corfield, n. y williams, j. preservation of archaeological remains in situ. 2011

8/3/2019 Corfield, N. y Williams, J. Preservation of Archaeological Remains in Situ. 2011

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e-conservationthe online magazine No. 21, September 2011



The fourth of the conferences on the Preservation

of Archaeological Remains In Situ (PARIS) was

held in Copenhagen from 23rd to 27th May. Previ‐

ous conferences have been held in London (1996

and 2001) and Amsterdam (2006). The conferenc‐

es are particularly focussed on the survival of ar‐

chaeological evidence (artefacts, environmental

evidence, stratigraphic and contextual informa‐tion as well as structural remains) when the envi‐

ronment of sites are affected by anthropogenic or

natural changes. Past conferences have focussed

on the nature of the ground environment, how

archaeological evidence changes through time

and what the impact is of short and long term

changes. Much of the earlier discussion was fo‐

cussed on wetland environments and saturated

urban deposits, partly because that was where agreat deal of the observations of change had

been undertaken and also because the impacts

of change were most readily seen in desiccated

wetland soils. There was also a predominantly

northern European bias in the papers presented.

The fourth conference showed a marked broad‐

ening of contributions, both geographically and

in the subject matter. The bias towards Europe

remained, with strong representation from Den‐

mark, the Netherlands, Norway and the United

Kingdom and lesser contingents from Eire, Swe‐

den, Finland, Germany, France, Belgium, Italy,

Portugal, Croatia and Azerbaijan. Single parti‐

cipants were from Turkey, Egypt, Pakistan and

the USA, while the southern hemisphere was rep‐

resented by Australia and New Zealand. PARIS

has become global!

The programme covered a wide range of topics

and was split between four themes:

‐ Degradation of archaeological remains

‐ Monitoring and mitigation case studies

‐ Protocols standards and legislation

‐ Preserving archaeological remains in situ ‐ can

we document it works?

Theme 1, Degradation of archaeological remainsincluded twelve papers. Because of the difficul‐

ties involved in evaluating the results from in vivo

experiments, microcosms in which the range of

variables can be controlled are invaluable and we

were given presentations using this method to

assess the decay rates for wood and to evaluate

impacts on the physico‐chemical and microbio‐

logy of wetlands caused by leaching from wood

treatedwith copper‐arsenic‐chromium preservative.

These were described and included follow up

work in the field to validate the study.

Review by Mike Corfield and Jim Williams

23‐27 May 2011

Copenhagen, Denmark

Organised by:Department of Conservation,National Museum of Denmark

PRESERVATION OF ARCHAEOLOGICAL REMAINS IN SITU (PARIS)

REVIEWS

24 e‐conservation

http://www.e-conservationline.com/



Experimental work in the marine or fresh waterenvironment is challenging and this was evident

in papers discussing the impact of erosion and

protection of sites in Lake Constance and Zurich,

a poster presentation on the problems of protec‐

tion on the Gulf coast of Iran, and a major study

of the effects of reburial of metal objects under

seawater as a means of ensuring the survival of

many thousands of artefacts recovered from

shipwrecks at the island of Marstrand, Sweden.The bioerosion of stone underwater is also an is‐

sue and we were shown how rapidly it can be de‐

graded by biological growth eroding the surface

and creating cavities to the extent that surface

detail is lost.

Evaluating the changes to burial conditions by

reference to the stratigraphic layers of corrosion

has been something that one of the reviewers

(MC) has long sought to see tested, so a paper on

this examining corrosion of ferrous artefacts from

an ironworking site in Normandy, France was verywelcome despite the risk of rapid change of cor‐

rosion species following excavation. Unsaturated

soils are notoriously varied and characterising

potential preservation without excavation is often

speculative so a paper reporting work to develop

methodologies for evaluating unsaturated soils

in Oslo was very welcome.

