AS15-1135(M)

Figure 202

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This Apollo 15 photograph depicts the sinuous Hadley Rille, the Apennine Mountains trending from lower left to upper right, and the smooth surface of Palus Putredinus (Marsh of Decay) in the upper left quarter. The Apollo 15 landing site at 26.4° N, 3.7° E (arrow) was selected because of the variety of important lunar surface features concentrated in the small area. The Apennine Mountains, with almost 5 km of relief in the area pictured, are a part of a ring of mountains that surrounds the Imbrium basin and in which very old rocks are thought to be exposed. The smooth lava flows of Palus Putredinus formed later, and Hadley Rille, sharply etched in the mare surface, is thought to be one of the youngest rilles on the Moon. The V shaped rille originates in a cleft at the base of the mountains in the south and gradually becomes shallower and less distinct to the north and west. Layered rocks crop out in its walls at several places. Near the landing site, the width of the rille is 1.5 km and its depth is more than 300 m.  M.C.M.