So under such conditions, the Mediterranean, and farther east the Black Sea, would shrink in area and the shorelines would be caked with salt layers on top of what had formerly been seafloor. But then, on occasion, the pathway to the main oceanic seas would be opened due to tectonic activity (regional uplift, for example), or perhaps a rise in sea level (say, ice sheets melting). When sea levels rose relative to the landmasses closing the Gibraltar and Bosporus Straits, great, cascading waterfalls of ocean water would re-enter the Mediterranean and Black Sea Basins to refill the seas and start the evaporative process all over again. This is believed to be what occurred in the Black Sea region about 10,000 years ago (perhaps giving rise to the Flood stories of many cultures, including that of the Old Testament’s Noah).

Keep in mind that this is a geological process occurring over millions of years. It is a cycle of structural isolation, climatic evaporation, chemical deposition, and eventual oceanic recharge. Suppose that this occurs again and again, because the story of geology is nothing if not the story of things occurring and recurring over long periods of time. The Earth, when you think about it, is nothing but the story of time. The salt layers could form up to many thousands of feet thick. This is, in fact, exactly what has occurred in both the Mediterranean and Black Sea basins over many periods of geologic time. Continued.

Now imagine this same evaporation and recharge processes occurring in ancient Triassic and Jurassic time, above the area that is now the southern Gulf coast of the U.S. and farther out into the deep Gulf of Mexico. During the periods when the shallow, Triassic-Jurassic seas were cut off from recharge by oceanic waters, the seas evaporated and left behind extensive bodies of salt evaporates. These deposits are the Louann and Sigsbee salts, and form the related salt basins. Understanding these formations is one of the keys to appreciating what Chevron and others have been doing in the deep-water Gulf of Mexico. Needless to say, Chevron did not figure out all of this by itself. This is part of the cultural and scientific legacy of our time.