The accretion process probably lasted for several thousand years before the moon was fully formed. Models suggest that impacts accompanying accretion caused heating of Tethys's outer layer, reaching a maximum temperature of around 155 K at a depth of about 29 km. After the end of formation due to thermal conduction, the subsurface layer cooled and the interior heated up. The cooling near-surface layer contracted and the interior expanded. This caused strong extensional stresses in Tethys's crust reaching estimates of 5.7 MPa, which likely led to cracking.