Oak Island Archaeology Update: Is there a tunnel on Lot 15?

In the wake of the first episode of the season 8 of The Curse of Oak Island (COOI), there is renewed speculation about tunnels, this time focusing on a channel-like structure on Lot 15, an area just to the west of the suspected Money Pit. Toward the end of season 7, the COOI team thought they might have found a secret tunnel leading from the basement of Samuel Ball’s house to the Money Pit area. Closer inspection shows it to be almost certainly a drain, either domestic or agricultural, of a type common in the 18^th and 19^th centuries. So what about this new channel structure? Is it the entrance of another tunnel to the Money Pit?

Channel-like structure on Lot 15

It is certainly larger than the drain at the Samuel Ball house, and at a steeper angle. Its sides are clearly built up and reinforced with rocks. The team found at least one fragment of what looks like slag in the channel. Slag is a by-product of the refining of ore to produce metal. Interestingly, the soil at the top of the picture and along one of the walls of the channel seems significantly reddened.

This is sometimes referred to as rubefied soil, and is often interpreted as evidence of heating. It is hard to tell from this picture whether it really is rubefied soil, and recent experiments have shown that the relationship between heating and rubefication is not as straightforward as we sometimes assume in archaeology, but, it could be an indication of heat.

Given the presence of slag and the possibility of rubefied soil, there are three main likely archaeological explanations for a structure like that on Oak Island, and all three are mentioned in the episode. Unfortunately, none of them need to involve a buried treasure.

The structure could be the remains of a foundry of some kind. It would have to be a very small-scale or occasionally used foundry. Foundry sites are usually covered in mountains of slag, so unless the slag heaps are well separated from the pit, or unless the site was thoroughly cleaned up at some point, I think it is unlikely to represent a foundry, and almost certainly not a commercial one.

It could be related to some forging operation, which can also produce small amounts of slag, and which is found in many contexts like 18^th and 19^th century Oak Island. Forging, however, is not often associated with large flow-channels like the one found here. However, some fairly large-scale casting, of lead, for example, could be.

The third possibility mentioned in the episode is that this is a tar kiln. Those usually do have large flow channels, and there is plenty of heating going on, which would account for the rubefied soil. Tar production was an important industry in the region for a long time. It was practiced at both industrial and domestic scales, for various commercial and household needs. However, as can clearly be seen in these images from a recent Andreas Hennius article, the tar is usually quite visible.

There is definitely an interesting archaeological question here. Someone, at some point, clearly made a flow channel, and whatever they used it for probably involved some serious heating. It left behind at least a little bit of slag, and no immediately visible tar. I hope that later in the season, we see what is at the lower end of the flow channel. It may reveal either tar or slag, or perhaps something else entirely. I especially hope that we get a carbon date. In any case, eventually, the archaeological reports will tell us.

Ever hopeful, the COOI team suggest that a tar kiln makes sense, if someone was depositing a treasure and had to build a very deep shaft to hide it. They would need to treat wood, etc. Yes, this is all true. But as always with the COOI interpretation, it certainly doesn’t need to be true, and isn’t actually likely to be. There are several simpler explanations, all involving known social and historical processes in the region.