The caves are a repository of deep time. Some of the formations in the older parts of the cave have been found to contain uranium minerals, which can be used by geologists in radiometric dating. One sample from these formations has produced an age of 320,000 years and, since the cave must have developed before any formations could grow, it may possibly be much older.
This region in the Fermanagh–Cavan borderlands, on the slopes and shadows of the Cuilcagh, is rich in prehistoric sites. Nearby, at the Cavan Burren Geopark, you’ll encounter Neolithic dolmens, Chalcolithic wedge tombs, and Iron Age forts. Here, however, there has been so far very little evidence of human activity at the cave until much more recent centuries. Though prehistoric human remains have been found within the cave, they are believed to have found their way into the cave by having been washed down the river, rather than having been interred like those found at Dunmore Cave in Co. Kilkenny.
In many cultures, caves are a liminal space. The cave mouth is a threshold between the world we know above, and the unknowable dark depths of the Underworld. That’s why they feature so prominently in some of humanity’s oldest tales. Like the Epic of Gilgamesh that was first set down around 1800 BC, and which tells the story of the Sumerian hero Enkidu who reappeared from a long imprisonment underground in the Netherworld. Similar journeys end as darkly for Orpheus, Hercules and Aeneas as they do for their counterparts in Finnish, Inuit, Aztec, Mayan and Hindu mythology. In Ireland, caves were also treated as a place of portent. Sites like Oweynagat and Dunmore Cave have many stories and folklore attached to them. Here at Marble Arch Caves the folklore suggested that the caves may be home to witches, ghosts or more worrying still, fairies, the daoine sídhe, (Irish fairies are not like Tinkerbell). With such folklore it appears that people largely kept their distance, though the caves were well known locally. In the early 18th century, Reverend William Henry ventured a little way into the cave mouth and described some of the features that he saw.