"It’s complete vandalism," he said. "We have dug in the area since 2005, carefully sieving and working at times with toothbrushes. And for them to have come in and done things with a hand drill and just smashed through the surface is really upsetting and appalling."
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Of particular significance were a series of remarkably well-preserved footprints left by aurochs — a species of cattle believed to have first appeared on earth 2 million years ago and that went extinct in the 1600s.
“The fact this lasted for 6,000 years and has been smashed through in 25 minutes is an utter shock,” he added.
For its part, Highways England denied its workers had done anything wrong.
"No damage has been caused to archaeological layers," said a spokesman for the government-owned company. "Our assessments so far indicate that construction of the scheme will have no significant effects on the Blick Mead area, and the works have been undertaken in a highly professional manner, with an archaeologist on site and with due care being exercised at all times.”