Buried nearly a kilometre beneath the Atlantic seabed west of Guinea-Bissau lies a geological time-capsule: gigantic 117-million-year-old mud waves sculpted by dense, underwater avalanches. A new study published in Global and Planetary Change reveals that these ancient structures were formed when early Atlantic waters carved through the Earth’s crust, much earlier than previously believed. This discovery reshapes our understanding of Atlantic Ocean formation, offers fresh perspectives on Cretaceous climate shifts, and provides clues to tectonic movements that governed our planet’s evolving geography. From deep-sea sediment patterns to global carbon cycles, these mud waves, once hidden, now tell a story with far-reaching implications for modern geology and climate science.
Underwater mud waves push the Atlantic’s birth date back to 117 million years ago
Recent research published in Global and Planetary Change (2025) by Duarte, Nicholson, and colleagues has shed new light on the early history of the Atlantic Ocean. Using a combination of modern seismic imaging and archived drilling data from 1975, the team identified a series of massive 117-million-year-old mud waves buried deep beneath the Atlantic seafloor. These geological giants, stretching over a kilometer in length and rising hundreds of meters high, were formed when dense, salty water from the young North Atlantic spilled into the deeper southern basins, creating powerful underwater currents. The composition and layering of these mud waves reveal that such flows occurred far earlier than previously believed, suggesting that the Equatorial Atlantic Gateway, the oceanic passage linking the northern and southern Atlantic opened sooner than most geological models predicted. This pushes back the estimated timeline of when the Atlantic became a fully connected ocean, making the discovery a crucial piece in reconstructing Earth’s plate tectonic and oceanographic history. Not only does this finding refine our understanding of how and when the Atlantic took shape, but it also offers insights into the role of deep-water currents in shaping the seafloor over millions of years.
Sediment patterns illuminate early ocean currents and climate change
The formation of these 117-million-year-old mud waves was far more than an isolated ocean-floor event, it represented a profound turning point in Earth’s climate and geological history. When the young North Atlantic’s saline waters finally breached into the long-isolated southern basins, they encountered dense, carbon-rich deep waters that had been locked away for millions of years. This sudden mixing unleashed colossal underwater mud avalanches, cascading across the seabed with immense force and reshaping the ocean floor’s topography on a scale rarely seen in Earth’s past.The consequences reached far beyond the geology. This tectonic–oceanic upheaval likely interrupted one of the planet’s most important climate-regulating processes: the long-term burial of carbon in marine sediments. By disturbing these ancient, carbon-heavy layers, the event may have kept vast amounts of greenhouse gases circulating in the atmosphere, helping sustain the elevated global temperatures characteristic of the mid-Cretaceous, a period often referred to as one of Earth’s “greenhouse worlds.” Such persistent warmth not only influenced ocean chemistry and circulation but also shaped the evolution and distribution of marine life for millions of years afterward.Understanding precisely when the Equatorial Atlantic Gateway opened is therefore critical. It marks the moment the Atlantic transitioned from a series of isolated basins into a fully connected ocean, altering heat and nutrient flows on a global scale. By reconstructing this event, scientists can better model ancient ocean currents, climate feedback loops, and the deep-time mechanisms that still echo in today’s climate system. In essence, these mud waves are not just relics of a vanished seafloor, they are a geological signature of the forces that have shaped, and continue to shape, Earth’s climate trajectory.
Why this discovery matters: from paleoceanography to climate modelling
Knowing that the Atlantic began to take shape around 117 million years ago, evidence preserved in those colossal buried mud waves, significantly sharpens scientists’ ability to model ancient ocean behaviour, tectonic shifts, and climate feedback loops. This revised timeline offers a clearer window into how early ocean gateways controlled the movement of heat across the planet, regulated carbon sequestration in marine sediments, and set the stage for long-term cooling or warming trends.By tracing these deep-time processes, researchers can better understand the intricate relationship between ocean circulation and Earth’s climate system. Crucially, such knowledge is not confined to the past, it provides a framework for anticipating the effects of today’s oceanic changes. From accelerating polar ice melt to shifting global currents, the same mechanisms that once shaped the Cretaceous world could, in altered form, dictate the trajectory of our future climate.Also read| Study reveals nature’s hardest teeth: Chitons inspire future material design
