Gardener vs. Rock: Rock Declares Overwhelming Victory

My first two attempts at planting my last Evergreen Sumac (Rhus virens) met with enough limestone that I had to make other plans: the first led to a Chinese Mahonia (Mahonia fortunei) taking the proposed locale, the second is still being pondered but will likely end with Cast Iron Plants.

Then came my third attempt.  And, of course, I discovered rock.

Fortunately my initial excavation had uncovered an edge, so I kept digging outward to find the other sides.  And digging...and digging...and digging.  Holy moly!

I thought I had unearthed large stones before in my garden, but now I realized they were just the appetizers.  This may well be the main course.  I finally found a second edge but, by this point, the stone measured nearly nine feet across the front.

And then, at the back, I discovered yet another thinner layer of rock on top.

Further digging allowed me to better define it's size - about three foot across the front.

Eventually I found the larger rock's other edge - but only to discover another rock laying immediately adjacent to it.

I'm beginning to be amazed that I've been able to plant anything back here - and worried that, even though I dug pretty deep when planting, the plants may still be sitting in soil that is too shallow.

Obviously my entire plans for the area are undergoing a massive rethink.  Everything is on hold as I continue to excavate my limestone layers.