United States. National Park Service

“ The majestic beauty of the bridge affects people in many ways. The delicate balance, graceful sweep, symmetry, beautiful toning of color, and superb setting of this rainbow-shaped stone arch suggest Divine guidance during its creation. The aborigines must have sensed this, for they built altars here.
Rainbow Bridge stands in the semidesert country of southeastern Utah. It nestles among canyons carved by streams that wind their way from the northern side of Navajo Mountain toward the Colorado River. It spans Rainbow Bridge Canyon and the tiny streamlet in its bottom. ”

“ Thus, the canyon spanned by Rainbow Bridge came into being.
Mother Nature used the less severe forces of weathering for shaping and polishing the outline of Rainbow Bridge. For example, when moisture freezes within a crevice it exerts pressure on the surface of a rock and causes the outer portion to shell off, forming a relatively smooth surface. The Navajo sandstone is particularly subject to this type of weathering. It is porous and the curved 4 layers of the cross-beds are held together with weak, natural cement that is easily removed by percolating water. ”

“ Water dripping into the pools near the bottom of Rainbow Bridge Canyon is from rain water that has seeped down through the Navajo sandstone. When the water reaches impervious rock layers in the underlying Kayenta, it is concentrated, but eventually it seeps out along the walls of the canyon, forming springs.
Plants grow in profusion nearby. Maidenhair fern and wild orchids are nestled in the shade. In addition, there are Indian paintbrush, loco, lupines, daisies, asters, yucca, sunflowers, evening-primroses, columbine, scarlet-bugler, and mariposa-lily. ”