Multiple ice flow directions during the Fraser Glaciation in the lower Skagit River drainage, northern Cascade Range, Washington

Stratigraphic mapping and pebble-count data suggest that ice flowed in three different directions in the lower Skagit drainage of the northern Cascade Range during the Fraser Glaciation (∼ 10K to 20K BP). Glacier reconstructions suggest that till exposed at one site in the lower Skagit Valley was deposited by a Baker Valley glacier that flowed westward down the Skagit Valley during the early part of the Fraser Glaciation (Evans Creek Stade). Stratigraphic relations show that the Cordilleran Ice Sheet subsequently advanced up the Skagit Valley and into the Baker Valley during the Vashon Stade. Flow-direction indicators, as well as clast compositional variations in till and recessional deposits of Vashon age, indicate that this upvalley, eastward-advancing glacier was later overwhelmed by southeast-flowing ice of the Cordilleran Ice Sheet which entered the Baker Valley across the valley divide to the northwest.