Dry tears
The previous chapters give enough information to swim into our visions, with a piece of driftwood in shallow waters with cockles... The vision of the pebble may be particularly personal: for example, thinking about Naranath one may already be drawn into a cosmos of ideas, from classical philosophy to all sorts of other shimmering psychedelic thoughts.
What we find now in the third strophe is "a bare winding carcass", that is "stark".
The lyrics actually become stark, as the harsh word "carcass" comes suddenly, but it makes clear that the song is not just an idyllic description of a shore: we understand there's something sad, too.
Thinking about Last Island, it would be normal to imagine the carcass of a man. The flies around the carcass, which "scoop up meat", could suggest an even starker image: at first sight it's almost repugnant, like a scene from a splatter movie. The "dry tears" at the end of the strophe don't soften the starkness too much, and could even be interpreted as tears of torn flesh. We could find a similar "going into the flesh" image, still at first sight, thinking about the "blanched bones" in Syd's song "Wolfpack", where there are tears too, this time more obviously as tears of sadness and grief:
Tears
The life that was ours grows sharper and stronger away and beyond
Short wheeling, fresh spring
Gripped with blanched bones, moaned magnesium, proverbs and sobs