The Watchman, Zion National Park, Utah

As one of our nations first national parks, Zion was formally designated in the year 1919. In this photograph, the massive Navajo Sandstone formation known as The Watchman (right) towers above a grove of bright autumn-hued cottonwood trees lining the banks of the Virgin River as the first snows of the season dust the peaks. Located near the south entrance to Zion Canyon, The Watchman is representative of the monolithic Navajo Sandstone formations which line both sides of this deep canyon. The Navajo Sandstone of the Colorado Plateau attains its maximum exposed thickness of nearly 2300 feet here in the Zion region. Approximately 190 million years ago, a vast sea of windblown sand similar to today’s Sahara covered much of Utah, Arizona and northwest New Mexico. As these dunes were subsequently buried beneath additional layers of sediment, dissolved minerals in groundwater percolated down through the sand and cemented the grains together into what we now call the Navajo Sandstone. Massive tectonic forces have since pushed this layer high into the Utah sky where the relentless forces of erosion have sculpted the landscape we see today.