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Gullies on Mars could have been formed by recent periods of liquid meltwater, study suggests

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Image of the Terra Sirenum and its gullies captured by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter. Credit: NASA/JPL/Univ. of Arizona.

A study led by Brown University researchers offers new insights into how water from melting ice could have played a recent role in the formation of ravine-like channels that cut down the sides of impact craters on Mars.

The study, published in Science, focuses on Martian gullies, which look eerily similar to gullies that form on Earth in the Dry Valleys of Antarctica and are caused by water erosion from melting glaciers. The researchers, including Brown planetary scientist Jim Head, built a model that simulates a sweet spot for when conditions on Mars allow the planet to warm above freezing temperatures, leading to periods of on Mars when ice on and beneath the surface melts.

The scientists found that when Mars tilts on its axis to 35 degrees, the atmosphere becomes dense enough for brief episodes of melting to occur at gully locations. They then matched the data from their model to periods in Mars history when the gullies in the planet’s Terra Sirenum region are believed to have expanded rapidly downhill from high elevation points—a phenomenon that could not be explained without the occasional presence of water.

“We know from a lot of our research and other people’s research that early on in Mars history, there was running water on the surface with valley networks and lakes,” said Head, a professor of geological sciences at Brown. “But about 3 billion years ago, all of that liquid water was lost, and Mars became what we call a hyper-arid or polar desert. We show here that even after that and in the recent past, when Mars’ axis tilts to 35 degrees, it heats up sufficiently to melt snow and ice, bringing liquid water back until temperatures drop and it freezes again.”

The findings help fill in some of the missing gaps on how these gullies formed, including how high they start, how severe the erosion is and how far they extend down the side of craters.

Previous theories suggest Martian gullies were carved by carbon dioxide frost, which evaporates from soil, causing rock and rubble to slide down slopes. The height of the gullies made many scientists theorize that meltwater from glaciers had to be involved because of the distance they traveled down the slopes and how eroded the gullies looked. Proving liquid water could exist on Mars since it disappeared so long ago has been difficult because temperatures typically hover about 70° below freezing.

The results from the new study suggest that gully formation was driven by periods of melting ice and by CO2 frost evaporation in other parts of the year. The researchers found this has likely occurred repeatedly over the past several million years with the most recent occurrence about 630,000 years ago.

They say that if ice was present at gully locations in the areas they looked at when Mars’ axis tilted to about 35 degrees, the conditions would have been right for the ice to melt because temperatures rose above 273° Kelvin, equivalent to about 32° Fahrenheit.

“Our study shows that the global distribution of gullies is better explained by liquid water over the last million years,” said Jay Dickson, the study’s lead author and a former researcher at Brown who’s now at California Institute of Technology. “Water explains the elevation distribution of gullies in ways that CO2 cannot. This means that Mars has been able to create liquid water in enough volume to erode channels within the last million years, which is very recent on the scale of Mars geologic history.”

Despite doubts about meltwater being possible and scientists never being able to model the right conditions on Mars for ice to melt, the researchers were convinced that the meltwater theory was accurate because they had seen similar features firsthand in Antarctica. There, despite the , the sun is able to heat ice just enough for it to melt and for gully activity to occur.

The new study is a continuation of previous research the team started decades earlier looking at Martian gullies. In a 2015 study, for instance, the researchers showed it was possible that there may have been past periods on Mars when water was available to form gullies if Mars tilted on its axis enough. The findings encouraged them to model what that tilt was and match it with the locations and altitudes of gullies that have formed.

The paper raises anew the fundamental question of whether life could exist on Mars. This is because life, as it’s known on Earth, goes hand in hand with the presence of liquid water. Mars will eventually tilt to 35 degrees again, the researchers said.

“Could there be a bridge, if you will, between the early warm and wet Mars and the Mars that we see today in terms of liquid water?” Head said. “Everybody’s always looking for environments that could be conducive to not just the formation of life but the preservation and continuation of it. Any microorganism that might have evolved in early Mars is going to be in places where they can be comfortable in ice and then also comfortable or prosperous in liquid water. In the frigid Antarctic environment, for example, the few organisms that exist often occur in stasis, waiting for water.”

The study also introduces the importance of these gullies in terms of potential targets to visit during future exploration missions on Mars.

More information:
J. L. Dickson, Gullies on Mars could have formed by melting of water ice during periods of high obliquity, Science (2023). DOI: 10.1126/science.abk2464. www.science.org/doi/10.1126/science.abk2464

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Gullies on Mars could have been formed by recent periods of liquid meltwater, study suggests (2023, June 29)
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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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