Geological Chronicle
Drygalski lies along the Moon’s southern limb and partly overlies Ashbrook to the west, on the far side. The smaller crater Boltzmann is just north. From Earth, the limb location restricts observation; even under favorable libration, Drygalski is viewed from the edge. The Sun lights it only at an oblique angle, close to south polar craters permanently shielded from sunlight.
Subsequent impacts have worn and eroded the outer rim, leaving a rugged, mountainous ring overlaid in places by small craters. Drygalski P crosses the southwest rim where it joins Ashbrook, and Drygalski V lies along the north-northwest inner wall. A small catena begins tangentially at the northern outer rim, then arcs north toward Boltzmann. South of the crater, two or more small craters form a short valley.
Parts of the interior floor within the inner walls are flat and level after lava resurfacing, especially in the south and east. The western floor is rougher and marked by several small craterlets. A rugged central peak rises at the midpoint, with smaller ridges along its flanks; an infrared spectrum of pure crystalline plagioclase has been identified on the peak. Drygalski is named after the German geographer and geophysicist Erich D. Von Drygalski (1865 to 1949).