HOLOCENE PALEOENVIRONMENTAL RECORD PRESERVED IN A PARAGLACIAL ALLUVIAL-FAN, SUNWAPTA PASS, JASPER-NATIONAL-PARK, ALBERTA, CANADA

The soil stratigraphy of a 1.5 m section in the distal portion of a pa raglacial alluvial fan in Sunwapta Pass, Jasper National Park, has bee n examined as part of a long-term investigation into Holocene palaeoen vironments of the area. The section is complex and its characteristics are a result of both episodic sediment inputs and pedogenesis. A seri es of sediments comprising debris-flows and aeolian material including three discrete tephra layers (Mazama, St. Helens Yn, Bridge River) un derlie the present day soil. Multiple criteria, including stratigraphy , radiocarbon dates, glass shard morphology, and electron microprobe a nalysis of glass and titanomapetite composition, confirmed the identit y of the tephras. Most fan development occurred before deposition of M azama tephra. Pedogenesis has been active on the fan throughout the Ho locene. Soils have formed between phases of sediment deposition during periods of greater relative site stability. Soil horizonation is best developed where tephric material has influenced soil chemistry and cl ay mineralogy leading to the formation of Brunisols. The sequence of e vents inferred from the Icefield Fan's stratigraphy accord well with t he Holocene palaeoenvironmental history inferred from other sites in t he Canadian Rockies.