The view of Mt. Saint Helens from the Johnston Ridge Observatory.
There is a decent article about research being done at a dissected caldera system in the Italian Alps’ Sesia Valley. The caldera in question is the Permian in age (248-298 million years old) so don’t expect to find it in the GVP database, but the outcrops of this ancient caldera are especially well exposed, allowing for a cross section of volcano and plutonic rocks across 25 km of crustal depth (all of which is now at the surface thanks to hundreds of millions years of tectonics). It does sound like a great location that exposes some of the volcanic-plutonic plumbing system that we don’t really understand, but I’m not 100% sure about calling it a “rosetta stone” – there are a few systems in the southwest U.S. (and Maine for that matter) that expose both the volcanic and plutonic parts of an ancient volcano (but the press loves any “supervolcano”). Take note, the image at the top is, in fact, the Bishop Tuff in Long Valley, not anything from this Italian study.
It seems that the visitors’ center at Mt. Saint Helens will be getting some help over the next year to make it a little more user-friendly. I like that, but reopening the Coldwater Creek visitors’ center might be nice, too.