AS15-0321(P)
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A larger scale view of part of the area of figure  192  shows the bend in Rima Prinz 11. It and Rima Prinz I form subparallel linear depressions that originate in small craters on the north flank of the crater Prinz. Both make right angle bends about 1/4 to 1/3 of the way from their source. The maximum width of the part of Rima Prinz II shown in this photograph is about 1.5 km. It is at least 100 m deep in the dark mare materials, and shallower in the rugged and older circumbasin (terra) materials. The rille is normal to the terra ridge where it cuts across the ridge, and is younger than the youngest materials it incises.

The processes by which lunar rilles form are open to controversy. Their sinuosities lack the characteristics of meanders in most terrestrial streams. The rims along the north portion of Rima Prinz II have both a rectilinear zigzag pattern and subdued arcuate sinuosity. In general, a concave reentrant is opposite a protruding wall. The rille floor displays the same crater density and the same crater size distribution as the mare materials adjacent to the rim. The morphological evidence, therefore, suggests that tensional stresses in the lunar crust probably caused the rille floor to subside between the steep normal faults that form the rille walls. The zigzag pattern of the walls probably is caused by irregular faulting along conjugate joints and fractures in the lunar grid.   -M.J.G.