100 megatons..
The Russians had designs for 100 megaton H-bombs, but never actually tested any.. ( not sure if they ever built one or not )
The Yucatan crater is estimated to be 110 - 125 miles in diameter. I don't know if there is any reliable estimate of depth.
Here's a link to an interesting article..
http://www.space.com/scienceastronomy/planetearth/asteroid_jello_001122.html
Says the crater is 100 - 150 miles wide..
I would have to revise my estimate another power of 10....
1,000 megatons.. or .. 1 to 1.5 GIGATONS..
Yeah.. I just posted a revised estimate after doing a little googling..
Over a decade of boiling temperatures and a nearly constant fires are rather a more serious problem for plant life...
I thought the Cretaceous extinction took about a million years?
One unforseen effect of this, because of the easier path, has been the early emergence of the "liberal" gene, which ideally would have been suppressed for a long, long time. Also, one can note that humans were to have started in north america rather that africa. Also, this event gave a big boost to cockroaches and rats, both of which were originally planned to exist in much smaller populations.
Lisa Simpson - "So a screamapillar has decided to inhabit your area. Things you need to know: 1) without constant reassurance it will die 2) it is sexually attracted to fire.
Homer - "Are you sure God didn't want this thing to be extinct!"
Who would have thought that one of the Planets in our solar system would have experienced multiple hits even during our life times (comet striking Jupiter).
Archival ping.
Over a decade of boiling temperatures and a nearly constant fires are rather a more serious problem for plant life...
Three-points for that one :)
Cans of Spam.
Just like us.
Obviously, 1.0 to 1.0.
;^)
I understand that scientists wanted to re-create the original event to verify the events. But they decided not to when they realized that re-creation would involve Michael Moore, a bag of beans, and a whole host of ethical issues.
Science is a process of discovery and refinement. Earlier in our history, people believed that the Earth-centered model for our solar system was accurate. Continued observation and modeling proved that the Heliocentric model to be correct. Hypotheses are brought forward and investigated, few stand the test of time...and aren't you glad of this? Else we would still be using beads, chants and rattles as a first line of defense against disease.
And of course two planets don't fit with our current hypotheses. Actually, I'm surprised more doesn't "fit" with our level of understanding. Did you know how to ride a bicycle the first time you tried? It took numerous falls and scrapes before you learned to keep the thing upright. So it is with Science.
As Stephen Hawking said, "The big bang happened, but can we say that a supreme being did not use that method to "create" the universe?" It is something that must not be left out.
I do not rule out the efforts of a Creator, but I do think He used His own natural laws to bring all into being.
Actually, what is seen is the ionization of the atmosphere.
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