Category Archives: Geology

Balkanatolia: the forgotten ancient battleground where mammals fought for supremacy in Europe

Map showing Balkanatolia 40 million years ago and at the present day. Credit: Alexis Licht & Grégoire Métais.

For millions of years, Western Europe’s megafauna was literally worlds apart from that in Asia, owed to impenetrable natural barriers that allowed species on both continents to evolve and diverge. But that all changed in the blink of an eye, geologically speaking, after the more robust and adaptable Asian mammals poured into Europe, where they quickly replaced the endemic fauna. How exactly this event, known as the Grande Coupure, panned out has always been a mystery, but a new study is filling the gaps in our knowledge by proposing an interesting hypothesis: the Asian mammals invaded through an ancient landmass called Balkanatolia.

If the name Balkanatolia rings a bell, it’s because it refers to the present-day regions of the Balkans and Anatolia, which 50 million years ago formed an isolated archipelago, separate from the neighboring continents of Europe, Africa, and Asia. The name Balkanatolia was recently given by researchers at the French National Center for Scientific Research in a new study that highlights the biogeographic province’s major role in the Grande Coupure, which occurred some 34 million years ago.

That’s because examinations of previous fossils found in both the Balkan peninsula and Anatalonia — some of which date as far back as the 19th-century– performed by the researchers led by paleogeologist Alexis Licht showed that Asian mammals started colonizing southern Europe as early as 5 to 10 million years prior to the Grande Coupure.

In a subsequent review of this fossil record, the researchers uncovered patterns that allowed them to reconstruct the biogeographic history of the region over the span of millions of years.

The researchers found that for much of the Eocene Epoch (55 to 34 million years ago), the Balkans and Anatolia harbored homogeneous terrestrial fauna, which was distinct from that in continental Europe and Asia. Some of these mammals included marsupials of South American origin and large herbivorous mammals resembling hippos, known as Embrithopoda. The presence of these distinct animals just makes sense for an isolated archipelago, which is why the researchers proposed the existence of Balkanatolia.

However, Balkanatolia would soon be greeted by some uninvited guests. New fossil deposits from Büyükteflek in Turkey, dated to 38 to 35 million years ago, clearly belonged to mammals with an Asian lineage — the earliest of their kind discovered in Anatolia until now. These include fossils belonging to Brontotheres, huge animals resembling large rhinoceroses that died out at the end of the Eocene.

From this amalgam of fossils from different eras, the researchers pieced together a story: Balkanatolia comprised a single landmass isolated from the rest of the continents beginning with 50 million years ago, but would be colonized some 40 million years ago by Asian mammals. How exactly these animals reached the archipelago is not understood, but it seems like the region became a stepping stone for the Asian mammal invasion. The straight Eurasian route through modern-day Russia was not a viable route due to the huge glaciers and other geographical obstacles.

It is likely that a major glaciation event, which lowered sea levels some 34 million years ago, formed a bridge between Balkanatolia to Western Europe, releasing the floodgates of invasive Asian species. In no time, Western Europe endemic animals like Palaeotheres, an extinct group distantly related to present-day horses, but more like today’s tapirs, became extinct and were replaced by more diverse and resilient fauna including mammal families found today on both continents.

In other words, these findings suggest that the Grande Coupure was actually a two-stage event. In the first event, Asian mammals colonized Balkanatolia, where they replaced much of the existing fauna. Then, taking advantage of shifting geographical conditions due to climate change, the invasive species continued their conquest in the rest of the European continent.

“This colonization event was facilitated by a drop in global eustatic sea level and a tectonically-driven sea retreat in eastern Anatolia and the Lesser Caucasus during the late middle Eocene. These paleogeographic changes instigated the demise of Balkanatolia as a distinct biogeographic province and paved the way for the dispersal of Asian endemic clades before and during the Grande Coupure in western Europe,” the authors wrote in their study published in Earth-Science Reviews.

The story of King Tutankhamun’s dagger forged from a meteorite just got a whole lot more interesting

Most iron objects from this era are heavily corroded, but the dry conditions in Tutankhamun’s tomb kept the dagger rust-free. Credit: Daniela Comelli.

King Tutankhamun, or King Tut for short, became ruler of Ancient Egypt more than 3,300 years ago when he was just nine years old. He died just a decade later, ending a rather unmemorable rule. In fact, the only remarkable thing about the Boy King is his death itself — specifically his burial. After years of excavation, British archaeologists found King Tut’s tomb in 1922, and nothing could have prepared them for the “wonderful things” they found there.

Tutankhamun’s tomb had been filled with precious objects to aid the Pharaoh on his journey into the afterlife. These included numerous exquisite artifacts such a crook and flail (the fundamental symbols of royal power in Ancient Egypt) made of gold and colored glass, elaborate pieces of jewelry, musical instruments, and even board games. This sensational trove of artifacts instantly turned King Tut into the most famous pharaoh on the planet.

Among these unprecedented riches, archaeologists also uncovered two beautiful daggers: one made almost entirely of gold, the other from iron with a hilt and sheath made of gold. While the gold blade is fitting for a man of King Tut’s status, the dagger made of iron seems rather perplexing at first glance since this was still the Bronze Age, a time when craftsmen had yet to perfect their metallurgical methods required to work with iron ore’s high melting point (over 1,500° C or 2,700 ° F).

But later investigations performed with modern analytical tools showed that the iron dagger was actually forged from a meteorite rather than from inaccessible iron ore deposits. This makes sense, considering the historical context. In 2017, Albert Jambon from the Institut de minéralogie, de physique des matériaux et de cosmochimie in France showed that all iron used during the Bronze Age was meteoric. Space artifacts, as it turns out, aren’t as rare as we might think.

In other words, the Boy King’s blade was literally extraterrestrial — the most fitting final parting gift for a royalty who was thought to descend from divinity.

A gift from the sky

The length of the dagger is ~35.2 cm (~21.8 cm for the blade and ~13.4 cm for the hilt) and that of the sheath is ~22.5 cm. 

In 2016, researchers from the Polytechnic University of Milan, in Italy, confirmed Tut’s dagger was truly made of a meteorite, which contained a ratio of nickel and cobalt that matched well with the composition of 11 iron-bearing meteorites analyzed in the same way. However, while this study answered what the original meteorite must have looked like, it didn’t tell us where it came from.

To better understand the origin of King Tut’s dagger, researchers from the Chiba Institute of Technology in Japan conducted a non-invasive chemical analysis of the premised artifact by shining X-rays onto it. The analysis revealed elements like iron, nickel, manganese, and cobalt, with sulfur, chlorine, calcium, and zinc found in greater abundance in the blackened spots on the blade, Gizmodo reported.

A similar elemental composition was reported by previous studies, but this time around the researchers also reported a cross-hatched texture, known as a Widmanstätten pattern, on both sides of the dagger. The Widmanstätten pattern has a chemical structure typical of an octahedrite, the largest and most common group of iron meteorites. Most originate from the Asteroid Belt between Mars and Jupiter.

To investigate if their hunch was correct, the Japanese researchers compared the results of the chemical analysis with the pattern on Shirihagi, a 22-kg octahedrite that was found in Japan in 1890, whose iron was used to forge a number of premium katanas acquired by the Taisho Emperor. Apparently, weapons made from meteorites were in great demand by royalty the world over.

The Widmanstätten pattern also hints at how the meteorite was processed by the ancient Egyptians. The cross-hatched texture, along with the presence of iron sulfide, hints that the dagger was forged at low heat, likely under 950 °C (1,742° F).

Most intriguing, the extraterrestrial dagger wasn’t forged specifically for King Tut or his burial. The Amarna letters (15th-14th century B.C.) —  diplomatic correspondence, almost all written in Akkadian, an international language at that time — mention an iron dagger in a gold sheath that was gifted to Pharaoh Amenhotep III, Tutankhamun’s grandfather, by the king of Mitanni, an ancient kingdom in the region of Anatolia, with the occasion of the pharaoh’s wedding with the daughter of the Mitanni king. Since iron tools were exceedingly rare during the Bronze Age, let alone a dagger meant for a pharaoh, there’s a good chance Tut’s meteorite dagger was passed down to him as a family heirloom, the Japanese researchers note. Christine Lilyquist, the Lila Acheson Wallace Curator of Egyptology at The Metropolitan Museum of Art, first proposed in 1999 that the Amarna iron dagger and King Tut’s meteorite blade are one and the same.

King Tut’s dagger is now on display at the Egyptian Museum of Cairo.

The findings were reported in the journal Meteoritics and Planetary Science.

UPDATE (27/2/2022): The article was corrected to clarify the link between the Amarna iron dagger and the meteorite blade, as well as mention Dr. Lilyquist as the first researcher who proposed the two historical artifacts may be one of the same.

The Bulge is back: Three Sister volcano in Oregon triggers swelling but is unlikely to erupt

Using satellite images and GPS instruments, geophysicists monitoring the Three Sister volcanoes have found a subtle but noticeable uplift around 3 miles (5 km) away from the South Sister volcano. While researchers are now keeping a closer eye on it, they say this type of uplift has happened before and there’s no need to worry.

Image credits: USGS.

The Three Sisters are closely spaced volcanic peaks in Oregon, USA. They stand over 10,000 feet (3,000 m) in elevation, being the 4th, 5th, and 6th highest peaks in Oregon, respectively. But researchers are more interested in their volcanic activity.

While the North and Middle sisters haven’t erupted in the past 14,000 years (and it’s considered unlikely that they will erupt again), the South Sister last erupted 2,000 years ago, and could easily do so again at some point in the not-very-distant future. In the 1990s, researchers detected tectonic uplift around this volcano, prompting the United States Geological Survey (USGS) to closely monitor the area.

The USGS is now tracking developments around the South Sister using GPS networks and satellite data. Radar satellites can highlight areas of uplifting (where the surface is bulging) or downwelling (where the surface is moving downwards). Then, ground-based GPS measurements are used for more precise measurements. Although the current uplifting isn’t as fast as the maximum rate observed in 1999-2000, it is “distinctly faster” than the normal rate of uplift, the USGS says.

Image credits: USGS.

The uplift is believed to be caused by pulses of magma accumulating under the volcano, some 4 miles (7 km) below the surface. While magma accumulation is associated with volcanic activity, eruptions are generally preceded by other detectable signs — most importantly, lots of small earthquakes, but also ground deformation and geochemical changes. There seems to be no sign of any of that around the Three Sisters.

