Why is no halite present among the evaporites of the Paradox Formation in Arches National Park?

Answer 1

The arches at Arches National Park are the result of differential erosion of sandstone between parallel joints or cracks in that sandstone. These particular joints were created when the sandstone layer was undermined by groundwater dissolving the salts out of the underlying layer of rock known to geologists as the Paradox Formation. As the overlying layer of sandstone slowly collapsed into the void created by the dissolving salts, the parallel joints were formed. Later, erosion of the sandstone between the joints created the arches. Even later, someone thought that this would make a good place for a National Park. In short, the arches at Arches National Park exist because the halite of the Paradox Formation was dissolved and removed by groundwater.