The complex 300 million-year story of the formation of the rock wonders in Arches National Park features powerful tectonic movements, retreating and advancing seas, flowing salt deposits, faulting, collapse, uplift, and the forces of erosion, especially water. Although area geologic events that came before contributed to the landscape we see today, the formation of Arches really begins to take shape 65 million years ago, when geologic forces warped and cracked deeply buried sandstone rock layers. Then about 15 million years ago, movements in the Earth’s crust caused the entire region to rise thousands of feet, not as mountains, but as an elevated surface, creating the Colorado Plateau. What had been a sea-level depositional landscape where sediments accumulated became a high-elevation erosional landscape where water and gravity continually draw material to lower elevation areas.