Dredgers-and-Archaeology-Shipfinds-from-the-Slufter

DREDGERS AND ARCHAEOLOGY: Shipfinds from the Slufter

rERlE VAN WE1 N, \1

DREDGERS A N D ARCHAEOLOGY Shipfinds from the Slufter

J. Adams A. F. L. van Holk Th. J. Maarleveld

Archeologie onder water, 2e onderzoeksrapport Ministerie van Welzijn, Volksgezondheid en Cultuur

Alphen aan den Rijn 1990

ARCHAEOLOGICAL SURVEY

Grootschalige locatie voor de berging van baggerspecie uit het benedenrivierengebied.

Initiative: Gemeente Rotterdam Rijkswaterstaat Provincie Zuid-Holland mei 1990

Two versions of this report, fitting in different series and thus with different covers but otherwise indentical are published by:

Projectorganisatie Grootschalige locatie Gemeente Rotterdam Rijkswaterstaat Provincie Zuid-Holland

ARCHAEOLOGICAL SURVEY Grootschalige locatie voor de berging van baggerspecie uit het benedenrivierengebied

Correspondence: Dienst van Gemeentewerken Galvanistraat 15 Postbus 6633 3002 AP Rotterdam

Afdeling Archeologie Onder water Ministerie van Welzijn, Volksgezondheid en Cultuur

as

OREDGERSANDARCHAEOLOGY Shipfinds from the Slufter

ISBN 90-800467-1-X

This second version can be ordered by giro transfer of dfl. 45.- (plus dfl. 5.-for postage and handling) on girobank accountnr. 374082 Afdeling Archeologie Onder water Eikenlaan 239 2404 BP Alphen aan den Rijn Supporters of the Glavimans Stichting are granted a dfl. 10.- discount.

TABLE OF CONTENTS

S u m m a r y Samenvat t ing In t roduc t ion

PRELIMINARY RESEARCH

1. Prel iminary archaeological survey of the Slufter p ro jec t 1.1 Objectives 1.2 Introduction to the area 1.3 Geological survey 1.4 Historical information 1.5 Potential for archaeological sites 1.6 Conclusions and a line of action 1.7 Changes in planning

ARCHAEOLOGY OF THE SLUFTER

1. Wrecksi te S L 1 1.1 Circumstances of discovery

1.1.1 The first hit 1.1.2 Preliminary assessment 1.1.3 Adjustment of the order of sand extraction 1.1.4 On-site inspection

1.2 Description of the recovered remains 1.2.1 The ship 1.2.2 Ship's fittings 1.2.3 Associated finds

1.3 Analyses 1.3.1 Dendrochronological analysis 1.3.2 Caulking and luting materials

1.4 Evaluation 1.4.1 The site 1.4.2 The ship

2. Wrecksi te S L 2 2.1 Circumstances of discovery 2.2 Description of the recovered remains 2.3 Analyses 2.4 Evaluative considerations

3. Wrecksi te S L 3 3.1 Circumstances of discovery 3.2 Description of the recovered remains 3.3 Analyses 3.4 Conclusions

4. Wrecksi te SL 4 4.1 Circumstances of discovery

4.1.1 The first hit 4.1.2 On-site inspection 4.1.3 Considerations and decisions 4.1.4 Clearance 4.1.5 Renewed considerations


4.3 Analyses 4.3.1 Wood species 4.3.2 Dendrochronological analysis 4.3.3 Caulking and luting materials 4.3.4 Copper alloys 4.3.5 Coal

4.4 Evaluation 4.4.1 Introduction 4.4.2 The site 4.4.3 The ship and its construction 4.4.4 Developments in ship construction 4.4.5 Historical setting of ship and ship type 4.4.6 The cargo 4.4.7 Date of shipwreck

4.5 Conclusion

5. Wrecksi te SL 5 5.1 Circumstances of discovery 5.2 Description of the recovered remains 5.3 Analyses 5.4 Discussion

6. Wrecksi te SL 6

7. Miscellaneous f inds

EVALUATION

1. Dredgers a n d archaeology

2. Object ives a n d planning

3. Prospects

4. Genera l approach a n d l imitat ions 4.1 Formal setting 4.2 Technical scope 4.3 Methods

5. Resul ts 5.1 Introduction 5.2 Direct results

5.2.1 Shipping and shipbuilding 5.2.2 Wrecksites and site formation 5.2.3 Geology and geographical history

5.3 Experience

6. Recommendations

APPENDICES

Appendix I Introduction to dendrochronological analysis 157 Appendix I1 Selection of historical documents that are relevant to the study 161

of the ship at SL 4 Appendix 111 Conservation and artefact filing 167

Glossary 169

Verklarende woordenlijst 18 1

References 191

Acknowledgements 197

SUMMARY

In September 1987 the Slufter, a large scale disposal site for contaminated dredged material adjacent to the Maasvlakte was put into use. Its realization had taken eighteen months of dredging and construction and many years of preparation. Through its realization the environmental problems of the storage of contaminated material which must continuously be dredged from the channels and basins of the port of Rotterdam in order to guarantee its accessability, were alleviated for the mid term. This, however, was not its only result. A work of this magnitude has many side-effects. Most of these were thoroughly studied in advance and an Environmental Impact Statement [E.I.S.] was part of the decision-making procedure. The present report deals with archaeology, an aspect which was not considered at the time but which has been given ample consideration since it was pointed to at the end of E.I.S. procedure. Realization of the Slufter inter alii implied that 37 million m' of sediments which had been deposited in the outer delta of the RhineIMeuse estuary would be moved and thus loose their original integrity. On the face of it this may not seem very significant. However such earth-moving will also obliterate any data relating to the formation of the area which can be derived from its original stratigraphy as well as any data or remains relating to its former use by man. It is an aspect which will easily attract attention whenever visible remains and monuments outcrop at the surface but which is of equal importance when the cultural heritage is buried in deep sediments. To accomodate for archaeology - for preservation of the cultural heritage - in a large-scale dredging project is not an easy task. One of the main problems in planning is that the cultural values involved are not known in advance. Paradoxically it is just the fact that any vestiges and remains are undisturbed and thus unknown that determines their potentially great value. In the Slufter project this basic problem was considerably reduced by a preliminary survey.

