Clay- Good for Sculpting. Bad for Plants.

Yesterday as I dug the two holes needed to plant my blueberry bushes I reconfirmed the knowledge that my ground is all clay.  I mean I knew this, but I've been concentrating on digging around in the beds in which have been maintained in the past.  This soil is light and perfect making it hard to imagine that a mere 6 inches below the surface everywhere else in my yard is thick with clay.  I literally could take the clay out of the ground here, mold it and fire it.  It is that thick.  My goal is to eventually turn all of this clay land into viable land to plant.  Until then, I see a lot of pottery in my future ;)