During the winter, winds carry moisture from the Pacific Ocean across several ranges and basins between California and Colorado. When lofted off the dry plateau and pushed up against the abrupt slope of this 11,402-foot mountain, clouds form and congregate above its summit. On the day I made this photograph, a vaporous shroud veiled the sun above the tilted plain. Filtered shafts of sunlight spread from behind a cumulus cloud, resembling a spiritual apparition, and for a moment, conjuring the opening lines of Genesis.

Mount Lamborn is a prominent peak marking the western edge of the Rocky Mountains, a mile above the North Fork of the Gunnison River and not far from the Colorado-Utah border. Ancient upwellings of magma from the Earth’s deep interior created the Rockies. Looking east from the town of Paonia, the rolling foothills of juniper and piñon give way to the sudden ascent of Mount Lamborn’s pyramidal face.

Further east lies a mélange of intertwined ranges stretching 200 miles to Denver, where the Great Plains begin. To its west lie the red-rock canyonlands of eroded plateaus, vaulted arches, and desert rivers. When I lived in Paonia, I enjoyed daily hikes across this threshold (geographically known as an ‘ecotone’) between two distinct geologic and botanical regions, with a mountainous network to the east and vast drylands to the west. Despite living there a decade ago, I still remember how distinctly different the air felt, as I traversed from the desert's dry warmth into the conifer-scented alpine air.