It did not predict what would be found during construction, but it indicated possibilities as well as sensitive areas. On the one hand it showed large sequences of sediments to be archaeologically sterile, thereby considerably reducing the extent of sediments deserving archaeological attention. On the other hand it opened the possibility to set priorities by making the archaeological potential explicit. A line of action deployed on the basis of this preliminary survey set the terms for appropriate action to various kinds of discovery:

archaeological attention would be focused on shipwreck-sites; wreck-sites related to a navigation channel which had passed North of the area from medieval times onwards were deemed to deserve more care than wreck-sites relating to a channel to the South which came into use in the 18th century; wreck-sites containing considerable remains in structural cohesion were deemed to deserve more attention than dispersed sites; all on-site archaeological work had to be practicable and reasonable within the limitations set by the construction project; it would be made possible by a flexible approach to the order of construction; overall delays had to be avoided but optimal opportunities for on-site observations would be created by tackling the most sensitive areas first.

In this dynamic set-up it was essential that a quick assessment of any discovery could be made by on-site archaeological staff. The principle aim of the archaeological endeavour was to document what would otherwise be lost. Although the preliminary survey and the line of action were completed in advance of the actual start of construction, no agreement had been reached as to which authority was to bear the extra cost of the archaeological survey. A factor which indubitably explains

SUMMARY

part of the reticence at this stage was the lack of tangible evidence referred to above. The municipality of Rotterdam provided the most necessary means in advance after the first wreck-sites had actually been found. While sketching the preparatory phase as well as outlining the difficulties encountered the present report is mainly concerned with the archaeological documentation and research as such. In total six wreck-sites were discovered in the dredged area. One site [SL 21 might be of medieval date, the others are younger. Subsequent research proved three sites [SL 1, SL 3, SL 51 to have formed after the same wrecking event, even though they are over 1 km apart. The remains discovered indicate a medium sized vessel which wrecked late in the 18th century. Its study and recording showed interesting detail in the construction of this typical Dutch-built vessel. Part of its fittings, rig and inventory could also be documented. A slightly younger wreck was found at site SL 4. It was preserved virtually complete and must have gone down during or around the 1840's. In the light of its relative young date, the complexity of excavating a complete ship and the priorities set in the line of action the site as such was abandoned archaeologically. However the study of a large hull section which was raised during clearance operations proved most rewarding. It showed a vessel of north-eastern English build engaged in the coaltrade with Rotterdam. Although quite common in its day it represents a class of vessel on which historical data is far from complete. Its study provides detailed and accurate information on its construction. Integration of these archaeological data in the aggregate knowledge of early 19th century shipbuilding and the collier-trade showed it to be particularly rewarding with respect to constructional detail and a better understanding of long term development. For one thing it provided information on aspects that were never written down. For another it provides a valuable means of cross-checking between historical documentation where it appears to be comprehensive and reality as demonstrated by the archaeological remains. It shows assertions to be generalisations or simply incorrect. It also elucidates aspects which are equivocal in the archival record. By providing a clue to historical documents it thus augments our knowledge of early 19th century shipbuilding far more than one might anticipate. However the main purpose of the archaeological work during the realization of

the Slufter was documentation, and documentation is its main result. This applies to the sites mentioned in this summary as well as to the other dispersed discoveries. Both the scale of the project and the attempt to integrate measures for archaeological recording into its organisation are unusual. All in all it resulted in new information on shipping and shipbuilding, wreck-sites and site formation as well as the geology and the geographical history of the area. All this information would have been lost if no attempt had been made to document it. Although far from advertising dredging as an archaeological technique the report concludes that dredgers and archaeology should not be treated as two incompatible phenomena. Wherever there are clear indications that [as yet unknown] archaeological values are threatened by large scale marine engineering this should be taken into consideration. A preliminary survey, a clear line of action and priorities set in advance will make an effort for archaeological documentation quite manageable and will considerably reduce the risk of unanticipated discoveries. If sensitive areas are to be dredged the experience of the Slufter-project has shown that flexibility and a few basic requirements for timely assessment and recording may safeguard valuable information. However, there should be agreement in advance on the way in which the unavoidable costs will be met.

SUMMARY

SAMENVATTING

Aan de westzijde van de Maasvlakte is in zee de Slufter aangelegd, de grootschalige locatie voor de berging van baggerspecie uit het benedeizrivierengebied. Na vele jaren van voorbereiding en achttien maanden baggeren en bollwen kon deze stortplaats in september 1987 in gebrurk worden gesteld. Er is daarmee voor de middellange termijn een milieuhygieniscl~ verantwoorde oplossing gekomen voor de problemen van her-ging van verontreinigd havenslib dat bij voortduring uit de Rotterdamse havens moet worden gebaggerd om deze op diepte te houden. Dat is echter niet het enige resultaat, want een werk van deze omvang heeft vele neveneffecten. In de voorbereidingsfase zijn veel van deze aspecten onder de loupe genomen en in de besluitvormingsprocedure was een milieu-effectrapportage [M.E.R.] opgenomen. Het voorliggende rapport is gewijd aan de archeologie. Dat is een aspect dat indertijd buiten beschouwing is gebleven, nlaar dat ruime aandacht heeft gekregerz sinds het 01) 11et eind van de M.E.R.-procedure onder de aandacht is gebracht. De aanleg vaii de Slufter betekende onder meer dat 37 miljoen m3 sediment in de voordelta vaii Rijn en Maas zou worden vergraven en daarniee zijn oorspronkelijke samenhang zou verliezen. Op het eerste gezicht lijkt dat misschien niet zo bijzonder, maar door dat graafwerk wordt ook alle iiiforniatie uitgewist die men aan de grondlagen kan ontlenen. Enerzijds gaat lzet daarbij on? informatie over de opbouw en het ontstaan vaii het gebied zelfen anderzijds om spore11 en overblrj~selen die inzicht kunnen verschaffen over de wijze waarop de mens het gebied in vroeger tijd heeft gebruikt. Het zijn aspecten die onmiddellijk in het oog springen wanneer er overblijfselen en n~olzumenten aan ket bodemoppervlak zichtbaar zijn, maar die van even groot belang zijn wanneer het cultureel erfgoed schuil gaat onder dikke lagen sediment. Bij grootschalige zandwinning rekening houdeiz met de archeologie - met als doe1 het cultureel erfgoed te behouden - is geen gemakkeljke taak. Vooral het feit dat niet van

te voren bekend is om welke culturele waarden het gaat, maakt het bijzonder lastig. Paradoxaal genoeg draagt juist het feit dat de sporen en resten voorheen onberoerd zijn en dus princ~pieel onbekend, in belangrijke mate brj aan de potentiele archeologische waarde van het gebied. Bij het Slufter-project is dit zoveel mogelijk ondei-vangen door een vooronderzoek. Hoewel niet in detail kon worden voorspeld wat er gevonden zou worden kon we1 worden aangegeven wat de mogelijkheden waren en welke gebieden bijzondere aandacht behoefden. Van grote pakketten afzettingen kon worden vastgesteld dat deze vanuit archeologisch oogpunt als steriel konden worden beschouwd, waardoor het aandachtsgebied aaizzienlijk kon worden verkleind. Bovendien maakte het vooi-onderzoek het mogelijk om prioriteiten re stellen, doordat het inzicht gaf in het archeologisch potentieel. Op basis van het vooronderzoek werd een plan van aanpak opgesteld, waarin bepaaald werd wat er re doeri stond bij welk type ontdekking:

