In Arches National Park, more than 2,000 natural stone
arches - largest concentration in the world - are found.
The Entrada Sandstone top layer has been
fractured by criss-crossing cracks, as the underlaying
salt bed moved because of the pressure of the top layer.
Over time water seeped into the cracks, enlarging
them with the freeze-thaw cycle, resulting in
free-standing fins which were attacked by wind and water
until the cementing material gave way and chunks of rock tumbled
out. The fins which did not collapse despite their
missing sections became the arches.
The short and popular Windows trail let you visit three of the
most impressive arches. South Windows (barely seen on the
left), with a 105 ft span and a height of 65 ft is the third largest arch in the Park.
North Window, with 93 ft span and a height of 51 ft, is cut
from the same sandstone fin - together they form the
Spectacles. Turret Arch (seen through North Window)
measureing 39 ft wide by 64 ft high is distinguised by
the tower which borders it.