Origin of the polygons and the thickness of Vastitas Borealis Formation in Western Utopia Planitia on Mars

Many middle scale (about 100m cracking space) polygons are located between the area of the giant polygons and the thumbprint terrains in Western Utopia Planitia. Most of the patterns are located on Vastitas Borealis Formation. The polygonal patterns have frequently been associated with collapsed features, such as a covered trough like features(the width of the underground crack is approximately 400–500 m). The thickness of the surface materials (6–12 m), where polygonal patterns occur, was calculated based on the space of cracking relationship. Polygonal networks with strongly oriented features and parallel to the contour line are likely caused by structural (geological) origin as well as bending forces from the center of the basin.