Abandoned Natural Arch

(Morphologic type)

Examples: Delicate Arch, Cox Canyon Arch, Royal Arch, Square Arch, unnamed arch

This type of natural arch is invariably isolated and the lintel is arched. The opening is usually a semicircular aperture, although in some cases it is an oval aperture. There are two roughly vertical abutments, each having a vertical rise greater than its horizontal extent.

For many natural arches of this type, the lintel and abutments form a single strand of rock whose breadth varies little over most of its curved length. In other examples, one of the abutments is noticeably broader than the lintel and other abutment, but this broadening is roughly in the plane of the opening aperture.

Natural arches of this type are considered old, i.e., at the end of their lifecycle. Although there is no conclusive evidence for a specific formation process, it is clear that the natural arch continues to survive due to compression strengthening. Compression strengthening made the remnant rock more resistant to erosion than the rock that once surrounded it, and hence, gave it its characteristic arched shape. This type of natural arch is rare.