All in all, this suggests that the volcano is still active, but there are no signs of an impending eruption. The volcano’s alert level and color code remain at Normal / Green.

How the USGS is tracking activity around the Three Sisters. Credit: USGS.

The Three Sisters volcanoes formed in the Pleistocene and belonged to a volcanic area that was very active from around 650,000 and about 250,000 years ago. The South Sister is the youngest and tallest of the three volcanoes, and unlike its sisters, it has an uneroded summit crater about 0.25 mi (0.40 km), which hosts a lake (called the Teardrop Pool).

An eruption from the South Sister would pose a significant threat to nearby life, with geologists estimating a proximal zone of danger extending from 1.2 to 6.2 miles (2-10 km) around the volcano summit. How flows would run down the sides of the volcano, threatening everything in its path, and the nearby city of bends would be covered by tephra some 2 inches (5 cm) thick.

The Teardrop Pool on South Sister is the highest lake in Oregon. Image via Wiki Commons.

Liquid water on Mars? Actually, probably not

A view of Mars’ south pole. Research led by The University of Texas at Austin found that a 2018 discovery of liquid water under the Red Planet’s south polar cap is most likely just radar reflecting from volcanic rock. Credit: ESA/DLR/FU Berlin.

In 2018, a NASA announcement got us all excited. The study, based on an interpretation of radio data, suggested that there may be liquid lakes under the ice cap at Mars’s south pole. “We interpret this feature as a stable body of liquid water on Mars,” the authors wrote in the study.

“Here, we aim to determine if Martian terrains today could produce strong basal echoes if they were covered by a planet-wide ice sheet,” the researchers write in their paper.

“We find that some existing volcanic-related terrains could produce a very strong basal signal analog to what is observed at the South polar cap. Our analysis strengthens the case against a unique hypothesis based solely on liquid water for the nature of the polar basal material,” they add.

Water signals

Researchers have put several scientific instruments on and around Mars. Among them is MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) — a low-frequency radar developed by researchers working in Italy. Radar waves from MARSIS can penetrate through ice (and to a lesser extent, through rocks), offering clues about the surface as well as the subsurface of the Red Planet.

When the radar waves encounter a different surface (for instance, when they pass from ice to rocks), a part of their energy is reflected back. Based on this type of data, certain deductions can be made about the layers through which the waves passed — but the results are not always clear.

For instance, the 2018 study concluded that a “shiny” patch (a patch that is very reflective to radar data) close to Mars’ frozen south pole could indicate a subsurface lake, 1.4 kilometers (0.87 miles) under the ice.

MARSIS data showing an area of high reflectivity (dark blue) that was thought to be water. Credit: USGS Astrogeology Science Center, Arizona.

If this were indeed the case, and Mars were to host a network of such lakes, it would be groundbreaking. Not only would this mean that life may still exist on Mars, but it could also be very helpful in the case of a human Martian colony. But right from the get-go, this interpretation had critics.

For instance, a 2019 lab study that simulated the conditions on Mars concluded that these areas are simply too cold to host liquid water, even salty liquid water (which stays liquid at colder temperatures). Instead, the authors of that study suggested that the reflective patch is a clay mass.

Now, a new study suggests that neither of those is true, and the patches are simply volcanic rocks.

A song of rocks and water

The new study, led by planetary scientist Cyril Grima of the University of Texas Institute for Geophysics, opted for a clever trick to explain the nature of the reflective patch. They wondered what they’d see if they “covered” all of Mars with an ice sheet, just like at the South Pole? In other words, if we replicated the conditions where the reflective patch was discovered all over the planet, would we see any others like it?

The answer turned out to be ‘yes’.

Mars as it might appear covered in ice. The red spots are reflective patches. Image credits: Cyril Grima.

Researchers found a bunch of reflective patches scattered across the Red Planet. The researchers overlaid these patches with a map of the Martian geology, noting that they neatly matched the outline of volcanic rocks.

This idea makes sense, because just like water and clay are reflective, so too are volcanic rocks. Also, Mars has a lot of volcanic rocks, not all of which have been mapped yet; it’s possible that such an area may lie around the south pole, unbeknownst to researchers.

“I think the beauty of Grima’s finding is that while it knocks down the idea there might be liquid water under the planet’s south pole today, it also gives us really precise places to go look for evidence of ancient lakes and riverbeds and test hypotheses about the wider drying out of Mars’ climate over billions of years,” says planetary scientist Ian Smith of York University in Canada, who led the frozen clay study.

Relative reflective strength of Mars if the surface was entirely covered by a 1.4-km dirty ice sheet. Credits: Grima et al, 2022.

Ultimately, while this latest study suggests the reflective patches are volcanic rocks, it’s possible that the last word is still out. The odds of them being liquid water seem to be quite slim at the moment, but whether they’re volcanic rocks, clay, or something else entirely is not at all clear. Isaac Smith, a Mars geophysicist at York University who was not involved in either study, believes this is a good example of how science should work.

“Science isn’t foolproof on the first try,” said Smith, who is an alumnus of the Jackson School of Geosciences at UT Austin. “That’s especially true in planetary science where we’re looking at places no one’s ever visited and relying on instruments that sense everything remotely.”

Hopefully, future missions and studies will help shed more light on what lies under the Martian surface.

The study was published in Geophysical Research Letters.

Stunning satellite observations show Tonga eruption effects in unprecedented detail

The Hunga Tonga-Hunga Ha‘apai volcano erupted on January 14, causing massive shockwaves and tsunamis that lead to 3 deaths and caused substantial damage to the Tongan Islands. Thanks to satellite imagery, researchers were able to observe this process in stunning detail. Here are some of these observations.

Ashes and cooling

The eruption released vast quantities of aerosols into the atmosphere. These particles reached the stratosphere, some 9 miles (15 km) above the surface. The stratosphere is a dry part of the atmosphere without clouds or humidity — so everything that reaches the stratosphere has little to interact with and is easily observable from above. 

The ashes from volcanoes consist largely of sulfur dioxide; once this sulfur dioxide reaches the atmosphere, it filters out some of the solar rays, producing a cooling effect. This effect can be quite powerful. Nearly 31 years ago, the Pinatubo volcano, in the Philippines, released 15 million tons of sulfur dioxide into the stratosphere. This tremendous amount took about two years to be depleted through chemical reactions, temporarily cooling the atmosphere by about 0.6 °C on average around the globe. 

Pinatubo’s eruption was used as a source of misinformation by climate denialists who wanted to diminish human interference from global warming — a volcanic eruption only produces temporary effects. As a matter of fact, Pinatubo’s effect was predicted by a climate model, which confirmed the predictions from climate models as reliable sources.

Image credits: Japan Meteorology Agency.

The eruption of Hunga Tonga-Hunga Ha‘apai is not as strong as Pinatubo’s, but the ashes will cool the air a little bit. However, it’s important to keep in mind that this won’t have any significant effect on climate change.


When the volcano sent ashes flying into the air, it caused a disruption in the atmospheric pressure levels. Just like hitting a drum’s membrane, the explosion pushed the air and changed the air pressure globally.

Researchers monitor these pressure changes through instruments called barometers. But because the planet is very big, the sudden change in air pressure due to the eruption took a while to reach different parts of the planet. For instance, it took 15 hours to reach the University of Hertfordshire Observatory in the UK, which is 16,500 km (around 10,253 mi) away from the volcano and it was registered by their barometer.

The propagation of the wave becomes very clear when we piece together a series of barometer detections. This was registered by the United States’ station on January 15:

The eruption was also a source of waves in the atmosphere, sending concentric ripples traveling the planet’s atmosphere as if it is not such a big deal. A stunning animation of the event was produced by theNational Oceanic and Atmospheric Administration (NOAA)’s GOES-West satellite, displaying the waves traveling the atmosphere just after the eruption.

The initial atmospheric response to the eruption was captured by Mathew Barlow using NOAA’s GOES-West satellite infrared radiance data (band 13). This sequence is based on images taken 10 minutes apart, and colors show the difference in infrared radiance between each time step. Credit: Mathew Barlow/University of Massachusetts Lowell.

So where do these waves go? Well, if you’re a flat-earther, this may upset you. Because the Earth is round, the wave travels to the furthest point, until it reaches a point and becomes a wave source itself that travels all the way around again, gradually losing energy until it disappears. 

There were also some “eyewitnesses” of the process. Registered by the Gemini Observatory at Maunakea in Hawaii, the following video shows a bunch of clouds moving normally, but the thin ripples that appear in the sky were caused by the eruption waves.

Never before could we monitor the atmospheric response to events such as this eruption, this is thanks to the number of cameras we have everywhere and better sensors to register the impacts. We didn’t have a fast way to communicate before, in this case, a few hours after the activity was possible for scientists to share their observations and shock everyone on how interactive the Earth system is. Let’s wait for the next crazy atmospheric phenomenon to leave us in awe.

What is the world’s deepest cave?

Credit: Daily Sabah.

With a record depth of 2,212 meters (7,257 feet), the Verëvkina (Veryovkina) cave is the deepest cave measured thus far in the world. It’s located in the Arabika Massif in Abkhazia, a breakaway region of Georgia that is supported by Russia. Despite its complicated geopolitics, the region is home to not one but four of the deepest caves on Earth.

A decades-long history of exploration to reach the world’s deepest cave

Verëvkina was first discovered in 1968 by Soviet speleologists who only explored a section 115 meters deep (377 feet) and couldn’t comprehend the true scale of this gigantic cave system. In 1983, an expedition led by Oleg Parfenov climbed down a well that led the researchers to a new branch of the cave where they recorded a depth of 440 meters (1,443 feet). It was only much later, in the early 2000s, that new expeditions at Veryovkina were organized by the Moscow-based Perovo Speleo and Speleoclub Perovo caving organizations.

The work proved highly difficult and treacherous. The deeper the researchers went, the more it took for them to bring excavated material to the surface and the greater the mortal peril of collapse. After a few minor expeditions, the researchers finally broke through and reached new sections with a depth of over 1,000 meters (3,200 feet). This victory inspired Russian speleologists to keep exploring, launching expeditions every two to three months until they finally hit gold in 2017 and achieved the world's greatest depth for a cave system.

