One of my most memorable hiking adventures was walking up the North Fork of the Virgin River, navigating its narrow canyon in southwestern Utah's Zion National Park. At the trailhead, I stepped off the riverbank and into the stream. As I walked against the current, I absorbed the vertiginous scene, gazing up at the 2,000-foot-high vertical Navajo Sandstone cliffs on either side. I felt small, almost invisible.

I walked through the Zion Narrows, where a ribbon of rich blue sky lit the constricted walls. Sunlight reflected off the warm-toned rim of the ravine, adding a subtle blend of colors. I was drawn to a small cascading waterfall etched by radiant light, with a gentle stream spilling down a damp wall covered in moss, lichens, and algae. Later, I learned its name: Mystery Falls. In 1977, the side canyon that feeds the falls was first hiked. Faced with the final 120-foot rappel down the slick face of the waterfall to the canyon floor, the hikers wondered how they would find enough secure footing to descend this slippery incline, calling it a “mystery.”

Sourced at the crest of the Colorado Plateau, this elevated and deeply incised plain spans much of Utah and parts of neighboring states. Over time, geological forces have uplifted the land several thousand feet. Spring snowmelt swells this tributary of the Colorado River, and sudden downpours in the high country can trigger flash floods, increasing stream flow a hundredfold. Consequently, the river's erosive power has carved—and will continue to deepen—this channel through the heart of Zion.

Commentary and research by James Baker.