Salt Polygons in a Saharan Chott

Salt Polygons in a Saharan Chott is an original illustration set in Chott El Jerid, Tunisia. It lies in the subtropics, where the climate is hot desert — evaporation far outruns rainfall.

A vast flat depression stretches from white and rose salt polygons to a thin mirror of shallow brine, crossed by darker mineral seams. Heat haze lifts above the crust, low barren mountains rim the north, and a distant line of date palms marks an oasis fed beyond the empty basin.

Why does this flat basin alternate between brine mirrors and salt polygons?

Water carrying dissolved salts occasionally spreads into this closed depression but has no outlet, so intense Saharan evaporation concentrates brine and leaves a cracking crystalline crust. Repeated wetting and drying organize the surface into polygons and colored mineral bands, while fossil groundwater supports oases only at the margin. The enclosed basin, transient sheen, salt geometry, and abrupt palms define a northern Saharan chott.

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