What really happened when the “dino-killer” asteroid hit earth

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Source: BBC

By Jane Palmer

Where armies of trees once stretched skywards, seemingly escaping from the thickets of ferns and shrubs that clawed at their roots, only scorched trunks remain. Instead of the incessant hum of insect chatter blotting out the sound of ponderous giant dinosaurs, only the occasional flurry of wind pierces the silence. Darkness rules: the rich blues and greens, and occasional yellows and reds that danced in the Sun’s rays have all been wiped out.

This is Earth after a six-mile-wide asteroid smashed into it 66 million years ago.

“In the course of minutes to hours it went from this lush, vibrant world to just absolute silence and nothing,” says Daniel Durda, a planetary scientist at the Southwest Research Institute in Colorado. “Especially in the thousands of square miles around the impact site, the slate was just wiped clean.”

Much like putting in all the edge pieces of a jigsaw, scientists have outlined the lasting impacts of the meteor strike. It claimed the lives of more than three-quarters of the animal and plant species on Earth. The most famous casualties were the dinosaurs – although in fact many of them survived in the form of birds.

But filling in the details, especially what followed the impact and what enabled some life to survive, has proved more challenging.

The Chicxulub impact crater is buried (Credit: D. van Ravenswaay/Science Photo Library)

The Chicxulub impact crater is buried (Credit: D. van Ravenswaay/Science Photo Library)

The idea that the dinosaurs were wiped out by an asteroid strike was first proposed in 1980. At the time it was a controversial suggestion.

We will get to look at what is likely to be a sterile ocean at ground zero right after the impact

Then in 1991, geologists discovered the impact site: a crater 180km (110 miles) across on Mexico’s Yucatán Peninsula. They named itChicxulub, after the nearest town.

The crater was far from obvious, because it is underground. The northern half is also offshore, buried under 600m (660 yards) of ocean sediments.

So in April 2016, researchers began drilling nearly a mile down into the offshore section of the crater, to extract core samples 10 feet (3m) long. The team will analyse these extracts for changes in rock type, tiny fossils and perhaps even DNA trapped in the rock.

“We will get to look at what is likely to be a sterile ocean at ground zero right after the impact, and then we can watch life come back,” says Sean Gulick of the University of Texas Institute for Geophysics, who is involved in the drilling.

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