How were the spectacular rock formations of arches national park formed?

The rock formations of Arches National Park were formed from the weight of rocks that were formed from the accumulated debris deposited there.

Explanation:

Arches National Park is located in a region above a large layer of salt. This salt layer is the result of the evaporation of a sea that existed over 300 million years ago. When the sea evaporated, it left a large layer of salt and an empty space that contributed to the accumulation of many detrists that were carried to the region by wind and rain. These debris accumulated and merged to form large rocks on top of the salt layer.

These rocks became too heavy and that weight forced the salt layer below them to begin to change state and become fluid. This change of state caused the salt layer to push the rocks upwards, creating the large formations that are observed in Arches National Park.