My older dog ate a bone on the gravel and  my 11 week pup started eating the gravel where the bone had been.Have now disinfected the area but he is still eating gravel.It has been coming out the other end but this is still worring me, is there anything more that I can do?

You could try spraying bitter apple on the area (available from vets).
It depends on the size of the gravel..but if he shows any signs of sickness, loss of colour, diarrhoea etc (or, you just want to ease your mind) then I would suggest a quick trip to the vet for an Xray. Chances are the bits will go through safely, but you never know.