I'm building a deck on my vacation, spending about as much time correcting mistakes as actual building.
One of my mistakes was apparently where I chose to put the footers.
That's a 5 gallon bucket for scale. The pile of rocks is about 2/3 of what I had to remove in order to dig 2 holes 40 inches deep. After about 16 inches with the post hole digger, it was pretty much continuous rocks, all removed by hand once loosened up with various tools. When I pored concrete for the first hole and went to backfill, I didn't have enough dirt...Notice that the rocks are fairly clean. Old as our house is, there was apparently something on the lot before, and they built over rubble.
Bella is fascinated by the big holes in her yard. Before I got the camera out, she stuck her head in the form up to her neck. 20 minutes after Home Depot closed, I discovered I'm a bit short of the concrete I need, so I covered the hole with a tarp. She was still circling the hole with her ears forward, looking puzzled.