Photostratigraphy, a new method of aerial photo interpretation, establishes local photostratigraphic correlation frameworks with relative chronostratigraphic significance. This method is based on the analysis of strata geometry, their relationships, and the photographic aspect of the rocks for identification and hierarchic organization of photostratigraphic units. The definition of these units does not presuppose any a priori genetic implications. The units represent volumes of rocks bounded by surfaces with chronostratigraphic significance. Photostratigraphic units contain time-transgressive photofacies and photofacies units, which record lithologic and depositional characteristics of the strata. The procedure for establishing photostratigraphic correlation frameworks is illustrated through examples from the south-central Pyrenees. Direct integration with field data allows the comparison of photostratigraphic frameworks with frameworks based on other stratigraphic criteria. Photostratigraphy is proposed as an independent and relatively rapid, preliminary approach to the study of a basin.