The kaleidoscopic nature of Arizona's scenery, climate, vegetation, water supply, wild life, and industry is due fundamentally to contrasting geologic circumstances. Highway travel provides an opportunity for the interested spectator to observe and to question. This road guide, emphasizing geologic and related observations, will assist travelers in developing an additional awareness and appreciation for a part of our natural environment. The text, illustrations, and appendix are designed to accommodate varying degrees of interest ranging from those of the general reader to those of professional geologists desiring a brief account of the geologic framework of a portion of Arizona.