Bentonite to seal a pond, with rocks

Hi,

I want to create a pond using bentonite clay. I have read enough so that I have an idea of how to achieve it. But there is one question I can't figure out the answer to.

Is it possible to create a proper seal where bentonite meets rock? Where the bentonite only partially covers the rock, so that the top part of the rock is exposed?
Or will the water get between the rock and the bentonite, and destroy the seal?

Se pictures below.

Eivind, welcome to the forum!

We tried to seal our pond with bentonite and we were unsuccessful.  

I am assuming it was because we have lots of rocks.

I wonder if the bentonite clay is added thickly that this might work?

I hope someone will give you a better answer.

Some background knowledge
"Bentonite is a clay consisting mainly of smectite minerals, commonly formed by decomposition of volcanic ash or tuff, or sometimes from other igneous or sedimentary rocks.
Bentonite is a very plastic clay that shrinks (or swells) markedly in response to the removal (or addition) of water.
There are three main types of bentonite:
high swelling (sodium)
low swelling (calcium)
moderate swelling (intermediate sodium-calcium) bentonite.
The sodium bentonites are the most useful because of their greater swelling capacity.
They are used mainly as bonding clay in foundries, in drilling mud, in animal feed pellets, and for civil engineering "applications"

I am guessing at the moment that large loose rocks dont allow the swelling required to actually create the seal.