The research team, led by biogeographers working at the intersection of plate tectonics and genomics, constructed a new palaeogeographic framework spanning the last 35 million years. Rather than relying on broad regional tectonic models, the authors stitched together high-resolution reconstructions of Indonesian New Guinea and Papua New Guinea, which track the movement of crustal fragments in one to two million year time slices. These reconstructions draw on multibeam sonar, seismic surveys, isotopic dating, thermochronology and sedimentary records. The result is a dynamic map of what the team calls proto-New Guinea, the shifting mosaic of continental and oceanic crust along the northern margin of the Australian Plate that would eventually fuse into the world’s largest tropical island.

The model reveals something unexpected. For decades, some biogeographers argued that New Guinea was essentially submerged until about 15 million years ago, while others proposed it emerged far earlier. The new reconstruction shows that substantial land was present surprisingly early: roughly 330,000 square kilometres of emergent terrain existed by 35 million years ago, following the Peninsular Orogeny, when a volcanic arc called the Sepik Terrane slammed into the Australian Plate. Even during high sea-level episodes, proto-New Guinea persisted as an archipelago of large islands that periodically coalesced as sea levels fell, with emergent land fluctuating between roughly 210,000 and 320,000 square kilometres through the Oligocene and Miocene. For comparison, today’s island covers about 790,000 square kilometres.

Sea level proved to be the critical accomplice. When Antarctica first glaciated 34 million years ago, global sea level dropped by at least 50 metres, exposing vast shallow carbonate reef platforms that had built up along the Australian margin. The researchers reason that corals kept pace with rising seas for most of the Cenozoic, generating atolls and reef flats that repeatedly emerged during sea-level falls of more than 20 metres, forming temporary land bridges and stepping stones. Only during extreme highstands, such as the Mid Miocene Climatic Optimum, when seas stood more than 50 metres above the present, did the platforms stay drowned, and during the Pliocene a phenomenon the authors describe as the Pliocene Reef Gap meant that even later lowstands could not re-expose them, because coral growth had collapsed permanently in those areas.

Armed with this geological scaffold, the team quantified the changing distances between micro-tectonic landmasses, the coherent crustal blocks that drifted independently before merging into modern islands. Using GPlates and geographic information software, they measured pairwise distances every million years across 20 million years of history, applying a 10 kilometre uncertainty buffer. The analysis identified two golden windows for dispersal between New Guinea and Halmahera, an island now lying roughly 250 kilometres to the west. The first came around 13.8 million years ago, when tectonic transport along the Sorong Fault Zone brought Halmahera within 20 kilometres of proto-New Guinea while the Middle Miocene Climate Transition dropped seas by up to 50 metres. The second came around 8.2 million years ago, when a dramatic Milankovitch-driven lowstand exposed carbonate platforms and shrank water gaps of 60 to 70 kilometres to something far more crossable.

Enter the birds. The team built new dated phylogenies of the Paradisaeidae using randomly subsampled 10 kilobase genomic window alignments analysed in BEAST2, calibrated against the geological windows. Their enigmatic focus was the distribution of three species on Halmahera and nearby Obi: the dusky and Obi paradise-crows, Lycocorax pyrrhopterus and L. obiensis, and Wallace’s standard-wing, Semioptera wallacii. Two independent lineages on the same remote islands demanded an explanation. When the tree was calibrated to the older 13.8 million year window, the resulting divergence for Waigeo and Batanta endemics, Paradisaea rubra and Diphyllodes respublica, landed around 3.3 to 3.8 million years ago, during the high seas of the Pliocene Climatic Optimum, when those islands were more than 100 kilometres from New Guinea. Geologically, the researchers judged this scenario very unlikely.

The younger calibration told a far more coherent story. Under the 8.2 million year anchor point, both the paradise-crow ancestor and Wallace’s standard-wing lineage reached Halmahera within the same narrow window between 8.2 and 7.4 million years ago, plausibly hopping across emergent platforms via Obi and Bacan. The separation of the Obi paradise-crow from its Halmahera relative then falls around 1.9 million years ago, when Pleistocene cooling pushed seas 60 metres below present levels, allowing intermittent contact. The red bird-of-paradise and Wilson’s bird-of-paradise, endemic to Waigeo and Batanta, diverged from mainland relatives around 2.0 to 2.3 million years ago, precisely when the Sorong Fault had carried Waigeo closer than ever to the Bird’s Head Peninsula and when glacial lowstands repeatedly exposed land bridges. Every event in this scenario matches the geological record, whereas the older scenario fails on nearly every count.

The implications stretch far beyond birds-of-paradise. Songbirds, or oscine passerines, make up half of all bird species on Earth, and genomic evidence places their origin in the Australo-Papuan region before their worldwide radiation. Whether New Guinea could have hosted that early diversification has been fiercely debated. The new model shows that extensive, intermittently connected land existed on the northern Australian Plate from 35 million years ago, complete with wet forest refugia as Australia itself dried out. Independent evidence from lizards, insects, monotremes and pigeons is consistent with early colonisation of proto-New Guinea, suggesting the emerging archipelago served as an engine of avian diversity long before the modern island took shape.

What makes the study methodologically distinctive is its iterative, mutualistic logic. Geological reconstructions generated hypotheses about when dispersal was physically possible; phylogenetic divergence times then tested those hypotheses and, where they clashed, flagged which geological scenarios were most plausible. The same trick has previously clarified the amalgamation history of Sulawesi, and the authors argue that molecular clocks can serve as a genuine constraint on tectonic models, not merely a downstream beneficiary of them. Biology and geology, treated as partners, turn out to be more powerful than either discipline alone.

The study also carries a cautionary note for future biogeographic work across the Indo-Pacific, the largest expanse of tropical islands on the planet. Shallow marine carbonate platforms, often invisible in simple tectonic maps, acted as critical corridors that appeared and vanished with orbital-scale sea-level swings. Understanding their emergence history, the authors conclude, is essential for decoding the distribution of virtually any weakly dispersing terrestrial organism in the region. For now, the flamboyant birds-of-paradise have done what their forebears could not have imagined: carried rocks, reefs and shifting plates along on their wings, and helped geologists redraw the map of a vanished world.

