More Photos for Paradox Basin
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The Cache Valley in Arches
National Park is a good example of a collapsed salt anticline. At some time in
the past, Pennsylvanian salt beneath the anticline rose up towards the surface
of the Earth beneath the Cache Valley. Eventually the salt penetrated so close
to the surface that groundwater was able to reach the salt and the salt
consequently dissolved. Once the salt was removed the anticline above it
collapsed. The hill in the middle of the photo is composed of the Jurassic
Morrison Formation.
How did groundwater
reach the salt? Joints in the Slickrock Member of the Entrada Sandstone in the
Fiery Furnace area of Arches National Park are conduits for fluid movement.
These joints form where rocks are exposed to tensile stresses, along the crest
of an anticline for example.
More joints in the
Entrada. If these joints formed due to tension across the crest of an anticline
in which direction was the long axis of the anticline oriented? This photo is
taken just to the northwest of Arches National Park.