Desiccation mechanism for formation of giant polygons on Earth and intermediate-sized polygons on Mars: Results from a pre-fracture model

► We investigate the formation mechanism of large desiccation cracks on Earth. ► We model the stress buildup in a drying clay-rich soil by lowering of water table. ► The results agree excellently with water diffusivity values of clayey soils. ► Modeled cracking timescale agrees with theoretical values of 1-2 yr. ► We use the results to investigate similarly large cracks on Mars.