Subject of Research: Palaeo-tectonic reconstruction of New Guinea and its role in shaping Indo-Pacific avian diversification

Article Title: A new palaeo-tectonic model of New Guinea and its consequences for understanding Indo-Pacific avian diversity in space and through time

Article References: Jønsson, K. A., Webb, M., Fotheringham, J., Gunawan, I., Haryoko, T., Iova, B., Melia, S., Nagombi, E., Reeve, A. H., Blom, M. P. K., Irestedt, M., & Rijsdijk, K. F. (2026). A new palaeo-tectonic model of New Guinea and its consequences for understanding Indo-Pacific avian diversity in space and through time. Frontiers of Biogeography, 19, Article e200936. https://doi.org/10.21425/fob.19.200936

Image Credits: AI Generated

DOI: 10.21425/fob.19.200936

Keywords: biogeography, New Guinea, birds-of-paradise, plate tectonics, sea-level change, phylogenomics, dispersal, vicariance, passerines, Halmahera, palaeogeography, Sorong Fault Zone

The starting point is a deceptively simple observation: from an evolutionary standpoint, the frequency of complete speciation events is controlled by three processes—the rate at which populations split, the rate at which they go extinct, and the rate at which previously separated populations merge. On land, island biogeographers have long known that these rates vary with island age, area, isolation, elevation, and topographic complexity. Over the past decade, researchers studying terrestrial islands have incorporated the effects of Quaternary glacial-interglacial cycles, during which falling seas can fuse neighboring islands into a single landmass and rising seas can split them apart again. But the marine realm, where the habitat itself is submerged, has remained largely untouched by this fusion-fission framework.

The team’s solution rests on a quantity called the insular littoral area, or ILA: the submarine area between the mean sea level at any given time and the 50-meter isobath. The 50-meter cutoff matters biologically, because below that depth a gradual shift occurs in invertebrate species composition and algal diversity drops sharply. For gastropods and algae, 50 meters is the appropriate lower limit; for organisms with wider bathymetric ranges, such as echinoderms and bivalves, it extends to 100 meters, and for reef fishes with deep-dwelling adults, to 200 meters. Molluscs, with the best fossil record in insular habitats, remain the model group, and the 50-meter limit maximizes the visible effects of sea-level change on their habitats.

From this foundation, the authors carve out three new island categories. Solum islands, from the Latin for

The naming of the three island types reflects the authors’ habit of reaching into classical languages for terms that capture a geological relationship in a single word. Solum islands, from the Latin for “alone,” are islands whose surrounding seafloor drops below the critical depth threshold, so that even when glacial-era sea levels fell by more than a hundred meters, they never joined a neighbor. Their shallow marine habitats contracted and expanded through each cycle, but their biota remained genetically and ecologically isolated throughout the islands’ entire history. Soror islands, from the Latin for “sister,” occupy the opposite dynamic regime: the seafloor between neighboring islands lies deeper than fifty meters, so during interglacial high stands they appear as separate islands, yet during glacial low stands the intervening sill emerges or becomes shallow enough that the islands fuse into a single landmass. Each glacial-interglacial cycle therefore alternately connects and disconnects their shallow-water faunas, imposing a repeated rhythm of population merging and splitting that has no terrestrial analogue at this tempo. Moliones islands, named for the conjoined twins of Greek mythology born to Molione and Poseidon, represent the third case: two or more islands whose intervening seafloor is always shallower than fifty meters, meaning that from the perspective of a shallow-water marine organism they have always functioned as a single island, regardless of where the coastline happens to sit at any moment.

The classification is not merely descriptive. Because the three island types experience fundamentally different histories of habitat connectivity, they should generate different frequencies of the three processes that govern speciation: population splitting, extinction, and merging. On Solum islands, populations persist in continuous isolation, so splitting events driven by the physical separation of habitats should be rare, and the dominant evolutionary dynamics involve local extinction and recolonization shaped by island area alone. On Soror islands, by contrast, every glacial cycle offers an opportunity for previously separated populations to merge, and every interglacial cycle offers an opportunity for a once-continuous population to be divided. This oscillation is predicted to elevate both splitting and merging rates relative to the other island types, with consequences for how quickly new lineages arise and how often they collapse back into genetic contact. Moliones islands, functioning as permanent single units for shallow-water biota, should behave like Solum islands in terms of connectivity, but with the important difference that their effective littoral area is the combined shelf area of the whole group, potentially supporting larger populations and lower extinction rates.

To ground these concepts in real geography, the authors assembled a dataset of 324 islands spanning temperate and tropical climates and a deliberately broad geographic distribution. The classification revealed a striking asymmetry: only 50 islands qualified as Solum islands, standing alone through every sea-level oscillation. Seventy-seven islands fell into 20 groups of Soror islands, the true fusion-fission cases where glacial cycles repeatedly rewired connectivity. The largest share, 197 islands arranged in 34 groups, turned out to be Moliones islands, functionally conjoined for marine purposes no matter what the sea was doing. This distribution suggests that the image of oceanic islands as isolated dots in a vast sea, so influential in the terrestrial tradition of island biogeography since MacArthur and Wilson, may substantially misrepresent the marine experience: for shallow-water organisms, the majority of islands in the sample have always been connected to neighbors across shallow sills, and only a minority have known true isolation.

A second major contribution of the study is the recognition that sea-level change does not translate uniformly into habitat change. When sea level falls, the insular littoral area of an island may shrink, hold steady, or in some configurations even behave counterintuitively, depending on how the submarine terrain is shaped. The authors identify five general types of curves describing how ILA changes through a glacial-interglacial cycle, and they trace this variation back to the depth distribution across each island’s shelf. That depth distribution, in turn, is not random but reflects geological history. Young volcanic islands tend to have steep flanks and narrow shelves, so a given drop in sea level removes little habitat; old, subsiding islands may carry broad, gently sloping shelves where the same drop eliminates vast tracts of littoral ground. Tectonic setting matters, as does the presence of submarine and subaerial terraces, which are relict shorelines carved during earlier sea-level stands and which create stepped profiles that produce abrupt, nonlinear changes in available habitat as the sea crosses each terrace. Coral reefs add yet another layer of complexity, because reef organisms build structures that modify both the topography and the ecological character of the shallow seafloor, and reef growth can partially keep pace with or amplify changes in available habitat.

The Pleistocene context gives these dynamics their tempo. Over the past few million years, Earth has cycled repeatedly between glacial periods, when continental ice sheets locked up enough water to lower global sea level by well over a hundred meters, and interglacial periods like the present, when sea level stands high. For marine organisms restricted to shallow water, each cycle compressed their habitat into a narrow band around a lower coastline and then released it again across a broader shelf. Populations that today appear separated by deep channels may have shared larvae and genes only a few tens of thousands of years ago, when the channel floor was dry land or shallow sea. Conversely, populations that seem contiguous today may have been fragmented across separate basins during the low stands. The fossil record of molluscs in insular settings, the best preserved among shallow marine groups, offers a way to test these predictions, since shells archive both the presence of species and, through geochemical and morphological study, something of the environments they inhabited.

