The three authors of this book vary greatly in backgrounds and experience but share in the love of the land and a desire to impart their knowledge of it. Comparisons are made of the rock record of geologic events known to geologists, to the legends in stories known to traditional Navajos. Ages and environments of deposition of stratigraphic units' progress from the two-billion-year-old rocks that are exposed in the Inner Gorge of the Grand Canyon to succeeding rock units known to exist on and under the lands of Dine 'Bikeyah across the Colorado Plateau that were formed a few million years ago or less.

Geologists use observed fossil records and other geologic events to establish a Universal Geologic Time Scale that consists of four Eras of geologic time: the Precambrian, Paleozoic, Mesozioc, and Cenozioc eras. 

Navajo medicine men tell stories of their vision of the First Dark World, the Second Blue World, the Yellow Third World, and the Fourth White World. The stories show a major cycle of life beginning and extinction of variety of different species in the four worlds as does the geologic history in the four geologic eras.