Longitudinal and transverse waves

[Rashid101]

hey friends please solve my problem
Both longitudinal and transverse waves can propagate through a solid. A wave on the surface of a liquid can involve both longitudinal and transverse motion of elements of the medium. On the other hand, a wave propagating through the volume of a fluid must be purely longitudinal, not transverse. Why?

 

[crazy_photon]

I think because in the 'bulk' of the fluid there's no restoring force except to the compression -- hence longitudinal wave. At the surface because there's an interface, there's a restoring force that can support transverse oscillation to the direction of propagation.