The study’s predictions extend to speciation rates themselves. Shallow-water marine organisms on Soror islands are expected to show elevated rates of population splitting during fission phases, when rising seas subdivide once-connected habitats, and elevated merging during fusion phases, when falling seas reunite them. Whether this oscillation ultimately produces more species or fewer depends on the balance between divergence during isolation and homogenization during contact, a tension familiar from terrestrial fusion-fission studies but now, for the first time, framed explicitly for the sea. Extinction rates should track the ILA curves: islands whose littoral area collapses dramatically during low stands should suffer proportionally greater losses of shallow-water species, while islands whose ILA remains comparatively stable through the cycles should act as refugia. These differential responses across the five ILA curve types and three island categories provide a rich set of testable hypotheses for comparative biogeography.

What emerges from the extended SLS model is a picture of marine island biogeography in which the sea floor’s hidden topography, rather than the visible outline of coastlines, determines the evolutionary fate of shallow-water life. The depth of a sill between two islands, the slope of a shelf, the presence of an ancient terrace, or the growth of a reef can each decide whether populations merge, split, persist, or vanish as glaciers come and go. By classifying islands according to these submerged architectures, the study gives researchers a practical framework for predicting where speciation should be most active, where extinction risk concentrates during sea-level falls, and where the faunas of neighboring islands are, in evolutionary terms, a single interconnected population wearing the disguise of an archipelago.

Subject of Research: Extending the Sea-Level Sensitive dynamic model of marine island biogeography to include fusion-fission islands driven by glacial-interglacial sea-level cycles

Article Title: Extending the Sea-Level Sensitive dynamic model of marine island biogeography to include fusion-fission islands

Article References: Ávila, S. P., Múrias dos Santos, A., Melo, C. S., Porteiro, J. M., Medeiros, A. M., Baptista, L., Pimentel, A., Madeira, P., Rebelo, A. C., Hipólito, A., Voerman, S. E., Ávila, G. C., Moura, M., Berning, B., Rijsdijk, K. F., Martín-González, E., Quartau, R., Ramalho, R. S., & Johnson, M. E. (2025). Extending the Sea-Level Sensitive dynamic model of marine island biogeography to include fusion-fission islands. Frontiers of Biogeography, 18, Article e141200. https://doi.org/10.21425/fob.18.141200

Image Credits: AI Generated

DOI: 10.21425/fob.18.141200

Keywords: island biogeography, sea-level change, marine speciation, fusion-fission islands, insular littoral area, glacial-interglacial cycles, Solum islands, Soror islands, Moliones islands, Cabo Verde, Conus, shallow-water marine biodiversity

The research, led by Shizuka Takai of the Nuclear Safety Research Center at the Japan Atomic Energy Agency together with Tomoji Sanga, Taro Shimada, and Seiji Takeda, was published in the journal Earth Surface Dynamics. The team focused on six small rivers that dissect a staircase of marine terraces on a coastal plain roughly 30 by 50 kilometres in size, where the underlying rocks range in age from the Miocene to the Pleistocene and the land has been rising steadily at about 0.2 millimetres per year for the past 300,000 years. That combination of uniform lithology and uniform uplift makes the plain an unusually clean natural laboratory for isolating the physics of river incision.

At the heart of the study lies the detachment-limited stream-power model, a deceptively simple equation that expresses the long-term incision rate E as the product of an erosion coefficient K, the upstream drainage area A raised to a power m, and the channel slope S raised to a power n. The ratio of the two exponents, known as the concavity index, describes the characteristic downward flattening of a river profile, while K bundles together everything the equation does not explicitly resolve: the erodibility of the bedrock, the climate, and the hydraulic geometry of the channel. If the erosion rate can be measured independently, all three parameters can be recovered from the shape of the river profile as recorded in digital elevation data.

Measuring erosion rates, however, is where most previous studies have stumbled. The standard tool is the concentration of beryllium-10, a cosmogenic radionuclide that accumulates in quartz grains as they are exhumed from the landscape. That method works beautifully in quartz-rich granites but fails in the humid, tectonically restless terrain of Japan, where more than half of the surface geology consists of Paleogene and Neogene sedimentary rocks that contain little quartz and have been deformed and reworked in complicated ways. Cosmogenic clocks also integrate erosion over timescales that shrink as erosion accelerates, spanning roughly a hundred thousand years in slow eroding terrain but only centuries to millennia where rivers cut at several metres per thousand years.

Takai and colleagues sidestepped the problem by reading the erosion record directly from the landscape itself. The Kamikita Plain preserves a sequence of marine terraces formed during the high sea levels of Marine Isotope Stages 5e, 7, 9, and 11, whose ages have been pinned down by sediment-rate chronology, optically stimulated luminescence dating, and tephra and phytolith stratigraphy. Because the terraces were cut flat by the sea and then uplifted, the difference between a terrace’s reconstructed summit level and the modern riverbed, corrected for the thickness of overlying tephra and loess, gives the depth of rock the river has removed since the terrace formed. Dividing that depth by the terrace age yields an incision rate averaged over hundreds of thousands of years, exactly the timescale that long-term landscape forecasts require.

The analysis relied on high-resolution topographic data, combining airborne LiDAR and photogrammetric elevation models at five-metre resolution, smoothed with a 500-metre moving window to suppress measurement noise. The team identified the reaches where the rivers behave as detachment-limited bedrock channels, confirmed that these reaches lie upstream of the alluvium deposited as sea level rose during the Holocene, and extracted the channel steepness index and concavity using both slope-area regression and the integral chi-transform method. A statistical segment-fitting algorithm, evaluated with the corrected Akaike Information Criterion and validated through a thousand bootstrap trials, located the knickpoints, the abrupt changes in channel gradient that record disturbances migrating upstream through the profile.

The results were striking. The reference concavity came out at 0.44 plus or minus 0.10, squarely within the range expected for channels near steady state. Yet the slope exponent n, estimated across a range of assumed concavities from 0.4 to 0.6, consistently exceeded one, falling between 1.14 and 1.34. Nonlinearity of this kind implies that incision rate grows faster than proportionally with channel steepness, a behaviour consistent with global compilations that typically report n between one and two. The erosion coefficient K, by contrast, spanned a much wider range, from about four times ten to the minus seven to just over ten to the minus five, reflecting the sensitivity of this parameter to local conditions.

