So what you see here is a dude looking at a huge pile of dirt. Sometimes, though, the best stories are hidden in a huge pile of dirt.
He's at a road cut northeast of Helena, Montana. The pale stripe above his head is volcanic ash. I believe the dirt-and-rocks blend above it is flood tailings from the draining of an inland sea, but the original description (available at Earth Science Photo of the Day) does not mention that bit. It does talk about the ash layer though.
The ash layer came from Mount Mazama. If the name's unfamiliar, it's because we don't call the mountain that any more. We call it Crater Lake, Oregon. As the ash cloud flies, that's 550 or so miles on the other side of the Rocky Mountains from Helena. By road, according to a famous map/directions site, it's a little over 800 miles and is about a 14-hour drive in ideal conditions.
That must've been a REALLY big boom.
Aaannnnnnnnnnndddd of course I forgot to put the date in the title. Someone, anyone, help fix my goof?