Lake Terrell upland glacial resurgences and implications for late-glacial history, northwestern Washington State, U.S.A.

Abstract

New geomorphic data from the Lake Terrell uplands along the western margin of the Fraser Lowland in Washington reveal moraines (and (or) a complex grounding zone) and raised marine terraces. A large ridge that almost encircles the upland is asymmetric, and its surface material consists of fine- to coarse-grained diamictons. These ridges are argued to have formed adjacent to an ice margin near the marine limit, where the depositional processes are variable (e.g., ice-rafted rainout, dumping, sediment gravity flow). Multiple crests and crosscutting relations suggest that at least two glacial resurgences occurred during deglaciation of this area. The presence of these features, and their probable extent and stratigraphic position, raise several questions about relative sea-level history and ice margin reconstructions for this area.