There are at least two types of surface waves: Rayleigh and Love. Advected motion for a Rayleigh wave is elliptical.
Hang on... I failed to realize how complex the problem is. Segel's "mathematics applied to continuum mechanics" has *several* chapters on surface waves, and apparently draws a distinction between Rayleigh/Love waves (surface waves that exist in an *elastic* medium) and surface waves that propagate in a fluid. Slattery's "Interfacial transport phenomena" has an impenetrable section at the end... ugh.
I would start with the website, and if that's unsatisfactory, go to Segel's book (it's excellent), or alternatively, if you find a decent book or paper devoted to wave motion:
Sure enough- the results are found on page 41 of Stoker's book (eqn. 3.1.20), which also has a a set of images taken from the literature clearly showing the motion.