Using a series of camps along the way, it took expedition members more than four days to reach the terminal sump at a depth of 2,212 meters (7,257 feet). It takes roughly the same time to return to the surface, so the crew had to spend at least a week inside, which is a very long time for such an extreme environment. Due to the endless night, the cavers easily break their biorhythms, working at night and sleeping during the day. Thankfully, communication links with a surface base allow the cavers to contact the outside world and share updates about their progress.

The map is based on the profile by Perovskij speleo club (Moscow, pres. Aleksej Baraškov) of February 2020; surface contours and other data were obtained with the help of Perovo speleo team (also from Moscow, pres. Pavel Demidov). It was compiled February to July 2020 by Primož Jakopin - Klok, of DZRJL, Ljubljana Cave Exploration Society from Slovenia. Credit: Wikimedia Commons.

They had to descend thousands of feet on ropes and crawl through water- and mud-choked siphons. The cave goes down almost vertically and is full of wells with small horizontal passages. Starting from the depth of 800 meters (2,600 feet), water flowing through small tributaries splash water through the narrow passageways. This makes the cave extremely damp. The humidity is actually 100% and with a 4 °C to 7 °C temperature range, this means anyone descending will be freezing along the way.

Along the way, they collected samples of rare shrimp and scorpions, and possibly new species of microorganisms. There are also fossils, mainly imprinted on rocks, offering hints about how the cave's organisms might have looked millions of years ago, as well as how the cave itself and the surrounding mountains formed.

The caving heroes

Pavel Demidov in the camp -400 after the first rigging of Babatunda pit (155m). Veryovkina cave, 2016. Credit: Wikimedia Commons.

Pavel Demidov, the head of the record-holding expedition, was one of the first to reach it. He described Veryovkina "as if you have had a look at the far side of the Moon," referring to the alien environment of the cave. Right at the very bottom of the cave, there is a vast labyrinth

Demidov passed away on August 23, 2020, in Abkhazia while descending into an unexplored cave in the Arabika Mountain Range, not too far from Veryovkina. The 49-year-old man was killed by a large rock burst at a depth of 305 meters (1,000 feet).

Demidov's tragic death is illustrative of the kinds of dangers cavers face during their treks. In 2018, Demidov's team, which included Petr Lyubimov, Konstantin Zverev, Andrey Shuvalov, Evgeniy Rybka, and Andrey Zyznikov, as well as National Geographic photographers Robbie Shone and Jeff Wade, barely made it out alive after the cave was flooded. Heavy rains can cause water to collect, then, because of the volume, suddenly burst through cave openings.

Despite the extreme conditions, researchers continue to explore Veryovkina and other similar caves in Arabika Massive for various paleontology, biology, and microbiology projects. Some cave organisms may be beneficial to the development of antibiotics.

Four of the world's deepest caves are found in the astonishing Arabika Massive. Besides Veryovkina, these include Krubera-Voronja (2,199 m), Sarma (1,830 m), and Snezhnaja (1,760 m). This is no coincidence. All these caves are carved in karst terrain, which is a rugged landscape with a high elevation and very rich in soluble thick limestone.

#NameDepth (m)Length (km)Country
1Veryovkina Cave221213.5 km (8.4 mi)Abkhazia / Georgia
2Krubera-Voronja Cave219923.0 km (14.3 mi)Abkhazia / Georgia
3Sarma cave183019.2 km (11.9 mi)Abkhazia / Georgia
4Snezhnaja cave 176040.8 km (25.4 mi)Abkhazia / Georgia
5Lamprechtsofen173561 km (38 mi)Austria
6Gouffre Mirolda173313 km (8.1 mi)France
7Gouffre Jean-Bernard162526.6 km (16.5 mi)France
8Sistema del Cerro del Cuevón 15897 km (4.3 mi)Spain
9Wot-U-Got Pot 1560113 km (70 mi)Austria
10Sistema Huautla156089 km (55 mi)Mexico
11Chevé Cave153677.0 km (47.8 mi)Mexico
12Pantjuhinskaja Cave 15087.9 km (4.9 mi)Abkhazia / Georgia
13Sima de la Cornisa15076.4 km (4.0 mi)Spain
14Čehi 215055.5 km (3.4 mi)Slovenia
15Sistema del Trave 14419.1 km (5.7 mi)Spain
16Velebit caves14313.7 km (2.3 mi)Croatia
17Egma Sinkhole14293.1 km (10,000 ft)Turkey
18Boybuloq141514.8 km (9.2 mi)Uzbekistan
19Gouffre de La Pierre Saint-Martin 141083.6 km (51.9 mi)France, Spain
20Kuzgun Cave 14003.1 km (1.9 mi)Turkey
Top 20 world's deepest caves. Source: Wikipedia.

Thousands of other subterranean hidden marvels await discovery

Karst covers up to 25% of the Earth's land surface, and where there is karst, caves are bound to be close by. In fact, scientists believe there may be tens of thousands of undiscovered caves across the world. And some of them probably reach deeper than Veryovkina. The only limit is how far down groundwater can seep into limestone before the pressure becomes too great, and we know from the Soviet-era Kola Superdeep Borehole that this limit is far from being reached by a known cave.

The Kola Superdeep Borehole, the deepest hole in the world, drilled into the Earth from 1970 to 1994 until it reached a staggering depth of 12,262 meters (40,230 ft). Soviet geologists found water still circulating at depths of 6.9 km (4.3 miles), which is more than three times deeper than Veryovkina's cave floor.

One candidate for the title of the world's deepest cave is the Chevé Cave system, a sprawling underground complex in the Oaxaca region of Mexico, where water flow suggests it may descend nearly 2.57 km (1.6 miles) into the Earth. There may be many others waiting to be explored.

However, any super-deep caves are probably inaccessible from the surface and would require some drilling to reach them, provided that scientists can locate them. Remote sensing, such as electrical resistivity, seismic activity, and ground-penetrating radar only work up to a relatively shallow depth or don't have the necessary resolution to identify an underground passageway only a few feet in width.

But developing new methods to reach the world's deepest caves, however challenging, is worth it. Caves are filled with living organisms, particularly invertebrates and microbes, that could help scientists discover new antibiotics and other medicines. They are also time capsules of Earth's past climate, which refine climate models in order to have better projections of future trends.

Before the age of dinosaurs, car-sized millipedes crawled the Earth on hundreds of legs

Reconstruction of the giant millipede Arthropleura, which lived in the Carboniferous period, 326 million years ago. Credit: Neil Davies.

After a section of a cliff next to a beach in northern England fell onto the shore, it exposed the fossils of one of the biggest, baddest, creepy crawlers the Earth has ever seen. Paleontologists believe the fossils belong to a giant millipede whose many segmented legs could extend to as much as 2.6 meters in length, about the size of a sedan. The fossils were dated to the Carboniferous period, more than 100 million years before the first dinosaurs emerged.

When this peculiar creature, known as Arthropleura, was still alive, the land we now know as England actually lay near the equator. Instead of the dreary weather, Arthropleura basked in the tropical sun and munched on the abundant plants, although it likely supplemented its diet by hunting other smaller invertebrates and maybe even vertebrates like amphibians along creeks and rivers. With plenty of food, the giant millipede easily grew to gargantuan size, weighing up to 50 kilograms.

Each of its segmented legs measured 75 centimeters (2.5 feet) in length. In fact, these were the most preserved parts of the fossil, a rare find in itself since the bodies of giant millipedes disarticulate once they died. For this reason, Neil Davies, a paleontologist at the University of Cambridge and lead author of the study, believes the fossils retrieved from the British beach are actually a molted carapace that the animal shed as it grew and was later filled with sand. The implication is that Arthropleura may have grown even larger.

This is only the third giant millipede fossil that scientists have found thus far. The two other known Arthropleura fossils were found in Germany, and both were much smaller than the new specimen. But no fossilized head has ever been found, which makes it challenging to imagine what these crawling arthropods really looked and behaved like. Considering how rare and fortuitous this discovery happened to be though, we can’t ask for too much.

Fossilised section of the giant millipede Arthropleura, found in a sandstone boulder in the north of England. Credit: Neil Daves.

“It was a complete fluke of a discovery,” said Dr. Davies in a statement. “The way the boulder had fallen, it had cracked open and perfectly exposed the fossil, which one of our former Ph.D. students happened to spot when walking by.”

Scientists used to think Arthropleura grew to such large sizes thanks to more oxygen present in the atmosphere during the late Carboniferous and Permian periods, but the fossils come from rocks deposited before the very peak. Oxygen cannot solely explain Arthropleura‘s hefty frame. Instead, the researchers believe the millipede must have had access to a nutrient-rich diet.

“While we can’t know for sure what they ate, there were plenty of nutritious nuts and seeds available in the leaf litter at the time, and they may even have been predators that fed off other invertebrates and even small vertebrates such as amphibians,” said Davies.

Arthropleura spent at least another 45 million years crawling around the equator until it finally went extinct during the Permian. It could have been climate change that dried up the environment too fast for them to adapt. Alternatively, the rise of reptiles may have outcompeted them. Out goes giant millipedes, in comes dinosaurs.

If you’re close to Cambridge’s Sedgwick Museum after the new year, you can see the fossils on display with your own eyes.

The findings appeared in the Journal of the Geological Society.

Dinosaur-killing asteroid may have hit Earth during spring

Credit: Pixabay.

About 66 million years ago, one of the worst disasters in history happened after a large asteroid struck Earth offshore Mexico’s Yucatan Peninsula. The cosmic impact unleashed the force of 10 billion Hiroshima A-bombs and released gigatons of sulfur and carbon dioxide, which could have lowered surface air temperatures by a staggering 26 degrees Celsius (47 degrees Fahrenheit). This global winter lasted for years, enough to devastate plant life and everything else along the food chain. Around 75% of all animals and plant species went extinct, including the iconic dinosaurs (except for birds).

To say this was bad luck would be a huge understatement. If the asteroid’s course was just a tiny fraction of a degree different, it would have missed Earth. Were the impact site in a different place, things could have been different too. The time of the year may have also made a difference in which species were wiped out or spared.

