Description:Huge holes were dug in the ground for the extraction of marl, a heavy clay used to make saggars for use in pottery manufacture. This clay was ideal for this purpose, but because the saggars had a hard life they often got broken. The clay was always in high demand.
With new, cleaner firing methods the marl became redundant and many of these holes were abandoned. They became a danger to children during summer holidays as they filled with water. The slippery sides made them difficult to escape from.