Archaeology and Global Warming
[pg14]A recent symposium at the Royal Society in London was devoted to an episode in the mid Pliocene, 3 million years ago, when the mean temperature at the latitude of Britain was five degrees warmer than in recent (pre-industrial) times. So it was relevant to ‘worst case’ global warming, but how to the archaeology of Kent?
[fg]jpg|Fig 1. Soil Association 68 (Sheldwich and Maxted series): Ironstone probable. Land above 150 m elevation: ironstone possible. Ironstone smelted at named places believed to be Pliocene. Map drawn by John Hills of Christchurch University, Canterbury, using information from Soil Survey of England and Wales (with permission).|Image[/fg]
An initiative sponsored by the Wye Historical Society to explore Roman Wye was recently reported in this journal. It emerged that iron smelting was important here, and that the ore probably came from shallow pits on top of the Downs. Its age was occasionally shown by containing intensely weathered fragments of flint with a thick white crust. Such fragments were also found with ore in Roman smelters at Westhawk Farm and at Westwell. They could not be the familiar Wealden iron ore, which comes from geological formations older than the Chalk. But strongly weathered flints and chunks of ironstone are sometimes found on the top of the Downs, ascribed to tropical Pliocene (pre-Glacial) weathering.
This included the development of reddish tropical soils, such as are popularly called ‘laterite’.
In the following two million years there have been earth movements, raising the area at least 175 metres, and huge oscillations of climate including ‘periglacial’ periods with frost churning and solifluction. A soil map of Kent is the best guide to the occurrence of ironstone. Some lumps have been carried downhill, but not generally below the 150 metre contour. (Fig 1) shows these criteria, and some of the places where Pliocene ore has been smelted, at dates ranging from 50 BC. (Hawkinge) to 700 AD. (Canterbury).
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The most exciting is Lyminge where excavators found a solution hollow, beside the feasting halls of the Kings of Kent, filled with rubbish in the sixth century. In the middle, there is a layer, mainly of slag and other iron smelting debris, which dates from about 550 AD. In about 600 AD. Aethelbert’s Laws ranked the Royal Smith with noblemen. A smith needs iron, so the Royal Court of Lyminge owned an iron mine. Probably this was in West Wood, alongside Stone Street, where pits remain. The smelter must have been in Lyminge, near the rubbish filled pit.
(Fig 2) shows Dr. Paul Burnham, who is 92 years of age, in one of the pits at Westwood. If ‘Pliocene Iron’ is to be as well investigated as ‘Wealden Iron’, it needs younger archaeologists! Is there one in our Society?
Dr Paul Burnham is a former lecturer at Wye College, a long serving member of the Kent Archaeological Society and an expert in local history, architecture, soils and geology, and agriculture (past and present).
[fg]jpg|Fig 2. Paul Burnham in an ironstone pit at West Wood, probably part of an ‘iron mine’ in a charter of 689 AD. Photographed by Adrian Morris.|Image[/fg]