On a broader scale we heard a paper on the carbonrelease arising from desiccation of wetlands and

the risk that archaeological excavations in wet‐

lands might be contributing to greenhouse gas

emissions. The impact of building over archae‐

ological sites was discussed and moves towards

the development of a risk assessment system for

archaeological sites were highlighted. Finally the

question was asked whether preservation can be

predicted from monitoring results, the question

we would all like to see the answer to.

Round‐table participants, from left to right: Jane Sidell, Mark Pollard, Hans Huisman, Jens Rytter, Vicky Richards, Mike Corfield,

Henk Kars, Jim Williams, and standing at and by the podium, Henning Matthiesen and David Gregory, the conference co‐organisers.

REVIEWS

25e‐conservation




REVIEWS

26 e‐conservation

Overall, the papers in this f irst theme were excep‐

tionally broad in their subject matter and scope,

from small scale laboratory work to the large scaleanalysis of an entire urban area. All provided dif‐

ferent methods of quantifying degradation rates

at these different scales, demonstrating that we

have now, collectively, developed a range of tools

suitable for assessing the state of preservation of

most common material. What is less clear, for the

most part, and was not tackled in many of the

papers in this session, are the rates at which de‐

gradation processes are taking place.

Theme 2, Monitoring and mitigation case studies

comprised seventeen papers and again we were

offered a rich mix of papers covering marine and

coastal sites, wetlands and unsaturated sites,

broad scale urban evaluation, and, breaking new

ground (perhaps an unfortunate metaphor for

this conference), studies of the preservation of

sites in the Greenland permafrost and at the other

extreme, in Abu Dhabi, and in addition to ourusual span of materials, mudbrick in China.

It is impossible to cover the details of each of the

papers, but suffice to say that there appeared to

be the recognition that monitoring had to answer

questions, and that only in exceptional circum‐

stances could monitoring be justified over very

long timescales. A report of the important work

at Bryggen, Bergen, Norway demonstrated howpost‐construction monitoring of the impact of

the uncontrolled construction of a hotel at the

World Heritage Site of the medieval waterfront

of Bergen enabled the implementation of post‐

development mitigation of the damages caused

to organic structural remains.

Two papers (one from session 4) showed how

monitoring could be used to devise strategies that

would enable historic towns such as Trondheim,

Norway and Nantwich, England to continue to

evolve to meet the needs of modern life. Interest ‐

ingly, on many of the terrestrial sites presented

under this theme, monitoring was aimed at un‐derstanding unsaturated, rather than fully water‐

logged deposits. Techniques ranged from the use

of TDR, in situ redox and oxygen probes, to soil

and water analysis. Although there was no one

common approach used, the detailed analysis of

soil and water chemistry (anion and cation con‐

centrations for example), before and throughout

monitoring seems to be one of the more reliable

ways of characterising these very challenging

burial environments.

Taking to the water again, we were shown the sad

destruction of the Stirling Castle, one of England’s

finest seventeenth century shipwrecks as it be‐

came increasingly exposed by the movement of

the great sandbank that had hitherto protected

it. It was a graphic example of the challenges in‐

volved in trying to protect entire ships and their

contents in the dynamic marine environment.One of the other elements of the maritime envir‐

onment is wood borers and we were provided

with summary of work in the Baltic Sea, which is

increasing in salinity through the impact of cli‐

mate change as part of the EU project “WreckPro‐

tect” to develop protection strategies against

marine borers for underwater cultural heritage.

On the opposite side of the globe experimental

work to evaluate the options for protecting a19th century wooden hulled ship south of Free‐

mantle, Western Australia were described. In an‐

other departure for PARIS we were shown how

efforts were being made to conserve the extens‐

ive submerged upstanding remains of Roman vil‐

las at Baia, Naples, Italy, and to make them

accessible to scuba divers.

Theme 3, Protocols standards and legislation at‐

tracted fewer papers with eight contributors.

