Perspex test stakes have a number of steel rods attached at intervals along their length. The stakes allow us to monitor sedimentation changes on a site, by recording the level of the sediment on the stake. If the stake is recovered after a period of time, we can also measure the corrosion rates of steel rods. These results can be compared with other sites to allow us to compare processes on different sites. In addition, as the rates of corrosion of buried samples are a tenth of those exposed to seawater, the rods are sensitive indicators of periodic exposure.
On the Kinlochbervie site we could only find three sediment lenses deep enough to support the weight of the stake upright - there is very little sediment here.
The stakes were recovered in 2003 by divers from the RAF Lossiemouth club. Over an annual cycle the stakes showed that sediment levels were unchanged. Corrosion data further indicated that the sediment level in the deeper part of the site was static, that is there was no period of exposure over the annual cycle, possibly due to winter storms.
Results from this study indicate an environment that is very poor in sediment, and has very little current movement in response to tides. The deeper part of the site also appears to be sheltered from (winter) storms, which may, however, stir up sediment in the shallower part of the site.
The observed corrosion rates of the rods indicate a 'normal' environment in the shallows of the site, but very low rates for steel exposed in the deep part of the site. These rates are a factor of two less than any others we have observed around the coast of Scotland, and in isolation would suggest an excellent preservation environment for iron and other metals subject to oxidation in seawater.