AS15-9368(P)

Figure 218

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Rima Fresnel I (1) approximately parallels the Apennine Mountain front (2) along the eastern margin of the Imbrium basin. The rille and its several branches at the northern end fall into the class of linear rilles that are usually attributed to a ten signal structural regime causing the formation of grabens. Faults in the highlands (3), parallel to some of the rilles, support the contention of structural origin for the rilles. Some of the curvilinear segments of the rilles, however, suggest that they may have served locally as lava channels.

The rille traverses a plain that was called the Apennine Bench (4) and interpreted to be formed of older mare lavas (Hackman, 1966). The inside of the rille is flooded by younger mare lavas (Carr, Howard, and El Baz, 1971) (5), which also embay its northern truncated terminus (6). Some younger mare lavas may have poured over the bench material and buried a crater (7). Old lava benches on the inside margin of basins are a common feature on the Moon. They are usually crossed by old rilles and embayed and partially buried by younger lavas.   -B.K.L.