There was a tendency in this session to drift rather


http://www.prorestauro.com/



REVIEWS

Per Kristian Madsen, Director of the National Museum of

Denmark welcoming the delegates and opening the

Symposium.

e‐conservation

Conference breaks provided ample opportunity to share

experiences and exchange ideas.

e‐conservation 27

too far into straightforward cultural resource

management and this would be a danger for the

PARIS brand which has always tried to focus on

the importance of a sound scientific understand‐

ing to underpin the management of archaeolo‐

gical heritage. Nonetheless, the session did bring

in some new faces who will hopefully have bene‐

fited from the wider programme and who we hopewill return with examples of scientific studies of

the problems inherent in trying to preserve still‐

buried archaeological sites.

Some of the papers in this session reported on

efforts to establish sound management princi‐

pals to underpin their archaeological heritage.

The first paper described how the Norwegian Dir‐

ectorate for Cultural Heritage was using the workit had funded at Bergen to develop a toolbox that

would enable it to apply the same standards so

that the right decisions can be made in future

cases, whilst another outlined the development

of a new governmental body to oversee the ar‐

chaeological heritage of the Flanders region of

Belgium. One paper was concerned with the po‐

tential for soils to be used as indicators of the

preservation potential of sites, using both the soil

itself and its inclusions of, for example, calcareous

shells to indicate the pH of the soil. The paper

argued for more prior assessment of the soils

themselves to influence the design of monitor‐

ing schemes, and perhaps this paper would have

been better placed with the previous theme on

monitoring.

Two projects were concerned with the conserva‐

tion of exposed sites, one a Roman settlement at Ludbreg in Croatia, and the other a mosaic floor

in Turkey. A more seriously misplaced contribution

concerned the need for more coherent strategies

to ensure the proper curation and storage of the

many thousands of dendrochronological cores.

Interesting as these papers were, they were not

really in the spirit of the PARIS conferences and

would have perhaps have generated wider interest

at other venues.

Theme 4, Preserving archaeological remains in situ

‐ can we document it works? was perhaps the most

challenging of all the sessions. It was pointed out

that one of the first attempts to scientifically

monitor an archaeological site was only twenty

one years ago, and this site, the Rose Theatre in

London, has been continuously monitored since

then. This timescale is short by comparison with

the lifetime of most structures built over archae‐

ological remains and it is often hard to tell what




28 e‐conservation

REVIEWS

changes might take place before they can be re‐

examined. We were given a tour through sites in

London that had been first excavated up to 150 years previously, and when re‐excavated in recent

times were shown to be still in good condition.

However many of these were stone structures

or timber revetments close to the River Thames

where wood preservation has been shown to

be excellent.

The Rose Theatre itself is due to be re‐excavated

and there will be much interest in how effective

the reburial system has been, particularly as it

has become the benchmark for reburial at many

other sites. This was discussed in a paper which

also presented the preferred method for sealing

the site entirely so that the natural hydrology

alone maintains the site’s integrity. Equally in‐

teresting was the research into the impact of a

change in soil moisture content (SMC) that was

presented. It was suggested that a reduction in

SMC from 50% to 40% would to be likely to lead to

a 13% shrinkage in the important deposits of the

Rose Theatre. This is noteworthy as although other

projects have collected moisture data in the past,

few if any have used the data to any great effect.

The continuing information from the research at

Nydam Møse in Denmark was presented, and on a

shorter timescale, there were more results from

the reburial research at Marstrand (the RAAR pro‐ ject also discussed in session 1). The history of

monitoring peat extraction in England’s Somer‐

set Levels coupled with the peat wastage result‐

ing from land drainage was given together with

the hope that nature and archaeological conser‐

vation together with an aging farming community

may enable practical steps to be taken to begin the

long process of regenerating the peat, perhaps

driven also by the beneficial effect this would have

on carbon capture. Farming and drainage were also

critical elements in the management of the land‐

scape around the former island of Schokland. Re‐

sults of the monitoring that has been taking place

for 15 years since 1999 were presented and theefficacy of the various tools used was discussed.

