here for larger NASA image of Figure 211
Click here for larger NASA image of Figure 216
Click here for chart showing location
This oblique view of part of the flat floor of the ancient crater
Alphonsus shows faults that break the floor along straight line fractures.
Spaced at irregular intervals along some of the rilles are dark halo craters
that have broad low rims. The first detailed pictures of these craters
were taken by Ranger 9 in 1964 (Click on Section 44 below to see these
images). This photograph confirms the detail in the Ranger picture and
confirms the hypothesis that the dark halo craters are volcanic in origin.
Their constructional rims indicate that they cannot have formed by collapse
of material running back into the fault zone. The smooth rim deposits indicate
that fine grained material was ejected uniformly from the volcanic vent.
These deposits differ markedly from the ejecta patterns around bright,
young impact craters. -H.M.
Report Source: NASA SP-362, Page 206, Figure 216
This web page was created by Francis Ridge
for The Lunascan Project
Section Directories 44 and 55