Didn't notice when looking at the pool damage, but yea, with that huge agregate in the cross section, it looks like a dump of old concrete from when the house got built. Although I can't say I've studied at a lot of boulders when I was in the mountains (ski resorts, Grand Canyon, Black Hills, Slide Rock, etc.). I think we need more photos of your boulders (can you write FOH on them, so we know they are yours?).
