¹Harbison, Peter. Pilgrimage in Ireland: the Monuments and the People. Syracuse, NY: Syracuse Univ., 1992. 77, 182.
The journal Archaeology Ireland suggests a more humorous definition: "Gallarus: British Christians who settled in Co. Kerry in the 7th century driven mad by the ceaseless talking by the natives in odd accents promised God that they would build an oratory for him if he would do something about their endless talking. He did and they named it 'garrulous' but the natives had the last word as they corrupted it to gallarus over the years." ("Spoil Heap: A 'Dictionary' of Irish Archaeology." Archaeology Ireland 10.1 (1996): 36.)

²Harbison, Peter. "How Old Is Gallarus Oratory? A Reappraisal of Its Role in Early Irish Architecture." Medieval Archaeology 14 (1970): 34.
In 1756 Charles Smith reported that "some think" Gallarus may have been constructed using an earthen mold: "...a heap of earth was first raised, in the form of the inside of the cell, and that they built over it, and wedged in the key-stones at the top, over which are a range of loose stones laid like a ridge; and the structure being thus finished, they carried out all the earth at the door; and lastly, smoothed the walls on the inside with chissels, &c." (Smith, Charles. The antient [sic] and present state of the county of Kerry: Being a natural, civil, ecclesiastical, historical, and topographical description thereof. Dublin: Printed for W. Wilson, 1756. 192.) This book may be read in its entirety here.

³Rourke, Grellan D., and Jenny White Marshall. "The drystone oratories of western Kerry," in Marshall, Jenny White, Claire Walsh, Grellan D. Rourke, E. V. Murray, and Finbar McCormick. Illaunloughan Island: an Early Medieval Monastery in County Kerry. Bray, Co. Wicklow: Wordwell, 2005. 119-120.
The authors acknowledge that the stone oratories cannot accurately be dated. But they present structural evidence that Gallarus "...represents the final phase of the development of the drystone oratory." Citing the carefully chosen and worked stones that provide the maximum contact area for stability, and the fact that the lateral walls, unlike the gable walls, rise straight up for a meter before they begin corbelling inward, the authors conclude that these modifications are the primary reason why Gallarus is the only such structure still completely intact.

⁴MacDonogh, Steve. The Dingle Peninsula. Dingle, Co. Kerry, Ireland: Brandon, 2000. 175-77.
While the cross-slab beside Gallarus is common to Christian settlements from the seventh and eighth centuries, the oratory was likely built atop an earlier structure at this site. Its refined construction, principally its east window with the rounded arch, suggest a later date.
H.G. Leask in 1955 observed traces of "very fine lime mortar" used to fill the internal joints and provide pointing for the stones of the interior. (Leask, Harold G. Irish Churches and Monastic Buildings. Dundalk, Ireland: Dundalgan, 1955. 41.)

⁵Ua Danachair, Caoimhghín. "Some Primitive Structures Used as Dwellings." The Journal of the Royal Society of Antiquaries of Ireland 75.4 (1945): 210-12.
While some of the chocháin have been stabilized with mortar, or have even been roofed with concrete, this does not always bode well for their survival. "One old gentleman complained bitterly of these innovations and pointed out a clochán, on his property, which fell in shortly after being capped with concrete, as the extra weight was too much for the old stonework to bear." There are still dry-stone clocháin being built today.

⁶Cuppage, Judith. Archaeological Survey of the Dingle Peninsula: a Description of the Field Antiquities of the Barony of Corca Dhuibhne from the Mesolithic Period to the 17th Century A.D. Ballyferriter: Oidhreacht Chorca Dhuibhne, 1986. 286-89.
Peter Harbison quotes from O'Donovan's observations from his 1845 Ordnance Survey Letters: "This Cell or Little Chapel stands in a small graveyard now deserted. In this grave- yard to the North East of the building there is a standing stone with a cross sculptured on the West side of it. This stone is three feet six inches high, one foot one inch broad and four inches in thickness." (Harbison, Peter. "How Old Is Gallarus Oratory? A Reappraisal of Its Role in Early Irish Architecture." Medieval Archaeology 14 (1970): 36-37.)

⁷"Gallarus Oratory | Mysterious Britain & Ireland." Mysterious Britain & Ireland | Mysteries, Legends & The Paranormal. Web. 06 Oct. 2011. <http://www.mysteriousbritain.co.uk/republic-of-ireland/kerry/ancient-sites/gallarus-oratory.html>.
Harbison adds, "A detailed study of the literature on Gallarus reveals that the opinions of earlier authors were taken over almost in their entirety by later writers, who apparently never stopped to consider whether what they were copying from earlier accounts was founded in fact. The notion that Gallarus is one of the earliest church buildings in Ireland began with Smith in 1756 and is still current...these old ideas have cemented themselves into almost complete acceptance." (Harbison, Peter. "How Old Is Gallarus Oratory? A Reappraisal of Its Role in Early Irish Architecture." Medieval Archaeology 14 (1970): 47.)

⁸Petrie, George. The Ecclesiastical Architecture of Ireland: An Essay on the Origin and Uses of the Round Towers of Ireland. Dublin: Hodges and Smith, 1845. 130.

⁹Harbison, Pilgrimage 77, 82.
The author asserts that it is wrong to assume that Gallarus Oratory must necessarily be the first building to occupy its site simply because there were no resources for wooden construction nearby. "It is quite possible therefore that wood grew in areas where oratories of Gallarus type are found, and the argument that such oratories must have been the first churches built on the site because there could have been no earlier churches of wood is manifestly untrue. Similarly, the suggestion that Gallarus was contemporary with wooden churches in other parts of the country where wood was plentiful cannot be proved." (p. 44-45) Harbison continues, "my purpose in suggesting that Gallarus could be even as late as the 12th century is to abandon the age-old idea that the 8th century is the latest possible date. In the absence of a more reliable chronological pointer the date of Gallarus must rest entirely on circumstantial evidence, and remains an open question although I lean towards a date later than that heretofore accepted. But if Gallarus cannot be proved to date from the 8th century and could even be as late as the 12th, then there is no longer any reason to believe that it represents the oldest type of stone church in Ireland and the first stage in the evolution of Irish church architecture in stone." (p. 58)

¹⁰Harbison, Pilgrimage 181.

¹¹Chatterton, Georgina. Rambles in the South of Ireland during the Year 1838. London: Saunders & Otley, 1839. 133-35.

¹²Harbison, "How Old Is Gallarus Oratory?" 36.

¹³Hartnett, Henry. "Seamus Heaney's Poetry of Meditation: Door into the Dark." Twentieth Century Literature 33.1 (1987): 9-11.
The author quotes Heaney (a non-believer) in an interview saying that if all churches were like Gallarus Oratory, "congregations would feel the sense of God much more forcefully."

¹⁴Heaney, Seamus. Door into the Dark. New York: Oxford UP, 1969. 22.