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2006 Dig Diary

The Dyffryn Lane prehistoric ritual complex


The Dyffryn Lane ritual Complex: Excavation and Survey 2006

A fascinating and important complex of ritual monuments once stood alongside the river Severn about six miles upstream of the Breiddin hills in eastern Powys. At this point the Severn winds slowly down a broad valley, confined by quite steep slopes on either side and dominated by the isolated massif of the Breiddins to the North. The area seems to have held considerable attraction to the people of the later Stone Age and the Bronge Age. Great Numbers of monuments were built and used here over a period longer that which has passed since the Romans left Britain. In the four to five thousand years since their construction these once-impressive earth, timber and stone monuments have melted back into the countryside, effectively forgotten until the advent of aerial reconnaissance.

CPAT photo © 76-7-14 Right: The Breiddin hills dominate the Severn Valley near Welshpool.

Archaeological monuments have been photographed from a bird's eye view for almost as long as we have been able to get planes into the air. Only during the latter part of the 20th century, however has aerial reconaissance come into its own as one of the most used tools of archaeological research.

Regular flying along the Severn Valley several times a year, every year, since the mid-1970s, in varying crop and weather conditions, has produced evidence of many hundreds of vanished archaeological remains, the great majority being farmsteads of the Iron Age and Roman periods whose defensive ditches show dramatically again in ripening crops.

CPAT photo © 79-ch-16

Right: a defended enclosure near Llandyssil - almost invisible in grass to the left of the fence, but its ditches show very strongly in the cultivated field to the right. On the ground the colour changes will be visible, but only from some distance above can the pattern of the double ditches of this two-thousand-year-old defended farmstead be clearly understood.

The gradual revelation of a remarkable wealth of prehistoric ceremonial and funerary monuments along the Severn valley south of Welshpool is of especial interest however, partly of course because of the relative rarity of these sorts of momuments but also because of what their presence here says about the spiritual or social significance of this area to prehistoric people.

To either side of Dyffryn Lane just south of the A483 trunk road near Berriew lies a complex of monuments that would have been a dominant part of the Neolithic and Bronze Age landscape and of the lives of the people living here for many hundreds of years. The oldest sites are a Neolithic long barrow and a nearby enclosure, both of which are known to have been built about 3,500 BC, five and a half thousand years ago.

CPAT photo © 86-c-116 Right: A general view of the fields in which the Dyffryn Lane complex lies. The lane itself runs across the picture in the foreground.

An important part of the complex appears to be focused on an enclosure known as a henge. The distinctive component of a henge is its bank and ditch. Typically a circular or oval area was enclosed by ditch, the soil or rock from which was used to form an external bank. One or two opposed entrances ran through the bank and across the ditch to give access to the central area. Henges are perhaps the best known ceremonial monuments of the later Neolithic period, dating from about 3,000 to 2,500 BC though only a handful of similar sites are known of in Wales.

The henge at Dyffryn Lane appears to have had a long and complex history. It probably started life conventionally enough. We can see a single entrance about three metres wide on which one would have passed through the bank (the base of which is still just visible at ground level), then a causeway crosses the the five-metre wide ditch to give access to a space about fifty metres across internally. All this is typical of henge monuments known elsewhere in Britain. The Dyffryn Lane henge differs from many others at this point, however. At some time, possibly several hundred years after the henge was built, its use changed. A burial mound was constructed covering much of the central area. The dark mark that shows on air photographs taken in dry summers is caused by corn ripening more slowly over the deeper and damper soil of the remnant barrow mound.

CPAT photo © 86-c-119 Right: The henge ditch marked by unripened corn - a break can be seen in the ditch marking the single entrance. The henge bank would have lain outside the ditch, its base probably about twice the width of the ditch. We know now that the ditch was over two metres deep - the bank could have stood over a metre tall around the henge enclosure.

In the mid 19th century a local antiquarian, D Phillips Lewis, was told by the farmer of the impending removal of a stone 'which had so often interfered with the free passage of his plough' over the Dyffryn Lane mound. Phillips Lewis organised a small excavation, on which he was accompanied by the Vicar of Berriew and another antiquarian from Aberystwyth. At that time the mound stood over two metres high though continually ploughed and spread to some thirty-five metres across. The hired labourers explored around one large stone which the farmer had 'overthrown' the previous year', discovered two others, and also dug two 'broad trenches 'down to the level of the field below either of the stones'. Two of the stones had once stood well over a metre tall.

