The criticism of the date of the olive tree branch from Thera offered by Cherubini et al. (above) has to be fully supported. The attribution of the branch in question to the late part of the seventeenth century BC is by itself not unexpected, as most of the other radiocarbon dates of short-lived samples from the site of Akrotiri fall into the second half of that century. The attempt to produce a wiggle-match drawn from a succession of non-existent tree-rings in this branch, and to fit such a result into the general calibration curve to give the illusion of precision, however, does not pass the scientific test. Olive trees do not develop annual tree-rings. Furthermore, no proof could be produced that this branch was alive during the eruption. The olive leaves found in an underlying horizon had no connection to the branch and could have been preserved in dry ground like this for ages before the eruption occurred. The remains of the branch were not found in a tight-fitting context but in a much larger cavity and it seems that the outer part of the branch, including the bark edge (waney edge)—contrary to the assertions of Friedrich et al. (2006)—are missing. The other issue in this scientific discussion is that dating the Thera eruption by 14C is much more problematic than is acknowledged by scientists, since it clashes distinctly with historical and archaeological dating.

An olive branch is traditionally a symbol of peace, but not necessarily in the context of chronological problems in the Eastern Mediterranean region and the Near East during the second millennium BC. Cherubini et al. (above) strongly attack the radiocarbon dating by Friedrich et al. (2006) of an ancient olive branch, buried by volcanic tephra during the Minoan Santorini eruption. The criticism stems from their investigation of growth rings in modern olive trees on Santorini. The authors attempt with additional arguments, beyond their botanical investigation, to defend the traditional low chronology of the Santorini eruption of around 1500 BC. However, they ignore other crucial publications with radiocarbon dates concerning the Santorini eruption. In this response, we evaluate and negate their main arguments, and present our own conclusions.

Olive wood is difficult to date for a variety of reasons, the most important of which is that one cannot tell visually what is an annual growth increment (usually referred to as a ‘ring’) and what is a sub-annual growth flush of which there may be any number in one growing season. (I have been able to count a dozen or more flushes in olive wood where the end of the growing season was somewhat more clearly marked than usual.) If one cannot determine the ring boundaries with certainty, one cannot do tree-ring dating, period. For Egyptologists reading this note, acacia is just as bad, and for the same reason. For 25 years I had a couple of sections of olive wood in my dendrochronology lab. Every term I would challenge students to tell me how many rings there were on them. No two students ever came up with the same answer and neither could I. An inspection of two different radii on the same piece also yielded widely varying results. (A side issue, not relevant here, is that the size of the ring in an olive tree does not necessarily reflect climatic conditions but rather the energies of the farmer or gardener who brings water to it. Thus olive is useless for purely dendrochronological cross-dating purposes.

Paolo Cherubini and colleagues have demonstrated convincingly that the identification of olive wood tree-rings from Santorini is ‘practically impossible’. Thus, the single piece of evidence that might have persuaded some archaeologists to support the ‘high’ 1613±13 BC date for the Theran eruption is hors de combat. The Theran olive-tree branch has gone the way of the Greenland Ice Core results of similar date and which enjoyed a similar devoted following until shown to be from a different eruption. Taken with Malcolm Wiener's explicit exposé of the myriad shortcomings of 14C dating, especially for this time period and event, these results take us back to where we were before the ‘radiocarbon revolution‘, when the largest Holocene eruption in the ancient world happened as Minoan Crete enjoyed wideranging influence, perhaps even control, over the Aegean, when Late Minoan IA pottery styles proliferated, and Egypt was in the early stages of its New Kingdom period (Wiener 2012, 2013).

We are glad to see that our paper has stimulated a lively debate, and we acknowledge the appreciation of our work by Bietak, Kuniholm and MacGillivray as well as that of those who oppose our hypothesis (Bruins & van der Plicht, Friedrich et al., all above). The enigma of the dating of the Santorini eruption is a long-lasting one, and because of its bearing on the dating of several eastern Mediterranean civilisations, has attracted significant attention. The potentially great importance of the Santorini olive branch used by Friedrich et al. (2006) was that it came from the site itself, and possibly belonged to the destruction layer. As such, the sincere and serious attempt to date it made by Friedrich et al. (2006) should be appreciated. Unfortunately, large olive branches may exist as dead limbs for a very long time and thus represent earlier periods.

The temporary exhibition ‘Viking’ was on show at the National Museum of Denmark in Copenhagen from 22 June–17 November 2013, and will be on display in London from March–June 2014 and Berlin from September 2014–January 2015. The exhibition is accompanied by a catalogue, titled Viking, edited by Gareth Williams, Peter Pentz & Matthias Wemhoff.