The photographic collections held by the Services départementaux de restauration de terrains en montagne (Departmental Mountain Land-Restoration Services) illustrate a key episode in the history of French land modernisation. Their aim was to shape the climate by regulating the water regime to avoid natural disasters – flooding, landslides – and to establish territories that were subsequently considered a form of capital to be developed. From the end of the 19th century, mountains–as viewed by the State in its role as a territorial planner–were equipped with a variety of apparatuses that combined civil engineering and plant engineering. Methodically taken and circulated, photographs are today one element of engineers’ technical equipment. They are the material and symbolic vehicle of a sometimes ambiguous relationship with natural phenomena, which this text attempts to describe. the study of these texts fosters a historical reflexivity and contextualisation necessary to our environmental aspirations.