That’s what this is: one helluva huge debris avalanche. Thing goes nearly fourteen miles down the Toutle River Valley. It’s bloody ginormous is what it is. That’s it, there in the brown, on this lovely little map.
We all focus on the bits of St. Helens that went boom: do we really give the bits of it that went thump proper credit? We certainly will when I’m finished here. You see, the Rosetta Stones post I linked above is just the beginning: I’ve got Harry Glicken’s posthumously-published, nearly-as-large-as-the-debris-avalanche write up of his studies of the thing, and I’ve got a bazillion photos of the results of the avalanche as it was then and 32 years later, and I will, over time, make you intimately familiar with the thing. There are so many stories to tell emerging from just this one aspect of the eruption. Pretty scenery, now, too!
But here’s one image I want you to take away with you right now:
Keep in mind: that’s not one of the bigger boulders.
Go marvel at the largest landslide ever witnessed by lil ol’ us. Take to heart this lesson: what falls down the mountain can be as catastrophic as what explodes up and out of it – sometimes moreso. Because, my darlings, this shit can happen even in the absence of an eruption. Gulp.