Thursday, November 10, 2011

Davy Jones' Locker

An Open Letter to LCCHP and the Organizers of "Keeping the Lid on Davy Jones' Locker"
by Tom King

It would be nice to see someone put on a useful conference about the treatment of deep-water shipwrecks, but I have to be skeptical as to whether Keeping the Lid on Davy Jones' Locker: The Protection of Underwater Cultural Heritage from Titanic to Today will be it. I fear it will feature only the usual breast beating about how shipwrecks should be left alone and salvagers are inherently evil --- accompanied by the legal community's pondering on how to accomplish the former and castigate the latter.

Here are some facts that are unlikely to be discussed at the session:

1. Shipwrecks are deteriorating, both from natural causes and particularly as a result of modern methods of fishing, which plow up the bottom as effectively as agricultural land-levelers have torn up the Mississippi Valley.

2. Academic institutions and museums lack the financial resources to excavate everything that's being destroyed, or even a small percentage of it.

3. There are commercial salvagers who conduct very high quality archaeological excavations, and who have technological and financial resources that the academic community can’t touch (See, for example, the two recent publications by Odyssey Marine Exploration here and here --- which are substantial archaeological survey and site reports, some of which also document my point #1 above).

4. The only difference between such “salvage” and the work of academic underwater archaeologists (other than that, in my experience, Odyssey at least does better work) is that a percentage of the recovered material gets sold after it is described and analyzed.

5. Odyssey at least has rather strict protocols governing what can and can't be sold; what gets sold comprises mostly manufactured items of limited research interest;

6. We archaeologists used to claim that we were interested in the data from sites, not the goodies. The violent and near-mindless standard archaeological reaction to responsible shipwreck salvage proves that we've been dissembling all these years, or simply don't understand our own motivations.


This is just about the most sensible and forthcoming comment I have ever seen from an archaeologist regarding private exploration of "archaeological artifacts."

Those artifacts presently underwater are not the only ones that are rapidly deteriorating. A great many artifacts which are discovered on agricultural land are in the "disturbed zone" of tilled soil, which is how they have come to light since time immemorial: first from being turned up by farmers' ploughs, more recently from blips registered when their fields are walked by metal detectorists (whose electronic equipment actually does not penetrate to a depth very much greater that the depth of soil turned by a plough).

Artifacts buried in tilled soil are subjected to a variety of hazards ranging from illicit excavations of nighthawkers, which every responsible collector and antiquities dealer deplores and condemns, to the widespread use of corrosive chemicals in agriculture that creates a low pH soil or acidic environment. The latter includes the introduction of sodium and potassium chloride, whose pervasive presence in irrigation water has contaminated and poisoned agricultural land since the days of ancient Sumeria, creating saline deserts in many places including ancient Mesopotamia. Such acidic soils are not only poisonous to agricultural plants, they also pervade buried copper-alloy objects with chloride and other halide ions which may result in rapid deterioration after their excavation, a conservation hazard in many ways equivalent to what happens when metal artifacts are removed from a salt water environment.

Not nearly enough attention is being paid to the demonstrated fact that ancient artifacts are by no means securely preserved in their resting places. They are in fact always in danger there and that does not only refer to the possibility of illicit excavation. There seems to be a sort of myth in the minds of the credible to the effect that the archaeological environment is like the fossil record, that what is buried is safely preserved for all eternity until it becomes exposed to weathering or until it is disturbed by illicit excavation.

In reality the geological and chemical processes of fossilization do not preserve the original specimen. They instead replace it with a replica resulting from the pervasion of biological materials by water containing chemical substances such as carbonates and nitrates, to corrosion of metallic materials by the effects of acidic substances, to oxidation or reduction of carbon-based plant materials such as that which has resulted in the deposition of coal and peat deposits such as those which were laid down during the Carboniferous era.

The more recent equivalent to such gradual pervasion by aqueous solutions in groundwater and marine environments is corrosion of ancient metal artifacts and their replacement by the resulting corrosion products. This may involve the slow creation of a virtually exact replica which can tell its discoverers a great deal about the original, or more typically may result in a mere suggestion or trace of the original artifact that only indicates the overall shape and dimensions it once had.

The reality is that not only shipwrecks, but all submerged and interred ancient artifacts made from metallic or biological substances are slowly and inevitably deteriorating, and if not brought to light by exploration and subsequent conservation will, in time, disappear.


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