Photogeology: Part S: mare ridges and arches in southern Oceanus Procellarum

Low-relief mare features such as ridges and arches are best studied by using stereoscopic photographs taken at low Sun angles. Apollo 16 metric camera photography of the southern Oceanus Procellarum east of Letronne Crater reveals a diversity of subtle features (fig. 29-125) and adds significantly to an understanding of the forms of mare ridges and arches their relative ages, and their association with fractures and sinuous rilles.