Fire Cracked Pebbles are found on all Iron Age sites and seem to have been used as rudimentary Pot Boilers. The pottery vessels produced in that period tended to be very poor and friable and could not be placed directly on to a fire for cooking, so instead stones were heated in the fire and dropped into water in the pots or into clay lined pits filled with water for cooking or industrial processes.

These are found in great quantites in the area of boulder clay at Mellor where water is naturally held for a very long period after the rain. It may be that the line of pits were deliberately dug in this area for this purpose. They can be easily recognised by their sharp, broken faces and cracks on unbroken surfaces.

It had been assumed that these were largely of an Iron Age date but in 2004, however, excavation exposed a complex series of intercutting pits with large numbers of Fire Cracked Pebbles. However, environmental analysis of the traces of hazelnut, burnt bone and cereal type pollen gave very surprisingly early radiocarbon dates of BC 2920 to 2650 from the Late Neolithic and Early Bronze Age. It appears that the complex pattern of Iron Age gullies may effectively mask much earlier features