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Earth's oldest known impact crater may tell us a lot about our planet's frozen past – Space.com

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Scientists have identified the oldest known impact crater on Earth — and the ancient structure could tell us how our planet emerged from a long-ago frozen phase.

Yarrabubba Crater, a 43-mile-wide (70 kilometers) geological feature in Western Australia, is 2.229 billion years old, plus or minus 5 million years, a new study reports. That’s about half the age of Earth itself and 200 million years older than the previous record holder, the 190-mile-wide (300 km) Vredefort Dome in South Africa. 

Intriguingly, the Yarrabubba impact appears to have occurred just as our planet started coming out of a “Snowball Earth” period, when much of the planet was covered by ice. And that may not be a coincidence, study team members said.

Related: Crash! The 10 biggest impact craters on Earth

“The age of the Yarrabubba impact matches the demise of a series of ancient glaciations,” co-author Nicholas Timms, an associate professor in the School of Earth and Planetary Sciences at Curtin University in Western Australia, said in a statement.

“After the impact, glacial deposits are absent in the rock record for 400 million years,” Timms added. “This twist of fate suggests that the large meteorite impact may have influenced global climate.”

Ancient craters such as Yarrabubba are difficult to find on our active Earth. Many get buried when crustal plates dive beneath each other, and most others are worn away by wind and water over the eons.

Indeed, “Yarrabubba no longer even looks like a crater,” study lead author Timmons Erickson, from NASA’s Johnson Space Center in Houston and Curtin University’s School of Earth and Planetary Sciences, told Space.com.

But a different team of scientists — led by Francis Macdonald, now a geology professor at the University of California Santa Barbara — recognized Yarrabubba as such back in 2003, thanks to measurements of magnetic anomalies in the area and the presence of rocks shocked by an impact.  

It was clear that the Yarrabubba strike occurred long ago, but its exact age had remained elusive until now. In the new study, which was published online today (Jan. 21) in the journal Nature Communications, Erickson and his colleagues analyzed tiny pieces of Yarrabubba’s shocked rock. 

Specifically, the researchers studied grains of monazite and zircon that were recrystallized by the impact, measuring the amounts of uranium, thorium and lead contained in each. Monazite and zircon readily take up uranium but not lead when they crystallize, and uranium and thorium radioactively decay into lead at known rates. So, these measurements told the team how long ago that recrystallization occurred. 

Yarrabubba’s age is intriguing, because a lot was going on 2.229 billion years ago. For example, photosynthesizing cyanobacteria had just started pumping large amounts of oxygen into Earth’s atmosphere, initiating a dramatic process known as the Great Oxidation Event.

The planet also came out of a deep freeze — one of multiple snowball phases Earth has experienced during its 4.5-billion-year history — around the time of the Yarrabubba impact. To see if these two events might possibly have been connected, Erickson and his colleagues performed computer simulations of the Yarrabubba strike.

Related: Potentially dangerous asteroids (images)

This is not a crazy thought; after all, the catastrophic, dinosaur-killing impact of 66 million years ago is thought to have wrought much of its destruction via rapid and dramatic climate change.

The researchers’ models slammed a 4.3-mile-wide object (7 km) into a frigid Western Australian landscape, one covered by an ice sheet that ranged from 1.2 miles to 3.1 miles (2 to 5 km) thick in various runs. They found that such a strike would instantly vaporize between 23 cubic miles and 58 cubic miles (95 to 240 cubic km) of ice and cause up to 1,300 cubic miles (5,400 cubic km) of total melting.

This suggests that between 200 trillion lbs. and 440 trillion lbs. (90 trillion to 200 trillion kilograms) of water vapor, a potent greenhouse gas, were blasted into Earth’s upper atmosphere immediately after the Yarrabubba impact.

Not enough is known about the ancient Earth’s atmospheric structure and composition to confidently model how this injection of water vapor would have affected climate, Erickson and his colleagues stressed. 

“Nevertheless, considering that Earth’s atmosphere at the time of impact contained only a fraction of the current level of oxygen, a possibility remains that the climatic forcing effects of H2O vapor released instantaneously into the atmosphere through a Yarrabubba-sized impact may have been globally significant,” they wrote in the new study.

