Soil Development on Moraines of Taylor Glacier, Lower Taylor Valley, Antarctica1
- J. Pastor and
- J. G. Bockheim2
Soils were examined on moraines deposited by Taylor Glacier in lower Taylor Valley to determine changes in soil properties with time in an environment of extreme cold and aridity and minimal biologic activity. The soils range in age from 200,000 to 2.7-3.5 million years BP. Soil profiles contain a desert pavement over a weakly expressed B horizon, followed by permafrost, which may be “dry” or ice-cemented. The soils are alkaline (pH 7.5 to 9.0) and are enriched in salts. Based on X-ray diffraction, the salts are mirabilite (Na2SO4·10H2O), tachyhydrite (CaMg2Cl6·12H20), and halite (NaCl). Electrical conductivity of the salt-enriched zone ranges from 2.8 to 9 mmho cm−1. Sodium and chloride are the dominant ions in 1.5 soil/water extracts. Ion ratios suggest that the bulk of the salts are of marine aerosol origin. The soils are generally gravelly sands, but the amounts of clay (<2 µm) and medium+fine silt (2–20 µm) increase with soil age. Free iron also increases with age. Secondary clay minerals include montmorillonite, vermiculite, and interstratified layer silicates. The predominant clay mineral weathering process is hydration of mica. The age-soil property relationship may have been influenced by microclimatic variations, previous occurrence of lakes dammed by a westward flowing marine ice sheet, mass-wasting processes, and persistent ice-cemented frost table in the solum. The soils are classified as Pergelic Cryorthents, sandy-skeletal, mixed, frigid.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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