Beneath still waters lies a bed of shifting stone

DDWs March 2014 Vocabulary Challenge - Lentic

When I read the challenge word was lentic, the first image I had was of pebbles underneath water - an image from hearing Iain Macdonald sing, years ago, a particular track I've played a million times since. The song is called "Bed of Shifting Stone", and is from the album Beneath Still Waters.

You say that words weave pictures in your mind
and give you comfort when your alone
but just below the surface, undercurrents flow
beneath still waters lies a bed of shifting stone.

But the portrait of a man
are lines of a page
a distant figure seen but never known
we never know the painter, just the work he shows
we never know the fiddler who puts music in the bow.

I couldn't find a video of him singing this track - but this one is also from the same album.