We broke the drive from Crater Lake to Redwood National Park with a visit to the Oregon Caves. These are marble caves. The seventy-five minute tour leads through a series of beautiful and eerie chambers. Water drips through continuously, leaving calcite deposits in its wake that form all kinds of wierd and wonderful structures. Stalactites, stalagmites, and stranger shapes. I'll let the pictures at the right speak for themselves, but suffice to say a very pleasant interlude in the day.
Stalacmite
Wierd and wonderful calcite