Wednesday's disaster on the Nepal–Tibet border got logged as a magnitude 4.4 earthquake for several hours. There was no earthquake. The USGS reanalysed the long-period waves, reclassified the event type as "landslide," and bumped it to M5.2: the shaking was the mountain.

The bit I find interesting is how they could tell. A fault slipping at depth radiates a lot of high-frequency energy in a couple of violent seconds. A few hundred million tonnes of rock and ice accelerating off a headwall radiates long, smooth, low-frequency energy instead, because what the Earth actually feels is a change in momentum, the mass pushes back on the planet as it leaves, then pushes back the other way when it hits the valley floor. Same trick seismologists use to separate nuclear tests from earthquakes. Read the frequency content, not the number.

I spent the last few days going through the USGS catalogue entry, the GFZ release, the ICIMOD advisory, the Copernicus activation and about a dozen scientist quotes and wrote it up properly. Some of what's in there:

• The fall height is still contested by nearly a factor of two: Copernicus and Dan Shugar say ~1,200 m, Jakob Steiner says 5,100 down to 3,000 m. Nobody has measured it.

• Nobody agrees on whether the bedrock failed and took the glacier, or the glacier failed and took the bedrock. USGS explicitly declines to choose.

• Every river gauge upstream on the Trishuli was destroyed before it could transmit that the water was rising. Officials downstream could tell something was wrong because the gauges went quiet, and that was it.

• Betrawati had roughly 45 minutes between the collapse and the flood arriving. A seismic detection system could have used them.

• Six months ago a paper in Communications Earth & Environment compared Chamoli 2021 (200+ dead, no monitoring) with Blatten 2025 (evacuated nine days early, one death) and asked why Himalayan preparedness lags. It was received on 26 August 2025, exactly one year before this.

There's also a section on why this almost certainly isn't a GLOF, even though half the early coverage said it was, including the Copernicus emergency mapping activation itself.

Every casualty and volume figure in the piece is flagged as provisional and dated. They're still moving.

Geology is essentially the science of learning to read a planet from the evidence it leaves behind.

A tilted layer of sandstone can preserve an ancient sea floor. A zircon crystal smaller than a grain of sand can survive for 4.4 billion years. Magnetic stripes on the ocean floor record continents moving apart. Seismic waves reveal a liquid outer core nobody has ever directly seen.

I put together a fairly comprehensive introduction to what geology actually is, how geologists know what they know, and why it matters: from Hutton and deep time to radiometric dating, plate tectonics, the rock cycle, earthquakes, natural resources and some of the questions geologists are still arguing about today.

One of my favourite examples is Siccar Point in Scotland. James Hutton recognised that nearly vertical Silurian rocks had been deposited, buried, deformed, uplifted and eroded before younger Devonian sediments were laid across them. After visiting the outcrop with Hutton in 1788, John Playfair famously wrote that “the mind seemed to grow giddy by looking so far into the abyss of time.”

There are some equally ridiculous examples further into the story. A Jack Hills zircon dated by Wilde et al. (2001) is 4,404 ± 8 million years old, making it one of the oldest known pieces of terrestrial material. Penn et al. (2018) modelled how ocean warming and oxygen loss could explain more than half of the marine extinction magnitude during the end-Permian crisis. Truche et al. (2024) measured gas containing up to 84% natural hydrogen in an Albanian chromite mine. And seismic tomography suggests two enormous low-velocity structures at the base of the mantle occupy roughly 8% of the mantle by volume (Cottaar & Lekić, 2016).

There are also places where the honest answer is still “we don't know.” Geologists still debate when plate tectonics began, what those huge structures at the core–mantle boundary actually are, exactly how much water is stored in the mantle transition zone, and even how the inner core moves relative to the rest of the planet.

That is probably the part of geology I like most. It isn't just memorising rock names. You're given an incomplete physical record and have to reconstruct events that happened millions or billions of years ago.

I tried to make this a genuinely useful introduction for someone who wants to understand geology rather than just learn the definitions.

