PODZOLIC SOILS WITH LUVISOLIC-LIKE MORPHOLOGIES IN THE UPPER SUBALPINE SUBZONE OF THE CANADIAN ROCKIES. 1. STRATIGRAPHY AND MINERALOGY

A lithological and textural discontinuity within the sola of Podzolic soils of the upper subalpine bioclimatic subzone at Sunwapta Pass, Alberta was investigated. The physical and mineralogical variability of parent materials, and the origin and mode of deposition of an overlying silty deposit were evaluated. Evidence supported an eolian origin for the extensive, thin silty surficial deposits observed in the central Rockies. This material was composed of a mixture of volcanic ash and local detritus. Optical identification of the fine plus very fine sand fraction, separated according to specific gravity, indicated volcanic glass, quartz, and plagioclase to be abundant in the surficial material, and primary carbonate and quartz to be abundant in the underlying till. The clay-sized fractions in the surficial material were equally distinct from the underlying material, with amorphous material and chloritic intergrades present in the former, muscovite and chlorite below.