SOIL SURVEY

-27-profile development is frequently evident to at least 1 m from the surface, and lim ewas not encountered in erosion cuts or pits, some up to 2 m deep (see description o fOH 1) . The parent materials in the Yoho valley are calcareous medium textured til lmaterials . In these soils profile development is frequently evident to only 25 to 50 c mat which depth strongly cemented calcareous till material is encountered (see descriptio nof OG 1) .Soils of the Upper Subalpine and Alpine ZoneThe soils in this vegetation zone (generally greater than 2,000 m a .s .l .) aredominantly classified in the Podzolic order . Less than 30% ground cover is providedby trees, and the understory has a significant component of heathers . In exposed siteswhich have little available moisture dryas communities often occur and Brunisolic soil sare commonly associated with these areas . The soil-forming factors of climate an dvegetation result in soils with strongly developed horizon morphology . Also smal lchanges in microclimate (and other elements of the microenvironment) result i nsignificant changes in plant communities over short distances . Thus, a mosaic of soil sranging from strongly developed Podzolics to Brunisolics and some Regosolics (on stee pslopes) and Gleysolics (in depressions) is the usual pattern of soil distribution in thi svegetative zone . The Generalized Soils Map (in the pocket at the back of this report)shows this group of soils as being (1) mainly developed on till (see description of SK 1 )with significant amounts of colluvium, and (2) mainly developed on colluvium (seedescription of 00 1) with significant amounts of till . A "turfy" Ah horizon, a thin,sometimes absent, light-colored Ae horizon and a dark reddish Bf horizon is the commo nhorizon sequence . Depth to lime is quite variable but generally less than 1 m . Soil sin this zone are often affected by frost phenomena, resulting in various forms of patternedground such as earth hummocks and soil stripes .General Comment sAlthough Luvisolic soils have been identified within 30 miles to the wes tof Yoho (Kelley and Holland 1961) and within about 5 miles to the east of Yoh o(Walker et al . 1976) no significant areas were recognized within Yoho National. Park .