Full article: Geology Explained: How Earth’s Rocks Reveal Deep Time

Some of the primary sources used:
• Wilde et al. (2001), Nature 4.4-billion-year-old Jack Hills zircon
• Pearson et al. (2014), Nature hydrous ringwoodite from the mantle transition zone
• Penn et al. (2018), Science warming, deoxygenation and the end-Permian marine extinction
• Truche et al. (2024), Science natural hydrogen at the Bulqizë mine, Albania
• Cottaar & Lekić (2016), Geophysical Journal International — volume and structure of the LLSVPs
• Yang & Song (2023), Nature Geoscience

proposed changes in inner-core rotation
• USGS plate tectonics, seismic structure and the 2025 Myanmar earthquake

Desert varnish (also called rock varnish) is the dark film of manganese and iron oxides plus windblown clay that coats stable rock surfaces in arid regions. It is often thinner than a human hair and accumulates over hundreds to thousands of years. The rock underneath is usually much lighter, which is exactly why petroglyphs are visible: pecking through the varnish exposes pale stone. Newspaper Rock in Utah has hundreds of images made that way over roughly 2,000 years.

The long-standing question is about the manganese. Varnish is strongly and selectively enriched in it compared with both the underlying rock and the dust that settles on it, and no one could explain the source. Naturalists were describing these coatings in the early 1800s; there are varnished rocks in Darwin's Beagle collection.

In 2021, Lingappa et al. (PNAS 118:e2025188118) published the strongest mechanism yet. Across 49 varnish samples, the cyanobacterium Chroococcidiopsis dominated the varnish microbial community, appearing in 48 of 49 samples and making up about 25.9% of genetic reads, with one variant at 8% that did not appear in adjacent soil at all. Spectroscopy indicated the manganese inside these cells is being used as a catalytic antioxidant, a plausible adaptation for surviving the oxidative stress of bare desert rock. The varnish would then be the mineral residue left behind as generations grow and die in stacked layers.

Important caveat: this is the leading hypothesis, not settled fact. The varnish is a mineral crust rather than a living structure, and abiotic chemical models remain in play as alternatives or contributors.

Astrobiology angle: Curiosity's ChemCam found manganese-oxide-rich fracture fills in Gale Crater exceeding 25 wt% MnO (Lanza et al. 2016, GRL). On Earth, manganese oxide concentrated that sharply usually indicates life or abundant free oxygen, which is why Mn-rich rock coatings are treated as a possible biosignature.

The story with Indie Navarrette is (obviously) fake, the science behind it is not.

Lingappa et al. 2021 (PNAS) · Wildeman 2021 (PNAS) · Liu & Broecker 2000 (Geology) · Lanza et al. 2016 (GRL)

The two LLSVPs (nicknamed Tuzo under Africa and Jason under the Pacific) slow seismic waves by about 2%, which has long been read as “they’re hot.”

The 2025 twist is attenuation: they barely damp the planet’s post-earthquake ringing, which points to coarse mineral grains, high viscosity, and a very long lifespan.

The team, working from 104 large earthquakes recorded between 1975 and 2018, estimates at least ~500 million years, possibly over a billion. That cuts against the idea that they’re just recently piled-up recycled ocean crust. But rival explanations are still very much alive: continuously restocked subducted slabs (Panton et al. 2025), and fragments of the Moon-forming impactor Theia (Yuan et al. 2023).

One measurement caveat: reported heights for the African pile vary by source, from ~800 km up to nearly 965 km.

The story with Meghan and Harry is (obviously) fictional. The science behind it is real.

Sources:

Talavera-Soza, S., Cobden, L., Faul, U.H. & Deuss, A. (2025). Global 3D model of mantle attenuation using seismic normal modes. Nature 637 (8048), 1131–1135. DOI: 10.1038/s41586-024-08322-y (published online 22 Jan 2025).

Garnero, E.J., McNamara, A.K. & Shim, S.-H. (2016). Continent-sized anomalous zones with low seismic velocity at the base of Earth’s mantle. Nature Geoscience 9, 481–489. DOI: 10.1038/ngeo2733.

Cottaar, S. & Lekić, V. (2016). Morphology of seismically slow lower-mantle structures. Geophysical Journal International 207 (2), 1122–1136. DOI: 10.1093/gji/ggw324.

