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This oblique metric photo shows part of the lunar highlands where the ancient crust is saturated with large craters. Portrayed here are the crater Alphonsus (middle ground) and the ancient crater Ptolemaeus (fore-ground). The floor of Alphonsus is broken by faults that form a polygon roughly parallel to the walls. Dark halo craters lie along these faults. The rims of the dark halo craters fill in the fault troughs. This relationship indicates that the craters must have been formed by material ejected from the central vents rather than by collapse of material into the cracks. However, unlike impact craters with their hummocky ejecta and lines of secondary craters, the smooth rimmed deposits have been interpreted as fine grained volcanic ejecta.
Lunar transient events have been observed many times in the crater Alphonsus. Red glows have been documented and spectra have been recorded by Kozyrev (1971) that apparently confirm the existence of gaseous emissions. These events are thought to be related to orbital parameters; when gravitational stresses are high, the crust shifts and gas escapes from the interior at regular intervals. If this is true, a low level of activity still continues to affect the lunar crust and interior.
General and detailed contour maps have been made (Wu et al., 1972)
of Alphonsus using metric and panoramic photography obtained by Apollo
16. (See Figures 212,
Fig. 212 is outlined in this figure, and fig. 213 is outlined in fig.
212.) - Harold Mazursky.
Report Source: NASA SP-362, Page 202, Figure 211
This web page was created by Francis Ridge
for The Lunascan Project