de aandacht van archeologische zijde zou worden beperkt tot scheepsvondsten; aan eventuele scheepsvondsten die in verband konden wordeii gebracht met de vaargeul die vanaf de Middeleeuwen aan de noordzijde lungs het gebied had gelopen zou meer aandacht worden besteed dun aan scheepsvondsten die verband houden met de zuidelijk gelegen geul, die in de 18e eeuw irz gebruik is genomen; er zou meer aandacht worden besteed aan vindplaatsen met grote delen van een scheepsromp, dun aan vindplaatsen met verspreid, 10s materiaal; het archeologisch veldwerk diende doeltreffend te zijn en praktisch uitvoerbaar binnen de beperkingen van het project; het veldwerk zou mogelijk worden gemaakt door plooibaarheid en

SAMENVATTING

flexibiliteit in de volgorde van de zandwinning;

. vertraging in de totale uitvoering van het werk diende te worden vermeden, maar optimale condities voor het doen van archeologische waarnemingen zouden worden geschapen door de belangrijkste gebieden het eerste aan te pakken.

In deze clynamische benadering was het van essentieel belang dat iedere ontdekking onmiddellijk ter plaatse op waarde geschat kon worden door archeologen. De voornaamste doelstelling van de archeologische inspanningen was om vast te leggen wat anders verloren zou gaan. Het vooronderzoek en het plan van aanpak waren voltooid voordat met de aanleg werd begonnen, maar er was geen overeenstemming over de vraag welke instelling de kosten zou moeten dragen die met het archeologische onderzoek waren gemoeid. De terughoudendheid die in dit stadiunl werd betracht valt zonder twijjel voor een deel te verklaren uit het feit dat tastbare aanwijzingen ontbraken, een prohleem waar hierboven a1 op werd gewezen. Nadat de eerste historische schepen daadwerkelijk waren gevonden heeft de gemeetzte Rotterdam de meest noodzakelijke financien ter heschikking gesteld. Hoewel rle voorbereidingen, maar ook de moeilijkheden die het hoofd moesten worden geboden in grove lijnen worden geschetst is dit rapport eerst en vooral gewijd aan de archeologie zelf, de documentatie en het onderzoek. In totaal werden tijdens het werk op zes plaatsen sclzeepsresten gevonden. EE'n van de vindplaatsen [SL 21 zoil middeleeuws kunnen zijn, de overige zijn van later datum. Het onderzoek heeft aangetoond dat drie vindplaatsen [SL 1, SL 3, SL 51 resten bevatten van &in en hetzelfde schip, hoewel zij meer dun een kilometer uiteen liggen. Het gaat om een middelgroot schip clat op het eind van de 18e eeuw moet zijn vergaan en dat op typisch Nederlandse wijze is gebouwd. Het onderzoek heeft hzerover interessante details aan het licht gebracht. Ook konden delen van de uitrusting, de tuigage en de scheepsinventaris worden vastgelegd. Van iets later datum is het schip dat op vindplaats SL 4 werd aatzgetroffen. Het was zo goed als volledig behouden en moet omstreeks de jaren 1840 zijn gezonken. De rela fief jonge datering, de problemen die rijzen bij her opgraven van een compleet schip en de prioriteiten die in het plan van aanpak waren gesteld noopten ertoe de

vindplaats archeologisch op te geven. Toen de vindplaats vervolgens werd geruimd kwam een groot rompfragment als E'E'n geheel hovetl water en bleek het toch zeer de moeite waai-d dit te bestuderen. Het gaat om een schip dat in Noordoost-Engeland is gebouwd en dat met kolen op Rotterdam voer. Hoewel het indertijd een zeer alledaags schip moet zijn geweest zijn de historlsche gegevens over dit soort schepen verre van volledig. Het onderzoek heeft gedetailleerde en nauwkeurige gegevens opgeleverd over de bouwwijze. Het combineren van deze archeologische gegevens met hetgeen reeds bekend is over 19e-eeuwse scheepsbouw en kolenhandel bleek zeer verhelderend. Enerzijds gaat het daarbij om zaken waarover nooit geschreven is en bovendien levert her waardevolle gegevens om de uitgebreide historische docurnentatie te toetsen aan de werkelijkheid, zoals die in de archeologische overblijyselen besloten ligt. Stellige beweringen blijken daarbij generalisaties of domweg onjuist. Bovendien werpt het onderzoek llcht op aspecten die uit het archiefmateriaal otzduidelijk of cryptisch naar voren komen. Doordat het op die wijze een sleutel vormt tot historische documenten draagt het veel meer bij tot onze kennis van de 19e-eeuwse scheepsbouw dan men zou verwachten. Ondanks dit alles was de belangrijkste doelstelling van het archeologisch onderzoek tijdens de aanleg van de Slufter om vast te leggen wat verloren zou gaan, en dat is ook het voornaamste resultaat. Zowel de schaal van het project als de poging om archeologisch onderzoek in te passen in planning en organisatie van baggerwerk zijtz ongebruikelijk. Het heeft geresulteerd in nieuwe gegevens over scheepvaart en scheepsbouw, over schipbreuk en wrakvorrnitzg en over de geologie en geografische geschiedenis van het betreffencle gebied. A1 die gegevens zouden zijn verloi-en als de poging om ze vast te leggen acl~terwege was gebleven. Hoewel het zeker nief de bedoeling is om de bagggertechniek als een bruikhare archeologische opgravingsmethode te propageren besluit het rapport met de stelling dat zandzcligers en at-cheologie toch niet als twee volstrekt onverenigbare grootheden moeten worden gezlen. Wanneer er ergens duiclelijke aanwijzingen zijn dat vooralst~og onbekende archeologische waarden worden bedi-eigd door grootschalige waterbouwkundige projecten, dienf daaraan de nodige aandacht te woi-den gegeven. Een

SAMENVATTING

SAMENVATTING

vooronderzoek, een plan van aanpak en duidelijk gestelde prioriteiten maken een verantwoorde archeologische documentatie beheersbaar. De kans dat men tijdens het werk onvoorbereid wordt geconfronteerd met archeologische ontdekkingen, waarvan vertragingen van het project het gevolg kunnen zijn, wordt daardoor aanzienlijk verkleind. De ervaring van het Slufterproject heeft geleerd dat, wanneer in potentieel belangrijk sediment wordt gebaggerd, ~~aardevolle gegevens kunnen worden veilig gesteld door een flexibele opstelling en een paar basisvoorzieningen om ontdekkingen rijdig op hun ~ ~ a a r d e te schatten. Van groot belang is daarbij dat er op voorhand overeenstemming is over definanciering.