Discovering and dating additional ancient craters could help answer such questions. And there should be more such features out there to find, Erickson said. After all, Earth got pummeled by far more impactors in its youth than it does now. (By the way, the new study does not present the evidence of the oldest known impact. Researchers have found ejecta — bits of rock blasted out by asteroid or comet strikes — that are up to 3.4 billion years old. But their associated craters have not been identified.)

And geologists could conceivably get windows onto an even deeper past than that afforded by Yarrabubba, Erickson said. Researchers probably can’t untangle the complicated history of the oldest known rocks on Earth, which are 4 billion years old, he said, but they might have some luck with the ancient nuclei known as cratons. 

“They stretch back to 2.5 to 3.5 billion years old,” Erickson said. “I think, theoretically, it’s possible to find impact craters in that age range.”

Mike Wall’s book about the search for alien life, “Out There” (Grand Central Publishing, 2018; illustrated by Karl Tate), is out now. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook

Need more space? Subscribe to our sister title “All About Space” Magazine for the latest amazing news from the final frontier! (Image credit: All About Space)

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Here’s how Helene and other storms dumped a whopping 40 trillion gallons of rain on the South

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More than 40 trillion gallons of rain drenched the Southeast United States in the last week from Hurricane Helene and a run-of-the-mill rainstorm that sloshed in ahead of it — an unheard of amount of water that has stunned experts.

That’s enough to fill the Dallas Cowboys’ stadium 51,000 times, or Lake Tahoe just once. If it was concentrated just on the state of North Carolina that much water would be 3.5 feet deep (more than 1 meter). It’s enough to fill more than 60 million Olympic-size swimming pools.

“That’s an astronomical amount of precipitation,” said Ed Clark, head of the National Oceanic and Atmospheric Administration’s National Water Center in Tuscaloosa, Alabama. “I have not seen something in my 25 years of working at the weather service that is this geographically large of an extent and the sheer volume of water that fell from the sky.”

The flood damage from the rain is apocalyptic, meteorologists said. More than 100 people are dead, according to officials.

Private meteorologist Ryan Maue, a former NOAA chief scientist, calculated the amount of rain, using precipitation measurements made in 2.5-mile-by-2.5 mile grids as measured by satellites and ground observations. He came up with 40 trillion gallons through Sunday for the eastern United States, with 20 trillion gallons of that hitting just Georgia, Tennessee, the Carolinas and Florida from Hurricane Helene.

Clark did the calculations independently and said the 40 trillion gallon figure (151 trillion liters) is about right and, if anything, conservative. Maue said maybe 1 to 2 trillion more gallons of rain had fallen, much if it in Virginia, since his calculations.

Clark, who spends much of his work on issues of shrinking western water supplies, said to put the amount of rain in perspective, it’s more than twice the combined amount of water stored by two key Colorado River basin reservoirs: Lake Powell and Lake Mead.

Several meteorologists said this was a combination of two, maybe three storm systems. Before Helene struck, rain had fallen heavily for days because a low pressure system had “cut off” from the jet stream — which moves weather systems along west to east — and stalled over the Southeast. That funneled plenty of warm water from the Gulf of Mexico. And a storm that fell just short of named status parked along North Carolina’s Atlantic coast, dumping as much as 20 inches of rain, said North Carolina state climatologist Kathie Dello.

Then add Helene, one of the largest storms in the last couple decades and one that held plenty of rain because it was young and moved fast before it hit the Appalachians, said University of Albany hurricane expert Kristen Corbosiero.

“It was not just a perfect storm, but it was a combination of multiple storms that that led to the enormous amount of rain,” Maue said. “That collected at high elevation, we’re talking 3,000 to 6000 feet. And when you drop trillions of gallons on a mountain, that has to go down.”

The fact that these storms hit the mountains made everything worse, and not just because of runoff. The interaction between the mountains and the storm systems wrings more moisture out of the air, Clark, Maue and Corbosiero said.

North Carolina weather officials said their top measurement total was 31.33 inches in the tiny town of Busick. Mount Mitchell also got more than 2 feet of rainfall.

Before 2017’s Hurricane Harvey, “I said to our colleagues, you know, I never thought in my career that we would measure rainfall in feet,” Clark said. “And after Harvey, Florence, the more isolated events in eastern Kentucky, portions of South Dakota. We’re seeing events year in and year out where we are measuring rainfall in feet.”