This latter point was partly the subject of a new study that found the asteroid impact likely took place in the spring or early summer in the Northern Hemisphere. The findings are based on controversial fossils from Tanis, a site in North Dakota where paleontologists found a huge trove of fish fossils. The freshwater creatures are believed to have all perished just hours after the asteroid impact.

Robert DePalma, a doctoral student at the University of Manchester in the UK, was in charge of analyzing the fossils, which still preserved growth lines in their skeletons. These growth lines can trace the life history of the fish, not all that different from how growth rings record a tree’s history of drought and rainfall. Like barcodes, they enable scientists to deduce unique details like whether or not the fish had plenty of food during a particular season of their lives.

During spring and summer, the bones of fish grow a darker layer while lighter bands form in fall and winter. Previously, DePalma and colleagues published a study in 2019 that found a massive surge of water fell upon Tanis as a result of a vast earthquake triggered by an asteroid impact, rapidly depositing sediments that locked in the fish remains. The last growth lines observed in the bones of the fish were light, suggesting the asteroid impact occurred in the spring or early summer.

This line of reasoning is supported by isotopic analysis of the growth lines, since the two types of growth lines have different ratios of carbon.

“This project has been a huge undertaking but well worth it. For so many years we’ve collected and processed the data, and now we have compelling evidence that changes how we think of the KPg event, but can simultaneously help us better prepare for future ecological and environmental hazards,” DePalma said in a statement.

“Extinction can mark the end of a dynasty, but we must not forget that our own species might not have evolved if it weren’t for the impact and the timing of events that saw the end of the dinosaurs”.

Robert DePalma (L) and Professor Phil Manning at the Iridium-bearing KPg boundary clay layer capping Tanis. Credit: University of Manchester.

In addition, the team of researchers also analyzed fossils of leaves that were damaged by insects, as well as fossilized adult mayflies found at the site, which also match the seasonal timing.

“They all matched up…everything points to the fact that the impact happened during the northern hemisphere equivalent of Spring to Summer months,” said co-author Loren Gurche.

Scientists looking to reconstruct the aftermath of the asteroid impact that caused the fifth mass extinction need every bit of evidence they can gather to paint a more accurate picture. Knowing which season of the year the asteroid struck may prove very important. Certain animals, for instance, are more vulnerable during certain times of the year, such as periods of growth and reproduction.

The data could also be applied today, helping scientists better understand how contemporary life responds to global-scale hazards.

The findings appeared in the journal Scientific Reports 

Tank-like dinosaur fossil discovered in Chile could show how spike-tails became club-tails

Seventy-something million years ago, a dinosaur had the worst day. It got stuck, potentially in a quicksand-type trap, and never made it out. Now, paleontologists working in Chile have uncovered its fossil, which was excellently preserved — and they believe the dinosaur can help us better understand how an important group of dinosaurs evolved and developed in the Cretaceous.

The life appearance and environment of the new species of armoured dinosaur Stegouros elengassen. The image reflects the paleoenvironment of meanders and lake bodies in a deltaic fan at the edge of the old Austral basin, with plant assemblages reconstructed from fossils at nearby levels, typical of this region of Gondwana. Paleoartist credit: Mauricio Álvarez.

Ankylosaurs are a group of armored dinosaurs dating to the very end of the Cretaceous Period, about 68–66 million years ago. They measured up to 6-8 meters (20-26 ft), weighed 8 metric tons, and walked on four limbs. They had a large, robust body and were covered in extremely solid plates that served as a strong defense against predators. The bones in their skull and other parts of the body were fused together, making the entire structure even more solid. But most notably, they had a strong tail club that researchers believe was used to defend both against predators and in combat against other members of its own species. Ankylosaurs were built like a tank, and they could pack quite a punch as well.

We know a lot about ankylosaurs — or at least some of them. They evolved on both Laurasia and Gondwana, the two continents resulting from the break-up of the supercontinent Pangea. But while ankylosaurs from the northern Laurasia are rather well-known, those from Gondwana (which are the earliest group) are poorly understood. This new study could shed new light on them.

An early Ankylosaur

Armored dinosaurs from Gondwana are enigmatic, write the authors of a study describing the fossil from Chile — which is why the new find is so intriguing, said Alexander Vargas, one of the study authors, for ZME Science.

“The new dinosaur is a transitional ankylosaur: an evolutionary link between the typical Ankylosaurs of the northern hemisphere, and older lineages of armored dinosaurs. It is the first good skeleton from South America and the first named species of Ankylosaur for this continent (only unnamed scraps and pieces had been previously discovered) , and it proves that ankylosaurs from the southern hemisphere were radically different from those of the north, having separated from them very early in evolution, and evolving different kinds of tail weaponry.”

3-D model (sculpture) of the life appearance of the new species of armoured dinosaur Stegouros elengassen. Paleoartist credit: Lucas Jaymez. Social media: @dinoesculturas.

The newly-discovered dinosaur was named Stegouros elengassen. It has some of the distinctive skull features characteristics of other ankylosaurs, but the rest of its skeleton is strikingly primitive, showing stegosaur-type characteristics — stegosaurs lived much earlier, going extinct around 100 million years ago.

Stegosaurs also had a weapon-like tail, but unlike the ankylosaurs (whose tail is like a club), the stegosaurs’ tails consisted of spikes. The newly-discovered Stegouros has somewhat of a hybrid tail — it has seven pairs of flattened, bony deposits fused together, which could mark a transition from one group to the other.

The researchers were fortunate to find such a well-preserved fossil, Vargas explained.

“The fossil of Stegouros was preserved with its posterior half (“waist down”) fully articulated and complete, in a deeper position than the anterior half of the animal, which was scattered and missing a few elements. The evidence suggests that the posterior half of the animal was buried quickly at a river bank, while the upper half lay exposed for a while and fell apart before it, too, was buried. It is possible that this dinosaur was stuck in a death trap such as quicksand; its legs were straightened out, which is uncommon (they are folded in most carcasses), and it was also found belly down, unlike carcasses of armoured dinosaurs that have been transported by a river, which tend to be belly up.”

3-D model (sculpture) of the life appearance of the new species of armoured dinosaur Stegouros elengassen. Paleoartist credit: Lucas Jaymez. Social media: @dinoesculturas

However, the digging conditions were very rough, the researcher added in an email. The block of rock containing the fossil was on top of a very steep hill, and at some point, researchers only had five days of work until freezing conditions came. A small team of 5-6 people worked in rough conditions bordering hypothermia and one of them suffered an accident, falling down and breaking his rib.

In the end, though, this hard work and sacrifice bore fruit. In light of these findings, the authors conclude that after Laurasia and Gondwana split up, ankylosaurs on the two different continents also started evolving in different ways. However, the finding also shows just how much we have yet to learn about ankylosaurs, how they emerged and spread at the end of the Cretaceous.

Digital reconstruction of the unique tail weapon of the new species of armoured dinosaur Stegouros elengassen. The tail was encased in pairs of dermal bones; a portion of the dermal bones has been digitally sliced away, to reveal the tail vertebrae within. Different colors signal physically separate bones; many dermal bones have fused into a single unit (liliac). Credit: José Palma and Joao Francisco Botelho.

If you’re curious about what the day of an armored dinosaur in the Cretaceous was like, we asked Vargas just that. Here’s what he said:

“Stegouros lived in a delta that opened in a fluvial fan, like that of the Nile River, with winding rivers and islands between them We have found abundant evidence of Nothofagus forests, such as those found today from central to southern Chile, along with herbaceous vegetation and ferns. It is a typically southern environment from the late Cretaceous and one of the few continental deposits that we have in the entire Southern Hemisphere at this time. Stegouros was a herbivore that may have preferred living near water. It had a tough skin laid with small ossicles and larger osteoderms as well as its impresssive tail weapon so it probably got little trouble from predatory dinosaurs such as small Noasaurids or even large Megaraptorids (tough to chew).”

The research was published in Nature.

In Iceland, CO2 is sucked out of the air and turned into rock

A facility in Iceland is taking atmospheric carbon dioxide (CO2), the main culprit of climate change, and injecting it into volcanic rocks deep underground. While this is still early days and the volume of CO2 isn’t too great, this type of technology could be very important in the future.

The Orca plant. Image credits: Climeworks.

Even if we’d magically stop all our greenhouse gas emissions tomorrow, the inertia of our past emissions would still push the planet to warm a bit. If we continue “business as usual”, things will be way worse. So why don’t we just take greenhouse gases out of the air and store them somewhere safe where they can’t contribute to global warming?

The idea is not new, but of course, it’s easier said than done. Separating out the right gases, processing them, and storing them somewhere where they can’t escape back into the atmosphere are all big challenges — and doing them all together is even more demanding. But a company working in Iceland is not deterred.

Climeworks is a Swiss company specializing in carbon dioxide air capture technology. They’ve recently built a plant in Iceland called Orca that can capture 4000 tons of CO2 per year, making it the biggest climate-positive facility in the world.

Orca (the Icelandic word for energy) lies near the Hellisheiði Power Station — the third largest geothermal power plant in the world. It consists of eight containers stacked up two by two; fans in front of a collector draw ambient air, the air passes through a selective material that collects CO2, and the CO2-depleted air is then released at the back. It’s a bit like “mining” the sky for CO2 — simple in principle, though very difficult to implement.

What happens next is also not exactly simple. After the filter is full, it’s heated to around 100 degrees Celsius to clear the CO2 of any impurities, and then piped underground a distance of three kilometres (1.8 miles) to dome-shaped facilities in a moon-like landscape where it is dissolved in water and then injected under high pressure into basalt rock 800-2000 meters deep. The injection facility was developed by Carbfix which pioneered underground carbon storage.

The injection facility. Image credits: Carbfix.

The dissolved solution starts filling the cavities of the subsurface basalt and reacting with the rock, solidifying and turning into minerals in about two years.

To do this, you need the right geology, and Iceland offers just that. Much of Iceland is a basaltic field, where this dissolved gas can be safely injected. The only way the CO2 would be released into the air is in the case of a volcanic eruption, but the injection site was chosen in an area where the risk of an eruption is very low.

A core of basalt rock (black part) with the injected CO2 (white part). Image credits: Climeworks.

