sentences:  The ice layer covering the lake is composed of water ice with 10 to 20% admixed dust, and seasonally covered by a -thick layer of ice.Scientists' consensus is that a layer of liquid water exists beneath Europa's (moon of Jupiter) surface, and that heat from tidal flexing allows the subsurface ocean to remain liquid.It is estimated that the outer crust of solid ice is approximately 10–30 km (6–19 mi) thick, including a ductile "warm ice" layer, which could mean that the liquid ocean underneath may be about 100 km (60 mi) deep.