Storms are getting wetter as the climate change s, said Corbosiero and Dello. A basic law of physics says the air holds nearly 4% more moisture for every degree Fahrenheit warmer (7% for every degree Celsius) and the world has warmed more than 2 degrees (1.2 degrees Celsius) since pre-industrial times.

Corbosiero said meteorologists are vigorously debating how much of Helene is due to worsening climate change and how much is random.

For Dello, the “fingerprints of climate change” were clear.

“We’ve seen tropical storm impacts in western North Carolina. But these storms are wetter and these storms are warmer. And there would have been a time when a tropical storm would have been heading toward North Carolina and would have caused some rain and some damage, but not apocalyptic destruction. ”

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Follow AP’s climate coverage at https://apnews.com/hub/climate

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Follow Seth Borenstein on Twitter at @borenbears

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Associated Press climate and environmental coverage receives support from several private foundations. See more about AP’s climate initiative here. The AP is solely responsible for all content.

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‘Big Sam’: Paleontologists unearth giant skull of Pachyrhinosaurus in Alberta

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It’s a dinosaur that roamed Alberta’s badlands more than 70 million years ago, sporting a big, bumpy, bony head the size of a baby elephant.

On Wednesday, paleontologists near Grande Prairie pulled its 272-kilogram skull from the ground.

They call it “Big Sam.”

The adult Pachyrhinosaurus is the second plant-eating dinosaur to be unearthed from a dense bonebed belonging to a herd that died together on the edge of a valley that now sits 450 kilometres northwest of Edmonton.

It didn’t die alone.

“We have hundreds of juvenile bones in the bonebed, so we know that there are many babies and some adults among all of the big adults,” Emily Bamforth, a paleontologist with the nearby Philip J. Currie Dinosaur Museum, said in an interview on the way to the dig site.

She described the horned Pachyrhinosaurus as “the smaller, older cousin of the triceratops.”

“This species of dinosaur is endemic to the Grand Prairie area, so it’s found here and nowhere else in the world. They are … kind of about the size of an Indian elephant and a rhino,” she added.

The head alone, she said, is about the size of a baby elephant.

The discovery was a long time coming.

The bonebed was first discovered by a high school teacher out for a walk about 50 years ago. It took the teacher a decade to get anyone from southern Alberta to come to take a look.

“At the time, sort of in the ’70s and ’80s, paleontology in northern Alberta was virtually unknown,” said Bamforth.

When paleontogists eventually got to the site, Bamforth said, they learned “it’s actually one of the densest dinosaur bonebeds in North America.”

“It contains about 100 to 300 bones per square metre,” she said.

Paleontologists have been at the site sporadically ever since, combing through bones belonging to turtles, dinosaurs and lizards. Sixteen years ago, they discovered a large skull of an approximately 30-year-old Pachyrhinosaurus, which is now at the museum.

About a year ago, they found the second adult: Big Sam.

Bamforth said both dinosaurs are believed to have been the elders in the herd.

“Their distinguishing feature is that, instead of having a horn on their nose like a triceratops, they had this big, bony bump called a boss. And they have big, bony bumps over their eyes as well,” she said.

“It makes them look a little strange. It’s the one dinosaur that if you find it, it’s the only possible thing it can be.”

The genders of the two adults are unknown.

Bamforth said the extraction was difficult because Big Sam was intertwined in a cluster of about 300 other bones.

The skull was found upside down, “as if the animal was lying on its back,” but was well preserved, she said.

She said the excavation process involved putting plaster on the skull and wooden planks around if for stability. From there, it was lifted out — very carefully — with a crane, and was to be shipped on a trolley to the museum for study.

“I have extracted skulls in the past. This is probably the biggest one I’ve ever done though,” said Bamforth.

“It’s pretty exciting.”

This report by The Canadian Press was first published Sept. 25, 2024.

The Canadian Press. All rights reserved.

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The ancient jar smashed by a 4-year-old is back on display at an Israeli museum after repair

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TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.

Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.

Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.

The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.

The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.

It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.

Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.

Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.

Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.

Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.

Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.

The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”

The Canadian Press. All rights reserved.

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