Examined here are the three major subject areas that fall within photogeology: aerial photography and elementary photogrammetry; fundamentals of aerial photo-interpretation; and applications to the main fields of investigation. Instrumentation, the techniques of map compilation, quantitative determination of geological data, film and filter combinations, vertical exaggeration and radial triangulation are discussed, as well as the newer techniques of photography and remote sensing. Chapters describing geomorphology, lithology, structural geology, drainage, engineering geology, ground-water surveys and mineral and petroleum exploration are detailed and complete.