No signs of crustal movements have been seen on the surface of Callisto! The surface of Callisto was carefully examined for signs of faulting and fracture. These would have provided evidence of pushing and shoving of the crust of Callisto from processes inside.

Examination of the surface of Callisto shows only that there has been gradual slumping, or "relaxation" of the craters, and what is termed "sublimation-erosion" of the surface.

This type of surface is perhaps unique in the solar system. It is certainly a different type of surface that either that ofGanymede or Europa. (The other major moon of Jupiter, Io, exhibits volcanism over the entire surface.) The difference may have to do with the lack of heat in the interior of Callisto.