N.A.B.S.

There is an actual society whose entire mission is to study and record and measure and understand natural arches and bridges around the world.  Or maybe the universe.  Fascinating NABS website (Natural Arches & Bridges Society) can be found here!  Spend some time exploring their galleries and, if you dare, technical definitions.

A cool arch… in California.

      Strong Arm Arch, 6 feet across