LM05_18_Sept07.htm

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Lismullin Advisory Committee Meeting � 18 September 2007

Present: Mr. Finian Matthews, (DEHLG), Chairperson; Mr. Brian Duffy, Chief Archaeologist (DEHLG); Ms. Catriona Ryan, (DEHLG), Secretary; Mr Gerard Smith (DEHLG); Mr. Conor Newman (NUI Galway); Prof. Gabriel Cooney (UCD); Mr. Ronan Swan, Senior Archaeologist (NRA).

Prior to the commencement of the meeting, Mr. Newman stated that he wished to unreservedly withdraw remarks he had made recently on the Today with Pat Kenny radio show. It had not been his intention to impugn Prof. Cooney�s integrity and he wished to apologise accordingly.

Prof. Cooney welcomed and accepted the apology and looked forward to the committee�s concentrating on the business at hand.

The Chairman also welcomed these remarks as constructive and helpful to the Committee in seeking to take its work forward.

As the Site Director Aidan O�Connell was unavailable on the day, the senior site supervisor Alistair ? and Mary Deevy Senior Archaeologist NRA gave a presentation on progress to date on the site. The information given was drawn from the Director�s Progress Report (No. 3), a copy of which is attached to these minutes.

Following the presentation, the members inspected the site. It was subsequently noted that the presentation was most helpful to the members in their understanding of the ongoing work.

The chairman noted that references to monuments in the ownership or guardianship of the Minister should also make reference to those in the ownership or guardianship of a Local Authority. The Minutes of the previous meeting were approved subject to this amendment and any comments Dr Wallace might wish to add.

Additional information from CN and GC, in relation to the souterrain, has been incorporated into the Minutes of the meeting of 2nd August. These minutes were approved by the committee.

A Communications Protocol has been agreed between the NRA and ACS incorporating suggestions of the committee.

Site Directors Reports 1 & 2 have been posted on the NRA website. Report No.3 will be posted shortly. These reports will also be posted on www.environ.ie.

RS reported that the AutoCAD engineering drawings requested by Mr. Newman at the previous meeting were delayed as they were currently in PDF format and needed to be converted to AutoCAD. The AutoCAD material has since been forwarded to the Chairman and circulated to the committee.

RS set out the next steps in the excavation. With current staff levels the excavation will be completed in 9 to 11 weeks, weather permitting. Should conditions worsen, it will be possible to deploy more staff and speed up the work.

It was agreed that progress on the site was satisfactory. GC noted that the next area will be the most complicated area, going on the pre-excavation evaluation, and will take the most time.

CN asked that Steve Lancaster have a look at the new channel at the base of the hill.

The chairman was concerned that the computer generated images looked so realistic that they could be mistaken for photographs of actual upstanding features. It was agreed that there was a need to show what is actually there alongside what might have been there in the past. GC suggested that the actual photos be shown together with the reconstruction images and that the captions should be very clear as to the nature of the images.

CN pointed out that such reconstructions were a valid archaeological tool but suggested that the colours be changed to make the reconstruction obvious. He also asked that the spoil heaps be taken out and that, if possible, the reconstruction images should show the funnel entrance and passageway from the outer to the inner enclosure.

RS said that he would amend the images and circulate to the committee again before making them publicly available.

The Chairman informed the Committee that a submission on the souterrain, containing both the deliberations of the Committee and the Department�s recommendations, had been prepared for submission to the Minister.

GC and CN expressed concerns that, as the committee had not seen the report reflecting the views of the members, it would not be possible for the Committee to sign-off on that report. GC pointed out that, as the Minister had asked the committee a specific question on the future of the souterrain, then a specific response to that question was required.

In response, the Chairman explained that it was intended originally that the Committee�s views be incorporated in a Departmental submission to the Minister. However, he undertook to revise this approach by creating two separate documents (the Committee�s Report and a Departmental submission to the Minister). The report setting out the views of the Committee has since been circulated to the Committee.

It was also agreed that all reports from the Committee to the Minister would first be circulated to the Committee.

� The Committee expressed its appreciation of the opening presentation on the progress with the excavation and wishes to continue with this format for future meetings.

� The chairman mentioned the culverting works in relaton to the Gabhra River � Mr. Swan explained that these works had to start in advance of the end of September due to environmental constraints arising from the Fisheries Acts, as set out in the EIS.

� Rath Lugh � the chairman informed the committee that the Minister had written to Coillte, as owners of the site, to inform them of his intention to place a Temporary Preservation Order on the site of the national monument at Rath Lugh.

