Pebbles along the crests are as large as 6 centimeters in diameter. Velocities necessary to transport such large particles have been calculated to be 200 kilometers per hours. Viewed from above, the wedges form circular, polygonal, rectangular, stepped, and striped patterns. In the dry valleys, the valley floors generally comprise loose sand and gravel deposits with some scattered sand dunes. The sand and gravel surfaces often form polygon patterns, which are most visible after a light dusting of new snow settles in the cracks and outlines the polygons.
Unsorted polygons are the common pattern throughout the dry valleys.
Polygons have diameters from 10 to 30 meters, and associated wedges grow in thickness with each annual cycle. Initially, narrow cracks are formed, with slumping from the sides. The presence of a water-rich, active zone with thicknesses on the order of tens of centimeters promotes the formation of pattern ground. Flood plains and ice- cored moraines are particularly favorable environments. However, patterned ground persists through various terrains, including upland benches, sloping valley walls, and bedrock surfaces.