INTRODUCTION

The present report is the result of archaeological research carried out as part of a large marine dredging project: the realisation of a large-scale disposal site for contaminated dredged material, the so-called Slufter project. The site is situated to the West of Rotterdam, adjacent to the Maasvlakte [fig. 11. Dredgers and archaeology do not combine easily. Even on dry land the combination of archaeological and engineering interests is not always an easy one. Nevertheless a successful tradition of incorporation of archaeology in planning has developed [Klok 1987; Maarleveld 19891. In a marine situation both the scope of works, the machinery used and the complexity of archaeological recording tend to be bigger, and so are the difficulties that are to be met. It is thus quite understandable that archaeology in a rescue situation under water has so far largely remained untrodden ground. Nevertheless the ever growing extent of dredging activities and their utterly destructive effects on archaeological deposits are to be given serious consideration. In the present project a discreet attempt has been made to do so. As befits such an enterprise strong emphasis was lain on recording what would otherwise be lost. This implied a flexible approach to any discoveries that were made.

Slufter project The accessibility of the port of Rotterdam has to be guaranteed by continuous maintenance of appropriate waterdepth in the Lower Rhine reaches. Annually some 23 million m3 of sludge is dredged from the channels and basins. A substantial part of this, some 10 million m3, is so contaminated that it would be irresponsible to dump it into the sea. It has to be disposed of in another, more controllable, way. Ever since the beginning of the seventies finding appropriate disposal locations on dry land has become increasingly problematical. The Stuurgroep Berging Baggerspecie [S.G.B.B. - Steering committee for the

disposal of dredged sludge], set up in 1975, has devised short-term and longer term policies for the issue. In accordance with these policies the Municipality of Rotterdam, the Ministry of Transport and Public Works and the Public Authority Rijnmond [now Provincial Executive of South-Holland] announced their intention to solve the issue in medium-range planning through the realisation of a large-scale disposal site. A range of preliminary studies have resulted in an Environmental Impact Statement [E.I.S.] in 1984 [Gemeente Rotterdam et al. 19841. After an extensive decision-making process the necessary concession and permits were granted for the realisation of alternative I11 as described in the E.I.S. An optimization study successively resulted in a final plan in November 1985 [Gemeente Rotterdam et al. 1985b1 [fig. 21. In short the plan implies that the seabed adjacent to the Maasvlakte is locally excavated to a depth of 28 m. The extracted sand is used in the construction of a dike around the site to a height of 23 m. In total 37 million m3 of earth are moved. The dike encircles an area of 260 ha. The depot has a volume of 90 million m3. Over the years 150 million m' of uncompacted sludge can be accommodated, sufficient to bridge a fifteen year period [I987 - 20021. Started in May 1986 the construction was finished at a great pace. In September 1987 the disposal site was put into use.

Preliminary archaeological survey During the process of decision-making on the realisation of a large-scale disposal site objections were raised by the Minister of Welfare, Public Health and Culture [W.V.C.] because the Environmental Impact Statement made no mention of the cultural heritage. The possible effects on archaeological remains remained unstudied. The need to envisage any necessary archaeological investigations through reservations in the budget was stressed. These objections were successful1 in this way that the position towards archaeological remains was given ample

INTRODUCTION

consideration and that the effort of a preliminary survey was deemed necessary. Clauses on archaeological discoveries were included in the concession that was granted for the realisation of the disposal site. It was provided that the Director of the State Service for Archaeological Investigations [Rijksdienst voor Oudheidkundig Bodemonderzoek R.O.B.] was to be enabled to carry out archaeological investigations to the extent that would reasonably be possible without endangering the planned inauguration of the site through delays. Also a tight time- schedule for in situ work was defined. Simultaneously with further preparations for the project a preliminary archaeological survey was undertaken with two-fold aims:

to meet the demand for understanding where within the project area

archaeological remains could have been preserved, as well as

what the general characteristics of these remains were expected to be; to consider what measures could be taken to further appropriate handling of discoveries within the project.

The survey included both geological, geophysical and historical-geographical research. The formation of the area, the way in which it developed and the way in which man had made use of the successive circumstances were provisionally described. Natural channels that silted during the Middle Ages could be recognized. Covered by shoal- deposits those sediments had not been disturbed later on. On the basis of theoretical considerations on the formation and preservation of archaeological sites the historical and geological information was used to predict what kind of remains could be encountered. It was concluded that the sediments between 6 and 12 m below ordnance datum [N.A.P.] could contain wreckage from the period 1000 to 1500 A.D. The. discovery of such remains would be extremely important as they date from a transitional periodin shipbuilding from which very few shipfinds have been studied. As no major gullies seemed to have crossed the area later on it was thought to be unlikely that substantial ship remains of younger clate would be encountered, unless they be the remains of small fishing vessels. The report on the preliminary archaeological survey [Gemeente Rotterdam et al. 19861 shared the dichotomy of the survey itself. In addition to discussions on the relevant data it deployed a line of action to be followed during the construction phase of the project.

INTRODUCTION

[Fig. 11 The location of the large-scale disposal site Slufter. Situering van de grootschalige locatie Slufter.

[Fig. 21 General lay-out of the large-scale disposal site. Het uitgevoerde ontwerp van de grootschalige locatie.

Due to the extreme urgency of the realisation of the disposal site a keynote was that construction of the site itself could not be delayed. Operational delays of specific dredging machinery due to archaeological discoveries was to be offset by temporary shifting of activities. It was therefore recommended to excavate the most sensitive areas first. Simple electronic detecting devices would have to be mounted onto the dredgers. On-site archaeological expertise would be made available on a modest scale. The budget for this line of action was estimated at dfl 1,500,000: dfl 300,000 to be used on detecting devices and archaeological support, whereas the rest would account for stagnation and shifting of dredgers.

