These are toghers, a word borrowed from the Irish tóchar, meaning a causeway or road built across boggy ground by laying timber directly onto the soft surface. At Cooleeny townland alone, a field survey identified 44 of them, which gives some sense of how intensively this landscape was being crossed and managed during the Iron Age.

The survey, carried out by Gowen in 1999, found that most of the toghers were built using a combination of brushwood and roundwood laid together to distribute weight across the unstable ground. Six relied on roundwood alone, eight on brushwood alone, and one unusual example incorporated brushwood and gravel. What makes the Cooleeny toghers particularly striking is the variety of timber species identified across seventeen of the structures: alder, ash, birch, blackthorn, hazel, mountain ash, and willow. This is not a single material carelessly thrown down but a selection that suggests the builders were drawing on whatever grew locally and suited the job. Two of the toghers have been directly dated by radiocarbon analysis, returning Iron Age dates of 388 to 207 BC and 372 to 192 BC respectively, placing their construction somewhere in the centuries before the common era, during a period when Irish bogs were crossed regularly and purposefully by communities whose routes across the landscape we can still, in outline, follow.