The Atlantic Broke Through — And Refilled the Mediterranean in a Catastrophic Flood

The Mediterranean Sea almost disappeared. Around 5.5 million years ago, restricted connections with the Atlantic triggered one of the strangest environmental crises in Earth’s recent geological history. Water levels collapsed. Enormous salt deposits formed. Rivers carved deep valleys into newly exposed land. And parts of the Mediterranean became vast hypersaline basins. Then, around 5.33 million years ago, Atlantic water returned. What followed may have been one of the largest floods ever reconstructed from the geological record — the Zanclean megaflood. Models suggest that peak flows may have reached around 100 million cubic metres of water per second, while Mediterranean sea level could have risen by several metres per day. In this episode of Deep Time Files, we follow the evidence beneath the modern Mediterranean — buried canyons, seismic structures, salt deposits and flood scars — to reconstruct the moment an almost vanished sea came roaring back. Deep Time Files explores Earth’s lost worlds, extinct giants, geological catastrophes and the events that reshaped our planet. Earth’s Lost Worlds. Reconstructed. VISUAL NOTE This documentary uses licensed stock footage and scientific visual storytelling to illustrate ancient environments and geological processes. Some visuals may represent reconstructed environments rather than literal footage of past events. SOURCES Garcia-Castellanos et al. — Catastrophic flood of the Mediterranean after the Messinian salinity crisis, Nature (2009) Aloisi et al. — Chlorine isotopes constrain a major drawdown of the Mediterranean Sea during the Messinian Salinity Crisis, Nature Communications (2024) Haimerl et al. — Land-to-sea indicators of the Zanclean megaflood, Communications Earth & Environment (2024) Hsü et al. / later Messinian Salinity Crisis research on Mediterranean evaporites and desiccation #Mediterranean #Geology #AncientEarth