� Blundelstown � Mr. Swan suggested that the site visit to the Blundelstown Interchange took place following the next meeting of the committee and he undertook to arrange that the engineers be present for the visit. This was subject to all members being available for the next meeting.

The 2nd of October was provisionally agreed for the next meeting, depending on the availability of Dr. Wallace.

M3 Clonee-North of Kells Motorway Scheme

Lismullin National Monument (A042 & E3074)

Excavation in Quadrant A is complete in 18 of 20 grid squares and recording is being completed in the remaining two. The post excavation plans are currently being digitized.

Excavation in Quadrant C (the NW quadrant in which the inner enclosure is located) has now commenced following the completion of a series of works including trowel back, magnetic susceptibility survey, supplementary pre-excavation planning, and geoarchaeological control sampling.

Following the trowel back a sump hole was excavated in order to allow for pumping should the site flood in the future. Excavation of the later field ditch which bisects the site is being prioritized in order to assist in keeping water away from the inner enclosure.

The interim results of the magnetic susceptibility survey have been provided by Earthsound, and are attached. The combined surveys to date appear to suggest that there is a moderate degree of MS enhancement around the outside of the Outer Enclosure. In Quadrant C to the south of the later field ditch another zone of high MS data corresponds to previous magnetometer responses which suggest burning. This area corresponds to a number of pit features surrounded by an arc of postholes as visible pre-excavation. The inner enclosure contains some moderate MS enhancement with a concentration in the northern half which corresponds with the previous magnetometer survey responses and the features visible on the ground pre-excavation. There is strong MS enhancement just outside the inner enclosure on its NE side which corresponds very well with the enhanced patch identified in the magnetometer data. This may be associated with the slot trench identified on site which curves around this part of the inner enclosure. The enhancement funnels out in a NE direction. This may represent human activity on this axis or enhanced material may have been ploughed out in this direction.

Site works commenced on 7 August 2007, following approval to commence from the Minister�s Advisory Committee on 2 August.

As per standard procedure all works on site are recorded by reference to a grid which divides the site into 10m2 areas. In addition the site has been divided into four separate areas or quadrants: Quadrant A at NE, Quadrant B at SE, Quadrant C at NW and Quadrant D at SW (Fig 1).

The initial site clean-back and supplementary pre-excavation plan was carried out from 7�13 August in Quadrant A. Following additional geophysical survey and soil sampling for geoarchaeological study, as described below, excavation of the planned features in Quadrant A commenced on 15 August. Excavation is now nearing completion in Quadrant A. Excavation commenced in Quadrant C on 14 September.

The excavation is being carried out by twenty-eight archaeologists divided into four teams, each led by a senior supervisor. Supervisory staff attend weekly site meetings to review the ongoing works.

Prior to excavation an aerial topographic survey was carried out by BKS. The results of this survey have been produced as digital terrain models onto which the motorway landtake has been superimposed along with the preliminary excavation plan of the enclosure, the souterrain and the ringditch, and the new ringditch identified by geophysical survey outside the landtake to the SW of the enclosure.

The magnetic gradiometer survey identified a pear-shaped anomaly in Quadrant A which is labeled �A� on the interpretive drawing. It was interpreted as being likely to represent a ditch which appears to act as an enclosure adjacent to a large linear ditch. The potential pear-shaped enclosure measures 31m N-S and 23m E-W. In addition a small number of isolated circular anomalies which could represent pits or postholes were identified at the southern end of the pear-shaped enclosure.

No trace of a pear-shaped or similar enclosure has been identified through excavation in this area. Following post excavation recording it is proposed to excavate a box section through the edge of the identified geophysical anomaly in an attempt to identify the origin of this anomaly. The correlation between the anomalies identified on the magnetic gradiometer survey and the features confirmed as archaeological during excavation is ongoing, however excavators have reported that in general features close to the anomalies identified by the gradiometer survey have tended to be slightly richer in charcoal.

A magnetic susceptibility survey of Quadrant A was undertaken by Earthsound on 13 August. This detected a number of discreet zones which appear to relate to natural geology.

Under examination on site in the northeastern corner the high readings appear to relate to an area of underlying boulder clay, while at the northwestern corner and along the eastern side of Quadrant A the low readings refer to underlying gravels and sand respectively. At the southwestern corner, the high reading may be due to the presence of the palaeosoil that is located around the inner enclosure. This soil has been left in situ to be excavated and recorded as part of the �key area� identified around the inner enclosure.

