Geologic setting of Boulder 1, Station 2, Apollo 17 landing site

Boulder 1 at Station 2 is one of three boulders sampled by Apollo 17 at the base of the South Massif, which rises 2.3 km above the floor of a linear valley interpreted as a graben formed by deformation related to the southern Serenitatis impact. The boulders probably rolled from the upper part of the massif after emplacement of the light mantle. The massif exposures are suggested to represent the upper part of thick ejecta deposited by the southern Serenitatis impact near the rim of the transient cavity. The ring structure of the southern Serenitatis basin and the radial grabens that give the massifs definition were imposed on this ejecta at a slightly later stage in the basin-forming process. There is no clear-cut compositional, textural, or photogeological evidence that Imbrium ejecta was collected at the Apollo 17 site.