Geological Chronicle
D'Alembert lies in the Moon’s northern hemisphere, northeast of the somewhat smaller walled plain Campbell. It is a peak-ring basin, a formation with one interior topographic ring or a discontinuous ring of peaks and no central peak. Later impacts have worn its outer rim, which remains visible as a roughly circular ridge. Slipher lies astride the southwest rim, and d'Alembert Z intrudes into the north.
The interior floor is relatively level beside the rougher terrain around the rim. Slipher’s outer rampart and ejecta layers make the southwest floor more irregular. Two shallow clefts begin near the basin’s midpoint and reach halfway to the inner wall. The infrared spectrum of pure crystalline plagioclase has been identified on the south and central floor and southeast rim.
The crater dates to the Nectarian period. Its name honors French mathematician, physicist, and philosopher Jean d'Alembert (1717–1783); the International Astronomical Union officially adopted the designation in 1970.