Monument Valley on the Utah/Arizona Border
Before human existence, the Park was once a lowland basin. For hundreds of millions of years, materials that eroded from the early Rock Mountains deposited layer upon layer of sediment which cemented a slow and gentle uplift, generated by ceaseless pressure from below the surface, elevating these horizontal strata quite uniformly one to three miles above sea level. What was once a basin became a plateau.
Natural forces of wind and water that eroded the land spent the last 50 million years cutting into and peeling away at the surface of the plateau. The simple wearing down of altering layers of soft and hard rock slowly revealed the natural wonders of Monument Valley today.