This mystery photograph was of a dewpond near Cissbury. Dewponds, despite their name, collected rain water more than dew. They were created by ‘puddling’ clay and straw into a depression cut into the chalk. In the days when the South Downs were covered by great flocks of sheep, water was essential, but no ponds naturally occur on these porous chalk hills, so these man-made ponds were the only answer. No one is quite sure when the first dewponds were created, but the earliest references appear to be from the 17th century.
During hot summers, the water in the dewponds could evaporate and then the clay lining would crack and any subsequent rain water would seep through the cracks into the chalk. In recent decades several dewponds on the South Downs have been restored, but instead of clay and straw, plastic linings are used as these do not have the susceptibility to heat and sun of the clay-lined originals.