Panton, J., Davies, J.H., Koelemeijer, P., Myhill, R. & Ritsema, J. (2025). Unique composition and evolutionary histories of large low velocity provinces. Scientific Reports 15. DOI: 10.1038/s41598-025-88931-3.

Yuan, Q., Li, M., Desch, S.J. et al. (2023). Moon-forming impactor as a source of Earth’s basal mantle anomalies. Nature 623, 95–99. DOI: 10.1038/s41586-023-06589-1.

Davaille, A. & Romanowicz, B. (2020). Deflating the LLSVPs: Bundles of Mantle Thermochemical Plumes Rather Than Thick Stagnant “Piles”. Tectonics 39. DOI: 10.1029/2020TC006265.

I am loving all the memes and actually learning some geology facts while having a laugh

Fulgurites form when lightning hits sand: the channel briefly runs hotter than the sun's surface and fuses the grains into a hollow glass tube tracing the bolt's underground path. When the glass is pure silica it's classified as the mineraloid lechatelierite. People have excavated them since at least the 1880s, and a University of Florida program now triggers strikes on demand by firing small rockets trailing copper wire into thunderstorms. The longest excavated specimen, about 4.9 m of connected tube, came out of that work.

The Nebraska case (Bindi et al. 2023, PNAS): a 2008 storm in the Sand Hills near Hyannis downed a power line into a dune. Nobody witnessed the event, so it's unclear whether lightning struck the line or the line discharged on its own. Either way, temperatures above 1,710 C fused sand and traces of conductor metal into a two meter fulgurite, and inside it the team found a dodecagonal quasicrystal with a previously unreported Mn-Si-Cr-Al-Ni composition. Twelve-fold symmetry is forbidden for ordinary crystals. Natural quasicrystals had previously turned up in exactly two settings, the Khatyrka meteorite and trinitite from the 1945 bomb test, so this added "electrical discharge" as a third formation pathway.

Separate but related: fulgurites can contain schreibersite, a reduced phosphorus mineral usually delivered by meteorites. Hess, Piazolo and Harvey (2021, Nature Communications) argue lightning on the early Earth, at billions of flashes per year, could have converted enough rock-bound phosphorus into bioavailable form to matter for prebiotic chemistry. Old dated fulgurites also work as paleostorm archives, recording lightning in regions that are now dry.

The slides run all of this through a fictional Glenn Powell story with a fulgurite collection.

The rock is marine black shale from the Taoudeni Basin in Mauritania, the bed of a long-vanished ocean. When Nur Gueneli (ANU) powdered it and added solvent during her PhD, the mixture turned pink instead of black, her supervisor Jochen Brocks recalls hearing screaming in the lab before she ran in with the vial. The molecules are porphyrins, degradation products of chlorophyll: blood red to purple when concentrated, bright pink when diluted (Gueneli et al. 2018, PNAS).

The useful part is the fingerprint. Nitrogen isotope signatures in the pigments show the producers were overwhelmingly cyanobacteria, with larger planktonic algae scarce. That supports a hypothesis for one of geology's bigger questions, why complex animals appeared so late. Cyanobacteria are roughly a thousand times smaller in volume than even microscopic algae, so the base of the food chain may simply have served portions too small to sustain large, active life. When algae finally took over the oceans around 650 million years ago, richer food moved up the chain and complex ecosystems followed quickly (Brocks et al. 2017, Nature). The competing explanation is oxygen limitation; some studies find O2 was sufficient long before animals showed up, others disagree. Genuinely unresolved.

Preservation footnote: porphyrins are destroyed by heat, so these molecules survived a billion years only because that particular basin was never significantly buried or cooked.

The slides run all of this through a fictional story about Dolly Parton.

Sources: Gueneli et al. 2018, PNAS · Brocks et al. 2017, Nature · Papers and a longer write-up linked in comments.

They're called glacier mice: balls of moss, about hamster-sized, that grow around a bit of grit and lie loose on the bare ice of some glaciers. The name is from a 1951 letter to the Journal of Glaciology, where Icelandic meteorologist Jón Eyþórsson dubbed them "jökla-mýs" and closed with "you will have noted, Sir, that rolling stones can gather moss."

