Balance Oil on board, 6" x 6" $125.00 + $6.00 shipping in US. SOLD How sheltered a life have I led? Let me put it this way: before I visited the Southwest I thought balancing rocks only existed in Road Runner cartoons. I'm no geologist, so if I have this wrong someone straighten me out, but it's my understanding that these are remnants of a layer of sandstone that once covered much softer underlayers of ash or other sediments. As the forces of erosion broke through the hard shell, the softer underlayer began eroding away at a faster rate, leaving these rocks sitting high and dry. I read somewhere that while many of them look like they're ready to slide off their platforms, they rarely do. The underlayer compresses more on the tilted side, hardening it so it erodes more slowly. Meanwhile the side with less weight erodes away faster, and the rock tilts back the other way, keeping it balanced. In other words, they are giant teeter totters!