Soil development rates in the Transantarctic Mountains

Abstract

Soil chronosequences were identified at three sites (78–85°S) within the Transantarctic Mountains for determining rates of soil development in Cold Desert ecosystems. More than 175 soils were sampled in xerous and ultraxerous environments on moraines containing sandstone and dolerite and ranging from late Holocene (ca. 6 ka) to pre-late Quaternary (ca. 250 ka) in age. Based on five linear and nonlinear models, highly significant correlations ( P<0.01) exist between drift age and the following surface boulder weathering features and soil properties: percentage of boulders containing desert varnish, spalling, and pitting; depths of staining, visible salts, ghosts (pseudomorphs), and coherence in soils; electroconductivity in the zone of salt enrichment; and total profile salts. In the absence of leaching, soluble salts readily accumulate in Cold Desert soils. A morphogenetic sequence of soluble salts is presented that relates field observations with laboratory data. Soil color is highly correlated ( P<0.01) with dithionite-extractable Fe. Within a site, the proportion of clasts ≥ 15 mm on the surface of the desert pavement increases with time due likely to deflation of fines by strong winds. Therefore, the dominant processes in these Cold Desert soils are salinization, rubification (reddening due to oxidation of iron-bearing minerals), and desert pavement formation.