LITHOLOGY AND PATTERN SIZE OF PERIGLACIAL PATTERNED GROUND, WHITE MOUNTAINS, CALIFORNIA

Periglacial sorted polygon characteristics were compared between two lithologies, Mount Barcroft granodiorite and Campito sandstone, in the White Mountains of California. More than 30 landforms on each lithology were compared for overall pattern size, size of border clasts, and soil development characteristics. The size of the clasts was significantly different between lithologies, with the granodiorite weathering into much larger cobbles. Granodiorite cobbles averaged 24.3x17.9x10.3 cm, while the sandstone cobbles averaged 8.5x5.3x2.9 cm. Although the cobbles that form the sorted pattern borders are of significantly different sizes (p<0.001), the size of the landforms themselves is very similar (p=0.95). The similarity in pattern size suggests that the processes acting to form the sorted patterns are the same regardless of lithology and clast size. A soil profile development index (PDI) was used to compare soil characteristics between the two lithologies and between soils within and adjacent to the sorted polygons. Because no absolute age measurements are readily available, the PDI results provide relative age comparisons only. The PDI results help to provide insight into current periglacial processes by establishing relationships between relict patterns and their associated soils.