A marine shoreline preserved nearly 1.2 kilometers above today’s sea level in southern Türkiye is rewriting the story of how quickly mountains can rise. An international team led by Selma Sarı has identified what it reports as the world’s highest known late Middle Pleistocene marine deposits, exposed in the TOL-1 section of the Mut Basin on the southern margin of the Central Anatolian Plateau. The sediments formed during Marine Isotope Stage 7, a period broadly associated with the late Middle Pleistocene, approximately 243,000 to 191,000 years ago. Their present elevation, about 1,177 meters above mean sea level, provides an extraordinary geological record of the region’s vertical transformation. The findings, published in Geology, suggest that the landscape experienced surface uplift at an exceptionally rapid average rate of roughly 5.2 meters every thousand years.
At first glance, marine sediments found high in a mountain landscape may appear to be a simple indication that the land rose. In reality, determining how and when that happened requires separating several processes that can alter the elevation of ancient shorelines. Global sea level has repeatedly risen and fallen in response to the growth and melting of continental ice sheets. Local tectonic deformation can tilt or displace sedimentary basins, while erosion can remove parts of the original coastal environment. The research team therefore combined multiple independent techniques to establish the age, environmental setting, and original water depth of the TOL-1 deposits. Together, these methods transform the outcrop from an isolated geological curiosity into a precise record of regional uplift and the deep Earth forces that produced it.
The researchers used calcareous nannofossils and foraminifera—microscopic marine organisms whose shells and evolutionary changes are widely used to date sedimentary rocks—to constrain the age of the deposits. Calcareous nannofossils are planktonic algae that leave behind tiny calcium carbonate plates, while foraminifera are single-celled organisms that build distinctive mineral shells. Because different species occupied particular intervals of geological time and responded to changing marine conditions, their fossil assemblages can provide both biostratigraphic age markers and environmental information. The team also analyzed paleomagnetism, the record of ancient geomagnetic field behavior preserved by magnetic minerals in sediments. These measurements added an independent chronological framework, reducing the risk that the age estimate would depend on a single type of evidence.
Stable isotope measurements supplied another layer of information. Ratios of oxygen and carbon isotopes preserved in carbonate fossils and sediments can reflect changes in seawater chemistry, temperature, ice volume, and biological productivity. They do not function as a geological clock on their own, but when combined with fossil evidence and magnetic signatures, they can help identify the broader climatic setting in which marine deposition occurred. The TOL-1 section contains a combination of signals consistent with deposition during MIS 7, an interval marked by substantial climate variability and repeated changes in global ice volume. Establishing that the sediments formed during this specific period is crucial because it allows the ancient shoreline to be compared with known sea-level conditions rather than treating its modern elevation as a direct measure of tectonic motion.
One of the most innovative elements of the study was the reconstruction of the basin’s ancient water depth using ostracods. Ostracods are tiny crustaceans enclosed in hinged shells, and their communities are highly sensitive to salinity, water depth, oxygenation, temperature, and the connection between a basin and the open sea. Because different ostracod species prefer different habitats, fossil assemblages can act as biological depth indicators. By identifying the species preserved in the TOL-1 sediments and comparing them with modern ecological distributions, the researchers estimated the paleobathymetry—the water depth at which the deposits accumulated. This correction is essential: a layer now located at 1,177 meters elevation may originally have formed below sea level, but the amount of submergence must be estimated before the total tectonic uplift can be calculated.
The resulting uplift rate is striking even by the standards of active mountain belts. An average rise of approximately 5.2 meters per thousand years means that, over 100,000 years, the surface could be displaced upward by roughly 520 meters, assuming the rate remained broadly representative over that interval. Geological uplift is rarely perfectly constant, and the reported value is an average derived from the age and elevation of the deposits after accounting for their former marine setting and global sea-level changes. Even with that qualification, the rate indicates exceptionally rapid vertical motion. The study places a rare numerical constraint on when the Mut Basin changed from a marine environment into part of the elevated Central Anatolian Plateau, linking a visible landscape feature to processes occurring tens of kilometers beneath the surface.
