11Skellig Michael World Heritage Site Management Plan 2008 – 2018. Rep. Dublin: Department of Environment, Heritage and Local Government: Office of Public Works, 2008. 11.
The death of the monk is recorded in The Martyrology of Tallaght, written near the end of the eighth century by Mealruain. The Annals of Ulster provides the account of the plunder of the monastery by the Vikings. The Annals of Inisfallen refer to the death of Flann, son of Cellach, abbot of Scelec in 882.
It is clear that St. Michael's Church is of a later date due to its mortared straight walls and large stones, unlike the dry-stone corbeled oratories and beehive cells, the earliest structures of the monastery. (Horn, Walter, Jenny White Marshall, and Grellan D. Rourke. The Forgotten Hermitage of Skellig Michael. Berkeley:  University of California Press,  1990. 10-11.)
According to archaeologist Michael Gibbons, who has claimed the discovery of traces of previously unknown, and possibly earlier sets of steps on the island, the monks could have moved into a "pre-existing citadel." ("Skelligs Settlement May Predate Monastery." Clerical Whispers. 11 Aug. 2010. Web. 28 Aug. 2013. <http://clericalwhispers.blogspot.com/2010/08/skelligs-settlement-may-predate.html>.)
Skellig Michael is not alone as a monastic site named for the saint of high places. St. Michael's Mount in Cornwall and Mont St. Michel in Brittany come to mind, both Celtic in origin and both homes to monasteries.