The most intriguing finding concerns why n exceeds one. All the knickpoints the team identified were slope-break features rather than waterfalls, and nearly all of them cluster at similar elevations of roughly 25 and 50 metres above sea level, independent of lithological boundaries. That pattern points to knickpoints generated by past falls in sea level, which propagated upstream through the channels during successive glacial cycles, much like features documented on the Sanriku Coast some 50 kilometres to the south. When the researchers averaged erosion rates and steepness over entire channel reaches, the apparent nonlinearity weakened toward n of about one, suggesting that the observed exponent is largely a transient artefact of sea-level-driven knickpoint migration rather than an intrinsic property of the incision process. Physical mechanisms such as shear-stress thresholds and abrasion by sand derived from the soft bedrock may still contribute, and the authors note that disentangling these contributions will require further work.

The erosion coefficient told a cleaner story. Converting standard penetration N-values to unconfined compressive strength, the team found that the rocks underlying most of the study rivers have strengths of only about 1.2 to 3.1 megapascals, far softer than any bedrock in previous global compilations, which began at roughly 15 megapascals. Despite falling well outside that range, the estimated K values landed almost within the 90 percent confidence interval of the global relationship in which K scales inversely with the square of rock strength, a correlation originally established for much harder rocks. The agreement, with a coefficient of determination of 0.84 when the new data are combined with the global compilation, provides strong support for the idea that bedrock lithology exerts a first-order control on how fast rivers can cut.

Some systematic underestimation of K relative to the global trend remains, and the authors attribute it to three plausible causes: the transient steepening from migrating sea-level knickpoints, the use of present-day channel steepness as a proxy for long-term averages in rivers that have only gradually incised flat terraces, and the cohesive resistance of the semi-consolidated sandstones and siltstones, which standard geotechnical indices do not fully capture. Beyond its scientific interest, the work has a practical edge. Safety assessments for radioactive waste repositories, carbon storage sites, and landfills demand erosion forecasts over ten thousand to a hundred thousand years, and the parameters reported here, integrated over multiple glacial-interglacial cycles, offer a calibrated baseline for simulating future landscape evolution in the soft-rock terrains where much of Japan’s infrastructure sits. The team’s next step is to reproduce the plain’s past topography with coupled detachment- and transport-limited landscape evolution models, testing whether the numbers carved into its terraces can also predict what comes next.

Subject of Research: Parameter estimation of stream-power river incision models for soft sedimentary rocks using marine terraces in northeast Japan

Article Title: Parameter estimation of river incision models of soft sedimentary rocks – a case study on the Kamikita Coastal Plain, northeast Japan

Article References: Takai, S., Sanga, T., Shimada, T., & Takeda, S. (2026). Parameter estimation of river incision models of soft sedimentary rocks – a case study on the Kamikita Coastal Plain, northeast Japan. Earth Surface Dynamics, 14(3), 417-432. https://doi.org/10.5194/esurf-14-417-2026

Image Credits: AI Generated

DOI: 10.5194/esurf-14-417-2026

Keywords: river incision, stream-power model, soft sedimentary rocks, marine terraces, Kamikita Coastal Plain, knickpoints, sea-level change, erosion coefficient, concavity index, cosmogenic nuclides, landscape evolution, Japan

The team’s most significant technical achievement is the first foraminiferal zonation ever produced for the London Clay Formation. Earlier researchers, working as far back as the 1880s, had despaired of ever building such a scheme. Sherborn and Chapman noted in 1886 that regional variability among the shells was so pronounced that the word species should often be replaced by variety, and Bowen concluded in 1954 that no zonal scheme could be advanced for the formation based on foraminifera. Hart and his colleagues overturned that pessimism by carefully recording the first and last appearances of key taxa through the Whitecliff Bay and Alum Bay successions, defining eight zones they call Hampshire Basin Benthic zones, or HBB 1 to 8. Each zone is anchored on easily identified species such as Lobatula lobatula, Eilohedra vitrea and Cibicidoides alleni, and the scheme can be correlated between the two Isle of Wight sections using a distinctive planktonic datum first recognised by C. A. Wright in 1972.

Sampling the London Clay is far from straightforward. The cliffs are unstable, riddled with mudflows that tend to recur in the same places year after year, and the steeply dipping beds are subject to modern weathering that can selectively destroy fossils. The researchers found that samples taken from the foreshore, after storms had stripped away the modern beach, often yielded better preserved and more complete assemblages than cliff samples from the same horizons. They processed roughly two-kilogram samples using the white spirit method, which breaks down claystones and siltstones completely without damaging the microfossils, then washed the residues on a 63-micrometre sieve and examined four separate size fractions under the microscope. Erosion surfaces overlain by mudstone clasts and phosphatic nodules revealed hiatuses in the succession, suggesting that the London Clay of Whitecliff Bay and Alum Bay may be incomplete, a feature the authors suspect is the norm but is rarely described.

With the zonation in place, the team turned to palaeoecology. Using morphogroup analysis, planktic to benthic ratios, agglutinated to calcareous ratios, dominance and diversity indices, and Murray’s classic triangular plots, they reconstructed water depths through the London Clay. Their interpretation ranges from hyposaline, possibly river-mouth conditions to an open shelf environment between roughly 5 and 105 metres deep. Crucially, the maximum water depth in both Whitecliff Bay and Alum Bay falls within the interval of the Early Eocene Climatic Optimum, a prolonged hyperthermal spanning approximately 54 to 48 million years ago. When the two depth curves are superimposed, they overlap closely, and the planktonic datum coincides with the inferred maximum flooding in both sections. The authors suggest this sea level rise and fall within the EECO might represent a glacio-eustatic response to the warming, an intriguing possibility given that the event occurred in a hothouse world.

That interpretation, however, comes with caveats the authors are careful to spell out. The PETM, which occurred close in time to the EECO, is widely thought to have taken place in an ice-free world, making ice-driven sea level change difficult to invoke for the early Eocene. Modern calculations of ocean thermal expansion, based on NASA and NOAA data, suggest that warming of 0.6 to 1.0 degrees Celsius produces only a few centimetres of sea level rise, far too little to be detected in compacted Eocene mudstones. Alternative mechanisms remain on the table, including tectonic movements on the Sandown Pericline, as proposed by Stamp in 1921, or dynamic topography driven by the Iceland mantle plume, which Gale and Lovell have argued influenced sea level in the Anglo-Paris Basin into the Lutetian. The absence of any significant facies change accompanying the early Eocene depth maximum argues against a strong tectonic control, leaving the question open.

