A Revision in the Glacial History of Jackson Hole, Wyoming

Abstract

Timbered Island, a ridge of till in the Jackson Hole lowland, was originally interpreted as an end moraine constructed by a piedmont glacier extending eastward from the Teton Range. Instead, a study of till fabric suggests that Timbered Island was deposited along the western margin of a large ice lobe extending south into the lowland. The marked similarity in the till fabric of Timbered Island and other moraines deposited by the intermontane glacier in the northern part of the lowland suggests that all were formed in a similar manner. Timbered island has survived because its trend was parallel to the direction of meltwater flow during subsequent glacial advances, whereas segments of the moraine normal to meltwater flow would more likely have been buried or removed.