Yes, it does beggar belief that these two cairns could predate this wall - which I would estimate at circa 1875, give or take fifteen years. I have excavated one of these cairns and it does go rather deep into the peat. Quite nearby there is a seam of eroding peat and, within that, a bed of tree fragments (Scots Pine). Many of these bits of Original Forest bear cut marks and, as the depth of this seam and the base of the cairn is at the same depth, I judge them to of a similar date - give or take two hundred and fifty years, say.

Rather than knock these strange cairns I would be grateful if someone could identify other similar ones. It is wrong to entirely dismiss the old drystone walling gangs as savage brutes. Probably you have to be there. From the given map reference find the trackway below - it's called the Warded Way - and use that to get from the built road to the site. It's under the Right To Roam access agreements.