Admit it.  Driving into Smith Rock you’ve always wonder how the hell these rock formations got out there in the middle of all those rolling hills.  An interesting writeup from Sarah Garlick’s book Flakes, Jugs, and Splitters: A Rock Climber’s Guide to Geology addresses the mystery:

“The spectatular spires and walls of Oregon’s Smith Rock State Park are carved out of 30-million-year-old welded tuff and rhyolite rocks that formed from the ash explosions and lava flows of an eruptive volcano.  Geologists have identified a 230-square mile depression, called a caldera, that is all that is left of this ancient volcano.  A caldera is a giant crater that forms when a magma chamber beneath a volcano erupts a large volume of material.  The top of the volcano literally collapses into the newly emptied chamber, creating a huge depression.  Smith Rock State Park is on the northwest corner of what is now known as the Crooked River Caldera.”

The distinct pockets of Five Gallon Buckets were formed by air bubbles caught in the compressed volcanic ash that makes up the rock wall you see here

Interesting to think that Smith Rock is a mere corner of a huge crater.  One question bends to mind would be what about the rest of the outer edges of this crater?  Wouldn’t there be a circular path of jagged Smith-like remnants winding a 230-square mile path for hungry climbers to explore?  Hmm.

One wonders how this all looks from outer space.  I wonder if Google Maps can shed a nice visual on this caldera/depression.

But it gets more interesting, on the subject of the distinct rock tower Monkey Face:

Most of the crags at Smith Rock are made up of welded tuff, a rock that forms when hot ash, sprayed into the atmosphere from a volcanic eruption, settles onto the Earth’s surface in a thick sheet, hardening as it cools. Like lava, when ash cools it contracts, sometimes forming giant columns separated by vertical cracks.  The Monkey Face at Smith Rock is one of these columns of hardened ash, now weathered and eroded into it’s spectatular shape.”

It’s no wonder the features in the rock look the way they do.  All of the nubbins and chickenheads literally welded into the tuff itself.  When I first climbed at Smith I remember wondering whether these little rocks sticking out of the rock face would not break off under the stress of my weight.  Remarkably I have never had one break on me yet.

It’s an amazing testament that the geological processes make it so that we can essentially rock climb on hardened ash(!) that’s every bit as reliable as granite.

On that note, here’s a time lapse of Dwayne and myself climbing the last couple pitches of the ‘icon of ash’ itself.  Cheers.