Digging pond in shallow soil into rock advice please.

What happens if you hit rock when excavating your pond? In the video https://permies.com/t/170093/Hand-dug-pond-progress#1343313 Alex Moffitt posted on Jonah Bassmans's cool thread on digging a pond by hand, the presenter implies that you only displace the soil when making a new pond.  I'm thinking of making a pond on a plateau in my field, and I'm pretty sure I've only got about 18 inches of soil max. Really I'd like a habitat/recreation pond. I'm prepared for it to be just a recreation pond for the dog ;) but I'm still envisaging having to dig out some rock. We do have a little digger (2.4 Yanmarr) and the rock is typically quite fragile - called 'rotten rock' because it breaks up so well, so I think I'll be able to dig through it fairly easily. Is there something else I should be aware of about moving the rock? I know it makes another layer of material to manage, and that a keyway would need to lock into the rock on the downhill side. I'm prepared to bring in clay since I have none to speak of to seal it here. Is there something other than the shear hard work of rock breaking and moving?

Nancy,

If it is a small pond, have you considered renting a jackhammer?  I once used one to break up a cement pad about 5’ wide by 25’ long.  It took an afternoon and it was loud but it was not terribly difficult.  That cement was some hard stuff, and if your rock is indeed rotten (I have seen such rock and I have an idea of what you are talking about), I would think the jackhammer would cut through fairly quickly.

Just an idea,

Eric

Thanks Eric,
We actually have a small Kangoo type hammer somewhere (although I may employ my bigger half if it comes to that, he'll enjoy getting his tools out!) In our experience the digger will cut through the rotton stuff we have with a narrow bucket without too much effort. every now and then there is a hard layer of basalt, and then we would be in trouble.
If it's just the effort involved, then I can cope with that. I'm thinking the rock will give the dam a bit more stability to softening with seepage also.