Geology

Zion National Park is located at the western edge of the Colorado Plateau, which over the millennia has been uplifted, tilted and eroded into a series of stepped cliffs called the Grand Staircase. Slowly, this uplift caused the Zion area to rise from near sea level to over 10,000 feet in some places. When Zion was still a low, flat basin 240 million years ago, it was filled with sand, gravel and mud carried by streams from the surrounding mountains. Over time, layers of these materials were compacted into stone, while the rising land and a changing climate transformed a shallow sea into a desert. Later in its history, a landslide dammed the Virgin River, forming a lake. The river eventually breached the dam and the lake drained, leaving behind a flat-bottomed valley. You can still see evidence of these changes while touring Zion National Park.