However, as exciting and promising as this technology is, it won’t save us from climate change on its own. While Orca can suck up to 4000 tons of CO2 per year, the yearly global emissions are around 33.4 billion tons of CO2 — so the plant can dispose of 0.00001% of our yearly emissions. Climeworks says this is mostly a trial and it will achieve megaton removal capacity in the second part of the decade, but even one megaton is still a very small percentage of our emissions. To make matters even more complicated, the process is costly and requires large amounts of energy. While the plant is run on renewable energy, this still makes scaling more difficult.

In fact, carbon capture is making such a small dent in our total emissions that critics have argued that it’s a costly distraction from the real policy measures needed to fight climate change. It’s true that only reducing our emissions can prevent catastrophic climate change, but “you have to learn to walk before you can run,” says Julie Gosalvez, in charge of marketing for Climeworks.

Carbon storage is just emerging as a technology. It won’t help us fix climate change yet, but it can be important down the line — provided we have the right conditions for it. The only way it can work is if the world implements a carbon tax, and extracting carbon from the air is incentivized. This makes economic sense, but for now, there’s no such carbon tax on the horizon.

New mineral that shouldn’t exist at Earth’s surface found trapped in a diamond

Scientists found a mineral that was never encountered before in nature trapped in the dark inclusions of this diamond. Credit: Aaron Celestian / Los Angeles County Natural History Museum.

The most prized diamonds aren’t the largest, rather the purest. But one man’s trash is another man’s treasure. An impurity inside an inconspicuous diamond unearthed from an African mine in the 1980s turned out to be a new type of mineral previously unknown to science. This isn’t just any kind of mineral, either. It’s the only mineral formed in the planet’s lower mantle that we’ve ever found, and could thus greatly improve our understanding of Earth’s interior and how it formed.

The mineral in question, christened davemaoite after pioneering geophysicist Ho-kwang “Dave” Mao who studied how materials react to extreme pressure, was found in dark inclusions inside a diamond mined from Botswana. In 1987 it was sold by a gem dealer and changed hands until it reached the trained eye of geologists at the University of Nevada, Las Vegas.

“For jewelers and buyers, the size, color, and clarity of a diamond all matter. Inclusions — those black specks that annoy the jeweler — for us, they’re a gift,” said mineralogist Oliver Tschauner of the University of Nevada, Las Vegas. “I think we were very surprised. We didn’t expect this.” 

The calcium silicate compound was surprising because we should never have been supposed to find it. The mineral formed hundreds of miles beneath Earth’s surface, inside the lower mantle between the core and the crust where temperature and pressure are ungodly high. Davemaoite’s structure is supposed to collapse outside the high-pressure environment of the mantle but since it was trapped in a diamond, the toughest material known to man, the mineral survived.

So what looked like a dark blemish turned out to be one of the rarest finds a geologist can ever hope to discover. And since davemaoite can host uranium and thorium, radioactive elements that are responsible for heating up Earth’s lower mantle, scientists believe that the newly discovered mineral can help answer some questions about Earth’s interior, with wide ramifications. For instance, the movements inside the planet’s lowest layers is believed to at least partially drive plate tectonics.

Davemaoite is only the second high-pressure mantle silicate ever seen on Earth’s surface. The other, named after Nobel laureate Percy Bridgman, was found inside a meteorite.

“The two form an exclusive club as the only lower-mantle silicate minerals confirmed in nature,” said co-author Yingwei Fei of Carnegie Science.

Now that scientists know what’s possible, they’ll be on the lookout for other lower mantle minerals that could have existed under our noses for all this time.

“The discovery of davemaoite inspires hope for finding other difficult high-pressure mineral phases in nature,” Fei said. “Being able to obtain more direct samples from the inaccessible lower mantle would fill in our knowledge gap regarding the chemical composition and variability of our planet’s depths.”

Davemaoite has been officially added by the International Mineralogical Association to its list of known minerals. The findings appeared in the journal Science.

We are one step closer to forecasting how volcanoes will behave during eruptions

We tend to not think about it, but around 10% of the human population currently lives in the risk zone of active volcanoes. While the other 90% of us are relatively safe from the eruptions of smaller volcanoes (such as the Cumbre Vieja in La Palma, which recently erupted), if one of the larger magmatic systems were to erupt, we would all find ourselves in one hot pickle — no matter where we reside.

A crater inside the larger caldera of Nisyros Volcano, in Greece. The caldera was formed after a catastrophic explosion that disintegrated a large part of the volcanic cone almost 60,000 years ago, while the smaller crater is about 150 years old.

The problem is, we have plenty of those big, mean volcanoes to start with — and they’re often closer to home than you’d think. Even in Europe, where volcanic eruptions are relatively rare to begin with, there are Nisyros, Santorini, Hekla, or Campi Flegrei. We don’t even want to think about what an eruption from the likes of Yellowstone, Toba, or Tambora would bring — and yet we have to.

When volcanoes erupt

Nowadays, with the knowledge and technology we have at our disposal, it is pretty easy to know when a particular volcano is going to erupt. The rise of magma through the crust triggers swarms of small intensity earthquakes, it causes the rocks to bulge, and hot waters and gas to reach the surface well before the magma does, heralding incoming trouble.

What we don’t really know — and this has bugged volcanologists for decades — is how a volcano is going to behave during the eruption. Will it generate effusive eruptions that lead to relatively mild lava flows which can damage property but are relatively harmless to people? Or will it trigger violent explosions, which eject clouds of hot gas and ash, or even disintegrate entire volcanic structures, leaving behind caldera depressions instead of mountains?

To solve this problem, volcanologists have mostly focused on what happens in the volcanic conduit — the pipeline that connects the magma chamber to the surface. Once an eruption begins, magma ascends through the crust, generally for about 8-10 km before reaching the volcanic summit. During this ascent, what happens to the gas that bubbles in the magma is the key to how the volcano will erupt.

If, for example, the gas remains trapped in the melt and can’t escape to seep away, there’s a big chance the magma will explode. If on the other hand, the gas bubbles get to sneak out and leave the melt behind, or outgas, the explosive potential of the magma is neutralized and the volcano will likely ooze lava flows. Letting the gas escape is more or less like defusing a bomb, reducing the risk of a big explosion.

A simplified diagram showing what happens with the magma underground, as it ascends towards the surface. In both cases the eruption is imminent, but the difference is in what happens with the gas bubbles: the magma to the left will explode, while the one to the right will effuse.

It sounds simple, but it’s deceptively complicated. Decompression, changes in ascent velocity and melt viscosity, gas bubbling and percolation, stress buildup, the mechanical resistance of the melt, and all sorts of complicated interactions between melt, crystals, gas bubbles and country rocks, will all compete or cooperate to either block the gas in the magma, or to allow it to outgas. It’s so complicated in fact that we don’t yet have a clear understanding of how all these processes interact, and we are still unable to build robust numerical models to simulate all of them. Even if we would reach the required level of understanding, and if we’d be able to forecast eruptive styles based on conduit processes, it would only give us a few minutes’ worth of time to do anything about it since the magma is already on its way up.

A few minutes isn’t exactly enough to do that much in case of an incoming explosive eruption. It would give you the chance to open that bottle of wine you’ve been saving (because you may not get another opportunity) but not much more. But what can we do if we forecast the eruptive behavior of a volcano well before the eruption is even triggered? What if instead of mere minutes, we’d have weeks, months, years, even decades to prepare?

We can now stop dreaming about it and start planning, because we are one step closer to achieving this goal.

Predicting eruptions

A recent study published in Nature Geoscience by researchers from the Swiss Federal Institute of Technology (ETH Zürich, Switzerland) and Brown University (USA), with myself as one of the authors, makes a major breakthrough in the direction of forecasting eruptive styles. The question we designed the study around was: what if the magma chamber conditions can predetermine eruptive behavior, regardless (to some extent) of what happens in the conduit?

It should be possible, after all, since the magma entering the volcanic conduit inherits all its initial properties from the magma chamber.

The big difference between magma chamber processes and conduit processes is that whatever happens in the magmatic reservoir takes place over days, months, years, even thousands or tens of thousands of years, giving us ample time to detect changes. Indeed, this new study shows a striking correlation between how the magma is stored underground, and how it ultimately behaves at the surface.

The study is based on reconstructing the magmatic storage conditions of about 245 eruptions generated by 75 volcanoes worldwide, including some really famous ones. To achieve this, we relied on the chemistry of minerals and glasses from erupted products, which are windows to processes and conditions that had happened deep underground, and which we can’t really probe directly. Using this approach, we determined the temperatures of the magmas, the amounts of solid crystals floating in the melt, the content of dissolved gas it stored, and whether some of that gas might have started exsolving (or forming gas bubbles) while still in the magma chamber.

As was expected, low amounts of dissolved gas (generally lower than 3.5 wt% water) leads to effusive outpourings of lava, while higher water contents (roughly between 4 and 5.5 wt%) favor explosive events. Interestingly, however, crystallinity (the volume of solid particles in the magma) has an important say in this as well. When more than 40% of the volume of the magma consists of crystals, the eruption becomes mild no matter the stored gas content. This happens because the solid particles form a kind of skeleton that the gas bubbles connect to, allowing them to form finger channels that act like pipes. In this way, even if the magma has enough gas content to explode, the crystals help the gas permeate the melt efficiently and defuse the volcanic bomb. At the same time, a large amount of crystals increases the bulk viscosity of the magma and its resistance to flowing. By doing so, the magma is slowed down considerably on its way to the surface (even by ten times), allowing more time for the gas to escape through the finger channels.

Deposits generated by volcanic explosions at Nisyros Volcano, in Greece.

A key observation, which is counter-intuitive and bound to spark a debate in the volcanological community, is that at very high gas contents (more than 5.5 wt% water), the magmas start behaving effusively again. Why, though? The higher the gas content, the more explosive the magma should be, right? But as we found, this is not necessarily the case.

At very high dissolved gas contents, the melt is unable to store all its water in dissolved form anymore: as disseminated molecules. Instead, the molecules come together to form gas bubbles, or to exsolve. It’s very much like a stirred bottle of champagne. What we found is that magmas very rich in gas are also likely to contain quite a few gas bubbles in the magma chamber. Their presence dramatically changes how the eruption is initiated, and as a result, how it is likely to behave.

