Blue Lias is believed to have been quarried on the Polden Hills as early as the 15th century .
Blue Lias is was quarried in Puriton from the early 19th century until 1973 , when the local cement works closed .
Blue Lias is believed to have been quarried on the Polden Hills as early as the 15th century and was quarried in Puriton from the early 19th century until 1973 , when the local cement works closed .