Bryn Leadbetter, Project Archaeologist, Environmental Processing

In a far-flung corner of Whisby Lodge is a room visited by few. Room 4 (or 9) was once frequented by many. They came then, these folk, in search of tools, but now such utensils of mass earth removal are found elsewhere and there is no longer any reason to venture to this remote outpost. What takes place now in Room 4 (or 9), once likened to a cave, has been described as something akin to alchemy. I like this idea of my work being a dark art and I hesitate to discourage the thought, but in truth no such claim can be made.

In the simplest of terms environmental archaeology is the study of past people’s interaction with their natural environment – we use plant and animal remains to reconstruct ancient environments and farming practices and examine soils, sediments and other suitable deposits to explore how sites are formed. Pollen and isotopes are also studied, and much more still, but, sadly, nothing so wizard-y takes place in Room 4 (or 9).

Bryn floating

The samples of soil that we collect may contain minute/microscopic plant and animal remains that can tell us about the economy and diet of the people who occupied the site, and the natural environment in which they lived. Fragments of pottery, flint and other artefacts may also be present.

To extract these items from the ‘mud’ a water separation system is employed, in a process commonly referred to as flotation. This consists of a number of tanks and connecting pipes around which water is pumped on a continuous cycle, overflowing from one tank to the next. The sample is placed in the first tank onto a submerged 1mm mesh and agitated to break the sediment up and release any eco/arte-facts contained therein. Light material, such as grain, seed, charcoal and shell, will float to the top and is carried by the overflowing water through a 300 micron mesh (1000 micron = 1mm), where it is collected. This material is called the flot. The heavy fraction of bone, flint and pottery along with stones etc. will sink but is captured by the 1mm mesh. This is called the residue. The finest fraction of clay and silt will escape capture and settle to the bottom of the tank. Of course, the overflowing water is instantly dirty and the purpose of the other tanks is to allow as much silt/clay to settle before the as-clean-as-possible water is pumped from the final tank back into tank 1 and the cycle to continues. After drying and bagging the flot is sent to a specialist for analysis. I sort the residue and retrieve any bone, flint, pot and so-forth. A spreadsheet is kept for the documentation of all this activity – and that’s what I do in Room 4 (or 9).

Flot, residue and bagged flot