A way to date stone fish weirs ? Some perspectives.

Stone fish traps and weirs are the most common archaeological remains in fluvial and coastal environments. In Brittany, almost 800 of them were identified by Daire and Langouët (2014). Usually, these are made of numerous erected stones, that more or less precisely outline an alignment. Dating these remains represents a real archaeological issue, since stone fish traps have been raised for millennia, presumably from the early Neolithic to the Middle Ages. However, it is also a challenge as there is no organic matter preserved in the core of these structures.

 

In this presentation, we assess the age of fish weirs found in Brittany by comparing their altitude with the sea-level rise estimation curve since the last glaciation 20 000 years ago. A software named CHRONOE was developed in R in order to improve the reliability of the data, among which tidal curves (García-Artola et al. 2018). Statistical analysis – using the R package ArchaeoPhases (Philippe and Vibet 2020) – of the ages determined by CHRONOE for a corpus of    diverse stone fishing weirs, identifies periods of intensification and rarefaction of fishing using such structures. Thus, it is possible to discuss the evolution of fishing practices in human societies along the coasts of Brittany.

 

This work is the first step of a PhD Thesis; it will be followed by direct dating of stone fish traps. Indeed, rock surface luminescence dating \autocite{soh12} has been shown to reliably estimate the last time a rock surface was exposed to light (Sohbati et al. 2012) has been shown to reliably estimate the last time a rock surface was exposed to light (Freiesleben et al. 2015). Therefore, it will be applied to a few of these structures, after careful selection based on their presumed age. The bottom surface of sampled rocks from fish weirs will be sampled for OSL intensity profiling and burial dating. The numerical absolute ages given by obtained with OSL will then be compared to those assessed with CHRONOE, to discuss the reliability of the underlying assumptions and refine the model. Eventually, CHRONOE may hold the potential to date any submerged object whose utility (or existence) is linked with the intertidal zone.

Keywords : geochronology, OSL, archaeology, fish weirs.

 

References

Daire, M.-Y., & Langouët, L. (2014). Se nourrir le long des côtes bretonnes : Réflexions à partir d'une analyse diachronique des barrages de pêcheries. Actes des congrès nationaux des sociétés historiques et scientifiques, 138 (2), 105133.

Freiesleben, T., et al. (2015). Mathematical model quantifies multiple daylight exposure and burial events for rock surfaces using luminescence dating. Radiation Measurements, 81, 1622.

García-Artola, A., et al. (2018). Holocene sea-level database from the atlantic coast of europe. Quaternary Science Reviews, 196, 177192.

Philippe, A., & Vibet, M.-A. (2020). Analysis of archaeological phases using the R package ArchaeoPhases. Journal of Statistical Software, 93, 125.

Sohbati, R., et al. (2012). Optically stimulated luminescence (OSL) as a chronometer for surface exposure dating. Journal of Geophysical Research: Solid Earth, 117, 2012JB009383.