https://www.sciencedaily.com/releases/2025/06/250608222155.htm

"Beneath Earth s surface, nearly 3,000 kilometers down, lies a mysterious layer where seismic waves speed up inexplicably. For decades, scientists puzzled over this D' layer. Now, groundbreaking experiments by ETH Zurich have finally revealed that solid rock flows at extreme depths, acting like liquid in motion. This horizontal mantle flow aligns mineral crystals called post-perovskite in a single direction, explaining the seismic behavior. It s a stunning leap in understanding Earth s deep inner mechanics, transforming a long-standing mystery into a vivid map of subterranean currents that power volcanoes, earthquakes, and even the magnetic field.

"A seismic mystery nearly 3,000 kilometers underground has finally been solved: researchers found that solid rock flows horizontally, aligning minerals and causing a shift in earthquake wave speeds. This changes our entire view of Earth’s deep interior.

"Earthquakes, volcanic eruptions, shifting tectonic plates -- these are all signs that our planet is alive. But what is revealed deep inside the Earth surprises laymen and scientists alike: Almost 3000 kilometers below the Earth's surface, solid rock is flowing that is neither liquid, like lava, nor brittle like solid rock. This is shown by a new study by geoscientists led by Motohiko Murakami,

***

"For over 50 years, researchers have been puzzling over a strange zone deep inside the Earth -- the so-called D" layer, around 2700 kilometers beneath our feet. Earthquake waves suddenly behave differently there: their speed jumps as if they were traveling through a different material. What exactly happens at that layer of the mantle has been unclear for a long time, until now.

***

"Using a sophisticated computer model, they finally discovered something important: depending on the direction in which the post-perovskite crystals point, the hardness of the mineral changes. Only when all the crystals of the mineral point in the same direction in the model are the seismic waves accelerated -- as can be observed in the D" layer at a depth of 2700 kilometers.

"In an unusual laboratory experiment at ETH Zurich, Murakami has now proven that post-perovskite crystals align themselves in the identical direction under enormous pressure and extreme temperatures. To do this, the researchers measured the speed of seismic waves in their experiment and were also able to reproduce the jump that occurs at the D" layer in the laboratory. "We have finally found the last piece of the puzzle," says Murakami.

"The big question is: what makes these crystals line up? The answer is that solid mantle rock that flows horizontally along the lower edge of the Earth's mantle. Researchers have long suspected that this movement -- a kind of convection like boiling water -- must exist but have never been able to prove it directly.

"Murakami and his colleagues have now also demonstrated experimentally that mantle convection of solid rock is present at the boundary between the core and the Earth's mantle, i.e. that solid -- not liquid -- rock flows slowly but steadily at this depth. "This discovery not only solves the mystery of the D" layer but also opens a window into the dynamics in the depths of the Earth," Murakami explains."

Comment: our planet is still alive and changing/evolving. It is doing it at a given rate we who live here can tolerate.

https://phys.org/news/2025-04-scientists-microbes-earth-deep-soil.html?utm_source=nwlet...

"Scientists have discovered a new phylum of microbes in Earth's Critical Zone, an area of deep soil that restores water quality. Ground water, which becomes drinking water, passes through where these microbes live, and they consume the remaining pollutants. The paper, "Diversification, niche adaptation and evolution of a candidate phylum thriving in the deep Critical Zone.

***

"'The Critical Zone extends from the tops of trees down through the soil to depths up to 700 feet," Tiedje said. "This zone supports most life on the planet as it regulates essential processes like soil formation, water cycling and nutrient cycling, which are vital for food production, water quality and ecosystem health. Despite its importance, the deep Critical Zone is a new frontier because it's a major part of Earth that is relatively unexplored."

"Tiedje,...discovered in this huge, unexplored microbial world a completely different phylum, or primary category, of microbe called CSP1-3.

"This new phylum was identified in soil samples from both Iowa and China at depths down to 70 feet. Why Iowa and China? Because these two areas have very deep and similar soils, researchers wanted to know if their occurrence is more general and not just in one area, Tiedje said.

"Tiedje's team extracted DNA from these deep soils and found that CSP1-3's ancestors lived in the water—hot springs and fresh water—many millions of years ago. They underwent at least one major habitat transition to colonize soil environments—first topsoil and, later, deep soils, during its evolutionary history.

"Tiedje also found that the microbes were active. "Most people would think that these organisms are just like spores or dormant," he said. "But one of our key findings we found through examining their DNA is that these microbes are active and slowly growing."

"Tiedje was also surprised to find these microbes were not rare members of the community, but were dominant; in some cases they made up 50% or more of the community, which is never the case in surface soils.

"'I believe this occurred because the deep soil is such a different environment, and this group of organisms has evolved over a long period of time to adapt to this impoverished soil environment," Tiedje added.

"Soil is our planet's biggest water filter. When water passes through soil, it is cleaned through physical, chemical and biological processes. The surface soil, where most plant roots reside is often a very small volume of soil through which rainwater passes quickly. But the deep soil has a much larger volume. This is where CSP1-3 helps out. They live off the carbon and nitrogen that's washed down from the topsoil to complete the purification process.

"'CSP1-3 are the scavengers cleaning up what got through the surface layer of soil," Tiedje said. "They have a job to do."

"The next step, Tiedje said, is to culture some of these microbes in the laboratory and if they grow, we can then learn more about their unique physiologies that allow them to be so successful in this deep soil environment. This is not easy. Most of the microbial world is not cultured because it's so difficult to replicate the conditions in which they live and grow."

Comment: life everywhere on Earth contributes to the ecological balance. It grows with purpose. We will see more discoveries like this one.

https://www.livescience.com/planet-earth/geology/study-reveals-flawed-argument-in-debat...

"Earth's crust today has a surprisingly similar composition to the planet's first outer shell, or "protocrust," new research finds.

"This early rocky shell featured chemical signatures previously thought to occur only in continental crusts made by the process of subduction, in which one tectonic plate slides under another.

"But plate tectonics isn't actually required to produce these signatures, according to the new study published April 2 in the journal Nature.

"Scientists discover giant blobs deep inside Earth are 'evolving by themselves' — and we may finally know where they come from
Continent-size blobs in Earth's mantle are a billion years old, ancient crystals reveal

***

"Historically, the fact that chemical signatures seen in modern plate tectonic processes occurred in protocrust from Earth's first billion years, during the Hadean eon, had been used as evidence to support the theory that plate tectonics started nearly as soon as Earth had solid ground — roughly 4 billion years ago.

"'That's probably a flawed argument now," study lead author Craig O'Neill, a geophysicist at Queensland University of Technology in Australia, told Live Science.

