Soil Catena Chronosequences on Eastern Sierra Nevada Moraines, California, U.S.A.

Abstract

Soil catena development is traced through time by comparing soil catenas on Tioga, Tahoe, and Mono Basin moraines in two eastern Sierra Nevada, California, valleys, Green Creek and Walker Creek. Shortly after moraine deposition, slope adjustment takes place and a sandy colluvial wedge is deposited at the footslope. Since the Tioga glaciation of about 20,000 yr ago, A/Bw/Cox soil profiles have formed along the catena, and values of the profile development index, and weighted mean and accumulation index of laboratory properties are similar at most sites. Data for the Tahoe and Mono Basin catenas are used to track catena soil development for the preceding approximately 100,000 yr. In the most impressive case (Green Creek), Bt horizons have formed at most sites along the catena and profile development, as judged from both field data and laboratory data on pedogenic clay and iron, is best at footslope sites. However, in the stratigraphically important moraine sequence of Walker Creek, there are little or only subtle differences in total catena development values with time. Comparison with other recent studies indicates that these results are representative of a larger area in the western United States. When using soils for age differentiation of moraines, it is strongly suggested that footslope soils should be included in the analysis.