Implementation Completion of the preliminary survey and publication of the report Vooronderzoek Archeologie had no immediate consequences. The reason for this was a financial deadlock: who was to pay for archaeoIogica1 support and the implementation of the proposed line of action? The Ministry of W.V.C. as the responsible authority for the cultural heritage or the originators of the project that necessitated the excavation? The necessity to open the site for disposal of contaminated sludge in the autumn of 1987 meant that it was impossible to wait till a solution was found. In accordance with the tight time schedule realisation of the Slufter project was started in May 1986 without detecting devices having been mounted. The sequence of excavation, however, concurred with the sequence that was stipulated in the line of action. Shortly after the start of dredging two potentially interesting shipwrecks were discovered. Archaeological expertise was provided on an ad hoc basis but funds to proceed investigations were lacking. Thanks to the municipality of Rotterdam the deadlock was broken: it provided the most necessary means in advance. Since recruitment of competent archaeological staff did not at all prove easy at short notice it was only from the beginning of October 1986 that archaeological work could proceed with a complete crew. From then onwards the proposed line of action could be closely followed.

T h e present report The report on archaeological survey as part of the Slufter project is divided in three sections.

INTRODUCTION

In the first part the results of the preliminary geological and historical-geographical studies are described as well as the deployed line of action. The second part is devoted to the archaeology of the Slufter project proper. The third part is included for the purpose of evaluation, i.e. overall conclusions about the area researched, as well as some evaluational observations about the handling of archaeological information in connection with large engineering projects. Both the summary and the captions to the illustrations are presented in English as well as in Dutch. The report is supplemented with appendices and a bilingual [English and Dutch] glossary of maritime terms that appear in the text and captions.

Organisation and responsibilities For the purpose of archaelogical research within the Slufter project a working party was formed in September 1985. Its terms of reference implied:

guidance of the realisation of the Slufter as far as archaeological perspectives are concerned; mobilization of expertise and knowledge as well as aids and appliances; reporting and publicity; surveillance of planning and budget control.

The working party was composed as follows:

ir. R.G.J. van Orden Project-manager Large-scale disposal site, Public Works Department Rotterdam:

ir. J . Bakker Associate Project-manager Large- scale disposal site, Lower Rivers Directorate, Ministry of Transport and Public Works;

drs. Th.J. Maarleveld Ministry of Welfare, Public Health and Culture;

drs. L.M. Akveld Maritiem Museum Prins Hendrik, Rotterdam;

drs. M.C. van Trierum Office for Archaeological Investigations, Public Works Department Rotterdam.

The archaeological research was carried out by Jonathan Adams, AndrC van Holk and Thijs Maarleveld, the authors of this report. They were greatly assisted by many [see acknowledgements]. Overall coordination of survey and research as well as the final editing of the report have been the responsibility of the last author.

INTRODUCTION


1. Preliminary archaeological survey of the Slufter project 1.1 Objectives 1.2 Introduction to the area 1.3 Geological survey 1.4 Historical information 1.5 Potential for archaeological sites 1.6 Conclusions and a line of action 1.7 Changes in planning

NOORDZEE

MAASVLAKTE

[Fig. 31 Archaeological sites as previously revealed by dredging in the area: x concentrations of Mesolithic

artefacts; t shipwreck-sites predating 1800 A.D. ; 0 19th century wreck-sites. Archeologische vindplaatsen die bij eerderzuigwerk in het gebied aan het licht zijn gekornen: x Mesolitische vondstconscenrraries; + vindplaatsen van schepen die voor

1800 zijn vergaan; 0 vindplaatsen van 19e eeuwse

schepen.


P R E L I M I N A R Y ARCHAEOLOGICAL SURVEY OF THE SLUFTER PROJECT

1.1 OBJECTIVES The purpose of the preliminary survey

was to establish where archaeological remains were to be found and what kind of remains one had to reckon with. To this end the survey envisaged combining geological and historical information. A theoretical prediction was its aim, in combination of course with a practical guideline of how to cope with discoveries during the realization of the work. First of all it was to be established which sediments were to be considered archaeologically sterile and what kind of archaeological remains were to be encountered in those that were not. It was quite clear that during construction itself there would at the best be occasion for emergency measures. There would be little opportunity for extensive documentation of find circumstances and the geological situation. Studying these in advance would ease interpretation later on. Actual probing of the whole area [ca. 300 ha] was out of the question. Even if that approach could have been made practicable for such an extended and deep unit of sediments, there would have been neither funds nor time to realize it. The preliminary study thus focused on reassessment of previously collected data. It was carried out in the period September 1985 to March 1986. It resulted in a report that was published in April 1986 [Gemeente Rotterdam et al. 19861.

1.2 INTRODUCTION T O T H E AREA The Slufter area is situated in the

outer delta of the Rhinemeuse estuary. Ever since the North Sea came into existence it has been one of the few inlets in the coast of the Lowlands that offered a passage towards the interior of continental Europe. In historical times the estuary featured important shipping routes. Navigation, however, has greatly been affected by continuous changes in the course and depth of the natural channels. The geological and occupational history of the Rhine/Meuse estuary is rather well studied. Both the encompassing work of Geological Survey of The Netherlands

[e.g. Zagwijn and Van Staalduinen 1975; Schiittenhelm 19801 and the detailed case- studies of C. Hoek must be mentioned in this context. Recent overviews with ample references can be found in Hallewas and Van Regteren Altena [1980], Louwe Kooijmans [I9851 and Van Trierum and Henkes [1986]. The historical development of the foreshore and outer delta however, is largely inferred from the general development of the North Sea basin in combination with data collected further inland. On the archaeological contents of the deposits in the Slufter location nothing specific was known. The only indications were the finds made during and after other major dredging operations in the region. Mesolithic hunting and fishing equipment of Boreal Age has been found among material dredged form the Calandkanaal [Verhart 19881. A whole series of historic shipwreck sites has been disrupted during dredging activities in the Oostvoornse Meer, a few miles inshore. These activities took place in the late sixties and no attention was paid to archaeology at the time. How many sites were destroyed can only be guessed. Along the fringes alone, six historic wreck sites have since been discovered by sports-divers [fig. 31. One of these has been investigated by a group of diving hobby-archaeologists under the leadership of 0. Normann [Maarleveld 1982; Normann 19871, two others are currently under investigation by the Ministry of W.V.C.

1.3 GEOLOGICAL SURVEY In the course of the feasibility studies

for the construction of the large-scale disposal site, the area was surveyed geologically. Both deep corings and seismic/acoustical surveys were made. The collected data were - at that stage - analysed from a technical point of view only. The relative permeability and stability of the various deposits were more important in that context than their genesis [Gerneente Rotterdam et. al 19841. Nevertheless this data formed a good basis for further research, the


more so since [in view of several location alternatives] a much larger area had been studied than the ac t~~a l ly chosen site.

