Oregon Caves National Monument is one of the few marble caves in the world (only about 5% of all caves are marble caves) having been created when acidic rainwater dissolved the surrounding marble. In fact, Oregon Caves has long been known as the “Marble Halls of Oregon.” As you walk through the caves, you can see the marble in the cave walls and this is especially evident when you reach the Dry Room
The next stop on the Oregon Caves tour is at the Niagara Falls.