Soil formation in Antarctica is restricted by the limited extent of ice-free areas, continuous low temperatures and the paucity of liquid water. The soils of Beacon Valley are of the desert type: devoid of organic surface layer, coarse textured, very dry, pulverulent, and show little color differentiation. Patterned ground, mostly of sand-wedge, nonsorted polygons, is ubiquitous throughout the valley. Two mappable major soil units are distinguished in the northeast half of the valley. They are related to the age of the glacial deposits and to nonsorted polygons, which may be divided into well-developed and poorly expressed types. The soils of the well developed polygons appear immature in comparison to the more mature soils of the poorly expressed types. This distinction is valid morphologically, physically, and chemically. There is also a distinction between the soils formed in the troughs and more developed soils found in the ceters of the polygons. Patterned ground evolution depends on structure and consistency of soils. Sand-wedge growth is greatly affected by the degree of soil development in the troughs. Once the soils in the troughs have acquired a compound structure, they are not able to flow and fill the contraction cracks. Thus, the rate of sand-wedge growth will be reduced wince it depends on the availability of loose, free-moving materials. The lack of growth-rate uniformity may account for the observed discrepancy betwee the age of the wedges and the degree of soil development.