"'Yes, that signature forms today [through plate tectonics]," O'Neill said. "But the assumption that the Earth has always behaved as it does now, all through time, so you can extrapolate that back — that's obviously a bit fraught."

"The precise signatures under debate are trace elements, such as titanium and niobium, which combine in the crystal structure of rocks as they solidify from hot magma. However, the behavior of these elements depends heavily on the conditions around them.

"What O'Neill and his colleagues realized was that the chemistry of the molten, early Earth was quite different from today's.

"As the Earth solidified from molten rock, the iron-rich portions of that magma sank and concentrated, becoming today's metallic core. This means that the mantle became less rich in iron over time. As such, magma from the mantle found in modern subduction zones, such as the Pacific "Ring of Fire," might not act like the magma found on the early Earth.

"The researchers modeled the behavior of these trace elements under the conditions of the first few hundred millions of years of Earth, a time when the crust, core and mantle were still differentiating and the developing mantle was still iron-rich.

***

"But the whole planet probably transitioned to the plate tectonic system later, between 3.2 billion and 2.7 billion years ago. There's far more evidence of rocks getting recycled and pushed around during that time period, O'Neill argues. "The interesting debate from here on will be what is the interaction between these two signatures through time," he said. "When does the actual, modern signature become important, and is there a clever way to tell the two apart?'"

Comment: the science of crustal subduction dates from the 1960's. We've learned a lot since then but the story is still young and changing.

https://www.chemistryworld.com/news/mineral-extracting-microorganism-could-solve-early-...

"Nitrogen fixation – a key step for complex life’s evolution – could have been helped along by ancient bacteria living in shallow water that were able to extract molybdenum from rocks. That’s according to researchers who have demonstrated how this offers a plausible explanation to the paradox of how molybdenum-nitrogenase, the predominant nitrogen-fixing enzyme, could have evolved 3.2 billion years ago when Earth’s supply of dissolved molybdenum was scarce.

"DNA and proteins all need nitrogen. Without it, life as we know it could not have begun or evolved. However, on early Earth, most nitrogen was locked up in the atmosphere as highly stable and unreactive dinitrogen gas. Volcanic lightning is suspected to have kickstarted the availability of nitrogen for ancient life by zapping apart the triple bond of dinitrogen to form nitrates that rained down on Earth at least 3.7 billion years ago.

"By 3.2 billion years ago, according to a 2015 study that analysed the chemistry of such ancient rocks, lifeforms had already evolved the ability to pull nitrogen from the air and convert it into ammonia using a molybdenum-based enzyme. This was around a billion years before the two other nitrogenase enzymes that use different metals, namely iron or vanadium, are thought to have evolved.

"However, this presented a conundrum. At the time, dissolved molybdenum was scarce due to a lack of atmospheric oxygen to react with molybdenum-containing rocks and wash it into the ocean. So how did molybdenum-nitrogenase evolve as the prevailing nitrogen-fixing enzyme?

"Hailiang Dong at China University of Geosciences and colleagues have now shown in the lab that an ancient photosynthesising microorganism could have extracted the required molybdenum from molybdenite, or molybdenum disulfide, a mineral present in rocks on early Earth. This, they say, could have promoted the rise of nitrogen fixation via molybdenum-nitrogenase.

"To help solve the puzzle, the team looked to the ancient anoxygenic photosynthesising microbe Rhodopseudomonas palustris – a purple, rod-shaped bacterium found in marshy habitats. This has all three nitrogenase enzymes – molybdenum, vanadium and iron – and switches between them depending on metal availability.

***

‘'Our findings demonstrate that molybdenite can indeed support nitrogen fixation by R. palustris, with the rate of nitrogen fixation increasing in correlation with the concentration of molybdenite,’ says Dong. The results highlight that molybdenum-bearing minerals could have provided a crucial source of molybdenum for photosynthesising microbes in early, low-oxygen environments, such as shallow waters near land.

‘'The results look convincing to me and definitely offer a plausible mechanism for life to obtain molybdenum on the Archean Earth,’ comments Eva Stüeken, at the University of St Andrews, UK, who co-authored the 2015 study that discovered molybdenum-nitrogenase 3.2 billion years ago. However, she points out that other molybdenum sources, particularly in deep-sea hydrothermal vents, remain to be investigated for their potential importance for early life in the open ocean. ‘Nevertheless, the work definitely addresses an important biogeochemical problem,’ she says. ‘It is undoubtedly thought-provoking.’'

Comment: this is another intricate detail in how materials were made available for life to begin. As usual a helpful bacteria is achieving the goal.

https://www.sciencedaily.com/releases/2024/10/241011141553.htm

"Researchers have used the chemical fingerprints of zinc contained in meteorites to determine the origin of volatile elements on Earth. The results suggest that without 'unmelted' asteroids, there may not have been enough of these compounds on Earth for life to emerge.

"Volatiles are elements or compounds that change into vapour at relatively low temperatures. They include the six most common elements found in living organisms, as well as water. The zinc found in meteorites has a unique composition, which can be used to identify the sources of Earth's volatiles.

***

"Their results show that while these 'melted' planetesimals contributed about 70% of Earth's overall mass, they only provided around 10% of its zinc.

"According to the model, the rest of Earth's zinc came from materials that didn't melt and lose their volatile elements. Their findings suggest that unmelted, or 'primitive' materials were an essential source of volatiles for Earth.

"'We know that the distance between a planet and its star is a determining a factor in establishing the necessary conditions for that planet to sustain liquid water on its surface," said Martins, the study's lead author. "But our results show that there's no guarantee that planets incorporate the right materials to have enough water and other volatiles in the first place -- regardless of their physical state.'"

Comment: This study implies that receiving enough materials for life is a touch and go process, tenuous at best. This planet got it all. Chance or design? I pick design.

https://phys.org/news/2024-09-exceptional-fish-fossil-rethink-earth.html

"Coelacanths are deep-sea fish that live off the coasts of southern Africa and Indonesia and can reach up to two meters in length. For a long time, scientists believed they were extinct.

"In new research published in Nature Communications, we reveal the best-preserved coelacanth fossil ever found from the ancient period hundreds of millions of years ago when these ancient sea-dwellers first evolved. The fossil comes from the Gogo Formation on Gooniyandi Country in northern Western Australia.

"We also studied the evolution of all the hundreds of coelacanth species we know from the fossil record to find out what drove the creation of new species across the eons.

"The answer came as a surprise: the greatest influence on coelacanth evolution was not ocean temperature or oxygen levels but tectonic activity. When the vast plates of Earth's crust were moving around more, new species were more likely to appear.

