Millions of years ago most of what we now know as the southwestern United States was underwater. There were numerous lakes and seas and for millions of years, layer upon layer of sand and sediment settled on the sea floor and sand dunes were formed along the shores. These were compressed to form layers of rocks. Uplifts occurred over time, moving the layers upward, and breaking them here and there. The layers were exposed to the elements and began to erode.
In the 1870's Clarence Dutton, a geologist, first identified and described this area as a grand staircase comprised of five layers.