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This south looking oblique view, centered near 25.5° N, 50.5° W, depicts a prominent "cobra head" rille, Vallis Schroteri (Schroter's Valley). In the foreground is the Aristarchus plateau, and in the background the smooth surface of Oceanus Procellarum. The two large craters in the middleground are Aristarchus (38 km diameter) on the left, and Herodotus (30 km diameter) on the right. At first look the sinuous, flat floored Schroter's Valley and the tightly meandering channel within bear a striking resemblance to river valleys on Earth, and some viewers of the Moon have thought that sinuous rilles were formed by flowing water. In detail, however, sinuous rilles differ from river valleys in many respects; for instance, Schroter's Valley becomes smaller toward its downstream end. They are much like an entirely different terrestrial feature-lava channels. (See fig. 189.) Most geologists think that Schroter's Valley is a channel through which lava flowed from the circular crater at the "head" of the rille to the lower elevation of Oceanus Procellarum, a distance of approximately 175 km. Figures 186 to 188 are enlargements of the four sided areas outlined in this photograph. -M.C.M.
Report Source: NASA SP-362, Page 180, Figure 185
This web page was created by Francis Ridge
for The Lunascan Project
Section Directory 18