Parchmarks, visible as pale dots on the photo above, hinted to modern-day archaeologists that some of these stones still survive below the surface, forming a circle about 10 metres in diameter. These marks are again caused by differential ripening of the corn - in this case parching more quickly where it grows in the thin soil over the stones. The presence of these stones suggested that the henge could have had a stone circle standing within it, probably buried when the barrow was built. Stone circles (most spectacularly at Stonehenge and Avebury) were sometimes built inside henges hundreds of years after the henge itself was built, at a time when stone circles were apparently becoming the monument of choice throughout Britain. Were it not for the building of the burial mound over them here at Dyffryn Lane, these stones would probably have been removed long ago, once their spiritual significance had waned.

It is thought that henges were communal meeting places, perhaps used for secular activities such as trade and exchange as well as for ceremonial or religious purposes. It has been suggested that the area within the ditch was for ceremonial or sacred purposes and that the bank outside could have provided a stand for spectators or worshippers. For further information on henges the following websites are useful and themselves have further useful links Channel 4: History and Thornborough Henges, Yorkshire.

The valley-bottom location of the Dyffryn Lane henge, with the Severn nearby, is typical of such monuments elsewhere in Britain. Henges were often located near either rivers or the coast. An association with water might have had religious significance, or could merely have been convenient for access from a distance. Dyffryn Lane itself is an ancient trackway of some importance as it leads to an important ford across the Severn, linking West Wales and Middle England in the days before the turnpike roads. The proximity of the Dyffryn Lane henge to this access across the Severn may therefore also be significant.

CPAT photo © 86-c-120 Right: Two of the ring ditches near the henge, marking the positions of two more burial mounds.

Clustered around the henge are ring-ditches and burial mounds probably of later Neolithic to early Bronze Age date, having probably been constructed between five and three and a half thousand years ago. A standing stone called Maen Beuno stands in the hedge on Dyffryn Lane, near the henge; it probably also formed part of the complex. Most of these monuments are very difficult or impossible to see at ground level – being now ploughed almost flat. The builders of the barrows and the henge seem to have exploited natural gravel ridges to gain extra height however (and perhaps save some labour too) so with some practice and knowledge of where to look, you can still see some of them, the mound in the centre of the henge in particular still stands significantly higher than the surrounding field.

CPAT photo © 1242-19 Left: The Maen Beuno standing stone in a hedge near the henge.

Excavation and Survey 2006
CPAT’s 2006 work programme for the Prehistoric Funerary Sites project [link] included 6 weeks of excavation and survey on and around the Dyffryn Lane henge. The henge is protected as a scheduled ancient monument, but periodic ploughing is allowed and there has been some concern about the way that even this occasional cultivation is further flattening the monument.

A programme of trial excavation, topographical survey and geophysical survey was therefore undertaken with the aim of evaluating its current state of preservation and the effects of continuing agricultural erosion. It was also hoped it would be possible to date the stratigraphical sequence at the site using carbon dating, and to place the henge in its ancient environmental setting by sampling sealed soil levels dating back to the lifetimes of the henge and the barrow. Palaeo-environmentalists can use the pollens preserved in these soils to give us a number of snapshots of the local natural environment in which the monument had been built and used. A topographical and geophysical survey of the henge, its barrow and of adjacent monuments would also be made to help elucidate their form and condition.

The excavation and survey work was undertaken in association with the Department of Archaeological Sciences of the University of Bradford with grant aid from Cadw. The director was Dr Alex Gibson and CPAT provided the site supervisors. The project was also designed to form part of the undergraduate course for Alex’s archaeological students, by giving them practical experience of a variety of excavation and survey techniques.

Excavation

Photo: CRM

Right: July 2006: excavation under way - the henge ditch shows as a dark circular grass-mark in the field and can just be seen as a darker soil-mark in the excavated area

The Dyffryn Lane Excavation and Survey project started in early July. A machine was used to remove the ploughsoil over a quarter of the mound, and ditch, then the surface of the subsoil was patiently cleaned over by trowel. A two-metre wide trench was cut across the outer bank and across the ditch, which was found to have been just over two metres deep and five wide. The excavation extended over the top of the mound in the search for the trenches dug by Phillips Lewis and his colleagues in the 19th century.

