7Sweetman, David. "Earth and Timber Castles- David Sweetman - The Medieval Castles of Ireland." Castle Duncan Forums. Web. 08 Apr. 2014. <http://www.castleduncan.com/forum/index.php?/topic/1305-earth-and-timber-castles-david-sweetman/>
The author describes a "ringwork castle" as "...in its simplest form, an area enclosed by a fosse and rampart. It has also been defined as having a minimum height of 2m above the level of the outside defences with the enclosed area disproportionately small compared to the massive enclosing elements."
Commenting on fort's abandonment and destruction, Professor O'Kelly noted, "The Annals of the Four Masters has an entry for the year 1116 which says that Toirdeal- bhach Ua Conchobhair made a raid in which he burned and demolished Boromha and Ceann-Coradh. If this can be accepted as a reference to the particular site under discussion here, the primary fort was still occupied in the early part of the 12th century and perhaps it was this very raid which brought about its abandonment, though the excavation gave no evidence whatsoever of any burning of structures within the fort." (O'Kelly, Michael J. "Beal Boru, Co. Clare." Journal of the Cork Historical and Archaeological Society 67.205 (1962): 13-14.)