The towering cliffs that define Zion are Navajo Sandstone - ancient sand dunes compressed into rock over 180 million years. At up to 2,200 feet thick, this formation represents one of the largest sand dune deposits ever preserved in Earth's geological record. The original dunes covered an area the size of the Sahara during the early Jurassic period. Cross-bedding in the rock reveals the prevailing wind patterns of that ancient desert. Iron oxides create the red and pink hues; manganese and other minerals leave the dark streaks called desert varnish. When water infiltrates the porous sandstone and emerges as springs, hanging gardens of maidenhair fern and columbine cling to the cliff faces - fragile oases on walls of stone.

The trail to Angels Landing climbs 1,488 feet in 2.5 miles, finishing with a half-mile traverse along a knife-edge ridge where chains bolted into the rock provide the only security. On busy days, hikers wait in line to negotiate the exposed sections. The summit offers views up and down Zion Canyon that justify both the effort and the fear. The hike is not for everyone - several visitors have fallen to their deaths over the years - but it remains the park's most iconic trail, a physical challenge that rewards with a literal mountain-top experience. Rangers advise against the final section if you're uncomfortable with heights; the trail to Scout Lookout, just before the chains begin, offers nearly as spectacular a view.

Where the North Fork of the Virgin River cuts through the narrowest section of Zion Canyon, the walls close to twenty feet apart while rising over a thousand feet above. There is no trail through the Narrows - the river is the trail. Hikers wade upstream through water that varies from ankle to chest deep depending on season and recent weather. The canyon walls block direct sunlight for much of the day, creating an otherworldly glow as light reflects off the sandstone. Flash floods can raise water levels fifteen feet in minutes; the park closes the Narrows whenever upstream storms threaten. Those who get permits for overnight trips can continue sixteen miles upstream, camping on riverside sandbars, emerging into completely different terrain at Chamberlain's Ranch.

Most visitors never leave Zion Canyon, but the park extends far beyond the famous cliffs. The Kolob Canyons section, accessible from Interstate 15, offers finger canyons cutting into the same sandstone with a fraction of the crowds. The Kolob Arch, at 287 feet, ranks among the largest freestanding arches in the world - though reaching it requires a fourteen-mile round-trip hike. The park's eastern section transitions to slickrock terrain more reminiscent of Canyonlands, with the famous Zion-Mount Carmel Tunnel boring through the sandstone to connect the canyon with the high plateau beyond. The full park covers 229 square miles of canyon, mesa, and desert, from the Virgin River at 3,700 feet to Horse Ranch Mountain at 8,726 feet.

Zion receives nearly five million visitors annually - more than Yellowstone - concentrated primarily in the seven-mile-long main canyon. Private vehicles are prohibited on the Zion Canyon Scenic Drive from March through November; free shuttle buses carry visitors between trailheads. Angels Landing now requires permits obtained through an advance lottery. The Watchman and South campgrounds fill months ahead; the town of Springdale, straddling the park boundary, has grown into a strip of hotels, restaurants, and outfitters serving the crowds. Yet the park still offers solitude for those willing to work for it. The West Rim Trail sees a fraction of the traffic going to Angels Landing. Backcountry permits open vast stretches of wilderness. Even in the main canyon, an early start or late afternoon hike can provide moments of quiet contemplation beneath walls that dwarf human scale.