Scientists Discover 117-Million-Year-Old Underwater Sediment Waves, Show How the Atlantic Ocean Formed

The Atlantic Ocean today is a super hose of global weather, biodiversity, and commerce. However, despite its enormous presence and influence, answers about how this mighty ocean formed have remained a mystery. Experts have long debated the process and timeline behind the Atlantic’s birth, which first began with the deadly breakup of the supercontinent Pangea. Now, in a stunning discovery beneath the sea, experts believe they have found one of the solid proofs hidden in the ancient sediment waves west of Africa, according to Science Direct.

Roughly 400 kilometers off the coast of Guinea-Bissau, a team from Heriot-Watt University in Edinburgh discovered a stunning geological signature lying one kilometer beneath the ocean floor. Huge sediment waves, frozen in time for almost 117 million years. These unique structures, made of mud and sand, are not just geological misfits; they are a portal to the ancient world. In a statement, Dr Uisdean Nicholson, study author and geologist at Heriot-Watt University, said, "One layer was particularly striking: it included vast fields of sediment waves and ‘contourite drifts’ – mud mounds that form under strong bottom currents. Imagine one-kilometre-long waves, a few hundred metres high: a whole field formed in one particular location to the west of the Guinea Plateau, just at the final ‘pinch-point’ of the separating continents of South America and Africa," stated IFL Science.

These huge underwater figures were created during a critical event in Earth’s history, popularly known as the opening of the Equatorial Atlantic Gateway. This gateway emerged when South America and Africa began to separate, tearing apart the fabric of the supercontinent and setting the stage for the Atlantic Ocean’s formation. At the final point, super salty water from the South Atlantic met fresher northern waters, prompting a deep-sea ‘waterfall’ effect that sculpted the seabed into huge waves. He explained, "They formed because of dense, salty water cascading out of the newly formed gateway. Think of it like a giant waterfall that formed below the ocean surface," stated IFL Science.

This phenomenon did not just mold the seafloor, it also molded Earth’s climate. This particular sediment wave provides evidence that the Equatorial Atlantic Gateway opened around 117 million years ago, way earlier than previously believed, as per Science Direct. Dr Nicholson added, "Understanding how past ocean circulation influenced climate is crucial for predicting future changes. Today’s ocean currents play a key role in regulating global temperatures, and disruptions, such as those caused by melting ice caps, could have profound consequences," stated IFL Science.

As ocean waters began to flow through this new corridor, they connected with previously isolated, carbon-rich basins near the Equator. The aftermath of this was reduced Earth’s ability to bury carbon, triggering a prominent period of global warming during the Mesozoic Era—the age of dinosaurs and marine reptiles. This discovery, published in Global and Planetary Change, also revamps our understanding of the Atlantic's history, revealing that the birth of this huge ocean was not a singular event, but a two-phase process—first initiated around 117 million years ago, with a secondary widening stage at 113 million years.