Exploration of the Canal of Xerxes, Northern Greece: the role of geophysical and other techniques

Abstract

The Canal reputedly built on the orders of the Persian King Xerxes across a narrow isthmus in northern Greece to allow his fleet access into the Aegean in advance of the Persian invasion of Greece in the early fifth century BC must have been a remarkable engineering operation for its time. Yet apart from a depression in the central sector of the isthmus, almost nothing of this canal is visible today, nor are there visible remains of building structures and harbour installations; what information there is about it comes from accounts by ancient writers, notably Herodotus, and nineteenth century travellers. This paper describes the results of a large programme of survey aimed at detecting this putative, now buried structure and ascertaining whether or not it was a canal across the full width (2 km) of the isthmus. Following a detailed topographic survey, resistivity soundings and ground-penetrating radar were carried out principally in the central sector of the canal; the latter detected successive infillings of the canal but neither its original sides nor its bottom. Seismic refraction and reflection measurements, on the other hand, provided decisive evidence for the canal's existence in the central sector, with strong support coming from the analysis of sediment cores: its depth there is 14-15 m below the present ground surface, with top and bottom widths of 25-35 and at most 20 m respectively. The canal's northerly course has been defined but less confidently, whereas to the south the picture still appears incomplete. The canal may indeed have been built across the full 2 km, but the alternative hypothesis that it connected with the sea at only one end and that there was a (short) slipway at the other end cannot be dismissed. Whichever model is correct, a crucial finding from the sediment analysis is that the lifetime of the canal was short.