Gunner is so obsessed with cement/rocks. He will sniff the foundation like crazy. I recognize the potential danger of this, so what can I do about it? Is there a simple solution? Maybe, something is missing from his diet?
I don't know of any solution except to watch them when they are outside or crate them when you can't watch them.
Short of that, when you train your dog, be sure to train him to "leave it" and "drop it", along with "come" and "stay"...those commands will help you with just about any behavior problem.