This unusual rock formation formed when magma invaded the cracks of an ancient collapsed volcano here in central Utah around 30 million years ago.  As the magma cooled, it contracted.  Generally it is easier for the cooling magma to contract vertically than it is to contract horizontally, so numerous cracks occur along the surface of the magma that propagate downward leading to the formation of columns seen here.  In this case, the ancient vertical columns were later turned on their side so that they resemble stacks of wood and give the place it's name, "Paul Bunyan's Woodpile."

Over many many years, the constant freeze/thaw of water within the rock joints has led to the erosion of parts of the wall of one of the "woodpiles" creating a natural arch.

Fellow 360 photographer, Florian Eggenberger, starts his 360 photo next to the arch.  Calvin Jones, Florian and I spent a great afternoon hiking up to the woodpile, taking several 360s there and along the way.