General characteristics The RhineIMeuse estuary is characterized by deep quaternary sediments [see fig. 4, 51. The riverine sediments from the Under Pleistocene [Formatie van Tegelen; Formatie van Kedichem] are covered by marine sands which were deposited during the Eemian interglacial. These have been reworked during the Weichsel glacial and have partly been covered by the riverine Formatie van Kreftenheye, which is the youngest pleistocene deposit in the area. The first sediments from the Holocene period are a peaty clay layer, which has not been preserved everywhere. It is commonly named the layer of Velsen. During the Atlanticum this layer has been covered by tidal marsh sediments. The subboreal and subatlantic transgressions have caused alternating erosion and sedimentation, resulting in a complex intertwining of shoal-deposits and gully fillings.

Supplementary research A detailed reinterpretation of previously collected geological data [fig. 61 was carried out in the present context with the following objectives:

to understand the formation of those sediments that were liable to contain archaeological remains; to establish their distribution.

In pursuance of the aims set out above it concentrated on the genesis of the subatlantic sequence. In addition to the preceding field work a few coring samples were analysed palynologically. The geological survey thus dealt with three sets of data:

acoustical and seismic data; lithostratigraphical data; palynological data.

The results that are summarized here were published by Niessen [1986]. The acoustical and seismic data consisted of records that had been recorded with Sonia and Sparker devices. They were primarily made with the aim of charting the presence of the layer of Velsen. Because of its impermeability this layer could be extremely important for the technicalities of the disposal site, had it appeared to be undisturbed in the whole site area [fig. 71. Nevertheless the records do contain a lot of information on the younger sedimentation [fig. 81. Shoal-deposits and


[Fig. 41 [Fig. 71 Chronostratigraphical and Distribution of the socalled Layerof lithostratigraphical classification of the Velsen [hatched]. Quaternary. Verspreiding van de Laag van Velsen Chronostratigrafische en Igearceerdl. lithostratigrafische indeling van het Kwartair.

[Fig. 51 Chronostratigraphical classification of the Holocene. Chronostratigrafische indeling van het Holoceen.

[Fig. 61 Masterplan featuring the distribution of previously collected geological data. Kartografisch overzicht van de tijdens het vooronderzoek beschikbare geologische gegevens.

i


gully fillings could readily be recognized. The skew and orientation of gi~lly fillings could be deduced. The lithostratigraphical description of cores was essential as a clue to the Sonia and Sparker records [fig. 91. In combination the two sets of data to a certain extent allow for the venture of reconstruction of changes in the gully pattern and of the general direction of sedimentation in the area. Palynological analysis was carried out on two cores [fig. 10, 85.004 and 85.0081, thus providing a general basis for the dating of sediments. All in all the geological survey allowed the following general conclusions:

the holocene sedimentation reaches to a depth of around 21 metres below N.A.P. [Normal Amsterdam Level]; the top is composed of very young shoal deposits, 2 to 3 metres thick, hardly ever reaching to a greater depth than 6 metres; the subatlantic deposits reach to a depth of around 10 to 12 metres; older marine deposits reach to a depth of around 21 metres; the clayeylpeaty layer of Velsen is found at about 21 metres, at the basis of the holocene sedimentation; the direction of sedimentation in the subatlantic deposits has, in general, been from South going North. The gullies have shifted in that direction; in combination with the results of the palynological research of two seperate gully fillings it is assumed that all subatlantic gully deposits in the area have a late subatlantic date. 1.e. they are surely younger than 700 A.D. and have for the greater part been formed after 1300 A.D.

1.4 HISTORICAL INFORMATION In addition to the study of the area

itself it was thought to be essential to get a good overview of what could be said about the development of the area on the basis of historical information. For this purpose the historical geography was studied by Hofland. His results are summarized here. For his cartographic reconstructions the reader is referred to the original publication [Hofland 19861. Here only some rough sketches are given [fig. 111. Information on navigation in and beaconing of the outer delta does go back to 1280 A.D. A reliable reconstruction on the basis of historical data can, however, only be made

from 1540 onwards. The estuary has continually been very broad. Navigation channels have always been whimsical and water depth was never guaranteed for long. In late medieval times two beacons that are first mentioned in 1280 had to be moved several times. During the 16th century two alternative approaches were in use [three even at a certain time]. The southernmost of these approaches was the most important. It was located some 300 metres North of the Slufter site. The channel was buoyed along its northern bank only. Shipping was thus warned for the shallows along its northern fringes. What hazards shipping confronted southward of the buoys is not very clear. There was no question of the whole stretch between the buoys and the coast of Voorne being navigable. Off-shore both the Hinderplaat and the Westplaat had to be rounded. The Westplaat is of particular interest in the context of this study. From the end of the 17th century onwards the estuary narrowed. On the northern bank a recurved spit [dutch: haakwal] was formed, called the Beer [i.e. bear in English]. As it narrowed the tides were harnessed causing erosion at one place and sedimentation at another. The area of the Slufter disposal site was located in the sedimentation zone. Finally, in the beginning of the 18th century the ebb-tide eroded the Westplaat and forced a new passage. It was located some 100 metres South of the Slufter location and soon became the most important navigation channel. All in all the historical information allows for the following conclusions:

the Slufter location has been an area of shallows for the whole period for which historical data are available [i.e. from 1540 A.D. onwards]; channels of any importance have not crossed the location since; during the 16th century the most important navigation channel was within 300 metres North of the location; during the 17th century the shallows [Westplaat] extended towards the North; it is probable that during the 17th century the navigation channel did also shift to the North; in the 18th century a new passage through the shallows came to be used for navigation. That channel is located some 100 metres South of the Slufter location.

P R E L I M I N A R Y RESEARCH

1.5 POTENTIAL FOR ARCHAEOLOGICAL SITES Predictions on the archaeological

[Fig. 81 The interpretation of Sparker-record 22 showing the Holocene sedimentation. Interpretatie van Sparkerrecord 22 in het Holocene sedimentatiepakket.

[Fig. 91 Lithostratigraphical basis of interpretation. De lithostratigrafische grondslag van interpretatie.

[Fig. 101 Palynological analysis of two cores. Boorkolommen met pollenzones.