Finally, the evolution of monitoring over 30 years

in England was presented and an assessment of

the types of sites monitored, reasons from moni‐

toring and tools used was given. Recommenda‐

tions to help improve future monitoring projects

were presented. These included the need for more

assessment of the state of preservation of a site

before monitoring is considered; the need for a

proper project design to be developed at the out‐

set of the work; and finally that there should be

clarity about why monitoring is needed for a given

site and what can be done when monitoring data

suggest optimum conditions for survival are no

longer being maintained.

The conference finished with a round table discus‐

sion of the four themes lead by the session chairs.It is hoped that a summary of the main discussion

points raised by the panel and audience will be

collated for the conference proceedings (from

audio recordings). Some of the points discussed

included the extent to which we can quantify de‐

gradation states and rates (states, yes, rates, in

some cases); the need for more ground‐truthing

of model and microcosm research to take place on

actual archaeological sites; the need for morethought to go into designing monitoring schemes,

and for more assessment prior to monitoring; and

finally, a recognition that standards and protocols

can be useful in providing guidance to those

working in the discipline, but often need to be

re‐produced separately for each country due to

different legislation and burial environments.

Just before the discussion started, the session

was interrupted in order for a presentation to be

made to David Gregory and Henning Matthiesen,




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REVIEWS

Excursion to Roskilde in Viking ships.

the conference chairs. They were presented with an

award from the Sofie Elizabeth and Aage Rothen‐

bergs Scholarship in recognition of their research

in natural science at the National Museum. We

should also mention the other members of the

organising committee, Karen Brynjolf Pedersen

and Mads Chr. Christensen, who along with Hen‐

ning and David organised an extremely successful

and well run conference.

On the social side, there was an opening reception

in the entrance of the National Museum (the ven‐

ue for the conference) on the evening before the

conference began, a visit to on‐going excavations

in the city centre or a trip to see the ruins under

Christiansborg on the first evening, and the con‐

ference dinner in the Tivoli Gardens at the end of

the second day. The day after the conference itself was over there was an excursion to Roskilde that

included a fleet of Viking ships filled with deleg‐

ates sailing in the bay, and a conducted tour of

the cathedral, and finally, on the fifth (or sixth)

day (depending when you had arrived), an infor‐

mal, guided tour of the National Museum’s con‐

servation department at Mølleådalen near Brede.

The conference proceedings will be published in a

special issue of Conservation and Management of

Archaeological Sites in late 2011 or early 2012.

MIKE CORFIELD

Conservator

Contact: [email protected]

Mike Corfield has been a conservator and conser‐

vation manager in Wiltshire, Wales and with Eng‐

lish Heritage. In 1991 he became responsible for

the hydrological monitoring programme at the

site of the Rose Theatre. Later, he carried out

projects to study the hydrology of sites to increase

understanding of hydrology and the preservation

of organic remains. With their support and like

minded colleagues the first Preservation of Ar‐

chaeological Remains in Situ conference was held

in 1996, and in 1998 recognising that archaeolo‐

gical resource managers recommending mitiga‐

tion strategies needed to be supported by sound

scientific advice and accordingly a team of nine

regional scientific advisers were appointed. Mike

was appointed English Heritage Chief Scientist in

1999, and since his retirement in 2002 he has re‐

tained his interest in site preservation as a con‐sultant, carrying out projects for UNESCO in India

and Iran, and supporting academic research.

JIM WILLIAMS

Archaeological scientist

Contact: jim.williams@english‐heritage.org.uk

Jim Williams is an archaeological scientist, inter‐

ested in preservation in situ issues, specificallygroundwater monitoring and construction impacts.

Jim is a co‐author of the English Heritage docu‐

ment Piling and Archaeology, and has contributed

papers on preservation in situ to a number of

European conferences, and been involved with an

EC project on pile re‐use (RUFUS). During 2009

Jim took a secondment to coordinate the devel‐

opment of a UK‐wide National Heritage Science

Strategy. He is currently the English Heritage

Science Advisor for the East Midlands, a role that

he has undertaken on and off for the last 9 years.

http://www.heritagesciencestrategy.org.uk/

http://www.heritagesciencestrategy.org.uk/


corfield, n. y williams, j. preservation of archaeological remains in situ. 2011

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