"Coelacanths are "lobe-finned" fish, which means they have robust bones in their fins a bit like the bones in our arms. Scientists believe they are more closely related to tetrapods (animals with backbones and four limbs, such as frogs, emus and humans) than to most other fishes.

"Coelacanths have been around for a long time. The oldest known fossils are more than 410 million years old. But because these fossils are mostly fragments, we don't know a lot about what the earliest coelacanths were like.

"Later, during the age of dinosaurs which began around 250 million years ago, coelacanths became more diverse. In total, we have found traces of more than 175 fossil species from all over the globe.

***

"Our study of the new species led us to analyze the evolutionary history of all known coelacanths. In doing so, we calculated the rates of evolution across their 410 million year history.

We found that coelacanths have generally evolved slowly, with a few intriguing exceptions.

"Furthermore, we analyzed a series of environmental factors that we considered potential candidates for influencing coelacanth evolutionary rates. These included tectonic plate activity, ocean temperatures, water oxygen levels, and atmospheric carbon dioxide levels.

"Of all the variables we looked at, the one with the greatest influence on the rate of coelacanth evolution was tectonic plate activity. New species of coelacanth were more likely to evolve during periods of heightened tectonic activity, as seismic movement transformed habitats. (my bold)

"Along with our analysis of all fossil Coelacanths, we also had a close look at the two living species, Latimeria chalumnae and Latimeria menadoensis.

"At first glance, these fish look almost identical to some of their counterparts from hundreds of millions of years ago. However, on closer analysis we could see they were in fact distinct from their extinct relatives.

:While Latimeria has essentially ceased evolving new features, the proportions of its body and the details of its DNA are still changing a little. So perhaps it's not a "living fossil" after all."

Comment: plate tectonics are vital for life to appear, so this finding in Coelacanths is not surprising. Their current minor adaptations fit my thinking that major speciation is finished. Continental drift is very slow now which makes any new speciation very slow to appear if at all.

https://www.sciencealert.com/scientists-detect-invisible-electric-field-around-earth-fo...

"An invisible, weak energy field wrapped around our planet Earth has finally been detected and measured.

"It's called the ambipolar field, an electric field first hypothesized more than 60 years ago, and its discovery will change the way we study and understand the behavior and evolution of our beautiful, ever-changing world.

"'Any planet with an atmosphere should have an ambipolar field," says astronomer Glyn Collinson of NASA's Goddard Space Flight Center.

"'Now that we've finally measured it, we can begin learning how it's shaped our planet as well as others over time."

"Earth isn't just a blob of dirt sitting inert in space. It's surrounded by all sorts of fields. There's the gravity field. We don't know a lot about gravity, especially considering how ubiquitous it is, but without gravity we wouldn't have a planet. Gravity also helps keep the atmosphere snug against the surface.

"There's also the magnetic field, which is generated by the rotating, conducting material in Earth's interior, converting kinetic energy into the magnetic field that spins out into space. This protects our planet from the effects of the solar wind and radiation, and also helps to keep the atmosphere from blowing away.

***

"'It's called the ambipolar field and it's an agent of chaos. It counters gravity, and it strips particles off into space," Collinson explains in a video.

"'But we've never been able to measure this before because we haven't had the technology. So, we built the Endurance rocket ship to go looking for this great invisible force."

"Here's how the ambipolar field was expected to work. Starting at an altitude of around 250 kilometers (155 miles), in a layer of the atmosphere called the ionosphere, extreme ultraviolet and solar radiation ionizes atmospheric atoms, breaking off negatively charged electrons and turning the atom into a positively charged ion.

"The lighter electrons will try to fly off into space, while the heavier ions will try to sink towards the ground. But the plasma environment will try to maintain charge neutrality, which results in the emergence of an electric field between the electrons and the ions to tether them together.

"This is called the ambipolar field because it works in both directions, with the ions supplying a downward pull and the electrons an upward one.

"The result is that the atmosphere is puffed up; the increased altitude allows some ions to escape into space, which is what we see in the polar wind.

"This ambipolar field would be incredibly weak, which is why Collinson and his team designed instrumentation to detect it. The Endurance mission, carrying this experiment, was launched in May 2022, reaching an altitude of 768.03 kilometers (477.23 miles) before falling back to Earth with its precious, hard-won data.

"'And it succeeded. It measured a change in electric potential of just 0.55 volts – but that was all that was needed.

"'A half a volt is almost nothing – it's only about as strong as a watch battery," Collinson says. "But that's just the right amount to explain the polar wind."

"That amount of charge is enough to tug on hydrogen ions with 10.6 times the strength of gravity, launching them into space at the supersonic speeds measured over Earth's poles.

"Oxygen ions, which are heavier than hydrogen ions, are also lofted higher, increasing the density of the ionosphere at high altitudes by 271 percent, compared to what its density would be without the ambipolar field.

"What's even more exciting is that this is just the first step. We don't know the broader implications of the ambipolar field, how long it has been there, what it does, and how it has helped shape the evolution of our planet and its atmosphere, and possibly even the life on its surface."

Comment: This newly-found field protects our atmosphere adding to all the various special characteristics of this planet.

https://www.universetoday.com/167891/elliptical-orbits-could-be-essential-to-the-habita...

"However, it was not until Kepler’s observations that the planets followed elliptical orbits around the Sun (rather than circular orbits) that astronomical models matched observations of the heavens completely.

"As it turns out, this very quirk of orbital mechanics may be essential to the emergence of life on planets like Earth. That was the hypothesis put forth in a recent study by a team of astronomers led by the University of Leeds. According to their work, orbital eccentricity (how much a planet’s orbit deviates from a circle) can influence a planet’s climate response, which could have a profound effect on its potential habitability. These findings could be significant for exoplanet researchers as they continue to search for Earth-like planets that could support life. (my bold)

***

'It was not until Johannes Kepler introduced the concept of elliptical orbits that scientists could match their astronomical models to the observed motions of the planets. Since then, scientists have learned a great deal about orbital parameters – such as semi-major axis (a), eccentricity (e), axial tilt (?), inclination (i), and periapsis – and how they can influence a planet’s climate over time. These parameters have also become very important for exoplanet studies, as they are vital to determining if a planet could be “potentially habitable.”

***

"After running 30 simulation years for each case, they examined how both groups of exoplanets behaved regarding their climate response. This included latitudinal and seasonal variations in their hydrological cycle (sea ice, land snow, and clouds) and land habitability metrics like surface temperature and precipitation. As they indicated in their paper, exoplanets within the highly eccentric orbit group had 25% more habitable land area for more than 80% of their orbit, with an average increase of 7% for their entire orbital cycle.