[Fig. 111 An overview of the development of shipping channels in the RhineIMeuse outer delta, as derived from historical information. Beknopt overzicht van de onhuikkeling van scheepvaartroutes in de Maasmond zoals die kon worden afgeleid uit historische gegevens.

contents of a specific area are a most hazardous affair. Trusting careful analysis of geological and historical data, it is of course possible to make general inferences. Reliable predictions, however, can only be given in the negative. Sterile areas can be indicated. The possibility of striking on a certain type of site in other areas is, however, not a very tangible kind of data. It is something quite different from a positive prediction that something will be found. Nevertheless on the basis of the historical-geographical and geological information presented above some statements concerning any archaeological sites in the construction zone were made which in turn were used as a basis for a strategy. Chance finds after the construction of the Maasvlakte proved that the boreal deposits in what is referred to as the layer of Velsen contain remains of human activity during the Mesolithic. It would however be contrary to reason to suppose that proper attention could be given to any relating sites during the construction of the large-scale disposal site. Systematic investigation of these layers would be an extremely expensive affair, whereas clear-cut results are not indubitably to be expected. It would, however, be sensible to remain alert for chance finds of mesolithic tools in the dredged material. All sediments above the layer of Velsen are of marine origin. Any remains of human activity these might contain must have been brought by or through the sea. The only type of archaeological site one really has to reckon with is the site originating in shipwreck. Archaeological remains cannot be younger than the sediment they are contained in. The oldest topical sequence of marine deposits dates from before the start of the Subatlantic [i.e. before 900 B.c.]. It is certain that seafaring was already practised long before. Nevertheless, the chances of discovery of any wrecksites in the older sediments must be deemed negligible. Also the subatlantic sediments deserved most attention, even though it is true that the area might also contain remains of much older date. Traffic and the resulting losses have gained in intensity. Wether or not these losses can be traced depends on the processes that determine the formation and preservation of archaeological sites. By taking these into consideration the sensitive geological sequences can be defined even more precisely.

PRELIMINARY RESEARCH 23

Formation of wrecksites As stated above shipwreck is the main cause of archaeological site formation in the area. It is a process with its own dynamics. There are many reasons why a ship can come to grief. In general this happens more often near to shore or at the mouth of an inlet than on the high seas. A shallow estuarine area, like the outer delta of the RhineIMeuse, is particularly accident prone. The hydrographic situation in such an area changes quickly. Unfamiliarity with the local conditions and currents or just inattentiveness can easily cause grounding. The situation is worse in strong winds, especially with an onshore direction. Onshore - that is westerly - winds are most usual in the area. If grounding leads to wreck this may come about in two ways:

the ship stays were it stuck and is torn apart; the ship springs a leak but starts floating again and sinks elsewhere.

In the first instance the remains are exposed to extremely strong mechanical forces. They can be dispersed over a large area. The force of the breakers and the velocity of the breaking up process determine the size of individual bits and pieces. In the second instance the ship may sink in deeper water or slide down to deeper water if it sinks on the bank of a gully. In that case the chances of large pieces being embedded in the sediments in their entirety are much better. Once the remains have more or less settled the site is susceptible to a number of complex influences and transforms. At a shallow site the mechanical forces in operation will overrule all other factors. In general nothing remains undamaged in less than six meters of water on an exposed site along the Dutch coast. At a deeper site - i.e. in a gully - remains stand a better chance. Chemical degradation and attack by marine organisms are two, mutually intensifying agents affecting their preservation. The mechanical force of the currents is in some ways subordinate. It will in most cases more strongly act upon the environment than upon the remains themselves, as more often than not these have a greater resistance. However, by doing so the currents determine whether or not the remains are buried and to what extent they are exposed to the aforementioned chemical and biological attack. Changes in the course of gullies can produce repeated slowing and acceleration of this kind of degradation. If wreckage ends up in a sedimentation zone - for instance along a convex gully bank -



it can be covered rather quickly: the remains are no longer exposed to the oxygen rich seawater. The context may remain virtually unchanged until discovery. The only influence one has to reckon with is the mechanical force of compaction of the sediments. If a wreck ends up in the middle of a gully or in an erosion zone the situation will be much more complex. The wreck itself will obstruct the currents and will thus interfere with erosion and deposition processes. Scouring will intensify and it is not improbable that the remains or part thereof will slip into the gully so formed. The process may repeat itself time and again. It will only end if the geological circumstances change sufficiently to override the localised effect of the wreck structure or if, due to collapse or displacement enough water storage is attained for the rate of flow to diminish. In both cases sedimentation will occur and the remains will finally be covered after having been susceptible not only to chemical and biological degradation but also to mechanical damage as a result of displacement. The formation of the site will have affected sediments well beyond the local depth of the gully at the time of sinking. For the situation in the area concerned these theoretical considerations have the following consequences. Shipfinds with structural cohesion are not to be expected in those deposits that have formed on shoal tops [and in consequence have a purely horizontal stratigraphy]. In sediments that have been deposited in gullies such finds are only to be expected at a greater depth than six meters [under mean low water and to be corrected for the sealevel at the time of the gully's activity]. They are most likely to appear at the deepest spots of erosion that a phase of activity of a gully has caused.

1.6 CONCLUSIONS AND A LINE O F ACTION Consideration of the historical-

geographical and geological data in combination with the theoretical aspects elucidated above allowed some reasoning on which a line of action could be deployed. To begin with a quite substantial amount of sediment could -for all practical purposes - be considered to be archaeologically sterile. This applied both to the pleistocene sequence and to the holocene sequence predating the Subatlantic. This also applied to those sediments that lay at a shallower depth than 6 m below N.A.P., as well as to all those sediments that can be interpreted as shoal- deposits.

What remains to be scrutinized are the gully- deposits in the subatlantic sequence. These were supposed to extend no deeper than 12 m below N.A.P. Their build-up is the result of sedimentation in gullies migrating to the North. This happened after 700 A.D. and for the greater part after 1300 A.D. During the 16th century a gully that was used as an important navigation channel was situated some 300 m North of the construction site. During the 18th century a new passage was opened at 100 m South of the location. On the basis of this information it was inferred that the northern navigation channel had previously had a slightly more southerly course. It might have been in use before 1500 A.D. If any wrecksites related to that channel had been preserved they might be encountered in the northern part of the construction site. Wrecksites related to the southern channel would be much younger. They were more likely to be encountered in the southern part. In designing a strategy two straightforward principles took a keynote position:

the line of action should tune to the planning of construction; priority should be given to the most important sites.

However straightforward these principles may be, the practical appliance is very problematical. Nevertheless some a priori choices were made regarding both issues.

