AS15-0342(P)
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A view near the mouth of Schroter's Valley. Clearly shown are the old broad valley stage of formation of the valley-largely controlled by faulting-and the fresher, younger, meandering inner valley that probably represents a basaltic lava channel. Rocks returned by Apollo 15 from the banks of a similar channel are layered flows of vesicular (full of gas bubble holes) basalts. The valley drops 1600 m along its length a slope similar to terrestrial lava channels. Secondary craters from the bright fresh impact crater to the east show that the impact crater is younger than the valley. The valley like all terrestrial and lunar lava channels-gels narrower and shallower downstream, possibly reflecting the cooling of the lava and its loss of mobility as it gets farther from its source .    -H.M.