Lithospheric displacements on Europa have occurred at ridges, strike-slip faults, and dilational lineaments on a global scale over most of the geological age of the present surface. These features are consistent with the presence of a subsurface ocean which allows decoupling needed for horizontal motions and which is the source of new ice composing ridges and filling dilational lineaments.
Displacement features initiate as tidally-induced cracks and then evolve.
Ridges form when tidal cycling opens and closes cracks, extruding a icy slurry derived from ocean water. Dilational lineaments develop when an externally forced secular dilation superimposes upon daily tidal cycling. Dilation may be driven by walking on strike-slip faults linked to the dilating lineament. Accommodation of surface area added by dilation might occur through formation of chaotic terrain. The probable formation of cycloidal features by diurnal tides provides evidence that an ocean was present at the time of formation.