The sad story of deterioration

Although the unique properties of the peat at Star Carr has enabled many rare organic remains to survive for 11,000 years, in more recent years the peat has badly degraded leading to deterioration of the remains. The first signs that organic remains at Star Carr were no longer safe were uncovered between 2006 - 2010. In some of the bone and antler excavated during this period, the inorganic part - the bit that makes them hard - seemed to have been washed away. This left a jelly-like substance made completely of protein. A lot of the wood had been flattened, and some was found to be extremely crumbly.

This was a huge contrast to the pristine artefacts that had been found 60 years earlier, and indicated that something had changed at the site in recent years. Research has shown since that these changes in the artefacts were caused by changes in the burial environment. Almost all of these changes happened because the field in which the site is located was drained for agricultural reasons, although the underlying geology at the site was also an unfortunate contributor to the severity of the changes. Draining peat means that it is no longer saturated with water. This allows oxygen in, and biological decay to happen. As bone, antler and wood are such good sources of sugar and protein, these then get broken down.

But not only the archaeology is decayed - the peat itself starts to deteriorate, along with any environmental evidence such as plant remains or pollen. The loss of peatlands therefore represents the loss of a massive body of scientific evidence about the past. At Star Carr, the drainage combined with the unfortunate geology caused another phenomenon to occur - acidification. Although peat is normally acidic, we expect a pH in the region of 5.5. Some parts of the Star Carr site were measured to have a pH of less than 3. This is equivalent to vinegar, and explains why the mineral part of bone and antler disappeared so quickly - they simply dissolved!

Without the mineral part, the rest of the bone will quickly be destroyed by any biological activity. The wood at Star Carr was less affected by the acidity. However, the peat shrinkage caused a huge amount of damage. Because the wood was already decayed, and probably became even more decayed as the site dried out and let oxygen in, this meant it was very vulnerable to the changes in the burial environment. As the peat dried out, it shrank, putting pressure on the wooden artefacts and squashing them. This destroys surface details on the wood, like tool marks and ring counts, which archaeologists usually study to tell us more about the artefact.

Because of what happened at Star Carr, we are now increasingly aware that this can happen at other wetland sites, and that these special sites need to be better understood and protected.