AS16-1276(M)
.....

This photograph shows the crater chain of Figure 132  in its regional context (large arrows). Trending east-southeast, the chain sharply transects the Imbrium sculpture, which trends south-southeast (smaller arrows near margins). The difference in trends argues strongly against a common origin and somewhat less strongly against a related origin. The laser altimeter on board the Apollo 16 CSM showed that the area directly east of Ptolemaeus was one of the highest areas on the near side of the Moon along the ground track. The other anomalously high area was in the vicinity of the Apollo 16 landing site near Descartes. Also in the Ptolemaeus area the Apollo 16 mass spectrometer recorded an excepionally high ratio of aluminum to silicon. The relationship between high elevation and high aluminum content and the presence of a prominent crater chain are probably more than coincidental. One interpretation is that volcanism in this part of the highlands extended into a later period of time than in most other highland areas on the near side and that more differentiated materials were extruded. The crater chain may be related in origin to this late-stage eruption.   -H.M.