Comment: another unique characteristic of the Earth which led to seasons and stirred the evolution of life.

https://www.quantamagazine.org/physicists-pinpoint-the-quantum-origin-of-the-greenhouse...

"In 1896, the Swedish physicist Svante Arrhenius realized that carbon dioxide (CO2) traps heat in Earth’s atmosphere — the phenomenon now called the greenhouse effect. Since then, increasingly sophisticated modern climate models have verified Arrhenius’ central conclusion: that every time the CO2 concentration in the atmosphere doubles, Earth’s temperature will rise between 2 and 5 degrees Celsius.

***

"First, in 2022, physicists settled a dispute over the origin of the “logarithmic scaling” of the greenhouse effect. That refers to the way Earth’s temperature increases the same amount in response to any doubling of CO2, no matter the raw numbers.

"Then, this spring, a team led by Robin Wordsworth of Harvard University figured out why the CO2 molecule is so good at trapping heat in the first place. The researchers identified a strange quirk of the molecule’s quantum structure that explains why it’s such a powerful greenhouse gas — and why pumping more carbon into the sky drives climate change.

***

"...global warming is tied to a numerical coincidence involving two different ways that CO2 can wiggle.

“'If it weren’t for this accident,” Pierrehumbert said, “then a lot of things would be different.”

***

"A key question was the origin of the logarithmic scaling of the greenhouse effect — the 2-to-5-degree temperature rise that models predict will happen for every doubling of CO2. One theory held that the scaling comes from how quickly the temperature drops with altitude. But in 2022, a team of researchers used a simple model to prove that the logarithmic scaling comes from the shape of carbon dioxide’s absorption “spectrum” — how its ability to absorb light varies with the light’s wavelength.

"This goes back to those wavelengths that are slightly longer or shorter than 15 microns. A critical detail is that carbon dioxide is worse — but not too much worse — at absorbing light with those wavelengths. The absorption falls off on either side of the peak at just the right rate to give rise to the logarithmic scaling.

“'The shape of that spectrum is essential,” said David Romps, a climate physicist at the University of California, Berkeley, who co-authored the 2022 paper. “If you change it, you don’t get the logarithmic scaling.”

The carbon spectrum’s shape is unusual — most gases absorb a much narrower range of wavelengths. “The question I had at the back of my mind was: Why does it have this shape?” Romps said. “But I couldn’t put my finger on it.” (my bold)

***

"A photon of 15-micron light contains the exact energy required to set the carbon atom swirling about the center point in a sort of hula-hoop motion. Climate scientists have long blamed this hula-hoop state for the greenhouse effect, but — as Ångström anticipated — the effect requires too precise an amount of energy, Wordsworth and his team found. The hula-hoop state can’t explain the relatively slow decline in the absorption rate for photons further from 15 microns, so it can’t explain climate change by itself.

"The key, they found, is another type of motion, where the two oxygen atoms repeatedly bob toward and away from the carbon center, as if stretching and compressing a spring connecting them. This motion takes too much energy to be induced by Earth’s infrared photons on their own.

"But the authors found that the energy of the stretching motion is so close to double that of the hula-hoop motion that the two states of motion mix with one another. Special combinations of the two motions exist, requiring slightly more or less than the exact energy of the hula-hoop motion.

"This unique phenomenon is called Fermi resonance after the famous physicist Enrico Fermi, who derived it in a 1931 paper. But its connection to Earth’s climate was only made for the first time in a paper last year by Shine and his student, and the paper this spring is the first to fully lay it bare."

Comment: Note my bold. Is C0^2 so unusual a gas because it was designed to be different? Without global warming we wouldn't be here. This is another of Gould's 'contingencies' for life to occur.

https://www.sciencealert.com/mysterious-dark-oxygen-discovered-at-bottom-of-ocean-stuns...

"Chugging quietly away in the dark depths of Earth's ocean floors, a spontaneous chemical reaction is unobtrusively creating oxygen, all without the involvement of life.

"This unexpected discovery upends the long-standing consensus that it takes photosynthesizing organisms to produce the oxygen we need to breathe.

***

"The discovery of oxygen production by a non-photosynthetic process requires us to rethink how the evolution of complex life on the planet might have originated," says SAMS marine scientist Nicholas Owens, who wasn't involved in the research.

***

"In the midst of the Pacific Ocean, black, rounded rocks pepper the floor. Here, at depths of more than 4,000 meters (13,000 feet), oxygen levels slowly but surely keep increasing, the scientists' measurements showed.

***

"To investigate the mystery, the researchers collected some of the nodule rocks, to see if they were the source of this 'dark oxygen' production in the lab.

"Scatterings of these nodules carpet vast areas of the ocean's bottom. They're natural deposits of rare-earth metals like cobalt, manganese, and nickel, all jumbled up in a polymetallic mix.

"We value these exact metals for their use in batteries, and it turns out that's exactly how the rocks may be spontaneously acting on the ocean floor.

"'The researchers found single polymetallic nodules produced voltages of up to 0.95 V. So when clustered together, like batteries in a series, they can easily reach the 1.5 V required to split oxygen from water in an electrolysis reaction.

"It appears that we discovered a natural 'geobattery,'" says Northwestern University chemist Franz Geiger. "These geobatteries are the basis for a possible explanation of the ocean's dark oxygen production."

"'It appears that we discovered a natural 'geobattery,'" says Northwestern University chemist Franz Geiger. "These geobatteries are the basis for a possible explanation of the ocean's dark oxygen production."

While there's still much to investigate, such as the scale of oxygen production by the polymetallic nodules, this discovery offers a possible explanation for the mysterious stubborn persistence of ocean 'dead zones' decades after deep sea mining has ceased.

"'In 2016 and 2017, marine biologists visited sites that were mined in the 1980s and found not even bacteria had recovered in mined areas. In unmined regions, however, marine life flourished," explains Geiger.

"'Why such 'dead zones' persist for decades is still unknown. However, this puts a major asterisk onto strategies for sea-floor mining as ocean-floor faunal diversity in nodule-rich areas is higher than in the most diverse tropical rainforests."

"As well as these massive implications for deep-sea mining, 'dark oxygen' also sparks a cascade of new questions around the origins of oxygen-breathing life on Earth.

"Ancient microbial cyanobacteria have long been credited for first supplying the oxygen required for the evolution of complex life billions of years ago, as a waste product of photosynthesis turning sunlight into their energy source.

"'We now know that there is oxygen produced in the deep sea, where there is no light," says Sweetman.

"'I think we, therefore, need to revisit questions like: Where could aerobic life have begun?'"

