One more mystery solved by science: honeycomb patterns found in salt deserts around the world

Salt deserts are among the most extreme and inhospitable places on the planet and their bizarre and other-worldly polygon-shaped structures attract hundreds of thousands of tourists every year.

Now a team involving researchers at Nottingham Trent University and TU Graz in Austria has been able to explain the origin of these patterns and their iconic shape and size. The research is published in the journal Physical Review X.

Previously, it was suspected that the salt crust of the desert dries out and cracks form, around which the patterns grow. Another hypothesis suggested that the salt crust grows continuously and bends due to lack of space, forming the patterns.

Neither of these explanations, however, account for the consistent size—always one to two meters—and the honeycomb shape.

A more plausible explanation has now been provided by researchers, who describe how convection of saline water in the subsurface is responsible for the honeycomb-like formation of the salt patterns.

The constant size of the features and the speed with which the patterns grow can also be attributed to this, they say.

To get to the bottom of this mystery of nature, the team combined the research fields of fluid dynamics from physics and geomorphology from the geosciences and investigated the phenomenon from several directions.

They observed in laboratory experiments how saline water moves in sandy soils and analyzed in numerical simulations the length scale of the patterns under different conditions. In two field studies in California they observed the patterns in nature and collected samples to show that the currents in the subsurface mirror the patterns visible on the surface.

They were the first research group to record in a video how the salt pattern grows.

The evidence gathered by the researchers in experiments, simulations and field studies all points to a consistent picture.

The driving mechanism for pattern formation is the convection or circulation of salty water in the soil beneath the salt crust. The salt deserts in which these patterns occur are by no means bone dry and the highly salty groundwater often reaches up to lie directly below the salt crust. In these deserts you'd quickly reach that water digging by hand, although it would be far too salty to drink.