The results arrive of an analysis of soil samples taken from the Blue Boy Yard site. Dr Richard Macphail, dubbed our 'dark earth specialist', is a soil scientist specialising in archaeology. He has been comparing samples from the Blue Boy Yard excavation with others taken from the Greyfriars site.

The Blue Boy Yard samples are homogeneous in content, and include a large proportion of sand, silt and fine charcoal. This adds weight to the idea that the former Roman temple precinct was used as a cattle corral at some stage after the departure of the Romans because these materials would most likely either have been windblown or carried in on the feet of animals. The soil also shows signs of having been trampled upon, again probably by cattle.

Dr Macphail also measured the Ph values for the samples (these measure the relative acid/alkaline content). The Blue Boy Yard sample has a neutral pH value of 7.4, which compares with pH 8.4 for the Greyfriars sample. The higher value is more likely to be associated with sites where buildings have stood previously. A similar indication is obtained by testing the samples' reactions to dilute hydrochloric acid. A strong reaction is indicative of the presence in the soil of carbonate, which is found in mortar and would be likely if a building had once stood there. At Blue Boy Yard the soil showed no noticeable reaction, whereas the Greyfriars sample showed a strong one.

Dr Macphail explains how soil micromorphology can tell us a great deal about a site. A more detailed examination of the soil samples would involve him taking a column sample of undisturbed soil, putting a thin slice in resin and then looking for tell-tale features – such as the presence of dung, micro-organisms or more detailed soil chemistry – under a microscope.

The Blue Boy Yard site soil is now being subjected to microscopic examination: there is a moment of high excitement late in the afternoon when another of Time Team's experts, Margaret Cox, announces the discovery of lice in the soil – to go with the large quantities of human hair that have turned up in some of the pits being excavated. Closer examination under the microscope reveals that they are in fact fly larvae, but Margaret Cox is certain that some real lice will turn up sooner or later. In mid-afternoon, a bone 18th-century lice comb is unearthed, confirming her expectations.

Other finds include a wide variety of bones, tin-glazed pots and other pottery, including some creamware from the 1800s. The quality of the finds – and the discovery of things such as goose bones – indicate a diet and lifestyle enjoyed by the wealthier end of society at the time.

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4pm
As the excavation goes deeper and the pits are cleared, the number of finds dries up. So the mechanical digger is called upon again to remove the remaining debris and by 4.30pm the diggers are excavating down to natural layers.

6pm
Margaret Cox gets her head lice – found in human hair retrieved from the cesspits.

7pm
The trench is all but cleared of its medieval and post-medieval debris, ready for tomorrow's work on the Roman precinct metallings. Although the cesspits cut through the Roman layers over most of our excavation area, there is still a significant section of untouched Roman surface left. As Time Team Roman expert Guy de la Bédoyère explains, 'We've got to get rid of all the contamination from later periods before beginning to dismantle the Roman sections.' That done, tomorrow should finally see the team getting to grips with the Roman aspects of this excavation.

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