Stonehenge is being scanned using modern laser technology to search for hidden clues about how and why it was built. The survey includes all the visible faces of the standing and fallen stones of Stonehenge, including Station, Heel and Slaughter stones, as well as the top of the horizontal lintels which have never before been surveyed at this level of detail. Some ancient carvings have previously been found on the stones, including a famous Neolithic 'dagger'. The survey is already in progress and is expected to finish by the end of March.
     "The surfaces of the stones of Stonehenge hold fascinating clues to the past," said English Heritage archaeologist Dave Batchelor. The team will be looking for ancient rock art, but also for more modern graffiti, in a comprehensive survey of the site.
     The new survey will be the most accurate digital model ever for the world famous prehistoric monument, measuring details and irregularities on the stone surfaces to a resolution of 0.5mm. The previous survey in 1993 was photographic, and only measured to an accuracy of about 2cm. "This new survey will capture a lot more information on the subtleties of the monument and its surrounding landscape," said Paul Bryan, head of geospatial surveys at English Heritage. Laser scanning is also being used to map the earthworks immediately around the stone circle, and the surrounding landscape.
     The study will provide precise base-line data to monitor the physical condition of the monument which is subjected to daily weathering. Digital data of this unprecedented level of detail will also be a valuable resource to anyone who produces reconstruction models, drawings and computer generated images of the monument for public understanding and interpretation.
     
Edited from BBC News (9 March 2011), English heritage, RedOrbit (10 March 2011)