How? Well, this is where things get complicated again. Most volcanic eruptions are triggered when magma that is even hotter and comes from even greater depths, from the lower crust of the Earth, intrudes the shallow magma chamber of the volcano. Yes, for us volcanologists 10 km is shallow… This intrusion of hot magma into another body of liquid magma is known as magmatic recharge. As more magma is being crammed inside, the magmatic reservoir is being pressurized: it’s more or less like blowing a balloon that has no space to expand, while more air keeps on going inside. At some point, the balloon will just break. The same happens in a magma chamber: the rocks sealing it fail, and the hot stuff starts threading its way towards the surface.

If a magma chamber doesn’t contain gas bubbles (or contains very few of them), it pressurizes fast during magmatic recharge, and the eruption is triggered readily. When many gas bubbles are present in the magma chamber though, as the article highlights through numerical simulations, they act as a myriad of tiny cushions. Each gas bubble compresses to allow space for the extra magma that comes from below. This means that even more hot material needs to intrude the magma chamber until the surrounding rocks finally break and allow the material to erupt at the surface. More and more hot recharge coming in, and more time for it to interact with the magma chamber means that the resident melt heats up. Heating up a melt is like heating up honey: it becomes less viscous, and a less viscous melt is able to lose gas easily. See the connection?

Solidified lava flow generated by water-rich magmas rich in gas bubbles, from Nisyros Volcano, in Greece.

Basically, a magma chamber containing gas bubbles heats up more intensely before an eruption is initiated, it ends up feeding the conduit with a melt of lower viscosity which allows the gases to seep through it faster, and in addition it already has a multitude of gas bubbles that are ready to connect and outgas even at the base of the volcanic conduit.

In conclusion, what the article shows is a clear window of explosivity, at between 4-5.5 wt% water and at low to moderate crystallinities. All we need to do now is to find a way of looking inside active magma chambers and evaluate their state. Scanning something buried at a depth of about 8-10 km might sound science-fiction, but geophysics is here to do the job. One method, in particular, magnetotellurics, which uses the natural magnetic and electric fields of the earth, is capable to reconstruct the electrical resistivity structure of active magma chambers. By approaching the problem interdisciplinary and integrating the geophysical and volcanological data, we can use this electrical resistivity structure to estimate the crystallinity of the magmatic reservoir and to check whether significant volumes of gas bubbles are currently present or not in the magma chamber. These are two of the three key parameters required for the timely forecasting of the eruptive behaviour of volcanoes.

The study has been published in Nature Geoscience. Journal Reference:

Popa, RG., Bachmann, O. & Huber, C. Explosive or effusive style of volcanic eruption determined by magma storage conditions. Nat. Geosci. 14, 781–786 (2021).

Stellar pollution shows exoplanets are more diverse than we thought — but few are like Earth

Artist’s impression of an exoplanet. Image credits: IAU/L. Calçada.

For Earth to be able to support life, a lot of things needed to be just right. The Sun had to be the right size and brightness, and just at the right distance from the Earth; the atmosphere that protects the planetary surface from harmful radiation; the chemistry needed for water and the seeds of life; and a crust and plate tectonics. We don’t often think about plate tectonics as a key ingredient for life, but it is. Without a crust, plate tectonics couldn’t exist, and without plate tectonics, life as we know it couldn’t exist.

The crust is where dry, hot rock from the deeper parts of the Earth interact with the water and air on the surface, producing new minerals and rocks. New crust is constantly being produced and destroyed, and if this didn’t happen, the seafloor could become rigid and much more unfriendly to life. New research is suggesting that plate tectonics is essential to life as we know it.

There are also two types of crust on Earth: basaltic and granitic. The basaltic crust is dark and heavy, and sometimes called oceanic crust. Meanwhile, granite crust is light and accumulates into continent-sized rafts that move in this “sea of basalt.” It’s sometimes called continental crust. When an oceanic crust moves against the continental crust, the heavier and denser oceanic one subducts (or goes under the other one).

But our planet’s crust may be a rarity, at least in our corner of the universe.

Image credits: USGS.

Keith Putirka from California State University, Fresno, and Siyi Xu of the Gemini Observatory analyzed the atmospheres of 23 nearby white dwarfs, looking for signs of so-called “pollution” — chemical traces that stars can pick up from nearby planets as they explode into red giants.

“White dwarfs start out like our Sun, and late in life expand to become a red giant, and then collapse to a very small size – about the size of Earth,” Putirka told ZME Science. “As the star collapses, planets orbiting the star (at least those not obliterated during the red giant phase) can orbit close enough to the star that they are destroyed by tidal forces. The debris that results can fall into the star’s atmosphere. This infalling debris is the “pollution” that is measured by astronomers, and records the composition of the formerly orbiting planetary objects.”

The researchers found that some contain high amounts of calcium (Ca), but all have very low silicon (Si) and high magnesium (Mg) and iron (Fe) amounts. This suggests a composition closer to the mantle of exoplanets, and not at all what you’d expect to see from a planetary crust.

Roughly speaking, the Earth consists of a crust, a mantle, and a core. Although the movement of plate tectonics is driven by movement from the mantle, it’s the crust that is fragmented into rigid plates (hence the “plate” tectonics). But there seems to be no sign of a granitic crust — or even other crust types. So plate tectonics may have not existed on these planets, or if it did, it was very different from what we see on Earth.

Magma circulation driving the movement of plate tectonics.

“It’s hard to say whether granitic crusts might exist on other planets, or not,” Putirka explained to ZME Science. “In our Solar System, granitic crust only exists in any great abundance on Earth, and its abundance is probably related to our abundant surface water and plate tectonics, which are also unique to Earth. The exoplanets that once orbited white dwarfs have silicate mantles (all the rocky material between the iron core and the crust) that are very different from Earth – so different that plate tectonics and crust formation might occur very differently.”

“Some exoplanets may have mantle compositions that might yield very thick granitic crusts and more abundant continental material than on Earth. Others have mantle compositions that might not produce any continental crust at all. Many of these planets may look totally unlike anything we see in our inner Solar System.”

More questions

The findings have important implications for potential life on other planets — but it’s hard to interpret just what this means. But what is clear is that we need to have a broader view when we consider exoplanet environments.

“I think it’s fair to say that the trajectory of biological evolution is dependent upon geologic history. For example, if a planet has abundant water, but no granitic crust, then nothing like the terrestrial life as we see on Earth could possibly evolve – because there would be no terra firma for such evolution to take place. But we don’t yet know how such odd exoplanets (in the white dwarf database) might evolve from a geologic standpoint because, up to now, we have focused our laboratory experiments (on how rocks melt or deform) based on questions about how Earth-like (or Mars-like or Moon-like) planets might evolve. But the compositions we see in the white dwarf data indicate planets that are mineralogically very different, and so require new experimental studies.”

Ultimately, this study still shows that there’s plenty we don’t know about the Earth — if we did, we’d have a better idea of what makes it so special (if anything). There are still plenty of questions we need to answer about our planet, and only once we do (and once we study our solar system neighborhood more closely) will we be able to understand planets outside of our solar system as well.

“My take on our findings is that it reflects back on what we still don’t know about Earth and our rocky planetary neighbors.,” Putirka concludes “Earth not only has abundant water and life, but two very distinct kinds of crust – one of which (granitic, continental crust) is effectively unique in our solar system, and is essential for human evolution. Earth is also the only planet that has a long history of plate tectonics.”

“How and why did these features appear on Earth, and what inhibited their development elsewhere in our own Solar System? Tectonics and crust formation are surely sensitive to planet size, orbital radius, and planet composition. To what extent can we change any of these parameters and still end up with a habitable planet – and/or something that, geologically, looks roughly like Earth? We’ll have better answers to these questions when we conduct new experiments, and when we start exploring Venus, and when we shift our focus from trying to find life on Mars to instead better understanding the geological conditions that limited evolution there in the first place.”

The study “Polluted white dwarfs reveal exotic mantle rock types on exoplanets in our solar neighborhood” was published in Nature Communications.

Earth’s inner core may actually be mushy

In 1936, Danish seismologist Inge Lehmann performed a groundbreaking study showing that Earth’s iron-rich inner core is solid although it’s hotter than the sun’s surface. Since then, our understanding of the planet’s innermost layer has been constantly refined. Earlier this year, for instance, scientists in Australia showed that the inner core may be made of two distinct layers, which suggests perhaps two separate cooling events in Earth’s history. But that’s not all.

A new potentially textbook-altering study shows that the inner core may not be entirely solid — at least not in the sense that we image a solid material. Instead, scientists have found that the deepest layer of the Earth is made of a tangled bunch of solid surfaces that sit against melted or mushy iron.

Earth sounds more and more like a meat pie

Earthquake locations (red) and seismic stations (yellow). (Photo credit: Butler and Tsuboi, 2021.)

Although the inner core is obscured by more than 4,000 miles (6,300 km) of crust, mantle, and liquid outer core, scientists have a fairly clear picture of what goes inside the bowels of the Earth. How so?

Whenever a volcano erupts or an earthquake strikes, these events generate acoustic waves whose properties, such as direction, angle, and velocity, change predictably depending on the material they encounter.

There are multiple types of seismic waves, ignoring surface waves, which are responsible for the onslaught in the wake of some very powerful earthquakes. When studying the inner layers of Earth, geophysicists mainly focus on primary waves (P-waves) and shear waves (S-waves). P-waves travel through all types of mediums, whereas S-waves only travel through solid materials.

When seismic waves created by earthquakes hit the liquid outer core then travel through the inner core, seismic data gathered from stations across the world record an extra wave going off at right angles which can only be explained by a shear wave. This is how Lehmann showed that the inner core, which is about the size of the moon, is solid. It’s not all that different from how a doctor might use a CT scanner to image what’s inside your body without cutting it open.

Geophysicists are constantly learning new things about Earth’s inner layers as seismic data improves, helped by new tools such as machine learning algorithms and other AI machines. A new study led by Rhett Butler from the University of Hawaiʻi at Mānoa School of Ocean and Earth Science and Technology (SOEST), found that the inner core is not exactly solid. Instead, it’s a melange of liquid, soft, and hard structures. The heterogeneous composition is especially striking in the top 150 miles (240 km) of the inner core.

“In stark contrast to the homogeneous, soft-iron alloys considered in all Earth models of the inner core since the 1970s, our models suggest there are adjacent regions of hard, soft, and liquid or mushy iron alloys in the top 150 miles of the inner core,” said Butler. “This puts new constraints upon the composition, thermal history and evolution of Earth.”

