How did the Mediterranean fill up after the Straits of Gibraltar were breached?
The Zanclean Flood inundated the Mediterranean Basin after the almost complete evaporation of the Mediterranean Sea in the event known as the Messinian Salinity Crisis, around 5.6 million years ago. The exact nature of this flood, which occurred when Atlantic waters breached the present-day Straits of Gibraltar, had previously been poorly understood. It is thought that the deluge was most likely triggered by the sinking of a slab of lithosphere beneath the Betic-Rifean orogen. Studies of boreholes and seismic surveys taken from within the Straits have revealed deep, Messinian age incisions beneath the present-day sea floor. These cuts are seen to extend over 200km laterally and exceed 250 metres in depth on both Atlantic and Mediterranean sides of the Straits. These channels were previously thought to have been generated by headward erosion by rivers and streams during the period of desiccation. However a new study, by researchers from the Institut de Cièncias de la Terra, Jaume Almera