The second half of the story belongs to larger benthic foraminifera, the giants of the micropalaeontological world. These complex, symbiont-bearing shells, including the discoidal nummulitids and the cigar-shaped, porcelain-white alveolinids, are normally restricted to tropical and subtropical shallow carbonate shelves. Finding them in the clay-rich mid-Eocene sediments of southern England, at relatively northern palaeolatitudes, is highly unusual and points to a substantial warming episode. In the Whitecliff Bay succession, larger foraminifera appear in the Earnley Sand Formation and continue into the Barton Clay Formation, an interval embracing the uppermost Lutetian and lowermost Bartonian that straddles the Late Lutetian Thermal Event and the Middle Eocene Climatic Optimum, a short-lived warming of roughly 500,000 years duration around 40 million years ago.

The alveolinids are the star witnesses. Known in England from only three localities, including Fisher’s Beds 21 and 22 at Selsey Bill in Sussex and the uppermost Selsey Sand Formation in Whitecliff Bay, these fusiform shells also occur in pale limestones dredged from the sea floor of the English Channel. Dennis Curry collected such limestones from the R.V. Sarsia in 1955, and samples held by the British Geological Survey were re-examined for this study, with several confirmed to contain visible alveolinids. A vibro-core drilled between Jersey and the Cotentin Peninsula in 2009 recovered Eocene sediments with worn but unmistakable larger foraminifera, close to in situ mid-Eocene deposits near Valognes in Normandy. Taken together, these occurrences mark the northernmost known limit of Alveolina in northwestern Europe and sketch a picture of a warm, shallow sea covering much of the Channel region during the Lutetian.

The authors argue that this warm-water assemblage responds to the Late Lutetian Thermal Event, while the extension of the ranges of nummulitid species such as Nummulites prestwichianus and N. rectus into the lowermost Barton Clay Formation suggests that warm conditions persisted into the MECO, whose isotope signal lies low in that formation. Following Dawber and colleagues, they suggest both events may record a slight glacio-eustatic rise, and the presence of carbonate sediments resting directly on the basement of the Cotentin Peninsula supports a transgressive event in a marginal setting. Unlike the early Eocene case, mid-Eocene glaciation is more plausible, since ice-rafted debris has been reported from marine cores near Greenland back to around 44 million years ago.

What makes this study remarkable is its blend of Victorian field geology and modern micropalaeontological technique. The Whitecliff Bay succession was first described by Prestwich in 1846, and the larger foraminifera were figured by Carpenter and Dixon in 1850, yet the London Clay had never yielded a workable zonation until now. The paper is also a memorial to two giants of British micropalaeontology, John Murray, whose 1974 monograph with Chris Wright remains foundational, and Mark Alex-Sanders, whose doctoral-level work on the London Clay foraminifera underpins the new zonation and who died before his research could be published. The eight HBB zones, though of local application only, give the Hampshire Basin a biostratigraphical framework comparable to those long established elsewhere in the Anglo-Paris Basin.

For anyone wondering why shells smaller than a grain of sand matter, the answer lies in the deep-time perspective they provide. The Eocene hyperthermals are the closest analogues in the geological record to the greenhouse warming now under way, and understanding how sea level, water depth and marine ecosystems responded to those events helps calibrate expectations for the future. That a walk along an English beach at low tide, sampling vertically dipping clays once drowned under a warm shelf sea, can still yield new insights into global climate dynamics more than 250 years after the first fossil collections from these cliffs is a testament to the enduring power of patient, meticulous field science.

Subject of Research: Eocene foraminiferal biostratigraphy and palaeoecology of the Hampshire Basin, UK, in relation to Eocene hyperthermal events

Article Title: Can the distribution of foraminifera locate the Early Eocene Climatic Optimum (EECO) and Middle Eocene Climatic Optimum (MECO) events in the Eocene succession of the Isle of Wight (UK)?

Article References: Hart, M. B., Alex-Sanders, M. E. A., & Smart, C. W. (2026). Can the distribution of foraminifera locate the Early Eocene Climatic Optimum (EECO) and Middle Eocene Climatic Optimum (MECO) events in the Eocene succession of the Isle of Wight (UK)?. Journal of Micropalaeontology, 45(1), 315-334. https://doi.org/10.5194/jm-45-315-2026

Image Credits: AI Generated

DOI: 10.5194/jm-45-315-2026

Keywords: foraminifera, Isle of Wight, Eocene, EECO, MECO, London Clay Formation, hyperthermal events, palaeoecology, biostratigraphy, sea level change, larger benthic foraminifera, Hampshire Basin

The cores were drilled in July 2020 from the geotechnical drilling vessel MV Normand Flower, operated by Fugro, over just two days of fieldwork. In total, the team retrieved approximately 62 metres of sediment, with the deepest hole reaching 54.3 metres below the lowest astronomical tide. The drilling sites sit within the Hollandse Kust Zuid (HKZ) offshore wind farm zone, an area of roughly 225 square kilometres located 18 to 36 kilometres west of the Dutch coast, where water depths reach about 28 metres. That location was no accident. The team deliberately targeted the wind farm because it lies south of the maximum limits reached by Middle and Late Pleistocene ice sheets, which minimised the chance that glacial erosion had destroyed the sedimentary record, and because the site had already been imaged by an extraordinary wealth of high-resolution seismic survey data collected for wind farm development.

That seismic dataset proved central to the entire endeavour. Between 2016 and 2017, the survey company Fugro conducted comprehensive geophysical investigations on behalf of the Netherlands Enterprise Agency, imaging the shallow subsurface with a subbottom profiler, a single-channel sparker and a high-resolution multi-channel sparker. The single-channel sparker data, collected with a GSO 100-tip source operating at 200 to 300 joules and a peak frequency of 825 hertz, allowed the researchers to map two distinct high-amplitude reflector surfaces in the top 50 metres of sediment. Both reflectors correspond to peat deposits, which have distinctive acoustic properties because organic material attenuates and reflects sound differently from mineral sediments. The upper peat surface is continuous across most of the wind farm site, while the lower peat appears scattered but is attributed to the same stratigraphic level. By targeting boreholes where these peat reflections were present, the team maximised their chances of recovering sediments spanning one or more glacial-interglacial cycles.

