Here's the link to the Natural Landscape, Eroded category
I think this is the first category where all of my selections are sites that I've been to. The ones that stand out to me as suberb examples of erosion are:
1. Grand Canyon: My choice for canyons. Words can't do this site justice; it has to be seen and experienced for the vast wonder that it is.
2. Uluru-Kata Tjuta: My choice for freestanding rock domes. Uluru is such an iconic monolith that it deserves a mention on its own, but Kata Tjuta is just as impressive
3. Göreme National Park: My choice for eroded rock formations. This site is covered with fairy chimneys and rock-hewn homes that are incredible to see.
While Nahanni is listed in this category, I've always thought of it more in terms as an unspoiled North American river rather than as an example of a canyon. Since it's not in the river category, though, maybe it is deserving of making the list for this category. Also, poor Purnululu. In a category that already includes Uluru-Kata Tjuta, the Bungle-Bungles seem superfluous.