Comment: this teaches us to be careful in deep-sea mining. An important discovery, but photosynthesis is still the major source of oxygen. It is an interesting addition to origin of life studies.

https://www.sciencenews.org/article/sulfur-key-first-water-earth

"A chemical element that’s not even in H2O — sulfur — is the reason Earth first got its water, a new study finds, bolstering a similar claim made a year ago. The discovery means our planet was born with all it needed to create its own water and so did not have to receive it from elsewhere.

"Water is essential to terrestrial life, but Earth formed in a region around the newborn sun that was so hot the planet should have been dry (SN: 5/6/15). Now two independent studies of a specific type of meteorite reach the same conclusion: Lots of hydrogen — a key component of water — came to Earth not as H2O but instead bonded with sulfur. This allowed the hydrogen to survive the heat and later join oxygen, the most common element in Earth’s crust, to create water.

***

"The four planets closest to the sun — Mercury, Venus, Earth and Mars — all formed in the inner part of the solar nebula, the disk of gas and dust that spun around the newborn sun. The solar nebula’s inner region was so dense that friction heated it enormously, drying it out. Many researchers have therefore proposed that Earth got its water only after ice-bearing asteroids and comets born far from the sun hit Earth.

"In 2020, however, researchers reported a surprise: Hydrogen exists in rare meteorites known as enstatite chondrites, which resemble our planet’s building blocks (SN: 8/27/20). The discovery suggested that Earth’s building blocks possessed plenty of hydrogen right from the start, cosmochemist Laurette Piani of the University of Lorraine in Vandœuver-lès-Nancy, France, and colleagues found.

"But some scientists doubted the result. They feared that water on present-day Earth had contaminated the meteorites with hydrogen.

"Last year, the researchers in France reported that the hydrogen in enstatite chondrites is bonded to sulfur. Now another team has discovered that most of the hydrogen is locked inside pyrrhotite, a bronze-colored iron sulfide mineral, Thomas Barrett of the University of Oxford and his colleagues report in a paper submitted to arXiv.org on June 19.

“'Their arguments about the spectroscopic characterization of where the hydrogen is living in the rock are good,” UCLA cosmochemist Edward Young says of the latest work. That means the hydrogen is native to the meteorite and not the result of terrestrial contamination.

"Morbidelli agrees. “It explains why enstatite chondrites have hydrogen,” he says, calling the discoveries over the past four years a paradigm shift. “You don’t accrete water. You accrete hydrogen and oxygen separately in different minerals, and then they combine with each other.”

"That’s easy to do because early Earth was hot and molten, covered with a magma ocean. “You can think of a magma ocean as a big ball of hot oxygen,” Young says, because oxygen outnumbered all other elements in the crust put together. Just add hydrogen from Earth’s building blocks and you’ve got H2O.

"But Young questions whether Earth’s building blocks actually supplied most of the hydrogen in our planet’s water. He thinks the hydrogen also came directly from the solar nebula, which consisted primarily of molecular hydrogen, or H2, gas. And still more hydrogen, in the form of water, arrived when icy objects hit the Earth.

“'From an exobiology perspective, this study of the origin of water from enstatite chondrites is really important,” Morbidelli says. Sulfur is common — the tenth most abundant element in the cosmos — so even in solar systems that lack icy asteroids and comets, rocky planets should be able to acquire hydrogen and turn it into water, setting the stage for the possible development of life on these worlds."

Comment: Hydrogen and oxygen were among the earliest elements formed. And combined as H2O they create a miracle liquid which is found all over the universe. It is 70% of our surface. Our supply suggests the Earth was especially designed for life to appear.

https://www.sciencealert.com/life-only-needed-a-small-amount-of-oxygen-to-explode-scien...

"Now, new research scouring the globe for geological data suggests oxygen didn't flood the atmosphere and oceans a little over half a billion years ago, so much slowly dissolve into shallow basins and oceanic shelves.

"That doesn't mean oxygen played no role in kickstarting the burst of biodiversification that gave rise to all the weird, wacky and wild creatures we see today.

"'Cambrian animals likely did not require as much oxygen as scientists used to believe," says Erik Sperling, a geobiologist at Stanford University and senior author of the new study.

"'We found minor increases in oxygenation" – in sedimentary rocks formed on the bottom of ancient oceans – "that are at the correct magnitude to drive big changes in ecology."

"Without enough oxygen, single-celled organisms and other small creatures eking out an existence before the Cambrian explosion wouldn't have been able to grow much bigger and expand their body plans, scientists have reasoned.

***

"Their analysis of two trace metals, molybdenum and uranium, both indicators of global ocean oxygen levels, along with biogeochemical models of oxygen flows between the oceans and atmosphere, suggest that oxygen levels in the deep ocean didn't reach modern levels until 140 million years after the Cambrian explosion, in the Devonian period.

"'From a global perspective, we didn't see the full oxygenation of the oceans to near modern levels until about 400 million years ago, around the time that we see the appearance of large forests on land," explains Richard Stockey, a palaeobiologist at the University of Southampton, who led the study.

***

"The team's findings expand on the results of a 2017 study, which found shallow seas became oxygenated first, but atmospheric oxygen didn't reach modern levels until some 50-100 million years after the Cambrian explosion, during the Ordovician period that followed.

"However, other recent research has found that oxygen levels started rising in early Ediacaran period some 640–600 million years ago, in the first of three successive oxygen pulses that coincided with important evolutionary leaps in the lead-up to the Cambrian explosion.

"Meanwhile, other researchers contest that oxygen levels throughout deep time have been extremely variable so it's hard to say what effect they had on blossoming biodiversity."

Comment: Be clear in your thinking that oxygen doesn't cause anything. It's availability for use is the issue.

https://www.sciencenews.org/article/freshwater-earth-ancient-crystal-years

"Researchers analyzed oxygen molecules within 4-billion-year-old zircon crystals from Western Australia’s Jack Hills, one of the oldest rock formations on Earth. The relative proportions of oxygen’s heaviest and lightest forms, or isotopes, in the zircons are possible only if there been a significant amount of freshwater present, geochemist Hamed Gamaleldien of Khalifa University in Abu Dhabi and colleagues report June 3 in Nature Geoscience.

***

'Even if there was a freshwater cycle 4 billion years ago, that doesn’t mean there was necessarily life on Earth that far back, Gamaleldien says. “But at least we have the main ingredient to form life.” Currently, the oldest agreed-upon evidence for life on Earth comes from fossilized microbial mats, or stromatolites, in Australia’s Strelley Pool Chert (SN: 10/17/18). Those stromatolites date to 3.5 billion years ago.