Drilling in one of the busiest industrialised shallow seas in the world required careful negotiation of competing interests. The seabed of the HKZ zone is criss-crossed by cables and pipelines, dotted with platforms, and littered with shipwrecks, crashed aircraft and magnetic anomalies, some of which may be unexploded ordnance dating from the two World Wars. The researchers had to map all of these hazards before selecting safe drilling locations. Timing also mattered: final site investigations for the wind farm were underway in 2020, leaving only a narrow window before turbine construction began in July 2021. The wind farm, which now contains 139 turbines with a capacity of 1.5 gigawatts, enough to power 1.5 million Dutch households, was inaugurated in September 2023 and has been fully operational since December of that year. The scientific cores therefore represent a rare collaboration between academic research and the offshore energy industry, extracted from ground that is now literally the foundation of Europe’s renewable energy transition.

Because of pandemic-era operational restrictions, no scientists were aboard the drilling vessel. Instead, the team relied on remote communication while Fugro’s crew handled positioning and drilling. Surface positioning used two StarPack global navigation satellite system receivers, with underwater positioning provided by a Kongsberg Simrad HiPAP 500 ultra-short baseline system. Water depths were measured by multiple independent methods, including echosounders, the drill string itself, and conductivity-temperature-depth probes, and all depths were reduced to the lowest astronomical tide. Open-hole drilling removed the well-documented Holocene sands of the upper seabed, after which semi-continuous liner sampling began at 10 to 12 metres below the seafloor using thin-walled Shelby tubes 7.62 centimetres in diameter. The recovered cores were then transported to the British Ocean Sediment Core Research Facility at the National Oceanography Centre in Southampton, where they were split, imaged with X-ray radiography and laminography, and archived. Since 2021 they have been held in cold storage at the University of Leeds.

The sedimentary sequence inside the cores tells a striking story. Each of the five cores contains an upper and a lower peat unit, separated by semi-consolidated clays, silts, sands and gravels. The lowermost peat is primarily in situ woody peat, but its thickness varies dramatically between sites: in core RISeR_S1 it is less than 0.3 metres thick, an order of magnitude thinner than the roughly 3 metre thick peat deposit in RISeR_S7. In several cores the contact between the lower peat and overlying sediments is abrupt and erosional, while in others it grades gradually into clays, suggesting different histories of flooding and burial. Below the lower peat, the team identified a palaeosol, an ancient soil horizon, recognised by rooting features visible in X-ray laminography, a decalcified upper zone underlain by levels enriched with millimetre-scale calcium carbonate nodules, and distinctive steel-blue hues. These soils formed on land, in the open air, and their presence deep in the seabed is unambiguous evidence of a terrestrial environment.

Integrating the core descriptions with the seismic reflection data revealed how far these units extend laterally. The surface of the upper peat can be traced in the seismic profiles between cores RISeR_S1 and RISeR_S7, and between RISeR_S4 and RISeR_S6, even where a small channel form interrupts the continuity. However, a large channel incision separates the eastern part of the wind farm, where cores RISeR_S5 and RISeR_S6 were drilled, from the western part, so the team cannot yet confirm by seismic tracing alone that the peats on either side represent the same surface. The lower peat is laterally discontinuous between all the core sites, meaning correlations must rely on facies associations with the overlying and underlying units. The researchers caution that the vertical resolution of the multi-channel sparker data is limited to 50 to 100 centimetres, so thinner layers may be invisible, and sound-attenuating peat can mask the dominant lithology of adjacent units. These correlations, they stress, must ultimately be tested with biostratigraphical and geochronological laboratory analyses.

The interpretation of the wider sequence is where the findings become genuinely unexpected. While the in situ peats and their underlying palaeosols are unquestionably terrestrial, the intervening sands and clays could reflect fluvial deposits from the Rhine-Meuse system, including floodplains and channel-fills, or intertidal to shallow marine conditions in lower delta plains and lagoons. Notably, the team found no clear evidence of marine inundation within the cored interval, and the general lack of shells suggests open marine environments are not recorded there. The stacking of terrestrial soil-overprinted units without intercalated marine levels, yet preserved 40 to 50 metres below present sea level, requires a depositional model involving fluvio-deltaic cycles, slow subsidence rates and considerable elapsed time. The researchers tentatively assign the stratigraphy to a temporal window between 1.5 and 0.5 million years ago, after the southern North Sea basin was largely infilled by river deltas but before marine inundation during the sea-level highstands of the Middle and Late Quaternary interglacials. This is a marked contrast to the Late Pleistocene, Eemian age of around 129,000 to 116,000 years ago assigned in the initial wind farm site reports.

Establishing a firmer chronology is the team’s next challenge, and it is a formidable one. The sediments are far too old for radiocarbon dating, which reaches only about 50,000 years, and the traditional chronological framework for the Quaternary North Sea rests on pollen zonation schemes from the Netherlands and Britain that are complicated by variable pollen concentrations and the reworking of older taxa. The researchers are now pursuing detailed palynological analysis to tie the cores into the Dutch pollen chronostratigraphy, alongside experimental luminescence dating and palaeomagnetic investigation. Palaeomagnetic work is particularly promising because it could place the deposits before or after the Brunhes-Matuyama reversal at 774,000 years ago, cleanly separating Early from Middle Pleistocene. Together these parallel approaches should cross-validate the ages and the correlations between the five cores.

The stakes extend well beyond academic curiosity. The heterogeneous Quaternary sediments of the southern North Sea form the physical foundation for a rapidly expanding offshore wind industry, and understanding their architecture is critical input for ground models and geohazard assessment. More broadly, new chronologies for the RISeR cores will allow the vast archive of high-resolution seismic data gathered by the wind industry over the past decade to be transformed into modern geological subsurface models, enabling landscape-scale reconstructions of palaeoenvironmental change for chosen interglacials. During glacial lowstands, the exposed land south of the ice margins also served as a corridor for human migration into northwestern Europe, so refining the history of these drowned landscapes has implications for archaeology as well as climate science. In recovering a lost world from beneath the turbine foundations, the RISeR project demonstrates how industry and science can drill toward the same seabed and both come away with something valuable.

