Chicxulub Crater Reports Begin

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Posted on November 19, 2016 in Amazing Facts, Dating Methods, Geology, Physics, Solar System

Scientists who drilled into the large crater in southern Mexico have started interpreting the cores.

It’s going to be hard to separate the facts from the interpretations for this one. Drill cores from the southern Yucatan crater named Chicxulub are now being analyzed. What do they mean? The news reports freely speculate about unobservable events, mixing fact and fancy according to the current favorite narrative:

  • Dino-Killing Asteroid May Have Punctured Earth’s Crust (Live Science): “After analyzing the crater from the cosmic impact that ended the age of dinosaurs, scientists now say the object that smacked into the planet may have punched nearly all the way through Earth’s crust, according to a new study.”
  • Dinosaur-killing asteroid turned planet Earth inside-out (New Scientist): “An expedition to the Chicxulub crater has drawn a new timeline of how the cataclysmic impact that probably killed the dinosaurs happened – and how it may have carved out new niches in which life could flourish, even in the face of utter destruction.”
  • Asteroid impacts could create niches for early life, suggests Chicxulub crater study (Science Daily): “Around 65 million years ago a massive asteroid crashed into the Gulf of Mexico causing an impact so huge that the blast and subsequent knock-on effects wiped out around 75 per cent of all life on Earth, including most of the dinosaurs.”
  • Dinosaur-killing asteroid’s crater yields new clues (Fox News): “You know the story: About 65 million years ago, a huge asteroid slammed into the Earth, bringing the dinosaur era to an end and creating a massive crater in the process.”

Several new memes are emerging from the first reports from the expedition. For one, the impact punched through the crust. A second one says that the impact created new habitats for life. A third one, quite surprising, is that the asteroid strike created “instant Himalayas.” This one, described by the BBC News, is based on physical models of the geological rebound given the assumed size and speed of the impactor.

These show how the space impactor made the hard surface of the planet slosh back and forth like a fluid.

At one stage, a mountain higher than Everest was thrown up before collapsing back into a smaller range of peaks.

And this all happens on the scale of minutes, which is quite amazing,” Prof Joanna Morgan from Imperial College London, UK, told BBC News.

That’s a pretty clear case of catastrophism. The instant mountains are gone, of course, having collapsed. Only traces of the crater remain, detectable indirectly by the kinds of materials, by geographical anomalies like an arc of cenotes and limestone deposits, and by shocked minerals at various distances. Conclusions about the effects on life remain speculative (watch the word “likely”) –

The debris thrown into the atmosphere likely saw the skies darken and the global climate cool for months, perhaps even years, driving many creatures into extinction, not just the dinosaurs.

While the Chicxulub impact remains the most popular theory for the extinction of the dinosaurs, it leaves many questions unanswered: such as, why did all the dinosaurs (large and small) die all over the globe far from the impact, when many more delicate species, including butterflies, birds and amphibians, survived? Why did it simultaneously erase the pterosaurs and marine reptiles? How could an asteroid impact be so selective about what it kills?

At this point, the researchers seem more concerned about testing models of crater formation than answering those questions.

It’s good empirical science to drill for cores and study them. Models can estimate energy dissipation if the mass and speed of the impactor are reasonable; these can be tested against the crater evidence. Beyond that, be careful to separate fact from storytelling.

 

 

One Comment

EBCrider November 19, 2016

Instant mountains? There are similar mountains on Mercury on the opposite side of the planet from a large impact. It’s truly an amazing, nearly unthinkable, amount of energy that can cause such a thing.

As for the impact theory of extinction, one of the problems with it is that many dinosaurs lived for “millions” of years after the impact, and not just small ones. I believe you’ve reported on this problem in the past.

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