It is the tan cliffs that really tell the story of catastrophe. It was a disaster so huge that its dimensions were not recognized until fairly recent times. The cliffs of Smith Rock are part of the northwest corner of the Crooked River caldera, a sunken crater that is 25 miles long and 15 miles wide. Crater Lake's eruption produced around 15 cubic miles of ash. The Crooked River eruption produced around 200 cubic miles. Imagine a dozen Crater Lake eruptions happening at once and you start to get an idea. The eruption rivals some of the worst of the disasters at Yellowstone or Long Valley in eastern California. The only saving grace here is that the eruption took place around 29.5 million years ago. The magma chambers that fed the event have long since cooled.
Modern human beings have never experienced an eruption of this magnitude. The last one of this size worldwide, at Toba in Indonesia about 75,000 years ago, may have almost done in the human race (a controversial idea, but plausible). It involved around 470 cubic miles of ash.
I notice that Smith Rock sits at the south edge of totality during the coming Solar eclipse. If you are lucky enough to get to the park as a setting for this once in a lifetime event, I hope you'll spend a bit of time pondering the incredible history of these rocks as well.
For some detailed information about the history of the Crooked River Caldera, check this link.