Fascinating! I wish I had studied some geology. I learned here https://www.youtube.com/watch?v=oSSxdogrv1s that the mountains and lakes around Puget Sound run north-south because of glacial descent, and that the huge boulders we find scattered about the area are called 'erratics' as they were moved here by glaciers. I show everyone I can that video but I just get weird looks.

I wished the article had fleshed out the ramifications of the ice cap a little better.