How vanishing water leaves behind a hidden mineral blueprint

Nature · Published 2 October 2026 Swipe more like this →

In short: When water evaporates from a restricted basin, it leaves behind more than just dry ground. It leaves a precise, layered sequence of minerals that act as a geological clock, revealing the ancient climate and chemical history of our planet.

Evaporites are sedimentary rocks formed through chemical precipitation. This occurs when water evaporates from an aqueous solution, causing dissolved salts to reach saturation and crystallize. For these deposits to form, a water body must exist in a restricted environment where the rate of evaporation exceeds the inflow of new water. This typically happens in arid regions within closed basins, such as lakes or marine basins.

The mineral sequence follows a predictable order based on solubility, a phenomenon first demonstrated by Usiglio in 1884. In a laboratory setting using ocean water, the process begins when the water depth reaches about 50% of its original level, triggering the formation of minor carbonates. As the water level drops to approximately 20%, gypsum begins to precipitate. When only 10% of the original water remains, halite forms. This sequence continues with more soluble potassium and magnesium salts, such as sylvite, carnallite, and kainite.

These deposits are vital for understanding Earth's history and supporting modern industry. While marine evaporites are often thicker and more extensively researched, non-marine deposits—found in places like the Great Salt Lake or the Dead Sea—offer unique insights into past climates and tectonic shifts. Economically, they are indispensable: halite is used for food and can serve as a stable site for nuclear waste disposal, while nitrates from these deposits are essential for producing fertilizers and explosives. Even beyond Earth, satellite observations suggest that Saturn's moon Titan may host hydrocarbon evaporites in its liquid methane seas.

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