What they had disturbed was a horizontal-wheeled water mill, a type of early medieval milling technology in which the wheel lies flat beneath the millstone and is spun directly by water channelled through a penstock, a wooden trough that directs the flow onto dished paddles. Unlike the more familiar vertical wheel, no gearing is required; the paddle shaft connects directly to the millstone above. The design is simple, efficient, and, as this site shows, remarkably well-constructed for its age.

Subsequent investigation by C. Rynne, published in 1988, revealed the full layout of the mill in careful detail. The penstock, 2.3 metres long and 0.15 metres wide, had its fore-end cut at a downward angle of 25 degrees to direct water onto the wheel, and its upper edges were rebated to take a lid, with one of the accompanying timbers possibly pressed into service as a makeshift version of that lid. The headrace, the channel bringing water to the mill from the nearby stream, was traced for four metres to the west and ended in three neatly cut rock ledges that stepped the water down onto a rectangular platform cut into the bedrock. That platform, roughly 3.8 metres east to west and 2.5 metres north to south, supported the wooden foundations of the wheel-house itself. Two substantial sole-plates defined its north and south walls, and inside lay flooring planks, the hub of the horizontal wheel, and eight of the original dished paddles. The tailrace carrying water away from the mill was also cut into bedrock, and a large fragment of a runner millstone, the upper stone that rotated against a fixed lower stone to grind grain, was recovered from it, with a projected diameter of around 0.7 metres. Dendrochronological dating, tree-ring analysis applied to the preserved timber, placed the mill at around 833 AD, locating it firmly in the early Christian period in Ireland when horizontal mills of this kind were widespread. All the recovered timbers were taken to the Department of Archaeology at University College Cork for preservation. Nothing visible remains on the ground today.