Geological Chronicle
Positioned along the northern boundary of Mare Insularum where the basin meets Sinus Aestuum, Stadius is an ancient impact structure spanning 68.48 kilometers across. The feature has been largely smothered by subsequent basaltic lava, leaving behind an eroded ghost ring southwest of the crater Eratosthenes and east of Copernicus.
Only the northwestern portion of the crater rim remains substantially intact, connecting to a north-trending ridge line that extends toward the western ramparts of Eratosthenes. Across the rest of the perimeter, the boundary persists only as a ghostly trace of rises above the surrounding plains, showing no evidence of a central peak.
The flat floor inside the remnant is heavily scarred by secondary craterlets produced during the creation of neighboring Copernicus. To the northwest, an associated chain of craters extends in a linear formation that stretches outward toward Mare Imbrium.