Seeing back in time: the invisible burgh of Roxburgh
The royal burgh of Roxburgh was a major centre of population and influence in medieval Scotland and an international clearing-house for trade and commerce that attracted merchants from across Europe. In the course of being re-taken from the English by the Scots in 1460, the site was destroyed by fire, and the once bustling centre subsequently fell into decay. Although nothing remains of the original site today, this very neglect may well have preserved important information about the burgh.
In May of this year, as part of the Roxburgh project, RCAHMS began to undertake a systematic survey of the site with the object of generating a digital terrain model (DTM) of the survey area. When this is used in combination with other datasets, it will provide a common spatial basis for refining the research questions that may be developed for the royal burgh and its hinterland.
However, survey of the site presents particular problems due to the combination of a large survey area and relatively smooth land contours. The survey team used these conditions as an opportunity to trial and develop methods of rapid automated height data recording, using Global Positioning by Satellite (GPS) equipment. Digital terrain modelling requires large amounts of accurate height sampling, so - to record height data as efficiently as possible - two GPS antennas were mounted on the roof rack of a Landrover, and height points recorded automatically at set intervals as the vehicle was systematically driven over the survey area. For areas where the landrover could not gain access (steep slopes, for example, or ground adjacent to buildings and trees) height points were recorded manually with the GPS antennas mounted on a survey pole.
The first season's data has now been processed and the results are very encouraging, with the very slight remains of strip cultivation, trackways and burgh earthworks clearly visible on the DTM. With approximately half the site now surveyed, it is intended that the survey programme will continue in Spring 2007.