This is a togher, a type of wooden trackway used in early Ireland to allow passage across terrain that would otherwise have been impassable, and the example found here is about as elemental as they come.

The Cloonbreany togher is classified as a class 3 construction, meaning it was built using roundwood and loose brushwood rather than the more elaborate carpentry seen in some other examples, where split planks or pegged timbers were carefully assembled. At roughly 1.75 metres wide and only about 15 centimetres deep, it was a practical, minimal crossing, wide enough for a person or perhaps a laden animal, but not engineered to last beyond immediate need. The main timbers were birch and alder, both species well suited to wet environments. Alder in particular is known for its resistance to decay when kept permanently waterlogged, which is part of why these structures survive at all. The work of identifying and recording it was carried out by the Irish Archaeological Wetland Unit at University College Dublin, a research body that systematically surveyed Irish bogland for exactly this kind of perishable but revealing evidence of early movement and land use.