EXPERTS at English Heritage have found an ultra-modern solution to the age-old problem of the erosion of some of the region's most significant heraldic stone carvings.

Stonework on Sunderland's early-15th Century Hylton Castle gatehouse tower, which displays fine examples of royal heraldry, including Richard II's White Hart badge, has suffered damage from hundreds of years of rain, snow and wind.

Now specialised work using high-tech scanning equipment is taking place to measure the rate of decay - and find the best way of stopping it.

Stuart Chadwick, senior surveyor with laser scanning specialists Greenhatch, said: "The scanner actually revolves as it moves over the surface of the stonework. As it turns, it fires lasers in all directions, taking measurements at a speed of 500,000 points a second. When it has done a full sweep you get a threedimensional image, from which we can produce 3-D meshed models and elevations.

Ray Stockdale, works manager for English Heritage in the North-East, said: "The human eye can only see serious deterioration which has taken place over many years, whereas this method shows very small changes over a much shorter space of time that might be caused by wind erosion or rain.

"From this information we see what erosion is happening before it's actually visible and decide what needs to be done to arrest it and preserve this valuable stonework."

Kate Wilson, English Heritage's ancient monuments inspector, said: "Although the carvings at Hylton Castle are eroded, they remain a very visual display of the wealth and status of one of the North- East's great families."