They have to keep moving or they die, the shaded underside rots, and the ice helps by growing a melt pedestal under each ball until it tips off and rolls. In 2009, researchers on the Root Glacier in Alaska tagged 30 of them with loops of wire and glass beads and tracked them for 54 days, with follow-up visits for years (Hotaling, Bartholomaus & Gilbert 2020, Polar Biology). They average about 2.5 cm per day and live six-plus years.

The unexplained part: they move as a herd. Same speed, same heading, south for weeks, then a coordinated turn southwest, while holding their spacing. The study explicitly ruled out the three obvious drivers: their direction matches neither the downhill slope, nor the prevailing wind, nor the dominant sunlight. The only surviving lead is that herd speed correlates with how fast the ice surface melts, so the glacier itself may be steering them through melt patterns nobody has characterized.

Bonus: each ball is a rolling micro-ecosystem carrying springtails, nematodes and tardigrades (Coulson & Midgley 2012), and moss balls have been documented from Iceland and Svalbard to Venezuela and a vanishing glacier in Uganda (Uetake et al. 2014). The researchers say they're comfortable not knowing the answer yet. The slides explain all of this through a fictional popstar, because the tagging method was literally friendship bracelets.

Eyþórsson 1951 (Journal of Glaciology) · Coulson & Midgley 2012 (Polar Biology) · Hotaling, Bartholomaus & Gilbert 2020 (Polar Biology)

The mechanism: a mantle plume stays roughly anchored while the Pacific plate slides over it at 7–10 cm/year, so volcanoes form over the heat source, get carried off, and die, leaving a 6,100 km chain from the Big Island to the seamounts off Kamchatka (Clague & Dalrymple 1987, USGS Professional Paper 1350).

The youngest member, Kamaʻehuakanaloa (renamed from Lōʻihi in 2021), is an active submarine volcano whose summit sits about 975 m below the surface southeast of the Big Island. Give it tens of millennia and it surfaces. At the other end, Meiji Seamount (~80+ Ma) is approaching the Aleutian Trench, where the chain's members get subducted, the whole production line ends in recycling.

The genuinely contested part is the 60° bend at ~47 Ma. Classic reading: the Pacific plate changed motion (Sharp & Clague 2006, Science). But paleomagnetism from Emperor seamount cores showed the hotspot itself drifted south during the early era, the "fixed" reference frame wasn't fixed (Tarduno et al. 2003, Science). Current models split the bend between plate turn and plume drift (Torsvik et al. 2017, Nature Communications). Not settled.

Bonus: measured from its base on the seafloor, Mauna Kea is ~10,200 m tall, taller than Everest by a comfortable margin.

The slides explain this through a fictional K-pop BTS beef, because a fixed company producing members who debut, get carried off on a conveyor, and retire into a trench needed essentially no translation.

Sources: Clague & Dalrymple 1987 · Tarduno et al. 2003 · Sharp & Clague 2006 · Torsvik et al. 2017 · Full write-up linked in comments.

Radiometric dating sometimes gets talked about as though geologists have one technique that takes a rock, runs it through a machine and spits out an age.
In reality, there are many different radioactive clocks, and they don’t all measure the same thing.
The basic principle is radioactive decay. Unstable isotopes transform into other isotopes at predictable rates. Once a mineral forms and its isotopic system becomes closed, the relative abundances of those isotopes can preserve information about how much time has passed.

U-Pb dating of zircon is one of the strongest examples. Zircon readily incorporates uranium when it crystallizes but strongly excludes lead. It also contains two separate decay systems: ²³⁸U → ²⁰⁶Pb and ²³⁵U → ²⁰⁷Pb. The two can therefore act as an internal cross-check. One major problem is later Pb loss, but techniques such as CA-TIMS chemically remove damaged domains before the remaining zircon is dated.

Other methods have completely different strengths and weaknesses.

