A new Earth & Planetary Science Letters study reports that Venus may have once hosted oceans across roughly 90 percent of its surface before transforming into a harsh world. Researchers at the University of London argue that ancient marine sediments, submarine channels, and salt layers still scar the planet.
Re-Examining the Surface of Venus Using Magellan Radar Data
Earth and Venus share striking similarities in their fundamental planetary architecture. Both worlds possess roughly the same size, density, and mineral composition. Yet Earth remains lush and wet, while Venus operates as its extreme counterpart, characterized by ambient temperatures hot enough to melt lead, crushing atmospheric pressure, and choking clouds of carbon dioxide that drop sulfuric acid rain. Planetary scientists have long debated whether this hostile environment defined the planet from its inception or if a more temperate era preceded it.
Most of the concrete data regarding the Venusian landscape stems from NASA’s Magellan probe, which utilized radar to map the cloud-shrouded planet from orbit throughout the early 1990s. Those radar scans uncovered an intensely volcanic terrain, cataloging more than 85,000 distinct volcanic features across the globe. For decades, researchers treated these formations as standard products of interior heat and lava flows. A research team led by geologist Richard Ghail at the University of London challenged that consensus, asking whether a significant portion of those presumed volcanic structures actually originated in marine environments.
Polygonal Fault Systems and Ancient Seafloor Muds
The first line of geological evidence centers on vast terrains marked by giant polygonal patterns. Previous scientific models attributed these fractures entirely to volcanic rock cooling and contracting over time. However, the new study points toward a different terrestrial analogue: polygonal fault systems discovered in clay-rich marine sediments on Earth.
These fracture networks develop when thick layers of seafloor mud undergo burial and compaction, squeezing out trapped water like a sponge. As the sediments shrink and settle beneath an ocean, they form distinct polygonal geometries stretching for kilometers. Finding comparable structures on Venus suggests that similar sedimentary processes once operated on a planetary scale.
Submarine Channels Versus Traditional Lava Flows
The second major clue involves massive surface grooves known as canali. Historically interpreted as lava channels, these structures present distinct physical puzzles. Some of the channels extend for thousands of kilometers, stretching far beyond the distances that standard models suggest molten lava could realistically travel before cooling and solidifying.
The study posits that these pathways closely resemble submarine channels on Earth, which are carved by dense, sediment-laden currents flowing beneath an ocean surface. Supporting this marine hypothesis, nearly a third of the polygonal terrains connect directly to canali that emerge from smooth plains without any visible volcanic source, eventually terminating in deeper basins just as underwater drainage networks would.
Lowland Ridges and Massive Ancient Salt Deposits
The final piece of the puzzle links the lowlands of Venus to evaporated mineral deposits. Wrinkle ridges pattern the Venusian lowlands, and the research team suggests these formations overlie thick layers of salt left behind as ancient oceans dried up.
On Earth, the Mediterranean Sea deposited immense salt layers during the Messinian Salinity Crisis roughly 5.5 million years ago. Researchers calculate that an evaporating Venusian ocean could have produced a salt layer at least 64 meters, or 210 feet, thick—an accumulation heavy enough to deform the overlying planetary crust.
“While the interpretation of these features is not unambiguous, there is a compelling case that Venus once supported oceans, and perhaps life, across most of its surface.”
Richard Ghail, geologist at the University of London
Next Steps for Planetary Exploration and Future Missions
None of the three geological indicators is entirely conclusive on its own, as each could theoretically result from tectonic or volcanic processes. Yet when evaluated together, the data constructs a framework of a world that sustained vast bodies of water before a runaway greenhouse effect boiled them away less than a billion years ago.
Definitive answers will likely require new orbital hardware. Planetary exploration programs have largely bypassed Venus in recent years, but upcoming projects aim to change that dynamic. Both the European Space Agency’s EnVision mission and NASA’s VERITAS orbiter are scheduled to study the planet in far greater detail than Magellan, providing the high-resolution data geologists need to test the ancient ocean hypothesis.
Discover more from Archyworldys
Subscribe to get the latest posts sent to your email.