They've obviously never hosed mud off of them. Otherwise, they would understand why streams cut through loosely-consolidated pyroclastic deposits so much more quickly than metamorphic rock. And they'd know why we laugh so very hard when they try to compare stream erosion in the area of Mount St. Helens with the Colorado's long saw through the Colorado Plateau.
I feel for the trees that lost their lives so that this drivel could be published. At least part of that small forest will find a useful new life as post-consumer recycled paper.