A Partial Holocene Pedological and Archaeological Record from the Southern Alberta Rocky Mountains

Salvage excavations at an archaeological site (D1Po-20) located in the Front Range of the Rocky Mountains in southwestern Alberta revealed the presence of a series of living floors, radiocarbon dated at ca. 4000, 4700 and 6000 B.C., in association with the Ah horizons of a series of buried soil profiles. While archaeological information is minimal, analysis of the buried soils indicates that they formed under a different vegetation cover from that on the site today. The earliest soil, a Degraded Alpine Eutric Brunisol, inferred to have developed under subalpine to alpine vegetation and a cold wet climate, suggests depression of the timberline on the order of 600 m. These climatic characteristics are considered to reflect those of the last valley glaciation (Pinedale IV). The two later buried soils, Orthic Regosols, developed under grassland vegetation reflective of a drier warmer climate, indicating the lower tree line shifted upwards a minimum of 30 m. A return to “normal” climatic conditions is correlated with the onset of the Neoglacial dated ca. 2800 B.C. in the Southern Alberta Rockies.