These artificial islands, built up from timber, stone, peat, and brushwood, were constructed from the Bronze Age through to as late as the seventeenth century, and served variously as defended homesteads, places of refuge, and high-status residences. The Mayo landscape, threaded with lakes and bogland, was particularly hospitable to this kind of settlement, and dozens of examples survive across the county in varying states of visibility.

The crannog at Cornagashlaun is recorded as a monument, though the details of its construction, period of use, and any excavation history remain largely undocumented in what is publicly available at present. What can be said is that Mayo crannogs of this type typically appear as low, rounded islands, sometimes still ringed by the remains of a timber palisade beneath the waterline, and that their survival often owes something to the preserving qualities of the anaerobic lake sediments around them. Without more specific information on Cornagashlaun, the site sits in a category familiar to anyone who studies the Irish archaeological record, known, mapped, and protected, but not yet fully described.