Let's Get Rocked--Geology

I want to see unique natural geological sites. I don't want the run-of-the mill sites like the Grand Canyon but some more specific or unique. Something that will say " Wow, I want to go see that". No man made locations (e.g., pyramids or mounds). Example may include a hoodoo, cave, natural arch/bridge, dune, pillar, rocky outcrop, and etc.... No waterfalls or mountain! Repeat, no waterfalls or mountains.