chicken run/gravel boards

[fishpond]

Dear all
As some of you may be aware, I am in the process of building my run.
Started to dig a trench down one side(25ft) to take the mesh skirt and have now got a bad back and a trapped nerve and I have only gone down 8".
Decided last night to use slabs instead,.
Change of plan this morning though--now thinking of using concrete gravel boards 6ft x 1ft over the top of the mesh.(In case there is confusion these boards will be flat on the ground, not vertical)
With your wealth of experience, would these be sufficient at 1ft to stop foxy getting into base of run?

[Suechooks]

Someone gave me a couple of these and I put them as "thresholds" inside the run gates. They prevent (hopefully) Mr F. Ox and help prevent the entrances getting muddy. They are REALLY heavy though so watch you back if you already have a problem! Mine have been in situ about 4 -5 years along with all sorts of other stuff (sheets of weld mesh, concrete posts, slabs) around edges of the run and so far no issues with fox so it should work ok if you're sinking the wire as well.