The outer core is entirely liquid and much less controversial, with its molten iron in a constant churning movement, driven by convection as it steadily loses heat from the time Earth formed to the static mantle above. It’s this motion that generates our planet’s magnetic field like a dynamo, which cushions us from harmful radiation from the sun.

However, the outer core is influenced by the inner core. So having a better grasp of its true structure helps scientists form a better understanding of the dynamics between the inner and outer cores.

“Knowledge of this boundary condition from seismology may enable better, predictive models of the geomagnetic field which shields and protects life on our planet,” said Butler.

The findings appeared in the journal Science Advances.

Dog-sized scorpion was king of the sea 440 million years ago

Two hundred million years before dinosaurs emerged, sea scorpions were the bad boys of the sea. Researchers have now described a fossil dating from between 443 million and 419 million years ago that was perfectly equipped to take down every creature it encountered in the waters.

Credits: Nanjing Institute of Geology and Paleontology.

Eurypterids, as the sea scorpions are called, came in many shapes and sizes — and all were fierce predators. They ranged in size from just a few inches to the size of a human, and they probably struck fear into the hearts of all creatures in the sea (although not that many creatures had evolved proper hearts at the time).

Doctoral researcher Wang Han and Professor Wang Bo from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS) discovered a fossil of the eurypterid in southern China, in an area that was once part of an ancient continent called Gondwana.

Hundreds of millions of years ago, almost all the planet’s landmass was clumped together in a supercontinent called Pangea. At some point, Pangea broke into two continents called Laurasia and Gondwana, which continued to break apart into the continents we see today on the globe. All the previous fossils previously discovered from this group came from Laurasia, this is the first one from Gondwana.

The fossil dates from a period in the Cambrian called the Silurian, a very warm period when land flora and fauna were just starting to diversify. In particular, the fossil belongs to a group of sea scorpions called the “Mixopteridae”. We don’t know much about this group, and what little we know, comes from fossils described almost a century ago.

“Our knowledge of mixopterids is limited to only four species in two genera, which were all based on a few fossil specimens from the Silurian Laurasia 80 years ago,” said Prof. Wang.

The fossilized appendages of the sea scorpion, along with an artist’s recreation of what the species would have looked like. Image credits: Nanjing Institute of Geology and Paleontology.

The newly-discovered creature, named Terropterus xiushanensis, had barbed limbs, which were presumably used like a “catching basket” for capturing prey, a technique also used by whip spiders today. Other modern species of spiders use the same appendages to transfer sperm from the male to the female.

Researchers believe there are more fossils related to T. xiushanensis just waiting to be found, and finding these could help us better understand how life evolved in our planet’s geological past.

“Our first Gondwanan mixopterid — along with other eurypterids from China and some undescribed specimens — suggests an under-collecting bias in this group,” the researchers write in the study. “Future work, especially in Asia, may reveal a more cosmopolitan distribution of mixopterids and perhaps other groups of eurypterids.”

The study was published in Science Bulletin.

Rare tardigrade fossil discovered in 16-million-year-old amber

Tardigrades, microscopic animals that live in water and are really good at coping with extreme environments and surviving decades without food. But for all their resilience, they’re rarely fossilized. Now, in a new study, researchers have found a 16-million-year-old-fossil in an ancient piece of amber from the Dominican Republic. 

Image credit: The researchers.

Only two fossils of the creature were ever found before, although tardigrades have been around for over 90 million years. This last discovery is the first tardigrade fossil to be recovered from the current Cenozoic era, which started 66 million years ago. The researchers believe it’s the best-imaged fossil tardigrade to date. 

The tardigrade earned its own genus and name, Paradoryphoribius chronocaribbeus, because it’s so different from previously known specimens. It’s part of the modern tardigrade family Isohypsibioidea and it will help to better understand the evolutionary history of tardigrades, which are creatures of particular interest for researchers. 

“The discovery of a fossil tardigrade is truly a once-in-a-generation event,” Phil Barden, senior author of the study, said in a statement. “What is so remarkable is that tardigrades are a ubiquitous ancient lineage that has seen it all on Earth, from the fall of the dinosaurs to the rise of terrestrial colonization of plants. Yet, they are like a ghost lineage.”

The tardigrade was actually spotted by Barden’s co-author Brendon Boudinot, who saw it next to the ants that he had been analyzing in the ancient amber. At first he thought it was a crack or fissure that happened to look like a tardigrade. While extremely happy, he considered the discovery was “enough tardigrade luck for one career.”

The remarkable tardigrades

The researchers used a high-powered laser confocal fluorescence microscopy to look further at the fossil and its place on the tardigrade ancestral tree. This allowed to look at the specimen in very close detail. Then they compared it across morphological features associated with most of the tardigrade groups alive today, such as body surface and egg morphology. 

“The fact that we had to rely on imaging techniques usually reserved for cellular and molecular biology shows how challenging it is to study fossil tardigrades,” Javier Ortega-Hernandez, co-author, said in a statement. “We hope that this work encourages colleagues to look more closely at their amber samples with similar techniques to better understand these cryptic organisms”.

The discovery is only “scratching the surface” of our understanding of the tardigrades, the researchers said, hoping further findings could come in the future. The fact that this specimen was found in an amber deposit suggests that others could have been overlooked in the past. Finding more fossils would allow us to learn more about how tardigrades have changed over time. 

Around 400 species of tardigrades that have been discovered so far, and they seem to be able to survive in all sort of environments. From freshwater mosses to the deep ocean, these creatures can survive up to 30 years without food, temperatures going from absolute zero to above boiling and including in the vacuum of space. They are trully remarkable and worth studying further. 

For now, it’s all excitement among the group of researchers, who even wrote a song to commemorate the occasion. It goes like this: “Tardigrade amber fossils, there were only two. …Well now, there’s three. Now that you know there’s three, there’s another mystery. What could this fossil be? Well, look at our paper and you’ll see.”

The study was published in the journal Proceedings of the Royal Society B. 

Could fiber optic cables predict Iceland’s next volcanic eruption?

A team from ETH Zurich and the Icelandic Meteorological Office embarked on a seemingly bizarre mission. They deployed some 13 km (8 miles) of fiber optic cable on an active volcano in Iceland. The goal wasn’t to bring faster internet to the mountain trolls, but rather to see if the cables could sense slight tremors in the volcano — an indication that an eruption may be impending.

Image credits: ETH Zurich / Hildur.

The first earthquake detector was invented some 2,000 years ago, and while things have come a long way, the underlying principle is more or less the same: a ground tremor is passed through to a detector that records the movement (and its intensity) and then translates it into a readable measure. Early seismometers were analog, but in more recent times, they all use some form of digital recording.

But things have not stayed still in the world of seismology. In recent years, for instance, a new idea emerged among some researchers: what if we could use something else, something that wasn’t designed for earthquakes, to sense this movement? Something like, for instance, fiber optic cables.

The idea is not without precedent. Operators of critical infrastructure have long used these cables to monitor their facilities, and researchers thought they could use the same for earthquake study.

“The idea of using optical fibres for multiple purposes is nothing new,” says Andreas Fichtner, a professor of geophysics in the Department of Earth Sciences at ETH Zurich. Together with Fabian Walter, a professor at the Laboratory of Hydraulics, Hydrology and Glaciology (VAW), he wants to use this technology to monitor and study glacial earthquakes. “I’m particularly interested in tiny earthquakes that originate in the glacier bed.”

The key to this approach is the cable itself. The way fiber optic cables work, pulses of light of a specific wavelength are directed through the cable continuously from one end of the cable to the other. If the cable is moved or shaken, this will change how the pulses come back to the receiver.

By analyzing the interference in the returning signals, researchers can calculate when and where the earthquakes happen, and how strong they are — and the quantity of data that can be accessed this way is enormous. “You’re basically replacing thousands of seismometers with a single cable,” says Fichtner.

Project manager Fabian Walter (at rear) and his colleague Małgorzata Chmiel check if the cable is fully functional. (Photo: Wojciech Gajek)

The problem is that despite this large volume of data, it is not exactly high-quality data we’re talking about. The cable is less sensitive than a modern seismometer, but researchers hope they can compensate for this with the sheer volume of measured points. But it won’t be easy.

“Analysing it will be a tremendous job,” Fichtner tells ETH with a smile. “We will have to come up with methods to cope with the sheer quantity of data.” The researchers expect that the first measurement campaign will produce around 20 terabytes of raw data.

But the method is promising. For their worksite, researchers chose the Grimsvoetn volcano in Iceland — an active volcano. The idea is that glacial temblors can help researchers estimate when a volcanic eruption may be coming. But this isn’t their first rodeo. A study published by the same authors on a previous test site, on the Rhône Glacier in the Swiss Alps, is already challenging some of the existing theories in the field.

The study found that the glacial quakes occur in clusters, especially at the boundary between the ice and the underlying rock. This would imply that the glacier isn’t sliding smoothly (which would produce a different type of earthquake), but rather moves forward in a jerky motion.

“That’s not what you would expect based on current theories,” explains Walter. “Glaciologists assumed that glaciers could slide because the glacier bed was well lubricated with meltwater.” Some of the mini quakes in the Rhône Glacier occur as often as once a second, and are relatively small.

“My new hypothesis is that the sliding motion of glaciers is comparable to that of tectonic plates,” adds Walter. Most of the quakes measured in the Rhône Glacier have a magnitude of −1 to −2. “That’s roughly equivalent to ice cracking when you skate on a frozen lake,” he says. “It’s not something that you can feel like a real earthquake.”

Image credits: ETH Zurich / Hildur.

The approach could be used to boost earthquake preparedness, since the infrastructure is relatively cheap — and researchers could even piggyback on existing infrastructure. But Fichtner hopes to use this for more than just measuring earthquakes.

Most of what we know about our planet’s deep geology, we know from earthquakes. When seismic waves propagate through the subsurface, they pass through different environments differently, and by picking up this information, researchers can make deductions about the subsurface. Fichtner envisions one day using the fiber-optic networks in big cities to study the geological subsurface. This approach could be doubly useful, as it could identify areas prone to failure, like faults or subsurface voids. He’s already set a test environment in the city of Bern, Switzerland, and would like to see similar setups in other cities.