The magnetic susceptibility survey of Quadrant C was undertaken by Earthsound on 13 September and the preliminary results are attached. In summary the combined surveys to date appear to suggest that there is a moderate degree of MS enhancement around the outside of the Outer Enclosure. In Quadrant C to the south of the later field ditch another zone of high MS data corresponds to previous magnetometer responses which suggest burning. This area corresponds to a number of pit features surrounded by an arc of postholes as visible pre-excavation. The inner enclosure contains some moderate MS enhancement with a concentration in the northern half which corresponds with the previous magnetometer survey responses and the features visible on the ground pre-excavation. There is strong MS enhancement just outside the inner enclosure on its NE side which corresponds very well with the enhanced patch identified in the magnetometer data. This may be associated with the slot trench identified on site which curves around this part of the inner enclosure. The enhancement funnels out in a NE direction. This may represent human activity on this axis or enhanced material may have been ploughed out in this direction.

Dr Steven Lancaster (Headland Archaeology Ltd) is due to visit the site on 20th September to review the ongoing sampling, to examine the sectioned palaeosoil over the inner enclosure and to carry out a geoarchaeological assessment of the western landtake section.

On completion of the clean-back and geophysical survey in Quadrant A and in advance of the commencement of excavation, geoarchaeological samples of approximately 200g (1 small bag) were collected from the subsoil at 5m grid intervals, on 14-15 August. Approximately 100 samples were collected from Quadrant A. The grid samples are registered in a separate geoarchaeological sample register and are being retained on site for future assessment and analysis.

Dr Lancaster visited the site on 21 August to review the sampling methodology. A supervisor has been assigned to specifically coordinate sampling on site in accordance with the methodology agreed with Dr Lancaster, to ensure consistency of approach. In addition to grid samples, small sub-samples of all excavated archaeological deposits are being retained for geo-chemical analysis. The sampling strategy was reviewed to ensure that sufficient and appropriate samples were being retained for each requirement.

During this visit the excavated features in Quadrant A were examined. This included a box section excavated through two enclosure postholes, described below. This section had revealed a thin deposit layer between the postholes which was interpreted as a thin layer of palaeosoil and subsoil which had survived in a natural hollow. It was proposed that this palaeosoil would be sampled using a kubiena tin.

Additionally, a proportion of half-sectioned enclosure postholes were examined in order to establish their formation process. It was proposed that post-hole F3323 would be box-sectioned and sampled using a kubiena tin to include subsoil, primary and secondary posthole fills for geo-chemical analysis.

The potential buried soil within the interior is located around the inner enclosure and has not been cleaned back yet although a small portion of it extends into the quadrant currently under excavation. This soil will be sampled at a smaller grid interval of 2m. Some additional localized patches or areas of darker soil were noted in Quadrant A and it was agreed on site that these would be planned and sampled for geo-chemical analysis.

The control geoarchaeological sampling of Quadrant C took place between 13-17 September. The methodology was identical to that in Quadrant A except over the inner enclosure where the sampling frequency was reduced from 5m to 2m intervals.

In accordance with the method statement, a sample of all deposits and 100% of the fill material from each cut feature in Quadrant A is being retained for dating and palaeoenvironmental purposes. These samples will be processed through a flotation tank and sieves to extract suitable material for analysis.

Due to the large quantity of material being generated as a result of this extensive sampling exercise, a supervisor has been appointed, in addition to two assistants, to supervise the archiving of samples and finds.

To date two hundred and forty features or possible features have been excavated in Quadrant A. One hundred and three of these have been found to be non-archaeological including a modern geotechnical pit. One hundred and thirty-seven features are interpreted as archaeological - eighty are enclosure postholes, thirty-two are postholes off the line of the enclosure, fourteen are small pits inside the enclosure, eight are small pits outside the enclosure, one field ditch, one hearth, and one furrow.

The following works have taken place in Quadrant C (the NW quadrant in which the inner enclosure is located): trowel back, magnetic susceptibility survey, supplementary pre-excavation planning, and geoarchaeological control sampling. Excavation in Quadrant C has now commenced. Excavation of the later field ditch which bisects the site is being prioritized in order to assist in keeping water away from the inner enclosure.

Excavation is nearing completion in Quadrant A. Excavation is complete in 18 of 20 grid squares and recording is being completed in the remaining two. The completed post-excavation plans are currently being digitized.

Part of this quadrant corresponds with �the northwestern segment of the outer enclosure� which was identified as one of three key excavation areas in the Supplemental Method Statement for Lismullin National Monument (02 August 2007). In the northwestern segment key area, the pattern of postholes is more complex and there are a number of additional features clustered around the outer enclosure. Excavation of these features is complete and analysis is ongoing. No stratigraphic relationship has been recorded between the enclosure and these features. Their size, shape and fills are broadly similar to the range of size, shape and fills of the enclosure postholes, however these are not distinctive enough for this to be meaningful. One of these features however, in Grid 12, has produced sherds of what has been preliminarily identified as later Bronze Age coarse ware pottery (Eoin Grogan pers comm.).

