3D seismic imaging of the base of the giant Bajocian Louann Salt evaporite reveals, in exquisite detail, the nature of the pre-salt landscape. An arid desert terrain contains a network of incised rivers (wadis) flowing into a large, incised, meandering river, in turn flowing into a large lake in the middle of the basin. This lake was >1km deep, and its surface was ca. 750m below Bajocian sea level. At 170MA, a connection to the Tethys Ocean was opened, and the desert basin was flooded, allowing deposition of the salt in a deep-water basin. Simple calculations indicate that salt deposition was extremely rapid, with the entire multi-km thickness of salt deposited in a few tens of thousands of years.