In the southeast of Utah’s Zion National Park lies a set of colorful sandstone hills with an unusual pattern of crosshatched cracks. The grid-like cracks gave this formation its name: Checkerboard Mesa.
This majestic hill towers some 900 feet above the road, and its patterning is the result of processes that have been ongoing for thousands of years. The cracks appear in Navajo Sandstone, a prominent formation in Zion’s cliffs. Reaching a thickness of more than 2,000 feet in places, the sandstone is the result of ancient sand dunes that have been compressed into rock.
Vertical lines in this sandstone are the result of expansion and contraction, as the ground bakes under the hot sun in the day then cools when temperatures fall at night. This cycle is exacerbated by water penetration, which comes from rain and melted snow. The horizontal lines come from erosion from the wind; the rock gets sand blasted away along natural layered structures in a process known as cross bedding. Together, these effects give the north face of the mountain its characteristic checkerboard pattern.
In the 1930s, then-superintendent of Zion Preston Patraw called the area Checkerboard Mountain. Before then, it was commonly known as Rock Candy Mountain.
The hills closer to the south boundary of park, outside the main canyon, are much more exposed than those in the interior, and therefore tend to be more vulnerable to the effects of weathering. Checkerboard Mesa is by no means the only example, but because of its location near Highway 9, it may be the best known. Because these geologic processes are ongoing, the massive monoliths will slowly and eventually break down and once again become great dunes.