I certainly think it's carved, but why carve that 643m up a mountain? The stone is Wicklow granite and does not weather very much, so I don't think that's a big indication of age.

One thing that would bother me more than anything is that it's above the peat, which is probably about 6 foot deep up there. But then there has been a lot of peat erosion up there over the last 20 years so it could have been buried until recently.