"Cycles of evaporation and rain alter the chemical makeup of water molecules. When water evaporates from the ocean’s surface, leaving the salt behind, the lighter form of oxygen, oxygen-16, tends to evaporate faster than the heavier oxygen-18. That lighter water may then rain out over land, and perhaps evaporate again. Over time, the freshwater becomes more concentrated in oxygen-16 compared with the original seawater.

***

"The team then ran thousands of computer simulations to determine the likelihood of different explanations for the observed ratios. “We concluded that the main water on Earth was oceanic,” or salty, Gamaleldien says. “But only when we used freshwater [did] it create the results we see.” Furthermore, he says, the findings also suggest that enough land had emerged above sea level by that time to support a water cycle. Researchers have pondered whether Earth was completely covered by oceans between around 3 billion and 4 billion years ago.

***

“'The early Earth is really difficult [to study] because there are so few data points,” Reimink says. Ancient crystals like these remain the only clues scientists have to Earth’s earliest time, he adds. “We need to keep pushing the limits of these zircon grains.'”

Comment: fresh water requires dry land, so it is a matter of when that land appeared. The water allows life, salt or fresh. As a result, life started in the salty oceans and then evolved to fresh water on dry land.

https://www.scientificamerican.com/article/mysterious-dark-fungi-are-lurking-everywhere/

"Why This Matters: The land, water and air around us are chock-full of DNA fragments from fungi that mycologists can’t link to known organisms. These slippery beings are so widespread scientists are calling them “dark fungi.” It’s a comparison to the equally elusive dark matter and dark energy that permeate the universe. Like those invisible entities, dark fungi are hidden movers and shakers, prime examples of what E. O. Wilson called “the little things that run the world.”

***

"...mycologists have realized that such phantoms are everywhere. Point to a patch of dirt, a body of water, even the air you’re breathing, and odds are that it is teeming with mushrooms, molds and yeasts (or their spores) that no one has ever seen. In ocean trenches, Tibetan glaciers and all habitats between, researchers are routinely detecting DNA from obscure fungi. By sequencing the snippets, they can tell they’re dealing with new species, thousands of them, that are genetically distinct from any known to science. They just can’t match that DNA to tangible organisms growing out in the world.

***

"...their cryptic lifestyle has made it a maddening challenge for scientists trying to show how exactly they run it.

Taxonomists have described just 150,000 of the millions of fungi predicted by global biodiversity estimates, and recent discoveries suggest a huge portion of what’s left may be off-limits to routine biological investigation. “We have not even started to scratch the surface,” says Henrik Nilsson, a mycologist at the University of Gothenburg in Sweden. “I'd be willing to bet that the clear majority will be dark.” Given the central place of fungi in the web of life that sustains us, experts argue we should get a better grasp on them.

"Everything we know about dark fungi comes from environmental DNA, or eDNA. That term refers to strings of base pairs—the building blocks of DNA that are constantly sloughing off all living things. Researchers can analyze these free-floating bits of double helix to determine which species have been hanging around an area without seeing them. To identify fungi specifically, scientists look to a handy genetic marker called the internal transcribed spacer (ITS), which consists of several hundred base pairs that evolve quickly and thus help distinguish between species. Although the ITS is only a tiny fraction of the genome, researchers can single it out and amplify it with the same polymerase chain reaction technology used in COVID lab tests. If an ITS sequence is different enough from all others in genetic databases, it is thought to represent a new species, whether scientists lay eyes on its physical form or not.

***

"Every year researchers stumble on some 2,000 new fungi via the standard route, spotting them in nature or under a microscope. Yet a single eDNA study can register 10 times more dark fungi than that. As often as not, the fragments are among the most abundant DNA samples in their ecosystem. “I don’t think I ever saw an environmental sequencing study with less than 30 percent unknowns,” Nilsson says, and the ratio is typically much higher. Sometimes only a minority of DNA sequences can be classified at any meaningful taxonomic level, narrowing them from a kingdom (in this case, fungi) to a phylum and then to a class, and so on down to a species."

Comment: our knowledge of the Earth's ecosystem is still growing rapidly. It is an enormously complex at many levels: “the little things that run the world” are vitally important to humans, who would not otherwise be here. This answers dhw's ridiculous complaint about the 99.9% extinction rate in evolution. The necessary ecosystem variety of so many species is required for all to live. The 99.9% extinct are the direct ancestors of the now living.

https://phys.org/news/2024-06-bacteria-greenhouse-gases-previously-thought.html

"Caltech researchers have discovered a new class of enzymes that enable a myriad of bacteria to "breathe" nitrate when in low-oxygen conditions. While this is an evolutionary advantage for bacterial survival, the process produces the greenhouse gas nitrous oxide (N2O) as a byproduct, the third-most potent greenhouse gas, after carbon dioxide and methane.

***

"Most cells in the biosphere utilize certain proteins called reductases to breathe, or respire, oxygen, but Murali and her team discovered a wide swath of reductases that had evolved closely related proteins to respire nitric oxide, producing nitrous oxide in the process.

"Nitric oxide and nitrous oxide are intermediate chemicals produced during denitrification, the process by which bacteria break down nitrate, the chemical found in fertilizers. Bacteria are able to switch from respiring oxygen to nitric oxide in many different environments—wetlands, alpine soils, lakes, and so on—when oxygen levels start to drop below approximately 10% of atmospheric levels.

***

'Geobiologists had previously believed that anaerobic pathways like nitrate respiration evolutionarily came before the ability to breathe oxygen, in our early single-celled ancestors. This study "flips the script," according to Fischer, demonstrating that the proteins that enable nitrate respiration actually evolved from those that respire oxygen, two billion years ago.

"'Microbiologists often predict what metabolisms microbes are capable of performing based on comparative genomics," explains co-author James Hemp, a former Caltech postdoctoral scholar now of the company Meliora.bio in Utah.

"'However, these hypotheses are rarely tested experimentally. Our work has dramatically increased the biochemical diversity of one of the most studied enzyme families in microbiology. This should serve as a warning that automated metabolic analysis without experimental verification can lead to incorrect conclusions of the functions of microbes and communities.'"

Comment: the biochemical processes creating our atmosphere ae shown to be much more complex. This is added to our knowledge, showing all the interlocking layers that are beneficial.

https://www.sciencealert.com/earths-core-seems-to-be-wrapped-in-an-ancient-unexpected-s...

"The most high-resolution map yet of the underlying geology beneath Earth's Southern Hemisphere revealed something we previously never knew about: an ancient ocean floor that may wrap around the core.