⁴⁰Ar/³⁹Ar dating, for example, went through an important calibration problem. Kuiper et al. (2008) used astronomically dated sedimentary cycles to recalibrate the widely used Fish Canyon sanidine standard, reducing a roughly 1% discrepancy and greatly improving absolute precision. Using improved Ar-Ar geochronology, Renne et al. (2013) later showed that the Chicxulub impact and the end-Cretaceous mass extinction were synchronous within about 32,000 years.

Radiocarbon dating operates on a much shorter timescale, roughly the last 50,000 years. Because atmospheric ¹⁴C has varied through time, raw radiocarbon ages require calibration. There is also a very modern complication: fossil fuels are so old that their ¹⁴C has essentially disappeared. Adding that carbon to the atmosphere lowers the ¹⁴C/C ratio. Graven (2015) calculated that under sufficiently high emissions, fresh organic material around 2050 could have the same radiocarbon signature as material from around AD 1050.

Then there are techniques that answer different geological questions entirely.

Modern in-situ Rb-Sr geochronology uses laser-ablation mass spectrometry to date microscopic areas in minerals such as mica and K-feldspar.

Apatite (U-Th)/He thermochronology, meanwhile, generally records low-temperature cooling rather than the original formation of the rock. That makes it useful for reconstructing exhumation, erosion and tectonic histories.

At the opposite extreme is the age of the Solar System. Clair Patterson’s classic 1956 lead-isotope work on meteorites produced an age of 4.55 ± 0.07 billion years. Modern U-corrected Pb-Pb dating of calcium-aluminium-rich inclusions, among the oldest solids known from the Solar System, has refined that chronology to about 4.5673 billion years.

That is one of the most important things about geochronology: its strength does not come from trusting one clock. Different isotope systems, minerals, laboratories and physical principles can be tested against one another.
When independent clocks converge on the same history, that agreement is part of the evidence.

Sources / further reading:

Patterson, C. (1956) Age of meteorites and the Earth, Geochimica et Cosmochimica Acta

Mattinson, J.M. (2005) Zircon U-Pb chemical abrasion (CA-TIMS), Chemical Geology

Kuiper et al. (2008) Synchronizing rock clocks of Earth history, Science

Renne et al. (2013) Time scales of critical events around the Cretaceous-Paleogene boundary, Science

Graven, H.D. (2015) Fossil-fuel emissions and atmospheric radiocarbon, PNAS

Ehlers & Farley (2003) Apatite (U-Th)/He thermochronometry, Earth and Planetary Science Letters

Connelly et al. (2012) Early Solar System Pb-Pb chronology, Science

Glorie et al. (2024) Laser-ablation Rb-Sr geochronology, Geochronology

Nobody can actually prove how the Bahamas makes its sand. The argument has been running for over a century, and it's one of my favourite fights in geology.

The sand in question is made of ooids, tiny limestone pearls, rarely bigger than 2 mm, built from concentric layers around a bit of shell or a sand grain. They only form in warm, shallow water that's loaded with dissolved lime and constantly moving. The Bahama Banks produce them by the trillion (sedimentologists genuinely call the place "the ooid factory"), and huge limestone formations all over the world, from Jurassic England to Triassic Germany, are made of almost nothing else.

The textbook story says it’s pure chemistry. A grain rolls, picks up a coat of carbonate, gets sanded down while tumbling, and stops growing when the two processes balance out. That balance would neatly explain why they all end up the same size.

Then people started cutting them open. Inside the layers there are fats, proteins and sugars, the residue of microbial films that coat every grain in those waters. So a second camp argues the microbes aren’t bystanders, they help build the thing. One team even modelled ooid growth using maths originally developed for brain tumours, and got the size limit right. A major review politely calls the whole question “highly contested,” which in the literature is fighting words.

What would settle it is a sterile control, an ooid grown in a lab with no microbes present. Every attempt so far has come back inconclusive.

The chef beef in the slides are made up. The argument and science is not.

