Hoodoos, Wheeler Geological Area, CO: difficult to get to (the pictures & description make me believe it's worth the effort for the younger set). This area is a highly eroded outcropping of layers of volcanic ash which is the result of eruptions from the La Garita Caldera approx 25 Ma ago
Mushroom Rock, Little River Canyon National Preserve, Alabama. Several decades ago, a road crew constructing the original scenic drive is credited with saving this canyon landmark. Plans called for the rock formation we now call Mushroom Rock to be removed. Construction staff refused to blast it away. The crew built the road around it instead.