Soil formation in the Transantarctic Mountains from the Middle Paleozoic to the Anthropocene

In the Transantarctic Mountains (TAMs), soils from the middle Paleozoic and from the Oligocene to the present have been examined. Soils representing other sections of the geologic column are missing, probably because of the low proportion of ice-free areas (0.35%) in Antarctica. The evolution of soils in Antarctica reflects changes in climate and geologic conditions as the continent became separated and increasingly isolated from Gondwana. A greenhouse climate existed during the middle Paleozoic; and an icehouse climate began in the early Oligocene. The climate of the TAMs has become increasingly hyper-arid since the middle Miocene. Humans have had a dramatic effect on the climate of the TAMs during the Anthropocene. The first forest soils (under Callixylon–Archaeopteris forest) on Earth, identified as Alfisols, were discovered in Antarctica and assigned to the middle Devonian. During the Permian, Dicroidium forests covered Entisols and Inceptisols. In the Oligocene, Nothofagus–Podocarpaceae forests contained Gelisols. Miocene-aged soils enriched in silt are common in the TAMs, but they tend to be poorly developed because they have been eroded. A soil evolutionary sequence exists in the TAMs from the Holocene through the Pliocene that includes Glacic Haploturbels on ice-cored Holocene drift, Typic Haploturbels on late Pleistocene surfaces, Typic Anhyorthels on middle Pleistocene surfaces, Salic Anhyorthels on early Pleistocene surfaces, and Petrosalic Anhyorthels on Pliocene surfaces. These changes reflect gradual sublimation of ice in ice-cored drift and ice-wedge polygons, a recovery of the surface from cryoturbation, accumulation of salts, and eventual development of a salt pan. Soils of the TAMs are undergoing rapid change as the climate warms, including loss of semi-permanent snowbanks, an expansion of the hyporheic zone, flushing of salts from soils along valley walls, and the development of thermokarst.