Subject of Research: Middle Pleistocene terrestrial stratigraphy recovered from sediment cores in the southern North Sea

Article Title: The RISeR cores: unexpected and extensive Middle Pleistocene terrestrial stratigraphy in the southern North Sea

Article References: McGuire, A. M., Cartelle, V., Rush, G., Busschers, F. S., Cohen, K. M., Hodgson, D. M., & Barlow, N. L. M. (2025). The RISeR cores: unexpected and extensive Middle Pleistocene terrestrial stratigraphy in the southern North Sea. Scientific Drilling, 34(1/2), 29-39. https://doi.org/10.5194/sd-34-29-2025

Image Credits: AI Generated

DOI: 10.5194/sd-34-29-2025

Keywords: North Sea, RISeR cores, Middle Pleistocene, palaeosols, peat deposits, seismic reflection, offshore wind, sea-level change, Quaternary stratigraphy, scientific drilling, Rhine-Meuse, palaeolandscape

The research focuses on the area around the Darss Sill, a shallow submarine threshold that separates Mecklenburg Bay from the Arkona Basin and still acts as a bottleneck for water exchange in the modern Baltic Sea. Because the sill sits close to the isostatic zero line, the zone where the crust is neither rising nor sinking, it preserves an unusually clean record of past water levels. Yet despite its importance for understanding the entire Baltic’s postglacial evolution, the area had not been examined with modern high-resolution acoustic methods for roughly fifteen years. The new study closes that gap by combining multibeam echo sounder bathymetry, sidescan sonar mosaics, sediment echo sounder profiles, five sediment cores and underwater video footage into a single integrated reconstruction.

The story begins around 17,000 years ago, when the retreating Scandinavian ice sheet opened the Baltic basin to meltwater and the vast proglacial Baltic Ice Lake began to form. The researchers identified seismic units corresponding to two transgressive phases of this lake, separated by an erosional unconformity. Coarse-grained, organic-flecked sediments sampled in cores, including a piece of wood radiocarbon-dated to roughly 13,700 years before present, indicate a shoreline remarkably close to the study site during the lake’s initial phase. The spatial distribution of these deposits places a Baltic Ice Lake coastline at about 20 meters below present sea level along the northeastern margin of Mecklenburg Bay, confirming that the lake spilled across the Darss Sill and connected the region with the Arkona Basin to the east.

What followed was one of the most dramatic hydrological events in European prehistory. When the ice margin retreated from the Mt. Billingen area in central Sweden at the end of the Younger Dryas, the natural dam holding back the Baltic Ice Lake failed, and the water level plunged by an estimated 25 to 30 meters, possibly within just one to two years. Around 7,800 cubic kilometers of freshwater surged toward the North Sea, shrinking the lake’s surface area by nearly a fifth. In the study area, this catastrophe is written into the seafloor as a widespread erosional unconformity that truncates the Baltic Ice Lake deposits, marking the onset of lowstand conditions when Mecklenburg Bay and the Arkona Basin were separated by exposed land on the Darss Sill.

As global sea level crept upward and isostatic rebound in central Sweden once again cut the Baltic off from the ocean, a new dammed freshwater body, the Ancylus Lake, formed around 10,800 years ago. Its transgression flooded the developing terrestrial environment of the sill, and the researchers found its highstand fingerprint in an unexpected place: a low-backscatter platform of laminated gyttja and peat lying in water depths of about 19 meters below present sea level. Underwater video revealed the platform as a smooth, erosionally truncated surface more than two meters high in places, with wood fragments protruding from its base. Radiocarbon dates on plant remains from the platform cluster between roughly 10,800 and 10,200 years ago, constraining the Ancylus Lake highstand and showing that lacustrine conditions persisted in the area until at least 10,200 calibrated years before present.

The most visually striking discovery, however, came from the period after the Ancylus Lake peak. The acoustic data revealed three continuous, roughly north–south-trending channel branches incised into the lake sediments, draining northward toward deeper water. The western channel averages about 280 meters wide, while the central and eastern branches are around 120 meters across, and where their bases are visible in seismic profiles they cut 6 to 7 meters deep. Because the channel infill consists entirely of Ancylus-period deposits dated to about 9,000 years before present, the channels record a water level drop of at least 6 to 7 meters following the Ancylus highstand, a moderate regression rather than the catastrophic drainage some earlier hypotheses proposed.

That finding matters because the outlet of the Ancylus Lake has been one of the longest-running controversies in Baltic Sea geology. Some researchers once argued that erosion of the Kadet Channel through the Darss Sill triggered a catastrophic outburst, possibly lowering the lake to global sea level within two to three years and carving a hypothetical mega-river dubbed the Dana River. Later work found no evidence of deeply incised channels or major delta deposits to support that scenario, and the new study adds further weight to the skeptics: the team found no trace of a large east–west-trending Dana River channel in their data. Instead, the modest 6-to-7-meter drop supports a gentler scenario, consistent with earlier suggestions of a calm drainage in which fluvial erosion and rising global sea level together accounted for the change.

The reconstruction also carries implications far beyond geology. From the Baltic Ice Lake through the Ancylus Lake stage, the region’s coastlines swept back and forth across areas that are now several meters underwater, and these were precisely the landscapes favored by Mesolithic hunter-gatherer communities. Previous discoveries in the western Baltic, including a submerged Stone Age hunting structure found in 2024 at depths of up to 21 meters, have shown how rich the flooded archaeological record can be. By pinning down where shorelines actually stood during each stage, the new paleogeographic maps give archaeologists a targeting system for locating drowned settlements, and the authors emphasize that similar preserved landscapes likely extend along the entire southern Baltic coast from the coastline down to about 20 meters of water depth.

Technically, the study demonstrates how much information modern marine surveying can extract from a modest patch of seafloor. Ten-meter bathymetric grids exposed meandering sand dunes up to two kilometers long, probably shaped by present-day bottom currents, alongside circular depressions and small cliffs carved into soft organic sediments. Parametric sediment echo sounders resolved seismic units only a few meters thick, while laser diffraction grain-size analysis and accelerator mass spectrometry radiocarbon dating, calibrated with the IntCal20 curve, anchored the sequence in time. Even the geometry of channel rims told a story: where erosion cut through cohesive, organic-rich gyttja into weaker sandy layers beneath, the resistant upper edges were left standing as ridges on the seafloor, mimicking the peat ridges that mark ancient riverbeds elsewhere on the Darss Sill.

Questions remain. The team could not determine exactly where the post-Ancylus channels met the remaining lake body, nor whether the widespread Holocene erosion they observed occurred during the regression itself or later, during the early Littorina Transgression, when rising brackish seas finally drowned the sill and established the modern Baltic. The drainage route of the Ancylus Lake, whether through the Great Belt or some other pathway, is still unresolved, and the authors call for future work directly east of the Darss Sill to close the gap. But the broader picture is now much sharper: a threshold region that was flooded, drained, flooded again and finally submerged, its entire 13,000-year water level history preserved in a few meters of sediment just beneath the waves, waiting for sonar, cores and cameras to bring it back to light.

