Need confirmation for supports to Ledge

I'm in the process of estimating a deck which will be basically set upon a sloped edge of ledge in the backyard of the homeowners. My thinking is to hammer drill some holes about 4" deep and epoxy the rebar pins in place. The pins will extend up about 8-10" and I'll tie some horizontal pieces to help keep the concrete support together.

Then I plan on forming some 8" square boxes that will conform to ledge slope and be about 8-12" high overall. The overall weight on these supports will be minimal per square ft. They'll be supporting a 4-6" x 20' platform and fro there some steps going down.

I'm heading to Cape Elizabeth this afetrnoon and take some pictures which I'll post tonight so as to give you guys a better perspective of the lay of the land. But in the meantime, is the approach above more or less the correct one when tieing into ledge? Just never had to do it before.

My only concern would be "shale ledge"

Dave...GBAR...Ron...Jaros...anyone. Your thoughts?