I don't understand the stones significance, surely whoever Adam & Eve are they will use other stones? Maybe it goes like this:
Eve: Ok Adam, time to die....
Adam: Yeah ok Eve, let me just get the stones......Eh? Hold on a sec, where are they?
Eve: Well that fella Jacks got them hasn't he?
Adam: Who? Jack? You mean that bloke from the future?
Eve: Yep. Well we'll just have to stay alive now, Go and tell Rose & Bernard to put the kettle on.
I suppose it could mean that Jack is Adam of course. Or has he created a time-loop-paradox-thing by picking them up? Also, we haven't seen the stones since he picked them up have we?