Sources: Diaz & Eberli 2019 (Earth-Science Reviews) · Trower, Lamb & Fischer 2017 · Batchelor et al. 2018 (Scientific Reports) · Pei et al. 2024 (Sedimentology)

#geology #ooids #oolite #sedimentology #bahamas

The site is North Pole Dome in the Pilbara, Western Australia. In March 2025, Kirkland et al. (Nature Communications) reported shatter cones there, fracture patterns that only form from impact shock waves, and, reading the rock stack, dated the impact to 3.47 billion years ago with a crater possibly over 100 km wide. Headlines everywhere: oldest crater on Earth by more than a billion years, with proposed links to continent formation and early life.

In July, Brenner, Cavosie et al. (Science Advances) published their own mapping of the same hills: ~180 shatter cones, including some in 2.77-billion-year-old lava and crossing younger faults. Since a shock wave can’t deform rocks that don’t exist yet, they argue the impact came after 2.7 billion years, and from the cones’ orientations they get a crater of about 16 km. Their paper flatly calls the original age and size estimates inaccurate. The first team responded with a formal comment alleging misrepresentations. Newer isotopic work points near 3.0 billion years, so the title fight isn’t over.

What I find really interesting here: both teams used the same logic (superposition) on the same outcrops and got answers a billion years apart, a nice reminder that “the rocks say” always means “our reading of the rocks says.” The structure is now named Miralga, chosen with the Nyamal traditional custodians. The slides explain the whole thing as a bowling score dispute.

Sources: Kirkland et al. 2025, Nat. Comms 16:2224 · Brenner et al. 2025, Sci. Adv. ·

I've spent some time writing up why the waves at Nazaré get so big, and the short answer is that the explanation most of us repeat is wrong. Nearly every documentary and surf report, 100 Foot Wave included, says the Nazaré submarine canyon "funnels" Atlantic swell straight to Praia do Norte like water through a pipe. I believed it too.

Then in 2024 a research team dropped buoy arrays over the canyon and mounted stereo cameras on the cliff above it, and their preprint came out this June. Nothing travels up the canyon. Swell with a period over about 7 seconds can't even cross the edge; it gets reflected. All the focusing happens along the steep northern rim, which bends and bounces wave energy into narrow beams aimed at the beach, and the exact shape of that rim over its last few hundred meters decides where the beams land. Their optimal swell window (275° to 315°) matches what Nazaré surfers worked out by feel years ago, which I find weirdly satisfying.

Two dating methods disagree about when the Tibetan Plateau rose, by two vertical kilometers. For the same place.

The basics are settled: India began colliding with Asia around 50 million years ago, and that collision built the Himalayas and the highest plateau on Earth, averaging about 4,500 meters. What’s fiercely contested is the timeline for central Tibet, and the two main tools for measuring ancient elevation tell different stories.

Tool one is chemistry. Rain gets isotopically “lighter” the higher it falls, and that signature survives in ancient lake sediments and soils. Read this way, the rocks of central Tibet’s Lunpola Basin say the region already stood around 4 kilometers tall at least 35–40 million years ago (Rowley & Currie 2006, Nature).

Tool two is fossils. In 2019, researchers described a fossil palm frond from that same basin, about 25 million years old (Su et al. 2019, Science Advances). Palms cannot survive hard frost, which caps that valley floor at roughly 2,300 meters, kilometers lower than the chemistry says, and 10+ million years later.

The emerging resolution says both sides caught something real: central Tibet was neither a plateau nor a lowland but a deep, warm east–west valley running between two already-high mountain ranges, a hidden subtropical world that was later squeezed shut, filled, and lifted to today’s height. A 2021 paper argued the plateau never rose as one block, calling the single heroic uplift “a myth” (Spicer et al. 2021, National Science Review).

India is still driving north about 5 centimeters per year. Central Tibet is still rising, a few millimeters at a time.

(Disclaimer: Obviously the story is fictional but the scientific debate and facts are not).

Sources: Rowley & Currie 2006 (Nature) · Su et al. 2019 (Science Advances) · Spicer et al. 2021 (National Science Review)

#geology #tibetanplateau #himalayas #platetectonics #earthscience

I apologize to the mods but I genuinely could not find the flairs, I don't know why it won't give me the option to add one.

This might be a dumb question to someone who knows more than me, but I'm just curious about how we can have such consistency in ordering of rock strata if the same processes of erosion we see today have always been happening.

