Heres a reference to it

In the townland of Derrycorr is a curious ancient road, formed of large oak trees placed longitudinally with planks of cleft oak laid over them transversely, and covered with sand and gravel about a foot deep, forming a road across the bog at a considerable depth below the surface, and in an excellent state of preservation, though, from the accumulation of superincumbent bog, the timber must have remained there for many centuries. The sand and gravel were evidently brought from Lough Neagh, from portions of petrified wood and chalcedony being intermixed with them; and the road, which was recently discovered while cutting turf, is traceable for nearly two miles to the Lough, and is supposed by the peasantry to have been constructed by St. Patrick, for the purpose of conveying sand for the building of Armagh cathedral. In the year 1815 a golden gorget, weighing 12 oz. and richly chased, was found in one of these bogs, and was purchased by the Rev. F. Gervais, rector of the parish.

.....my memory is that it predated st patrick by more than a thousand years.