Thinking about a small decorative pond. We do not have soil...we have rock. It is fractured limestone that can be dug/removed in large chunks. Once removed, you have a somewhat consistent depth shallow fractured rock depression. Water pours in between the cracks/voids so fast when it rains, it takes a absolute heavy down pour for any puddles to form...and if they do, its short lived. As a result, there are no natural ponds in my area.

So the question is, what the best approach to seal the cracks/voids between the rocks?

I have no knowledge of the problem that you face but someone will su before too long. Just wanted ta welcome ya to the forum.

Small and decorative.......Sounds like you need a liner.

Welcome to the forum!

FWIW they make kits for small ponds that include, among other things, liner and the underlayment. You might want to check them out.

small: 70 x40 foot, 1-4 foot deep
Irregularly shaped

There are multiple sites or small landscaping companies who could help you. Take a peek at pond liner inc, they have some kits that may be able to fit your needs.

Thanks for the helpful information.