Soils in a Geoecological Landscape Chronosequence on Glacial Drift in Southeastern Idaho

Abstract

At the southwest corner of Yellowstone National Park, one geologist has mapped glacial moraines of three ages and later another mapped moraines of only two ages. Soils, including topographic differences, indicate glacial drift of four ages. These appear to be related to late Pinedale, early Pinedale, Bull Lake, and pre-Bull Lake drift that have been dated in northwestern Wyoming. The limits of late and early Pinedale moraines appear to correspond closely with ecological map unit boundaries and have specific soils that reflect greater weathering and soil development on early than on late Pinedale moraines. The weathering and soil development trend continues onto Bull Lake moraines, reaching a maximum there, with thick fine-loamy (or loamy-skeletal) argillic horizons. Soil development is no greater on the older pre-Bull Lake moraines, presumably because of development retardation by cryoturbation and mass wasting or solifluction. Ecological map units based on soil mapping do not correspond to limits of pre-Bull Lake (or Sacagewa) till mapped by a geologist. If geologists and pedologists had collaborated when mapping surficial geology and soils at the southwestern corner of the Park, both geology and soils (or ecological unit) maps and reports might be better representations of the landscapes.