I think , Kaye, the first action is to get two things started as PRE-conditioning on the soil. As much mulch as possible (keeps a bit of moisture in the soil and allows that hard soil to soften-slightly). And perhaps throw down a cover crop that will break up the soil and loosen the rocks, such as daikon radish. Not really intended to harvest, but intended to leave in the soil. When you are ready to actually grow other things , you will need to mow or cut the tops off, let the radishes rot in the ground and it will break up that clay and loosen rocks for you. The following year (or if you are really industrious, maybe the same year) plant a few trees that , again will start to break up hard clay with their roots, perhaps nitrogen fixers to add to the soil and begin to provide tiny bits of shade to keep the soil softer. After a few years of mulching, cover cropping and tree growth, you may be able to describe quite a different soil condition. I would leave most rocks there unless it is just not possible. Then use the rocks you take out to create rock features that allow you to plant plants behind them for wind protection or...add soil over a pile of rocks and plants IN them for plants that need a drier root area (like Mediterranean type plants-olives or citrus) It is ALWAYS in the preparation. The more thoughtful planning and prep, the easier the task later.