Extract

McConnell et al. (2015) claimed that the absence of Middle Ordovician back-arc volcanic rocks in the Bellewstown terrane in the Irish Caledonides implies that the Tetagouche–Exploits back-arc basin never existed in Ireland. The emphasis on the absence of evidence surprised us, because ‘absence of evidence is not evidence of absence’. However, if they are correct, their interpretation has major implications for the tectonic processes responsible for the final closure of Iapetus.