Murray, I've dug a lotta holes down here in Florida and it's fairly common knowledge amongst us that the moon has an effect on either the pile of dirt you have dug up or the size of the excavated area. Sometimes there's not enough to fill in the hole to the top and sometimes you have to haul it away. Especially true when replacing hydraulic automobile lifts in service stations. We always made note of this odd phenomena as it meant more work for us. (i.e. either shoveling dirt back on the truck or finding a place to swipe a bit more from the customer's neighbor to finish the job)