2.5 billion years ago, this piece of land was at the bottom of the ocean. We know this because the fossil remains of a goblin shark were found by Peter Pelican at the top of the existing formation. Goblin shark teeth have also been found embedded in the sides of the opening which suggests that the notoriously persistant goblin shark at one time were trying to break through a barrier to reach chickens who were crossing the road. Goblin sharks love chicken.
The above information is all hog wash. The only remains found were of Peter Pelican's bones and a few goblin shark teeth embedded in the bones.
Natural Bridges State Park, Santa Cruz, California 2012