Cement industry The southeast of England has abundant resources of clay and chalk. The first mining activity known in the area was for flint, a rock commonly found across the North and South Downs and in the Weald. This was used for tools. Swanscombe was important in the early history of cement. The first cement manufacturing works near Swanscombe were opened at Northfleet by James Parker, around 1792, making "Roman cement" from cement stone brought from the Isle of Sheppey. James Frost opened a works at Swanscombe in 1825, using chalk from Galley Hill, having patented a new cement called British Cement. The Swanscombe plant was subsequently acquired by John Bazley White & Co, which became the largest component of Blue Circle Industries when it formed in 1900. It finally shut down in 1990. Between 1840 and 1930 it was the largest cement plant in Britain. By 1882 several cement manufacturers were operating across the north Kent region, but the resulting dust pollution drove the people of Swanscombe to take legal action against the local cement works. Despite various technological innovations, the problem persisted into the 1950s, with telegraph lines over an inch thick in white dust. Modern cement kilns in Kent using chimneys 170 m (550 feet) in height are now said to be the cleanest in the world. However, the neighbouring Medway towns are reported to be the most polluted inhabited area in the UK, and the cement industry contributes to acid rain in Scandinavia. Blue Circle The Associated Portland Cement Manufacturers (APCM), later known as Blue Circle Industries, came to the area in 1900 and by 1920 owned four local factories located at Swanscombe, Northfleet, Greenhithe and Stone. By 1970 the North Kent cement industry had evolved to become the largest centre for the production of cement in Europe, supporting a long tradition of research and development to perfect the processes used in the manufacture of chalk-based products. Since then the industry has declined considerably due to the potential for more economic manufacture elsewhere, and by 2007 only two operational kilns remained, both at Northfleet. all have been removed. Developments One of the large quarries created as a legacy of the cement industry, between Watling Street and the village of Stone, is the site of the Bluewater (shopping centre), one of the largest such centres in Europe. An adjacent quarry is to be given up for housing