This beach is a spit - actually a tombolo. Whereas the main beach to the east appears to have an ample sediment supply and a fairly simple relationship to waves wrapping into the bay from the south, this western beach is confused by a lack of sediment and a more complicated, albeit less energetic, wave regime. The small barrier beach itself consists of a shingle ridge and a mixed beach of sand and scattered pebble.
Not to second guess the monks who retreated from Skellig Michael to build this abbey 800 years ago, but they seem to have picked a poor building site (at least in the long term). Bedrock ledges and a rocky lag on the foreshore probably help to protect this promontory a little bit, but it looks like that without the big concrete wall (which I'm sure was built much more recently), most of this site would be long gone.
I've got a lot more photos of Ballinskelligs - the beach, the McCarthy Mor Castle, and the Priory - over on the other blog.