"This thin but dense layer exists around 2,900 kilometers (1,800 miles) below the surface, according to a study published in 2023. That depth is where the molten, metallic outer core meets the rocky mantle above it. This is the core-mantle boundary (CMB).

"Seismic investigations, such as ours, provide the highest resolution imaging of the interior structure of our planet, and we are finding that this structure is vastly more complicated than once thought," said geologist Samantha Hansen from the University of Alabama when the findings were announced.

***

"Hansen and her colleagues used 15 monitoring stations buried in the ice of Antarctica to map seismic waves from earthquakes over three years. The way those waves move and bounce reveals the composition of the material inside Earth. Because the sound waves move slower in these areas, they're called ultralow velocity zones (ULVZs).

"'Analyzing [thousands] of seismic recordings from Antarctica, our high-definition imaging method found thin anomalous zones of material at the CMB everywhere we probed," said geophysicist Edward Garnero from Arizona State University.

"'The material's thickness varies from a few kilometers to [tens] of kilometers. This suggests we are seeing mountains on the core, in some places up to five times taller than Mt. Everest."

"According to the researchers, these ULVZs are most likely oceanic crust buried over millions of years.

***

"It's tricky to make assumptions about rock types and movement based on seismic wave movement, and the researchers aren't ruling out other options. However, the ocean floor hypothesis seems the most likely explanation for these ULVZs right now.

"There's also the suggestion that this ancient ocean crust could be wrapped around the entire core, though as it's so thin, it's hard to know for sure. Future seismic surveys should be able to add further to the overall picture.

"One of the ways the discovery can help geologists is in figuring out how heat from the hotter and denser core escapes up into the mantle. The differences in composition between these two layers are greater than they are between the solid surface rock and the air above it in the part we live on.

"'Our research provides important connections between shallow and deep Earth structure and the overall processes driving our planet," said Hansen."

Comment: a planet grows bit by bit so the deeper we study the older we go.

https://phys.org/news/2024-06-earth-great-oxidation-event-

"About 2.5 billion years ago, free oxygen, or O2, first started to accumulate to meaningful levels in Earth's atmosphere, setting the stage for the rise of complex life on our evolving planet.

"Scientists refer to this phenomenon as the Great Oxidation Event, or GOE for short. But the initial accumulation of O2 on Earth was not nearly as straightforward as that moniker suggests, according to new research led by a University of Utah geochemist.

"This "event" lasted at least 200 million years. And tracking the accumulation of O2 in the oceans has been very difficult until now, said Chadlin Ostrander, an assistant professor in the Department of Geology and Geophysics.

"Emerging data suggest that the initial rise of O2 in Earth's atmosphere was dynamic, unfolding in fits-and-starts until perhaps 2.2. billion years ago," said Ostrander, lead author on the study published June 12 in the journal Nature. "Our data validate this hypothesis, even going one step further by extending these dynamics to the ocean."

***

"The "smoking gun" evidence of an anoxic atmosphere is the presence of rare, mass-independent sulfur isotope signatures in sedimentary records before the GOE. Very few processes on Earth can generate these sulfur isotope signatures, and from what is known their preservation in the rock record almost certainly requires an absence of atmospheric O2.

"For the first half of Earth's existence, its atmosphere and oceans were largely devoid of O2. This gas was being produced by cyanobacteria in the ocean before the GOE, it seems, but in these early days the O2 was rapidly destroyed in reactions with exposed minerals and volcanic gases.

"Poulton, Bekker and colleagues discovered that the rare sulfur isotope signatures disappear but then reappear, suggesting multiple O2 rises and falls in the atmosphere during the GOE. This was no single "event."

"'Earth wasn't ready to be oxygenated when oxygen starts to be produced. Earth needed time to evolve biologically, geologically and chemically to be conducive to oxygenation," Ostrander said. "It's like a teeter totter. You have oxygen production, but you have so much oxygen destruction, nothing's happening. We're still trying to figure out when we've completely tipped the scales and Earth could not go backwards to an anoxic atmosphere."

***

"The team examined thallium isotopes in the same marine shales recently shown to track atmospheric O2 fluctuations during the GOE with rare sulfur isotopes.

"In the shales, Ostrander and his team found noticeable enrichments in the lighter-mass thallium isotope (203Tl), a pattern best explained by seafloor manganese oxide burial, and hence accumulation of O2 in seawater.

"These enrichments were found in the same samples lacking the rare sulfur isotope signatures, and hence when the atmosphere was no longer anoxic. The icing on the cake: the 203Tl enrichments disappear when the rare sulfur isotope signatures return. These findings were corroborated by redox-sensitive element enrichments, a more classical tool for tracking changes in ancient O2.

"'When sulfur isotopes say the atmosphere became oxygenated, thallium isotopes say that the oceans became oxygenated. And when the sulfur isotopes say the atmosphere flipped back to anoxic again, the thallium isotopes say the same for the ocean," Ostrander said.

""So the atmosphere and ocean were becoming oxygenated and deoxygenated together. This is new and cool information for those interested in ancient Earth.'"

Comment: it is amazing how complex the oxygenation event was. It was not just cyanobacteria churning it out.

https://www.sciencedaily.com/releases/2024/06/240610140249.htm

"Scientists theorize that ice ages occur for a number of reasons, including the planet's tilt and rotation, shifting plate tectonics, volcanic eruptions, and carbon dioxide levels in the atmosphere. But what if drastic changes like these are not only a result of Earth's environment, but also the sun's location in the galaxy?

***

"...found evidence that some two million years ago, the solar system encountered an interstellar cloud so dense that it could have interfered with the sun's solar wind. Opher and her co-authors believe this shows that the sun's location in space might shape Earth's history more than previously considered.

***

"Our whole solar system is swathed in a protective plasma shield that emanates from the sun, known as the heliosphere. It's made from a constant flow of charged particles, called solar wind, that stretch well past Pluto, wrapping the planets in what NASA calls a "a giant bubble." It protects us from radiation and galactic rays that could alter DNA, and scientists believe it's part of the reason life evolved on Earth as it did. According to the latest paper, the cold cloud compressed the heliosphere in such a way that it briefly placed Earth and the other planets in the solar system outside of the heliosphere's influence.

"This paper is the first to quantitatively show there was an encounter between the sun and something outside of the solar system that would have affected Earth's climate," says Opher, who is an expert on the heliosphere. Her models have quite literally shaped our scientific understanding of the heliosphere, and how the bubble is structured by the solar wind pushing up against the interstellar medium -- which is the space in between stars and beyond the heliosphere in our galaxy. Her theory is that the heliosphere is shaped like a puffy croissant, an idea that shook the space physics community. Now, she's shedding new light on how the heliosphere, and where the sun moves through space, could affect Earth's atmospheric chemistry.

