INTRODUCTION Glaciation of Mission Valley The Cordilleran Ice Sheet invaded northwestern Montana multiple times during the Pleistocene, overtopping mountain ranges, widening pre-glacial river valleys, and depositing moraines composed of clay-gravel diamicts that often lack a full complement of boulders. Mission Valley is a structural trough that extends south of Flathead Lake between Polson, MT and the Ravalli Hill divide. Two prominent, horseshoe-shaped moraines indicate the

This article and a more detailed guidebook (free PDF download) explores the spectacular calcretes of south-central Washington. The thick, bright white CaCO3-rich paleosols overprint the Pliocene Ringold Fm, Plio-Pleistocene fanglomerates, pre-Wisconsin flood gravels, and early Palouse loess. The blanket-like hardpans formed in alluvial sediments low in the landscape where strong evapotranspiration moved large volumes of water through the soil column via vegetation rooted near