The Calico Hills are the remains of a red sand dune field thought to be one of the largest ever on earth. Over time, underground water moving through the dune field carried away much of the original color but left behind calcium carbonate, which cemented the sand. The dunes were then compressed and lithified under the weight of overlying deposits that would eventually erode away, exposing the striking formations we see today.

Sweeping curves in the rocks developed while the dunes were still active

The 2006 Scenic Fire touched nearby slopes, but washes at the base of the Calico Hills were largely unaffected

This part of Nevada was on the ocean floor 600 million years ago, and Utah was a coastal region

A beavertail cactus may appear smooth, but clumps of glochids - or tiny spines - cover the pads

Sandstone is a relatively soft rock that's susceptible to wind, water and freeze-thaw erosion

Cross beds in the sandstone originate from the continued movement and succession of dunes in an active field

View of the Calico Hills and Calico Basin from Turtlehead Peak, a much older limestone monolith directly above

Red hues in the rock come from iron and similar trace minerals that have oxidized, or rusted

The Calico Hills are a tiny remnant of a sand dune field thought to be among the largest to ever form on earth

Mojave creosote has been found to have 78 chromosomes, while Sonoran creosote has 52 and Chihuahuan only 26 (courtesy of the NPS)

Though most visitors simply improvise across the rocks, the Calico Hills Trail runs nearly two miles long and is ideal for families and runners