“The fiber geometry was very simple – that’s one reason why Bern was the ideal test site,” Fichtner reflects.

It’s remarkable to think that infrastructure designed for something completely different could prove useful in so many different ways. Fiber optic cables are already starting to offer a relatively inexpensive way of measuring even the tiniest earthquakes. Soon enough, we may have cheap and capable seismic networks beneath our very feet — in the form of cables.

Ice cores, ash, and palm leaves manuscripts helps researchers sort volcano mystery

An immense volcano erupted in the year 1257 AD. It ejected huge amounts of gases, as well as ash and pumice, creating a blanket around the entire planet and affecting its climate. It was potentially the largest eruption in the past 7,000 years — but which volcano was it?

Usually, it’s pretty clear which volcano is responsible for big eruptions, but in this case, researchers weren’t sure until recently. Using multiple lines of evidence, they now believe the Samalas volcano in Indonesia was the culprit.

The crater of the volcano is now covered by a lake. Image credits: Petter Lindgren.

A forgotten Pompeii in the Far East

When a volcano erupts, it spews out gases and minerals that eventually fall onto the ground. In large eruptions, these products can travel hundreds or even thousands of kilometers before landing — and in the very largest eruptions, the entire planet is covered in a thin layer of ash that can be traced back to the eruption.

This was the case with a mysterious eruption from almost 800 years ago. Its traces were spotted at both poles, in ice cores coming from both the Arctic and the Antarctic. Because a new layer of ice is laid every year in these areas, researchers can date individual layers very accurately, which also allows them to date events such as volcanic eruptions.

Volcanic deposits were dated to 1257/1258 AD, and the eruption seemed to be extremely powerful — eight times stronger than Krakatau (in 1883) and two times stronger than Tambura (in 1815). Researchers also corroborated the data from ice cores with evidence from tree rings and computer models, confirming the year of the eruption. But identifying which volcano was responsible was still a challenge — until researchers analyzed an old historical record called Babad Lombok.

Written in Kawi (or Old Javanese) on palm leaves, Babad Lombok details the history of the Lombok island. Lombok is an island in West Nusa Tenggara province, Indonesia, home to almost 4 million people. The palm leaves record focus mostly on religion, but they also detail the catastrophic eruption.

Example of a different palm leaf manuscript. Image credits: Sarah Welch.

“Mount Rinjani avalanched and Mount Salamas collapsed, followed by large flows of debris accompanied by the noise coming from boulders. These flows destroyed Pamatan. All houses were destroyed and swept away, floating on the sea, and many people died. During seven days, big earthquakes shook the Earth, stranded in Leneng, dragged by the boulder flows, People escaped and some of them climbed the hills,” the text reads.

The Salamas caldera is still active, with eruptions still occurring today at this site. A volcanic cone is developing in the area, and the entire caldera is now partially covered with water, forming a lake. If the historic text was right and Salamas was the volcano responsible for the 1257 eruption, that’s where researchers had to look for more answers; and they did.

Fieldwork in the area showed rich volcanic deposits all over the region — deposits whose chemistry fit with the one found in the ice cores. The researchers also found no trees growing in the immediate period after the eruption, further supporting the idea of a cataclysmic eruption in the area.

When the team mapped the deposits and created a model of the eruption, they found that it must have risen 4,200 meters above sea level (13,800 feet), with the ash column going as high as 42 kilometers into the sky (it's plausible that it even went over 50 km) -- being visible (and potentially audible) for hundreds of kilometers. The eruption ejected some 40 cubic kilometers of material, the models suggested.

A massive eruption of this scale would have been catastrophic to the local populations. In addition to the eruption itself and all the ejected material, when the hot lava reached the seawater, it created scorching steam explosions. Then there was the pyroclastic flow, a hot mess consisting of ash, rocks, and gases moving at over 100 km/h; later there came the ash deposits (which reached 35 meters), and later still, the climate started to cool down. The locals didn't stand a chance. The capital of the Lombok Kingdom, a city called Pamatan, was wiped from existence. Researchers still haven't uncovered it yet, but if rediscovered, it could very well be a Pompeii of the East, they say.

"These results solve a conundrum that has puzzled glaciologists, volcanologists, and climatologists for more than three decades. In addition, the identification of this volcano gives rise to the existence of a forgotten Pompeii in the Far East," the study authors explain.

Image credits: Lavigne et al (2021).

This eruption was one of the strongest in recent geological history. It ranks as a 7 on the Volcanic Explosivity Index, a logarithmic scale (i.e. a 7 eruption is 10 times stronger than a 6 eruption, and 100 times stronger than a 5 eruption). For comparison, Mount St. Helens is a 5, and the Yellowstone supereruption from 600,000 years ago is an 8.

 "At least 40 km3 (dense-rock equivalent) of tephra were deposited and the eruption column reached an altitude of up to 43 km. Three principal pumice fallout deposits mantle the region and thick pyroclastic flow deposits are found at the coast, 25 km from source. With an estimated magnitude of 7, this event ranks among the largest Holocene explosive eruptions."

This isn't the first time Samalas was linked to the 1257 eruption. Previous studies from 2013 and 2016 also suggested this possibility, but until now, the existing evidence was scattered and unclear. This study does a great job at tying everything together, and showing how one of the most transformational events in the area unfolded and where it happened. It also hints at where the lost city of Pamatan could lie.

Volcanic eruptions like this one can change the course of history, and understanding them can help us not just understand previous eruptions and their impact better, but also help us know what to expect.

The study was published in PNAS.

Ancient turtle embryo preserved inside thick, tough egg

Some 90 million years ago, when dinosaurs were still roaming the land, a turtle laid eggs. We’re not sure what happened with most of them, but one never hatched. Now, researchers have found and analyzed that egg.

Illustration of a nest of land-dwelling turtles in the family Nanhsiungchelyidae. Image credits: Masato Hattori.

In 2018, a farmer discovered the egg and donated it to researchers. The finding came from what is today China, and based on its size, the turtle must have been about as big as a human — or even larger.

Fossilized eggs are, in general, very rare. Fossilization tends to require specific conditions, and soft eggs normally don’t withstand the processes. But this was a fortunate exception. The dinosaur came from Neixiang county, which is well-known for its dinosaur eggs. Initially, that’s exactly what researchers thought they were dealing with.

The egg, about as big as a billiard ball, was unlike any other dinosaur egg researchers had seen. But when paleontologists Fenglu Han and Haishui Jiang took a closer look at it, they realized that not only it wasn’t a dinosaur egg, but it also had a surprise inside: an embryo.

If turtle egg fossils are rare, the odds of such fossils being preserved with an embryo inside are astronomic. With the help of the embryo, which was imaged inside the egg, the team was able to identify the fossil.

Image credits: Yuzheng Ke.

The team used micro-computed tomography (CT) and initially found a mixed jumble of tiny bones inside. They then created a 3D replica of each individual bone and then put it all together. Remarkably, the embryo turned out very similar to what can be seen in today’s turtles. It was about 85% formed, the researchers say; it may have tried to hatch, but failed. Two other eggs from the same species and the same period have suffered the same fate.

Perhaps even more striking is the shell of the egg. At two millimeters thick, this is some 4 times thicker than even the thickest turtle eggs that are produced today. This shell would have allowed water to seep through, so these ancient turtles likely buried the eggs inside the cold, moist soil, keeping them safe from the arid environment of the late Cretaceous (and any predators that would wander about).

Unfortunately for this species, while most turtles managed to survive the extinction that wiped out the dinosaurs, the thick-egged turtles didn’t make it — and this type of thick eggs was never again seen for turtles.

In fact, it may be possible that the egg itself was what brought the demise of the species, or it could be that these specialized turtles couldn’t adapt to the dramatic shifts ushered in by the Cretaceous extinction. More research is needed before we can figure out what happened.

The study was published in the journal Proceedings of the Royal Society B: Biological Sciences.

The oldest animal life on Earth was discovered in Canada: 890 million years old

A Canadian paleontologist may have found the earliest evidence of life on Earth — and it’s much older than we thought.

a. and b. show the fossils that Turner believes show evidence of sponge life; compared with the spongin skeleton of a modern sponge, shown in c. Image credit: Turner, 2021, Nature CC by 4.0

Life as we know it took a pretty funky turn around 541 million years ago. That’s when a period called the Cambrian emerged, and with it, the so-called Cambrian explosion ushered in practically all major groups of animals. It lasted for about 25 million years and resulted in the divergence of life as we know it.

Before the Cambrian explosion, life on Earth was simple and small. It was composed either of individual cells, or of microscopic, multicellular organisms — or at least so we thought.

Scientists have found some evidence of animal life existing before the Cambrian. In particular, some sponges (immobile aquatic animals) seem to have emerged before the Cambrian. But how long before it?

According to a recent study, the first sponges emerged a whopping 350 million years before the Cambrian — or 890 million years ago.

“If I’m right, animals emerged long, long before the first appearance of traditional animal fossils,” study author Elizabeth Turner told Nature. “That would mean there’s a deep back history of animals that just didn’t get preserved very well.”

The fossils discovered by Turner, from a remote area of northwestern Canada accessible only by helicopter, resemble some modern sponges known as keratose demosponges. The researchers dated the layer of rocks in which the sponge fossils were found, a solid analysis tool that leaves little room for question regarding the fossils’ age. The identification as sponges also seems pretty clear.

“This organic skeleton is very characteristic [of sponge fossils],” explained geobiologist Joachim Reitner, who reviewed Turner’s study ahead of publication. “[T]here are not known comparable structures.”

But a finding that would force us to reconsider the evolution of life on Earth won’t happen easily, and Turner’s peers are rightfully raising all sorts of questions regarding the fossils. Some point out that the findings may not be fossils at all (but rather other structures), while others are focusing on another question: if life emerged a few hundred million years before the Cambrian, why haven’t we found any fossils of it until this?

Ultimately, if the finding is confirmed, it will help us understand the evolution of life on Earth.

“We are animals,” Turner said. “And we have a big brain, and we’re capable of wondering about stuff, and we wonder how we came to be. 

“What happened before, and what was it like? How did it begin?” she said. “This is really digging into that. I’m shaking up the apple cart.”  

The study has been published in Nature.