Dinosaurs have been extinct for millions of year, but they continue to fascinate us because of their massive size, the funky headgear of a Triceratops and Stegosaurus and the huge teeth and ferocity of a Tyrannosaurus Rex. After studying the DNA in the water of Loch Ness in Scotland, scientists have just claimed that the Loch Ness monster thought to be a lost dinosaur, may actually be a giant eel but it does not stop the believers who flock to Scotland in an effort to catch a glimpse of a dinosaur. Perhaps the fact that they are extinct makes them a touch safer to approach and study. Who has not looked at an elephant and thought, “ok, big daddy, there used to be dinosaurs that were a lot bigger than you and thank goodness they are dead.” We are also fascinated by dinosaurs because we fear that the same death-by-asteroid awaits us. The most credible theory of the mass extinction of the dinosaurs is that a giant asteroid hit the earth and caused a cloud of dust blocking out the sun that killed off the plants and led to a slow, hungry death for the dinosaurs on the other side of the world which were not killed on impact. Recently other theories have seen the light that looked at the slower effect of climate change that is believed to have caused the extinction of the ichthyosaurs, a fish-like reptile that vanished before the mass extinction of dinosaurs. But now scientists have found new evidence of the asteroid in the Gulf of Mexico which supports the theory that it caused a sudden mass extinction of the dinosaurs and as Robert Lee Hotz writes in the Wall Street Journal, it includes minute by minute evidence of what had happened to the earth the moments after the asteroid hit our blue planet. He also examines whether we could meet the same fate. – Linda van Tilburg
Scientists discover new evidence of the Asteroid that killed off the dinosaurs
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Their analysis of these new rock samples from the Chicxulub crater, made public Monday, reveals a parfait of debris deposited in layers almost minute-by-minute at the heart of the impact during the first day of a global catastrophe. It records traces of the explosive melting, massive earthquakes, tsunamis, landslides and wildfires as the immense asteroid blasted a hole 100 miles wide and 12 miles deep, the scientists said.
The sediments also offer chemical evidence that the cataclysm blew hundreds of billions of tons of sulphur from pulverised ocean rock into the atmosphere, triggering a global winter in which temperatures world-wide dropped by as much as 30 degrees Fahrenheit for decades, the scientists said.
“It tells us what went on inside the crater on that day of doom that killed the dinosaurs,” said Jay Melosh, a geophysicist at Purdue University who studies impact craters and wasn’t a member of the drilling team. “All of this mayhem is directly recorded in the core.”
The scientists in the drilling consortium, led by geophysicist Sean Gulick at the University of Texas in Austin, who was co-chief of the $10 million project, published their research in the Proceedings of the National Academy of Sciences. The project was sponsored by the International Ocean Discovery Program and the International Continental Scientific Drilling Program.
The scientists worked aboard a drilling ship called Lifeboat Myrtle anchored offshore from the Mexican port of Progreso. In 2016, they drilled into the crater’s inner rim for the first time, buried in the seafloor under about 1,500 feet of limestone deposited in the millions of years since the impact.
Geologists study rocks as a record of compressed time, with ticks of the geologic clock typically measured in layers that accumulate over thousands of years. In the Chicxulub crater, though, hundreds of feet of sediments built up rapidly, recording impact effects like a high-speed stop-action camera, the scientists said.
“Here we have 130 meters in a single day,” said Dr. Gulick. “We can read it on the scale of minutes and hours, which is amazing.”
The asteroid blasted a cavity between 25 and 30 miles deep in the first seconds of impact, creating a boiling cauldron of molten rocks and super-heated steam, according to the scientists’ interpretation of the rock. Rebounding from the hammer blow, a plume of molten rock splashed up into a peak higher than Mount Everest.
Within minutes, it collapsed into itself, splashing gigantic waves of lava outward that solidified into a ring of high peaks, the scientists said.
About 20 minutes or so later, sea water surged back over the newly formed peaks, covering them in a blanket of impact rocks, the scientists said. As minutes became hours, waves choked with shards of volcanic glass and splintered rock rippled back and forth, coating the peaks in a layer of impact rock called suevite, the scientists said. As the hours passed, the backwash of waves added more and more finely graded debris.
At the very top of the rock core, the scientists detected traces of organic matter and charcoal. “We think the reflected tsunami brought back these traces of land and these tiny, tiny charcoal fragments,” said Dr. Gulick. “The land was clearly on fire.”
Earth normally speeds through a cosmic rain of debris. In 2013, a relatively small meteor about 30 meters in diameter and weighing about 13,000 metric tons exploded in the air over Russia, damaging about 7,200 buildings and injuring about 1,400 people.
Inspired by the discovery of the Chicxulub crater in the 1970s, astronomers and NASA now routinely map the orbits of nearby asteroids and meteor swarms for signs of potentially lethal collisions. The space agency is planning a mission in 2021 to a nearby asteroid called Didymos to test ways to safely deflect a dangerous comet or asteroid before it strikes.
There are currently no sizeable asteroids known to be on a collision course with Earth, NASA astronomers say. The dinosaur-killing asteroid, estimated to have been up to 50 miles or so across, was likely an event that occurs only once every billion years, the scientists said.
“Impacts are a fact of life on Earth,” said Dr. Melosh. “But we know there are no big asteroids crossing Earth’s orbit.”
– Write to Robert Lee Hotz at [email protected]
