Same here except I live in very fertile valley with limestone rock outcroppings and ground they call Karst which is a geological formation shaped by the dissolving of layers of soluble bedrock (limestone) to form caverns, caves and sinkholes. Anyway, the limestone doesn't move without blasting so we work around it. It is not uncommon to find an outcropping of limestone incorporated into the basements and cellars of local homes. Needless to say, we often concrete a fence post in because we hit a BFR while digging postholes. Temporary or moveable fencing is ideal for this area.