Soil Evidence for a Glaciation Intermediate between the Bull Lake and Pinedale Glaciations at Fremont Lake, Wind River Range, Wyoming, U.S.A.

Abstract

Soils developed in glacial deposits in the Fremont Lake area of the Wind River Range of western Wyoming were investigated to provide a better basis for assessing the age and correlation of the deposits. Previous investigators have identified two sets of moraines in the area, assigning the older set to the Bull Lake glaciation and the younger set to the Pinedale glaciation. The Bull Lake is now commonly correlated with late Illinoian (marine-isotope stage 6) and the Pinedale with late Wisconsin (stage 2) and perhaps the later part of middle Wisconsin (stage 3). However, the soils developed in the youngest moraine of the Bull Lake set (moraine V) have characteristics such as soil morphology, clay content, and calcium carbonate content and morphology that are intermediate between those of the soils in the older Bull Lake moraines and those of the soils in the Pinedale moraines. We suggest that these soil characteristics reflect an intermediate age for this moraine, most likely early Wisconsin, correlative with marine-isotope stage 4.