Characterising the degradation of leather through the decades: Evidence from 50 years of excavations at Vindolanda Roman fort

Vindolanda Roman fort is an archaeological site preserved with both anaerobic and waterlogged deposits which is undergoing rapid changes due to extremes in climate change. Excavations began in the 1970s, uncovering some of the greatest finds from the Roman Empire, including organic artefacts of leather, wood and textile. The Vindolanda Museum holds nearly 7500 leather objects, including shoes, equipment, horse tack and manufacturing waste. Leather is an organic material that is vulnerable to rapid environmental change which impacts on its in-situ preservation. In this paper, we present data obtained from archaeological leather recovered during excavations from 1970 to 2023. The leather was subjected to a multi-analytical approach including Scanning Electron Microscopy (SEM), portable X-Ray Fluorescence (pXRF) and Fourier Transform Infra-Red (FTIR). Visualisation (100 μm–20 μm) using SEM indicated changes of ordered collagen fibrils in the leather discovered in the 1970s and 1980s to more fragmented, less ordered collagen fibrils from leather recovered in more recent years. These structural changes clearly indicate increasingly poor preservation for in-situ leather artefacts recovered from the site. Finally, the evidence presented challenges the idea that buried archaeological remains are ‘safe’ and that we should reserve sites for a future that may bring better scientific opportunities. If archaeological deposits are proven to have an increasingly limited lifespan, the strategies for their recovery, recording and analysis need to consider moving from ‘preservation in-situ’ to ‘rescue before loss’.