Lost at sea: Identifying the post-depositional alteration of amphorae in ancient shipwrecks

Abstract

The present paper sheds new light on the alteration of archaeological ceramics buried in marine environments by analysing in detail a large dataset of Hellenistic and Late Roman Republican transport amphorae from 15 sites along the well-known ancient maritime trade route off the Dalmatian coast in southern Croatia. These include amphorae from shipwrecks, kiln sites and settlements. Ceramic petrography and instrumental neutron activation analysis (INAA) have been used to compare sherds of amphorae made in the same workshop, of the same fabric and origin, but recovered from both shipwrecks and terrestrial sites and were therefore exposed to different burial environments over two millennia. The integration of both methods permitted the identification of differential microstructural and geochemical alteration of the amphorae under the sea relative to those found on land. By applying principal components analysis and test statistics, we have detected enrichment of As, Ca, Na, Sb, Sr and U and depletion of Ba, Cs, K and Rb in amphorae from the marine environment, relative to those buried on land. The implications of the study are discussed in terms of the provenance determination of amphorae from submerged environments and the reconstruction of ancient maritime trade routes.