| |
| | NABS - Natural Arch Formation |
 | | As stated in the definition of what natural arches are, they are formed by the natural, selective removal of rock. |
 | | When a vertical joint is present near, and parallel to, a cliff, e.g., as a result of stress relief exfoliation, its expansion may couple with other processes, e.g., wall collapse or cavity merger, to form various types of natural arches. |
 | | Differential erosion contributes to the formation of natural arches in several ways, e.g., the undercutting of harder layers of rock that are supported by softer layers. |
| www.naturalarches.org /archinfo/formation.htm (3151 words) |
|