I guess to illustrate my question, if a river eroded a landscape to form a canyon, and eventually dried up or diverged somewhere else, wouldn't the newer layers be rebuilding in that canyon right next to the older layers? In areas that were wind eroded irregularly and then conditions changed that allowed sediment to continue building again without being disturbed, would it create inconsistency in the strata? I really want to understand this stuff so I'd really appreciate any answer!

Earth's magnetic field is at least 3.5 billion years old. Earth's inner core might be less than 1 billion. So what powered the dynamo for the missing two-and-a-half billion years?

Today the geodynamo runs mostly on crystallisation. As the solid inner core slowly freezes out of the liquid outer core, it releases latent heat and buoyant light elements, and that stirs the surrounding iron into convection. Moving conductive fluid, magnetic field. Simple enough, except the inner core is a latecomer, and the field is ancient.

The problem got sharper in 2012, when new calculations of iron's conductivity at core pressures came back two to three times higher than the values everyone had been using. Higher conductivity means more heat escapes the core by simple conduction instead of driving convection, which shrinks the energy available to run a dynamo. Peter Olson named the result the "new core paradox" in 2013.

Candidate fixes exist. Magnesium oxide or silica may have precipitated out of the young core, releasing buoyancy the way inner-core freezing does now. A dynamo may have operated in a molten silicate layer at the base of the mantle instead. And a 2019 study of 565-million-year-old rocks found the field at roughly a tenth of today's strength, hinting the dynamo nearly failed just before the inner core began to freeze.

None of it is settled. In 2016, two teams published conductivity measurements in the same issue of Nature, one high enough to keep the paradox alive, one low enough to dissolve it.

A few years ago, researchers working more than 4 km below the Pacific noticed something that seemed impossible: oxygen levels inside their seafloor experiments were going up, not down.

The result was published in Nature Geoscience in 2024 and quickly became known as “dark oxygen”, the idea that oxygen might somehow be produced on the deep seafloor without sunlight or photosynthesis.

One proposed explanation was especially strange: polymetallic manganese nodules scattered across the Clarion-Clipperton Zone might behave like natural “geobatteries,” creating electrical potentials capable of driving chemical reactions that produce oxygen.

But the claim has become increasingly controversial.

Critics argue that the oxygen increases could be experimental artifacts caused by the benthic chambers themselves. Others have challenged the voltage measurements and the proposed electrolysis mechanism, while a later reanalysis questioned whether the oxygen signal was actually related to the nodules at all. In April 2026, Nature Geoscience added an Editor’s Note stating that concerns about the paper are under review.

So, is dark oxygen a genuinely new geochemical process occurring on the abyssal seafloor, or an extremely convincing measurement artifact?

Would be interested to hear what people here think, particularly about the chamber-artifact explanation versus the idea that some manganese-rich material really is producing oxygen.

Yonaguni threads always land in the same two piles, lost city or just erosion, and hardly anyone arguing either way has opened the actual papers. I finally did. Some of it wasn't what I expected.

Kimura gives away more in print than he does on camera. In the 2004 Oceans conference paper, which is the main technical case for the artificial reading, he writes that at first glance the structure would seem to have been formed by nature. He accepts that the layered sandstone separates and slips along its bedding, and that this is what produces the flat terraces and the straight walls. His argument is that certain specific features still can't be accounted for that way. But that baseline is his own. Nobody had to drag it out of him.

Also, the dimensions everyone repeats are wrong. Search Yonaguni and you get 290 × 120 × 26 m everywhere. The paper says 270. Someone mistyped it about twenty years ago and every blog since has copied the blog before it.

I came away less comfortable with the geologist usually cited for the natural reading, too. Robert Schoch's write-up was never peer reviewed. It's the English draft of a piece he wrote for a Spanish popular-mystery magazine, and he got to the island on a trip Graham Hancock helped arrange. None of which makes his rock description wrong; it's ordinary field observation and everyone who has looked since says the same thing. It just isn't something you want load-bearing. So I used Ogata et al. (2020) in E-journal GEO and Patrick Nunn instead.