One of the additional features identified in this key area included a pit from the surface of which numerous sherds of what has been identified as middle Bronze Age domestic cordoned urn pottery (Eoin Grogan pers comm.) have been collected. Preliminary investigations indicated that this pit did not appear to be stratigraphically related to the outer enclosure. Considering the early Iron Age C14 date received for the stakeholes, it was considered important to verify this and attempt to establish the relationship between this pit and the site as a whole. Excavation of the pit has been completed and has confirmed that it is not possible to stratigraphically relate the pit to the post enclosure. The excavated feature is an extremely shallow depression from the fill of which further sherds of identical pottery have been recovered. It would appear that this feature had been heavily truncated.

A range of dispersed small features including fourteen pits or postholes and a hearth have been recorded inside the enclosure. No distinct spatial patterns have been identified. Three small shallow pit features in Grid 3 have produced sherds of what has been preliminarily identified as later Bronze Age pottery (Eoin Grogan pers comm.). In addition a furrow and a modern square-shaped geotechnical pit have been excavated inside the enclosure in this quadrant.

To date none of the enclosure postholes have produced any artefacts, however their fills remain to be sieved. The current evidence of a number of apparently dispersed features producing bronze age pottery of different periods, and the early iron age C14 dates from a selection of enclosure postholes appears to indicate that these dispersed features represent earlier activity and are not directly related to the enclosure.

Excavation of the enclosure postholes in Quadrant A is complete. A total of eighty enclosure postholes have been recorded, sampled and fully excavated in Quadrant A. A further thirty-two postholes off the line of the enclosure ring have been excavated. The postholes have dimensions ranging between 15-23cm in diameter and between 15-23cm in depth. The postholes are generally arranged at 0.4-1m intervals and the enclosing rings 1.5-2.5m apart with apparent localized variations in their spacing.

Preliminary examination of the half sectioned postholes on site by Dr Steven Lancaster, as described above, concurs with the excavator�s interpretation that the posts were most likely driven into the ground (rather than being placed into a prepared posthole) and that the clay fill surrounding the postpipe has resulted from half driven posts being manually moved to gain more purchase in the ground before being driven further. As described above, a thin section sample from a specific posthole has been proposed in order to investigate this theory further.

A thin clay layer c. 2cm deep was recorded in the box section, between the two postholes. Three possible interpretations were initially considered for this deposit:

However, preliminary examination of this deposit on site by Dr Steven Lancaster, as detailed above, suggests that it is unlikely to be a trampled surface or bank material. A thin section sample of both this deposit and the underlying subsoil is to be taken for further analysis. An additional box section has been excavated through two postholes in Grid 12 in order to test if the palaeosoil recorded in Grid 11 extends through this area. No evidence of a similar deposit has been identified.

Excavation of the east-west aligned ditch is complete in Quadrant A. The ditch is cut by a figure-of-eight cereal drying kiln outside the enclosure on the basis of which a date range of late Iron Age to early medieval is currently suggested. Within Quadrant A it is 33m long by 0.95m wide by 0.4m deep and contains between 2 and 4 fills. The basal fills appear to have silted up over time indicating that this feature may have functioned as a drain. A ditch terminal has been identified adjacent to the eastern boundary of Quadrant A in Grid 11 representing a short break or causeway. A corresponding terminal is visible in Quadrant B where the ditch continues its course. The intersection between this ditch and a north-south aligned linear feature (F2724) in Grid 2 are being investigated. Quarter sections have been excavated at the point of intersection between these features however the stratigraphic relationship has not yet been confirmed due to the similarity of the fills. The quarter sections have been left open to the elements in an attempt to improve their visibility.

In general, conditions on site have been good since works recommenced. The sandbag cordon has assisted in keeping excessive silt from accumulating on the enclosure during heavy rainfall and this has been monitored and supplemented where necessary.

A sheet of plastic has been unrolled and positioned close to the enclosure for speedy deployment should it be deemed necessary.

A water bowser and hoses have also been provided on site and have been used to maintain optimum moisture levels in dry sunny conditions.

Following trowel back of Quadrant C a sump hole was excavated in order to allow for pumping should the site flood in the future. In addition excavation of the later field ditch which bisects the enclosure has been prioritized in order to assist in keeping excess water away from the inner enclosure.