As the Puget Lobe advanced, it deposited hundreds of feet of Lawton Clay, Esperance Sand, and Vashon Till. Meltwater flowing below the ice carved out troughs that we know as valleys.
Hood Canal and the rest of Puget Sound were created about 13,000 years ago, during the Late Pleistocene, by the Puget Lobe of the Cordilleran Ice Sheet.
The Skagit River was highly influenced by the repeated advance and retreat of the Puget Lobe of the Cordilleran Ice Sheet.
https://github.com/davepinch/pinchy.cc/blob/master/content/topics/geology/topics/puget-lobe/puget-lobe.md
On the west side of the Cascade Mountains, two lobes covered the Puget Lowlands. Along the north side of the Olympic Mountains the Juan de Fuca Lobe moved west, and between the Olympics and the Cascades the Puget Lobe moved south.
The Skagit River was highly influenced by the repeated advance and retreat of the Puget Lobe of the Cordilleran Ice Sheet.
