Historic fishing bait tanks lead to recording of unusual beachrock, raising questions about coastal erosion

A few months ago, in response to reports of presumed burial ‘cists’ eroding out of the cliff face in Foxton Bay on the Northumberland Coast, a mini rescue excavation was undertaken by Northumberland County Council Archaeologist Nick Best, Northumberland Coast National Landscape Officer Sarah Winlow and volunteer Coast Path Warden Mark Stevenson.

Burial cists are stone-lined graves usually dating from the Bronze Age but also the early medieval period. What was found in this investigation included the stone-lined pit previously recorded by AONB Officer Jessica Turner back in 2013. There was a second pit of the same construction immediately adjacent to the south, which had been newly exposed and was a fresh discovery for 2024. It appears there is also a third pit heading back into the cliff, but this could not be investigated further due to it being too dangerous under the slump of the cliff.

These pits are thought to be bait or fish tanks from the post-medieval or modern periods rather than burial cists. Key features of the tanks are side and base slabs made of shale and a thick clay lining. They are around 1m x 0.5m and an almost oval shape and have no top slabs.

As for further insight into their form and function, we are grateful for assistance from Adrian Osler, local resident and a former Maritime Curator at Tyne and Wear Museums, who drew our attention to a 19^th century reference to an inshore, coble fishery being established for the largely land-locked parish of Lesbury in the locality of Whaw Burn in the 17th century.

Adrian explains: “In the absence of direct evidence as to the purpose and date of these structures they are best considered reductively in respect of known historic shoreside activities, which could include bait storage, live catch storage or preserving lines and nets.

 "An association with the pre-industrial, coble-based inshore fishery seems possible but, if so, then these two structures are of a previously unknown regional type to me... they might plausibly have served for small-scale bait storage, but in respect of their size and positioning (vis-à-vis the tidal range) the holding of live catch seems less likely. Usage for fishing gear preservation seems remote since there is no apparent method of heating the structures’ contents and no surviving traces of tanning liquor.

“The principal baits used in inshore longline fisheries were limpets and mussels, either of which might convenience the fisher if held in large numbers in short-term storage in water. For example, ‘Bait [storage] pits’ cut into bedrock have been reported from Cresswell.”

The position of the tanks is puzzling. Tanks for bait or fish would obviously need to be on the shore, with the cliff behind them. Sarah adds: “What we were confounded by is the amount of material above the features - the boulder clay cliff here is over 3m in height and coastal erosion is causing it to slump.

“When we were on site digging, we heard lots of stories from passers-by about the rate of erosion of this part of the coast – and we know that the Northumberland Coast Path now follows the beach and the golf course have had to replace their fence periodically. Interestingly, one gentleman told us the Duchess of Northumberland had a cabin on this part of the cliff in the early 20th century which has long been lost to the sea.”

We called in a geologist to get a better understanding of coastal erosion processes. At our request, Northumbrian Earth geologist Ian Kille visited the site and has kindly provided a summary of the geology and outlined potential site formation processes.

The dig revealed the tanks were cut into ‘beachrock’, which Ian informs us is an unusual formation of laminated sand and seashells. There is a possibility the beachrock is man-made and could’ve been a mixture of beach sand and lime to stabilise the bait traps. But the assumption we’re working with is the beachrock offers evidence that the high tide mark in this location was at one point slightly further in land than today. So, the cliff line has moved and changed shape as it has eroded and has, in more recent times, slumped forward over what was shoreline.

The occurrence of beachrock is rare. Ian explains: “This layer of beachrock is a surprising as beachrock usually forms in tropical and sub-tropical environments, albeit it has been recorded further up the coast at Cocklawburn and at other locations. It can be ruled out that this layer was formed as part of the glacial sequence as temperatures would have been too low and sea level would have been much lower. Its position implies it was formed at a time when sea level is higher than it is now. There have been fluctuations in mean sea level in post glacial times which may account for this. This can only narrow the timeline for beachrock formation down to between approximately 1000-6000 years ago.”

Our current hypothesis is that the tanks were cut through the layer of beachrock at some point between the 17^th and 20^th centuries, when the cliff must have been further back although it is possible the tanks were cut into the foot of the cliff that had already slumped. In more recent times, the cliff has slumped further, and only in the past decade or so has more active coastal erosion freshly revealed these historic features.

The spring tides have damaged both exposed pits, and so our mini archaeological excavation was timely. In the past few weeks, the rate of erosion seems to have to slowed and the site now appears to be stable and covered once more by cliff slump. Thanks go to residents and our superb National Landscape Conservation Team Path Warden, Mark Stevenson, for keeping a close eye on this exciting site.