Here's what the tree looked like before it was removed.

And that leaves me with the following to work on:


And in particular the stump.

I expect to dig around this until it's isolated and then break it up into smaller pieces to get it out.
After a couple of days of digging, I have exposed a couple of big rocks in a 5 foot by 7 foot hole. I managed to pry the small one out and put it on the stump to get it out of the way. I pried another larger one up on top of another. I may need to break these into smaller chunks to make them manageable.

Under these rocks, about 21 inches from ground level, it appears I have a solid, smooth unbroken layer of rock, so that's about as deep as I can go.
After this work, it has rained, so I can't really do anything more until it dries up. And Spring Break is over, so it's back to digging only on the weekends.