Subject of Research: Postglacial water level changes and paleolandscape evolution of the Darss Sill region in the southern Baltic Sea

Article Title: Postglacial water level changes of a drowned lake and river system in northeastern Mecklenburg Bay, southern Baltic Sea

Article References: Granzow, J., Tauber, F., Arz, H. W., Geersen, J., & Feldens, P. (2026). Postglacial water level changes of a drowned lake and river system in northeastern Mecklenburg Bay, southern Baltic Sea. E&G Quaternary Science Journal, 75(1), 107-129. https://doi.org/10.5194/egqsj-75-107-2026

Image Credits: AI Generated

DOI: 10.5194/egqsj-75-107-2026

Keywords: Baltic Sea, Mecklenburg Bay, Darss Sill, Baltic Ice Lake, Ancylus Lake, sea level change, paleogeography, marine geology, sediment cores, radiocarbon dating, submerged landscapes, Mesolithic archaeology

True polar wander is a deceptively simple concept with profound consequences. Earth is not a perfect sphere; it bulges at the equator, and its rotation axis is naturally balanced by the way mass is distributed across the planet, much as a spinning top seeks a stable orientation. When geological processes—chief among them the sinking of dense slabs into the mantle, the rise of hot plumes, and the drifting of continents—redistribute that mass, the balance can be disturbed. The planet then responds by rotating its entire solid body relative to the spin axis until equilibrium is restored. Crucially, the spin axis itself, and with it the core and the planet’s climate belts, stay fixed in space. It is the land and the mantle that move beneath them.

The implications of such reorientations are enormous. Because climate zones remain anchored to the spin axis, a rapid shift of the solid Earth would drag continents through different latitudinal bands, subjecting them to abrupt changes in temperature, rainfall, and seasonality. Ocean circulation patterns would be disrupted, sea levels would rise and fall in distinctive geographic patterns, and the planet’s magnetic field, generated in the core, would record the shift in rocks forming at the time. Large or rapid episodes of true polar wander could therefore act as a hidden driver of climate upheaval, biological turnover, and environmental change—yet proving that such episodes happened in the deep past has proven remarkably difficult.

The central problem is one of mimicry. The most common tool for detecting past polar wander is paleomagnetism: when igneous and sedimentary rocks form, they lock in a record of the direction of Earth’s magnetic field, allowing researchers to infer where a continent sat relative to the poles at the time. But plate tectonics produces a similar signature. A continent that drifts northward because its plate is moving leaves the same kind of paleomagnetic trace as one that stayed still while the planet tipped beneath it. Disentangling the two effects has led to decades of conflicting interpretations, with some studies concluding that true polar wander has been negligible or persistently slow, and others arguing for brief, dramatic episodes of large-scale reorientation.

Domeier and colleagues approached this stalemate from an unexpected direction: the sea. True polar wander produces a predictable, globe-spanning pattern of continental flooding and exposure. As the solid Earth tips, regions moving toward the equator experience a rise in sea level relative to the land, because the equatorial bulge of the planet means lower gravitational potential at low latitudes, while regions moving toward the poles see the opposite. The result is a characteristic quadrupolar pattern—flooding and emergence arranged in a symmetric, four-lobed configuration across the globe—that no purely tectonic or climatic process can easily imitate. If rapid true polar wander occurred, ancient shorelines should record it in a coordinated, planet-wide signature.

To hunt for that signature, the team compiled reconstructions of continental flooding and exposure at ten-million-year intervals across the past 320 million years, spanning the late Paleozoic, the entire Mesozoic, and the Cenozoic. They then applied statistical modeling designed to detect whether the observed patterns of marine incursion and land exposure matched the geometry expected from rapid true polar wander, testing the fit against what could plausibly arise from plate motion and other processes alone. The method turns the global distribution of ancient shallow seas—long studied as a record of climate and tectonics—into a planetary seismograph for whole-Earth rotation.

The results were striking. The analysis revealed four intervals with statistically significant true polar wander signals. Two stand out in particular: the mid-Cretaceous, between roughly 100 and 90 million years ago, and the transition from the Late Jurassic into the Early Cretaceous, between roughly 150 and 140 million years ago. Both intervals were times of profound planetary change, with high sea levels, widespread greenhouse climates, and major reorganizations of tectonic plates. The finding broadly corroborates earlier paleomagnetic and plate-motion studies that had hinted at rapid reorientations during these periods, lending independent support from an entirely different line of geological evidence.

Just as important are the episodes the analysis failed to confirm. The study found little evidence for rapid true polar wander during most of the Cenozoic, the era that began 66 million years ago with the extinction of the dinosaurs and continues to the present. More provocatively, the data provide no significant signal supporting a long-debated hypothesis that the supercontinent Pangea moved rapidly northward during the late Carboniferous and Permian periods primarily because the planet tipped, rather than because its plates were driven by mantle convection. That proposed explanation, which had been invoked to explain puzzling features of the late Paleozoic record, now faces a serious challenge from the sea-level evidence.

The authors argue that their findings settle a long-running debate in a decisive way. As they state, the results refute the view of true polar wander as negligible or persistently slow, and highlight the need to consider it as an episodic control on sea-level change and, very likely, on other global environmental and biological dynamics. In other words, true polar wander should no longer be treated as a curiosity at the margins of geophysics, but as a recurring mechanism capable of reshaping climates and ecosystems on timescales that, in geological terms, are startlingly fast. Episodes that unfold over a few million years could coincide with, and perhaps help trigger, some of the major environmental transitions recorded in the rock record.

For researchers studying Earth’s deep past, the study opens a new window onto the interplay between the planet’s interior and its surface environment. The same statistical framework can now be refined and applied to finer time slices, potentially linking specific episodes of polar wander to known events such as oceanic anoxic episodes, biotic radiations, and extinctions. And because the mechanism depends on how mass is distributed in the mantle, the findings feed directly into models of mantle convection and plate-driving forces. The ancient shorelines of flooded continents, it turns out, keep a faithful record not only of where the seas once stood, but of moments when the planet itself rolled over beneath them.

Subject of Research: Rapid true polar wander episodes during the Jurassic and Cretaceous detected through ancient sea-level fluctuations

Article Title: Ancient seas reveal times when the Earth rapidly shifted relative to its axis

Article References: Ancient seas reveal times when the Earth rapidly shifted relative to its axis. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: true polar wander, sea level change, Jurassic, Cretaceous, paleomagnetism, plate tectonics, Pangea, mantle convection, continental flooding, Earth rotation, paleoclimate, Science journal