The broader significance lies in the tectonic setting of southern Türkiye, where the Anatolian region sits at the intersection of major convergent plate systems. Africa and Arabia move northward relative to Eurasia, while the Anatolian block is squeezed westward between surrounding faults and plate boundaries. In such environments, uplift can be produced by crustal shortening, fault-related deformation, changes in the thickness of the crust, or buoyant flow in the underlying mantle. The authors discuss deep-seated mechanisms including slab break-off and mantle flow as possible drivers of the rapid elevation gain. Slab break-off occurs when a dense piece of oceanic lithosphere that has descended into the mantle detaches from the portion still attached to a subducting plate. The removal of that dense downward pull can allow hot mantle to rise, increasing buoyancy beneath the overriding crust and promoting rapid surface uplift.
Mantle flow may amplify that effect. As a detached slab sinks or reorganizes at depth, the surrounding mantle can move into the space it leaves behind. Hot, relatively buoyant material rising beneath a region can support the crust from below, while changes in stress and temperature may trigger additional deformation in the upper plate. The TOL-1 record does not simply image these processes directly; instead, it provides a time-stamped surface response that geodynamic models must explain. That distinction is important. Rocks at the surface preserve the consequences of deep Earth dynamics, while seismic imaging, plate-kinematic reconstructions, and numerical models are needed to test the precise mechanism. By connecting the age of marine deposits with their present elevation, the study supplies the kind of quantitative benchmark that can distinguish gradual plateau growth from episodes of unusually rapid uplift.
The discovery also changes how scientists may interpret ancient marine deposits elsewhere in the Mediterranean and surrounding mountain belts. Elevated shorelines and marine sediments are often used to reconstruct former sea levels, but tectonic movement can complicate those reconstructions. If an ancient coastal deposit has risen hundreds or thousands of meters, its current position records both global climate-driven sea-level change and local vertical motion. The TOL-1 section is particularly valuable because it preserves several complementary indicators in one location: fossil communities, magnetic signatures, isotope data, and sedimentary evidence of a former marine environment. Such integrated sections are uncommon, and they can serve as calibration points for regional models of plateau development, basin closure, erosion, and earthquake-related deformation.
For Selma Sarı, the publication represents the culmination of early-career research conducted at Università degli Studi Roma Tre, but its implications extend far beyond an individual field site. The study presents southern Türkiye as a natural laboratory where a marine basin, a rising plateau, and active plate convergence can be read in the same sequence of rocks. Its central message is both dramatic and precise: landscapes that appear stable over a human lifetime may undergo astonishing vertical change when viewed across geological time, and those changes can sometimes be measured with meter-scale averages per millennium. By identifying the highest known late Middle Pleistocene marine deposits and reconstructing the forces that lifted them, the researchers have turned an ancient seabed into a vivid record of Earth’s restless interior—and a compelling example of how microscopic fossils can reveal the movements of entire mountain plateaus.
Subject of Research: Cells
Article Title: The world’s highest late Middle-Pleistocene marine deposits on the southern margin of the Central Anatolian Plateau (southern Türkiye)
News Publication Date: 25-Aug-2026
Web References: https://doi.org/10.1130/G55209.1
References: Sarı, S., et al. (2026), Geology, “The world’s highest late Middle-Pleistocene marine deposits on the southern margin of the Central Anatolian Plateau (southern Türkiye),” DOI: 10.1130/G55209.1
Image Credits: Photo credit: Selma Sarı.
Keywords: Central Anatolian Plateau, Türkiye, Mut Basin, TOL-1 section, Middle Pleistocene, Marine Isotope Stage 7, marine deposits, tectonic uplift, slab break-off, mantle flow, paleomagnetism, foraminifera, calcareous nannofossils, ostracods, paleobathymetry, marine geology, Earth sciences