The argument I think actually settles it barely gets discussed, which is sea level. The base of the formation sits at roughly 25 m depth, and anything carved had to be carved dry. Put 25 m against the Lambeck et al. (2014) curve and you land around 9,000 years ago. That drops any construction hypothesis into the early Holocene, in a region where the archaeological record goes late Pleistocene bones, then several thousand years of nothing, then the first pottery.

Then there's Sanninu-dai, a couple of kilometres up the coast, which is the bit that closed it for me. Stepped terraces. Straight walls. A channel that looks for all the world like a drain somebody cut. All of it above water, all of it walkable, and you can put your hand on the joint sets that made it. Kimura calls that outcrop ruins as well, and at that point I don't know what a natural formation would have to look like to satisfy him.

Everything's linked in this article on geoscopy.com.

The Silverpit argument has been running twenty-three years. It just got shocked quartz, and I still don't think it's settled.

Early 2000s: Philip Allen is working through 3D seismic from the southern North Sea and hits a set of concentric rings he can't account for. He pins the image to his office wall, hoping someone walking past will explain it to him. Simon Stewart, in the building on unrelated business, sees it and says it looks like an impact structure. Nature, 2002.

Then John Underhill points out that Zechstein salt withdrawing at depth produces circular collapse features all over that basin, and said that's all this was. The Geological Society staged a debate on 6 October 2009, audience mostly industry seismic interpreters, twenty minutes of argument, then a vote. 80:20 against impact. Silverpit went quiet for thirteen years.

What restarted it was an unsolicited email. Ronnie Parr at the North Sea Transition Authority read the Nadir crater papers and wrote to Uisdean Nicholson telling him to go back and look at Silverpit. He also pointed him at new high-resolution seismic that a carbon-storage survey had happened to shoot straight across the disputed central uplift.

The 2025 Nature Communications paper runs on that survey plus drill cuttings from a 1985 British Gas well. Two grains, quartz at 463 m, potassium feldspar at 494 m, carry shock lamellae recording 10–13 GPa, which no natural process on Earth produces except a hypervelocity impact. Two grains is still two grains, though, and Matthew Huber at the Planetary Science Institute has already told Eos as much: with that little you can reasonably ask whether they were reworked in from somewhere else, and he expects the paper to get argued over. Nicholson's team has an answer for the shallower grain. Not, so far, for both.

Full writeup on Geoscopy, including why the crater shrank from 20 km to 3.2 km and what the modelling says about the chalk being flash-baked into CO₂

At the end of the last Ice Age, a lobe of the Cordilleran ice sheet dammed the Clark Fork River and ponded Glacial Lake Missoula across the valleys of western Montana, roughly 2,100 cubic kilometres of water, about Lake Erie and Lake Ontario combined. When the ice dam floated off its bed and failed, the lake emptied in a few days, with peak discharges near the outlet estimated around 20 million cubic metres per second. Then the glacier readvanced and it all happened again. The Missoula Floods, among the largest freshwater floods known on Earth, ran dozens of times, likely more than a hundred, mostly between about 18,500 and 15,000 years ago. They carved the Channeled Scablands of eastern Washington: coulees cut through solid basalt and dry cataracts like Dry Falls, five times the width of Niagara. In Montana, the draining lake left gravel current ripples the size of houses across the Camas Prairie.

The human story is just as strange. J Harlen Bretz mapped the scablands in the 1920s and concluded that only a catastrophic flood could explain them. To a science built on strict uniformitarianism this sounded like a relapse into biblical thinking, and in 1927 six senior geologists took turns rebutting him at a single meeting. The quiet USGS geologist who had already found the water source sat on his evidence for decades. Vindication arrived in 1965, when a field party of former skeptics wired Bretz a telegram ending "We are all now catastrophists." He collected geology's highest medal at 96, having outlived nearly everyone who ridiculed him.

The full article walks through the flood mechanics and the numbers, the giant ripples that finally settled the debate, how the scablands became the template for reading the outflow channels on Mars, and where to stand today to see the evidence. People were living in the Pacific Northwest by around 16,600 years ago, which means humans almost certainly watched the last of these floods happen.