CPAT photo © 2159.61 Left: View along the north side of the excavation from the mound towards the ditch (with people standing in it) and bank beyond.

The very dry hot weather in the first part of July made both digging and interpretation difficult at first, but the Phillips Lewis trenches were eventually located on the barrow mound and emptied of their 19th century fill. This allowed us a view of three levels of soil: the barrow mound, the pre-barrow ground surface and its underlying subsoil. What had been a mound 'eight or nine feet above the field' in Phillips Lewis's day is now no more than half a metre high, as can be seen in this picture taken at the beginning of the excavation when small pits were being dug to test the depth of the ploughsoil before mechanical topsoiling began.

CPAT photo © 2155-06 Right: Test pits being dug by hand over the mound.

Five large stones were found within the mound material, with their tops in the plough soil, showing chips and scars made by modern ploughing. We could see that a further stone had been entirely removed with a grey soil backfiling the hole. Of the five surviving stones, at least two had indeed been dug out and reset lying flat, as described by Phillips Lewis. The five stones and the stone hole formed a semi-circle confirming the suggestion that they are part of a stone circle.

Below left: One of the stones probably laid flat by the farmer in the 1850s to avoid being hit by the plough lies next to another stone in the stone circle which is still in its original position. On the right, one of Phillips Lewis's trenches being re-emptied.

CPAT photo © 2159-163 CPAT photo © AMG 18

An important discovery was made as the students cleaned back over the outer edge of the ditch and onto the inner edge of the bank. A concentration of coarse thick pottery was found in a shallow pit which appeared to pre-date the outer bank. The pottery isMiddle Neolithic 'Peterborough Ware' dating to the period 3,600 to 3,000 BC. The pit also contained charred organic material including hazelnut shells, as did two small nearby pits, which may prove suitable for carbon dating. Other finds include some fine pieces of worked flint, including a barbed and tanged arrowhead found in the central mound.

CPAT photo © 2155-70

CPAT photo © 2155-66

Some of the burnt material (left) and Peterborough Ware (right) found in the pit.

Topographical Survey

CPAT photo © 2155-22

A detailed topographical survey of the henge was carried out before excavation. This involved taking close-interval readings using an Electronic Distance Meter (EDM): a laser aimed at a prism on the survey staff measures distances and records horizontal and vertical angles. The information recorded for each point is transmitted to a portable computer to produce a plan of the site. The software makes a contour plan by analyzing the spot height information and drawing lines joining points with the same value. These can be drawn at specified intervals – for the henge we made them just ten centimeters apart.

The results clearly show the outer bank, ditch and internal mound. Within the same field the two round barrows, or burial mounds, which still survive as slight upstanding mounds, were also surveyed in detail.

Results of the topographical survey of the henge (red=higher ground, blue=lower). The dark red is the barrow mound in the middle of the henge, the ground is falling away into a natural hollow at the top. The outer bank of the henge can also be seen now, almost impossible to recognise it by eye on the ground. For comparason, the air photograph of the same area is shown on the right.

Geophysical Survey

CPAT photo © 2159-53

The geophysics team used resistivity equipment which measures the ability of electrical current to pass through soil. Resistivity is linked to moisture content, and therefore porosity, so hard dense features such as rock will give a relatively high resistance (they show darker when the results are plotted), while features such as ditches (which retain moisture) give a relatively low response (showing lighter). The two barrows in the same field field as the henge were tested by this method. The results have largely confirmed (and accurately located) features that had previously been identified from aerial photographs.

Below: Results of geophysics resistivity survey of round barrows in the same field as the henge monument. (low resistance=lighter areas, high resistance=darker), with an air photograph of the same area for comparison. The linear marks represent old field boundaries. The broader anomalies of low resistance (light on the plot, dark green on the photograph) seen on the left and sweeping up from below the barrows are thought to be paleochannels, the fossilised beds of old water courses.

Post-excavation work now continues in Bradford and crucial to our understanding of the monument will be the radiocarbon dating of key contexts and features. It is already apparent that the stone circle was ruined before the central mound was constructed. What is less certain is the relationship of the henge to these central features.


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