Abstract: Complexes of underground batch retorts, designed to duplicate surface retort prototypes proven successful in use, which may extend for miles on branch drifts intersecting central main drifts above and below the retorts, the main drifts emerging at surface. The batch retorts are very large, deep, planned mine cavities, with relatively small upper and lower openings, remaining after shale oil ore has been extracted by vertical crater retreat stoping and free-fall controlled at the bottom opening. Resort openings are sealed after they have served their purposes, which enables the symmetrical progression of the upper and lower branch drifts along which the retorts are mined. The drifts provide access to blasting sites, conveyors for removing fragmented ore to be crushed and screened, and conveyors for returning processed ore to the retorts. Loading is accomplished through a retracting device which deposits processed ore with minimal free-fall, to avoid creating fines in the loading process.