Scientists discovered that Shalbatana Vallis, a valley near the Martian equator, provides strong evidence of ancient massive floods and a possible ocean [1, 2].
This finding alters the understanding of Martian hydrology by suggesting the planet once maintained a stable, large-scale body of water rather than isolated lakes. The scale of the geological features indicates a planetary environment far more active and water-rich than the current desert landscape.
Researchers used data from the European Space Agency's Mars Express spacecraft to analyze the northern lowlands [1, 2]. They identified Shalbatana Vallis as a valley stretching approximately 1,300 kilometers [1]. The region is characterized by chaotic terrain and collapsed channels, which planetary geologists said indicate that enormous floods of groundwater burst onto the surface billions of years ago [1].
These mega-floods carved the valley and left behind what researchers describe as a "bathtub ring" [2, 3]. This geological marker may show the contours of an ancient ocean that once existed on the planet [3]. According to the data, this ancient ocean may have covered about one-third of the planet's surface [3].
The discovery of the coastal shelf and associated shoreline evidence supports the theory that Mars had a long-term hydrosphere [4]. The presence of such a massive body of water would have required a thicker atmosphere and warmer temperatures than those present today.
Planetary geologists said the combination of the valley's length and the shoreline evidence suggests a systemic collapse of groundwater reservoirs that fed into a global basin [1, 3]. The research highlights the role of groundwater-driven events in shaping the Martian surface over eons [1].
“Shalbatana Vallis, a valley near the Martian equator, provides strong evidence of ancient massive floods.”
The identification of a 'bathtub ring' and a 1,300-km valley suggests that Mars did not merely have sporadic water activity, but a sustained ocean. If one-third of the planet was submerged, it increases the likelihood that Mars once possessed the necessary conditions for microbial life, shifting the search for biosignatures toward these ancient coastal regions.
