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ArchaeologyIronAge

Page history last edited by PBworks 14 years ago

Iron Age Archaeology

 

Iron Smelting

 

Locally iron smelting was important and is being researched by several of the groups. Surrey Heath Archaeological & Heritage Trust excavated a site at the Windlesham Arboretum under the direction of Geoff Cole between 1985 and 1992 with the permission of Major Spowers. Pottery, a coin and large quantities of slag were discovered. In a field on the opposite side of the M3 an iron age spear was found and identified by the British Museum. These finds are displayed at the Archaeology Centre at 4-10 London Road, Bagshot, Surrey. GU19 5HN. Tel: 07870 447810. Chairman Debbie Tabner.

 

The gold plated half stater was one of a few surviving coins from the reign of the celtic king ADDEDOMAROS found during an excavation at Windlesham Arboretum (SU 92326230) in 1989. It was in an unsealed context no.544 along with iron age slag below ploughed soil. Its diameter is 16.4 mm and its weight 1.63 g. It appears to be of low quality gold over a now rotted bronze core and its very light weight is due to this rotten core. Celtic metalwork has revealed an impressive knowledge of alloys and the methods of mass production.

Artistically the style is correct for this piece - see "Celtic Coinage in Britain" by Philip de Jersey in the Shire Archaeology series. It is a later Celtic rendering of the coins of Philip II of Macedon of the 4th century BC which showed the head of Apollo on the obverse and a two horse chariot (Biga) on the reverse. By 100 BC when these coins appeared in Britain all that was left of the chariot after centuries of copying was a stylized horse on one side and on the other a design variously interpreted as a solitary wheel, spirally leaves or corn ears. In the opinion of R.N.Clarkson this design represented the head of hair as depicted in the AB coin shown above on page 34, a design perhaps explained not so much a degeneration, but as the result of Celtic artistic license.

Explanation for the plated nature of the coin is not clear. It might possibly be a piece of economic necessity due to shortage of gold, or, of course, a downright spurious piece made to defraud - see "The Counterfeit coin story" by Ken Peters who is the latest authority on the subject.

What the coin was doing on the site is equally unclear. Since it was found in an unsealed context which appears to have been disturbed in both Roman and modern times, there is no way of telling whether its relationship with the slag was accidental, or for the purchase of iron, or whether it was a gift token.

Nothing much is known of Addedomaros apart from the few coins struck in his name (shown by the letters above the horse’s tail). He appears to have been a leader of the Trinovantes with their headquarters at Camulodunum (Colchester) or of a larger tribal grouping for about 10 years between 25 and 5 BC.

 

Iron-age smelting evidence from the Surrey Heath area

(extracted from a 1991 Trust newsletter written by Geoff Cole)

 

Iron-rich slag is the principal by-product of iron smelting and this material can appear as a heavy, spongy or dense once-molten solidified mass with glossy or vitrified surfaces. Specimens of iron-rich slag are known from West End, Bagshot village (archaeological excavations), Lutine Farm, Bagshot, Queens Wood, Bagshot, and from the archaeological excavations at South Farm, Lightwater, where quantities in excess of 4 tonnes [adjusted to include the 1.4 tonnes that we have sorted for the 1989-92 period] can safely be dated to the LPRIA period of c.1OOBC to 40AD. No evidence has yet been recovered for iron working in the Roman period.

The iron ore at Lightwater occurs as freely distributed nodules, probably Hematite rich, in the surface geology at depths of beyond 2 metres and appears to be confined to a linear strata along the valley of the Windle Brook. Nodules of ore have not been recovered from the excavations which are approximately 250 metres from the course of the brook.

Being a surface deposit, mining is likely to have been open-cast and it is considered possible that the principal lakes alongside the brook may be a legacy of the LPRIA open-cast mining operations. It may be significant that with the exception of the West End specimens, all other examples of iron-rich slag have been found in reasonably close proximity to lakes.

The furnace evidence from the Lightwater excavations include complete circular or rectangular furnace bottoms which represent the accumulated slag that had been expelled from the smelted iron ore and fragments of baked clay furnace linings. No examples have been found of slag-tapping furnaces although items of possible tap-slag are currently being examined.

Excavations during 1991 recovered several furnace bottoms which had been re-used in the early Roman period as packings around large posts. One of the examples had been split in antiquity, and from the examination of the interior, the particles of non-burnt charcoal and roasted ore could be clearly seen. At the time of writing, a large furnace structure is being excavated at Lightwater which appears to be a through draught type furnace having several phases of use. The structure was clay built and had collapsed inwards. Adjacent to the furnace was a pit full of unworked clay which may have been intended for use in future repairs to the furnace. Due to the stage of excavation reached, it is impossible at this time to ascribe an original use to this furnace, but the distinct lack of associated ceramic materials may be significant.

From these early days of research in the area of Surrey Heath and the distribution of the iron-rich slag specimens, it seems possible that iron workings may have been an important local industry some 2,000 years ago.

 

AN IRON SPEARHEAD FROM WINDLESHAM

 

During 1992 an iron spearhead was ploughed up in a field at .Windlesham very close to the M3. The farmer very thoughtfully brought the item into the Archaeology Centre for identification. At that time a visiting specialist in Medieval and Post-Medieval archaeology ruled out its provenance from those periods. Through the good offices of one of the Trust's Hon. Vice Presidents, Dr Simon James, the spearhead was taken to the British Museum for identification. There it was examined by Chris Spring in the Ethnographic Department and by Angela Evans who is a specialist in early Medieval archaeology. Neither of them thought the piece belonged to their respective provinces. Its Roman provenance was ruled out both by Ralph Jackson and Simon James.

However, Dr Ian Stead advised that, although little is known about British Iron Age spearheads its identification as such was not implausible. Parallels were suggested from excavations at La Tene in Switzerland and the recent shrine excavations at Gournay in Northern France. None of these contain perfect parallels which is not surprising as shapes and sizes vary greatly. However, the short socket, long blade, flaring shoulders and midrib are all to be paralleled among these objects and cumulatively make a good case for an Iron Age date for the Windlesham spearhead.

Dr Stead added that given the rarity of such finds and the good condition of the piece, it is unlikely to be a stray object. It it is Iron Age, there is a considerable chance that it comes from a grave and further discoveries may be made at the site.

We are extremely grateful to all of the specialists at the British Museum who very kindly examined this spearhead and especially so to Dr Ian Stead and Dr Simon James.

 

 

OUR PROGRESS REPORT [29.05.06]:

1. We have sorted, weighed [1.4 tonnes] and entered data by context on a data base for 1989-92.

2. George has entered the 1985-8 context data on the computer.

3. We have some interesting samples to ask you about.

4. We have had base 538 x-sectioned by a mason.

5. We have identified the positions of the bases on site plans and propose to place the contexts containing slag and/or iron-age pottery on the site plan.

6. We heard a lecture by JD Hill in which he stressed the need to date iron-age material and so propose to apply for grants to date the slag and pottery. What are the costs?

7. We want to do some chemical analysis to check possible local manufacture of the spear.

8. In the summer we would like to re-run the smelting experiment done in 1991 with advice from the Wealden Group and are going to invite them to comment on our analysis.

9. We would like to examine the Lightwater site for evidence of further smelting activity.

10. We assume that Iron-age ‘Gypsies’ smelted across the whole area of the Bagshot Beds and want to see whether samples of slag have been located elsewhere.

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