The biggest factor of decay here is root decay. There are plants everywhere, growing all over the rock faces. In fact, most of the rocks appear green because they are so covered by various types of lichen and moss. Root decay occurs when roots take hold in small crevices of rocks, and as the plant grows, it beings to break apart the rock.
 |
| Here are roots wrapping themselves around these rock formations, digging into crevices and slowly breaking down the rock. |
 |
| There are so much plant life growing on the rocks here that the rocks appear to be green in color. |
Salt decay also seems to be a large issue in the crater. Many of the rock faces show evidence of salt decay, which manifests itself as white coloring on the rocks. It can be seen in the photo below, right behind the palm tree on the right hand side. Salt decay happens when water moves through fractures in the rocks, leaving precipitate behind to crystallize, slowly breaking down the rock.
 |
| I'm sure the portal has nothing to do with rock decay...However, look, more root decay! |
There are also signs of pressure release, pictured in the rock formation below. Large shells have split off the sides of the rock from pressure. This is a much faster decay process than most. This rock also portrays spheroidal weathering very well, portrayed in the rounded edges at the top.
There is also probably some thermal expansion and contraction decay going on here because this rock formation is located next to a large set of hot springs that provide constant heat to the rock.
 | |
| Here you can see the hot springs on both sides of the rock. There also appears to be some salt decay on the formation as well. |
There are many types of decay in action in Un'Goro Crater. One can never be sure they identified them all. But one can be sure of the fact that wind did not create any of these structures.
