The Saddle Mountains; the evolution of an anticline in the Yakima fold belt

Abstract

The Saddle Mountains uplift is an asymmetrical, north vergent anticline with a length of about 110 km. It varies from an open to tight fold and is divided into six segments based upon differences in geometry. Flows of the Columbia River Basalt Group, intercalated sedimentary deposits of the Ellensburg Formation, and suprabasalt sediments thin over the uplift and thicken into the synclines. Variations in thickness are used to determine the timing of deformation and age of major and minor structures. The close correlation of growth rate of the folds with rate of magma supply of the Columbia River Basalt Group suggests that the Yakima fold belt resulted from the same tectonic processes that produced eruption of the Columbia River Basalt.--Modified journal abstract.