This photo was taken in Antelope Canyon, a short distance from Page, Arizona. This is a slot canyon - a narrow canyon worn in the red Navajo sandstone by water rushing through it.
The only light that enters the canyon is from a narrow opening at the top. As the sun moves across the sky, sunlight first hits the top layers of the rock and gradually moves further down into the canyon. This shot was taken near midday when sunlight (performing its magic on the red stone) flooded the canyon walls and floor.