Geological Chronicle
Plinius stands on the border between Mare Serenitatis to the north and Mare Tranquilitatis to the south. The impact crater measures 41.31 kilometers in diameter and is named after the Roman natural scientist Pliny the Elder, Gaius Plinius Secundus. In nineteenth-century observations, T. W. Webb recorded it as a terraced ring filled with hillocks.
Dating to the Eratosthenian age on the lunar geologic timescale, Plinius features a sharp, slightly oval rim with a terraced inner wall and an irregular outer rampart. It lacks a visible ray system. Just to the north lies Rimae Plinius, a system of rilles extending toward Promontorium Archerusia at its northwest edge.
The interior of the crater displays distinct terrain across its floor. An irregular central peak rises in the middle, presenting the appearance of a double crater formation under certain angles of illumination, with a cleft feature attached to its northern side. To the east, a smooth, level crescent curves around the central elevation, contrasting with the hummocky floor to the west.