re:active mountains
Glaciers, active fumeroles, a eruption only 200 years ago, hey, that's pretty energetic compared to the mountains here in the East! It's been 150 million years since any of the granite in the White Mountains was hot, let alone 1,500 million for the Rockies. Whereas much of what vanished on Mt. St. Helens in 1980, probably didn't even exist yet when Columbus crossed the Atlantic.
Stratovolcanoes are pretty empheral things geologically. While the Cascades should still be there in a million years, there will be a whole different set of glittering cones standing over the landscape. Pretty amazing.