Geophysical survey finds a surprise tunnel

Phase recently undertook a geophysical survey in the grounds of a former rectory house to determine if there were any buried structures associated with the old building. A large amount of worked stone had been dug up by the occupant over the years and he was interested to see what, if anything, was still buried. We carried out a ground penetrating radar (GPR) survey and found what appeared to be buried foundations located underneath a courtyard area.

Of immediate interest to the occupant however, were several anomalies suggesting the presence of a buried wall or path and a small drain located in the gardens. These weren’t major features but the client was so interested in seeing what they were that he got out a shovel and proceeded to dig down at the areas that we had indicated!

The first anomaly did indeed turn out to be caused by a buried footpath located at a depth of 0.6m, indicating that the gardens had been extensively landscaped since the path was last used. The second anomaly however was more of a surprise. Initially, much to our consternation, there did not appear to be any features at the depth identified by the GPR but then an opening in the side of the excavation was noticed and the cause of the anomaly became apparent. It was a mole’s tunnel!

Pleased with finding the cause of the anomaly but slightly guilty about disturbing the mole’s home the excavation was filled back in. Although the feature was not what was expected we were impressed with the versatility and sensitivity of the GPR system at being able to locate a relatively small void at a depth of 0.5m. To our surprise the client was also pleased at the discovery as for years he had wondered how the moles could travel so quickly from one end of his lawn to the other!