Jim Elbrecht wrote:

OK- so then I saw an article online that proposed mortaring a band of
round stones across the slope to hold the beach from slipping lower.
I'm in NY so I'm always conscious of frost heave and don't like the
idea of sharp broken edges of mortar on my pond liner. [it will be 45
mil EPDM]

I've been looking unsuccessfully for something online that discusses
doing the same thing with silicone

have you ever looked at the instructions for silicone cement? "Not for use
below the waterline". Paradoxical as this sounds, as it's used for
aquariums, it's true. Siliconing stones in a wet environment is useless.
I tried it for a reef in my cichlid aquarium, with disastrous
consequences... It works for holding glass plates together for two
reasons - they're _very_ smooth, and only an extremely tiny bit of the glue
is exposed to water.

or some flexible cement.

"Stuff" - polyurethane foam - works well, but should be painted to keep it
from sun exposure. It might be sufficient just to sprinkle sand over the
exposed foam, before it cures.
--
derek