***

"...If that had happened, says Opher, Earth would have been fully exposed to the interstellar medium, where gas and dust mix with the leftover atomic elements of exploded stars, including iron and plutonium. Normally, the heliosphere filters out most of these radioactive particles. But without protection, they can easily reach Earth. According to the paper, this aligns with geological evidence that shows increased 60Fe (iron 60) and 244Pu (plutonium 244) isotopes in the ocean, on the moon, Antarctic snow, and ice cores from the same time period. The timing also matches with temperature records that indicate a cooling period.

***

"The outside pressure from the Local Lynx of Cold Cloud could have continually blocked out the heliosphere for a couple of hundred years to a million years, Opher says -- depending on the size of the cloud. "But as soon as the Earth was away from the cold cloud, the heliosphere engulfed all the planets, including Earth," she says. And that's how it is today.

***

"This is only the beginning," Opher says. She hopes that this paper will open the door to much more exploration of how the solar system was influenced by outside forces in the deep past and how these forces have in turn shaped life on our planet."

Comment: if is amazing how many precise events occurred to shape our Earth as it now is. I doubt it is all contingent chance.

https://www.sciencenews.org/article/freshwater-earth-ancient-crystal-years

"Researchers analyzed oxygen molecules within 4-billion-year-old zircon crystals from Western Australia’s Jack Hills, one of the oldest rock formations on Earth. The relative proportions of oxygen’s heaviest and lightest forms, or isotopes, in the zircons are possible only if there been a significant amount of freshwater present, geochemist Hamed Gamaleldien of Khalifa University in Abu Dhabi and colleagues report June 3 in Nature Geoscience.

"The finding suggests that freshwater may have been actively cycling on Earth hundreds of millions of years earlier than previously thought. Past studies have found evidence that a robust water cycle, one that involved rain and evaporation from the land back to the atmosphere and then rain again, existed by at least 3.2 billion years ago.

"Even if there was a freshwater cycle 4 billion years ago, that doesn’t mean there was necessarily life on Earth that far back, Gamaleldien says. “But at least we have the main ingredient to form life.” Currently, the oldest agreed-upon evidence for life on Earth comes from fossilized microbial mats, or stromatolites, in Australia’s Strelley Pool Chert (SN: 10/17/18). Those stromatolites date to 3.5 billion years ago.

"Cycles of evaporation and rain alter the chemical makeup of water molecules. When water evaporates from the ocean’s surface, leaving the salt behind, the lighter form of oxygen, oxygen-16, tends to evaporate faster than the heavier oxygen-18. That lighter water may then rain out over land, and perhaps evaporate again. Over time, the freshwater becomes more concentrated in oxygen-16 compared with the original seawater.

"When that rainwater percolates through the ground, it can chemically react with the rocks themselves, or with magma within the rocks, imparting those lighter isotopic oxygen values — indelible clues that freshwater was present.

"The researchers analyzed oxygen isotopic ratios of more than 1,300 zircons. Most of the zircons had relatively heavy oxygen isotope values, as would be expected from seawater. But at two time periods, around 3.4 billion years ago and 4 billion years ago, the ratios indicated a greater proportion of lighter oxygen.

***

"The team then ran thousands of computer simulations to determine the likelihood of different explanations for the observed ratios. “We concluded that the main water on Earth was oceanic,” or salty, Gamaleldien says. “But only when we used freshwater [did] it create the results we see.” Furthermore, he says, the findings also suggest that enough land had emerged above sea level by that time to support a water cycle. Researchers have pondered whether Earth was completely covered by oceans between around 3 billion and 4 billion years ago.

"Gamaleldien and colleagues present a convincing case that there was freshwater cycling on Earth 3.4 billion years ago, corresponding to previous evidence for freshwater on Earth, says geochemist Jesse Reimink of Penn State. But “the jury’s still out” on whether that was the case 4 billion years ago."

Comment: whenever fresh water appeared there had to be land for it to fall on. In a purposeful design approach, develop organisms in the ocean, then have them move to land for more complex forms with larger more complex brains. It is a logical pattern such as a designer would produce.

https://phys.org/news/2024-05-mountain-linked-major-extinction-event.html

"As life on Earth rapidly expanded a little over 500 million years ago during the Cambrian explosion, Earth had tectonic plates slowly crashing into each other, building mountains and starting a series of unfortunate events that led to a mass extinction.

"These plate interactions further led to magma rising to the Earth's surface, large amounts of greenhouse gases entering the atmosphere, and rapid climate change. The resulting extinction decimated animal groups, like archaeocyathids (reef-building marine sponges) and hyoliths (animals with small conical shells).

"It's unusual to point to a tectonic cause for an extinction event," said John Goodge, a professor emeritus at the University of Minnesota Duluth, "but the evidence is compelling."

"Goodge and his colleagues realized the link to plate tectonics after comparing field notes from sites in Antarctica and southern Australia. They noticed that the two locations, which were once near each other around the equator as part of the supercontinent Gondwana, had nearly identical records of mountain building right before the extinction.

***

"It all started when Goodge and fellow scientists set up their bright yellow and blue tents on a snow-covered glacier in Antarctica. Over two field seasons, they traveled by helicopter and snowmobile to the Holyoake Range and examined fossils from the carbonate reef structures to pinpoint the extinction. A separate team found similar records in Australia in 2011."

The paper:

https://www.science.org/doi/10.1126/sciadv.adl3452

"The Cambrian explosion, one of the most consequential biological revolutions in Earth history, occurred in two phases separated by the Sinsk event, the first major extinction of the Phanerozoic. Trilobite fossil data show that Series 2 strata in the Ross Orogen, Antarctica, and Delamerian Orogen, Australia, record nearly identical and synchronous tectono-sedimentary shifts marking the Sinsk event. These resulted from an abrupt pulse of contractional supracrustal deformation on both continents during the Pararaia janeae trilobite Zone. The Sinsk event extinction was triggered by initial Ross/Delamerian supracrustal contraction along the edge of Gondwana, which caused a cascading series of geodynamic, paleoenvironmental, and biotic changes, including (i) loss of shallow marine carbonate habitats along the Gondwanan margin; (ii) tectonic transformation to extensional tectonics within the Gondwanan interior; (iii) extrusion of the Kalkarindji large igneous province; (iv) release of large volumes of volcanic gasses; and (v) rapid climatic change, including incursions of marine anoxic waters and collapse of shallow marine ecosystems."

Comment: all of this can only happen if a planet has plate tectonics. Gould said our arrival depended upon contingencies. Plate tectonics is a major one.