July 5, 2010

Chicxulub: The Extinction of the Dinosaurs

It has been commonly accepted for decades that, 65 million years ago, an asteroid hit the Earth and wiped out the dinosaurs.  This catastrophic event changed the course of evolution on this planet and, ultimately, allowed human beings to grow and flourish.   What is, perhaps, lesser known is where this asteroid landed.   This was the smoking gun that would prove the theory, but scientists and explorers scoured the Earth for years before it was finally found.

In March 2010, 41 international scientists met, in the USA, to evaluate the evidence.    The location had been strongly suspected since the 1970s, but this was the moment when all research had been completed and all conclusions picked over for validity.    They were finally able to proclaim the site with absolute certainty.  The deadly asteroid hit the Yucatán Peninsula, in Mexico, around the area where the village of  Chicxulub (pron. Chick-shoo-loob) now sits.  The March 2010 report may be read on-line here.

The Chicxulub crater is 112 miles (180km) wide.  There is evidence of impact down to 2000–3600 ft (600-1110 meters).  The asteroid that caused it must have been 6 miles (10km) in diameter.   Here's how that might have looked:



The impact of the asteroid would have detonated with the force of  4×1023 joules of energy.  That's 2 million times more powerful that the greatest of mankind's bombs.  Mega-tsunamis would have risen all over the Earth, some thousands of feet high.   The sky would have rained down with burning boulders, each causing their own atomic bomb style explosions, as they landed.   This would have been happening halfway across the globe, thus was the force that they were being thrown through the sky.   Meanwhile, the shockwaves through the Earth itself would have triggered volcanic eruptions and massive earthquakes.   All of this would have taken mere seconds to occur. 

For the creatures not killed in this sudden violence, then the next six months would have been deadly.   Soot and debris filled the skies, blocking out the sun and destroying vegetation.   The rock deep within the impact site contained a lot of carbonate and sulfate, which vaporized in the air to create a global rain of sulphuric acid.   This burnt the skin to the bone on contact.  Without food and with air and water laden with poison, 50% of the world's species of flora and fauna simply became extinct. 



After it was all over, the world looked like a very different place.   The huge predators, like Tyrannosaurus Rex, were dead.   The survivors tended to be those small enough to hide from the rain and to be able to live on small amounts of food.   It would also be very helpful to be warm-blooded, to counteract the global fall in temperature.    Those who made it through the apocalypse included the insects and the mammals.   In short, this was humanity's big chance to develop and, finally, take over the world. 

It is a musing of historians and scientists to imagine the 'what if' scenario of this asteroid never hitting the Earth.  For sure, the huge dinosaurs would have continued on for millions more years and may still be with us.  The number of mammals would have been kept down because of them.   Even  paleontologists cannot say with certainty whether human beings would have eventually evolved.   But even if we had, then it's difficult to imagine that the Earth would now be covered in our cities, technology and landmarks, when there were Tyrannosaurus Rexs trampling them all down again.

Of course, it's been 65 million years since the aesteroid hit the Yucatán Peninsula.   The crater has slowly been practically hidden by the land and sea on top of it.   It's clearly viewed from space, but from the ground, the best we have to see are a ring of cenotes marking out the crater's trough.   Nevertheless, Chicxulub is still worth visiting.  It retains its fishing port charm, while its beautiful beaches, chilled out atmosphere and delicious cuisine mark it as a favourite vacation spot for Mexicans.   For those who wish to see the environmental signature of the crater, then there are tours available within the village. 

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