The Planning of construction The planning of construction was such that the disposal site would be excavated in three phases [fig. 121. Excavation would be carried out by suction-dredgers in a breaching technique. In the first phase the holocene deposits would be removed to a depth of about 12 m [working depth and disturbance approximately 18 m: resulting water depth 12 m, due to spill]. In this phase dredging would be carried out in continuous shifts, 7 x 24 per week. Three dredgers would be involved, with a weekly production totalling 800.000 m'. In view of creating shelter for the dredgers it was preferred to commence excavation in the northern part. The dredged holocene material was to be used in the body of the dike around the disposal site. In the second phase the main part of the area would be deepened to 28 m. The extracted mix of pleistocene and holocene sediments would be used to strengthen the outer part of the dikes. In the third phase the inner side of the dikes would be dredged to the correct cross-section by means of cutter-suction dredgers. During

Zee .-> ,.. Homien

P R E L I M I N A R Y RESEARCH

-

-

[Fig. 121 Schematic representatlon of the techniques and order of excavation of the d~sposal site. In Phase 1 the bulk of the Holocene material is removed. The fine sands are used in the body of the surrounding dike. In Phase 2 a suction-dredger is used to remove the deeper Pleistocene deposits. These coarser sands are used to reinforce the embankment. Phase 3 is the final phase in which the inner fringes are finished to the appropriate cross- section. In de eerste fase van her werk wordt bet merendeel van de Holocene afzettingen verwijderd. Dit fJne zand wordt gebruikt als kern van de ringdijk. In de tweede fase wordt her bassin met een diepzuiger op diepte gebracht Het grovere Pleistocene zand dat daarbij vrij komt wordt gebruikt ter versterking van de oeverzone. In de derde fase wordt de binnenkant van bet bassin netjes afgewerkt Ook dan wordt er nog Holoceen sediment vergraven, maar het doen van archeologische waarnemingen is dan vrijwel niet meer mogelijk.


the latter two phases on-site work would be limited to 5 x 24 hours per week. The whole procedure, and especially the tight time-schedule, implied that it would be much easier to shift activities and thus accommodate archaeological discoveries at the beginning of construction rather than at a later stage.

The most important sites To decide on the relative importance of unknown sites is virtually impossible. The situation, however, was thus that a priori decisions had to be made as to determine what kind of sites were to be deemed important in this particular context. It is fully realised that these decisions are of a contestable nature. Considerations significantly affecting decision-making at this stage were

that only those sites would be taken into account where this would be technically feasible under the prevailing circumstances; that older sites would be deemed more important than younger ones.

As a result the area of concern was limited to the subatlantic gully fillings. This meant that no archaeological support was needed during the second phase of construction. During the third phase proper dealing with archaeological discoveries would be most problematical as there would only be limited possibilities to shift dredging activities. From an archaeological point of view the emphasis was thus on phase 1. Sand extraction was planned to begin in the northern part of the area. The first section of the dike to be constructed would create some shelter for the dredgers. Bearing in mind that the oldest known navigation channel by- passed the area just to the North and considering the fact that it would be more likely to encounter a wrecksite related to that channel in the northern part than anywhere else this decision was readily endorsed. It would, after all, be preferable to discover any important sites as soon as possible. Furthermore it was quite clear that attention could only be given to shipwreck sites containing sufficiently substantial structural remains. Small items would unquestionably go unnoticed. For proper planning it was essential to know what exactly could be recognized in time and into what categories the possible discoveries could be classified. To devise a method of timely detection in accordance with the proposed method of sand-extraction a series of tests were run on January 23 1986 at a nearby dredging site.

Several systems of acoustic detection were put to the test, while objects of differing sizes were lowered in the breach. A UDI Obstacle Avoidance Sonar mounted underneath the frontside of a stationary suction-dredger was found to satisfactorily register any objects protruding more than 1.5 m from the o~~tcropping sediments. Within the limits set by the available technology it would thus be possible to detect significant shipwreck sites as soon these started to uncover. Wreckage in structural cohesion measuring 5 x 7 m or more can be detected before actually coming loose, provided that the monitor is properly watched. Sites containing fragments of a smaller size only will, however, remain unnoticed. In consequence it was proposed to mount this system onto the dredgers. Detection of an anomaly on the sonar screen was to be followed by three consecutive actions:

monitoring of the anomaly would be continued for 15 to 30 min. to see whether indeed it represented a stationary object; dragging the breach with a grapnel from a small boat would start while the anomaly was being monitored in order to establish direct contact with the remains; shifting of dredging activity would be commenced as soon as the grapnel got stuck, in order to allow for diver- inspection.

The inspection serves technical as well as archaeological ends. It is to be carried out by an experienced diving archaeologist. It allows to assess whether there is any real obstruction hindering continued sand extraction and it also allows preliminary assessment of any archaeological values involved. Technically six alternatives have been anticipated:

fragmentary, loose or largely decomposed wreckage; part of a ship's bottom or side with heavy timbers, wooden fastenings and strong longitudinal cohesion, measuring up to 5 x 10 m; part of ship's bottom or side, lightly built, longitudinal cohesion in strakes only, measuring up to 5 x 10 m; ship's bottom or side, heavily built, measuring up to 7 x 17 m; ship's bottom or side, lightly built, measuring up to 7 x 17 m; larger entity or complete ship.

As the possibilities for prolonged on-site research in a situation like this are very limited due to adverse, unstable

circumstances and a very tight time-schedule quick removal for study elsewhere is to be preferred. For research it is of course preferable to remove a find as integrally as possible, surrounding sediments included. Taking this into account and also bearing in mind that removal of any overburden will make such operations incomparably more simple a detailed plan was framed for each of the given alternatives [Cemeente Rotterdam et al. 19861. Only the last alternative was left open-ended. In a case like that too many variables are involved and decisons have to be postponed to the very last moment when technical problems, the cultural importance and all factors that can be summarized with the term cost-effectiveness can best be assessed. In all cases it was to be the on-site presence of diving archaeological staff that was to guarantee the quick and responsible assessment necessary for ad hoc decision making. Their expertise was also needed for the reception, documentation, conservation and research of the finds. All in all the preliminary survey showed it to be highly likely that important discoveries would be made. A realistic line of action was deployed in accordance with the proposed technique of construction. The costs of satisfactory archaeological guidance of the project were estimated at dfl. 1.500.000 of which the greater part [dfl 1.100.000] was to be reserved for delays and shifting of the dredgers. It is to be kept in mind that large obstructions may cause this kind of expenses whether they are researched archaeologically or not. dfl. 200.000 was to be spent on archaeological staff and research, dfl. 100.000 for the necessary sonar equipment and another dfl 100.000 for other eventualities.

1.7 CHANGES IN PLANNING The strategy outlined in the plan of

action formed the basis for all decisions. There was however one essential point where strategy and reality did not meet from the very start. The contractor to whom the construction was allocated decided to use cutter-suction- dredgers for the sand extraction not only in phase 3 as demanded, but also in phase 1. For the kind of sediments involved the cutter- suction-dredger is normally too expensive an instrument. From a technical point of view and with respect to the tight time schedule this was considered to be a favourable decision. For the detection of archaeological sites this decision had grave consequences. Unlike the


pontoon of a suction-dredger, a cutter- suction-dredger is not a stationary instrument. Even if it dredges in a breaching technique it will still sweep to and fro constantly. The turning cutter-head will cause turbulence that will to some extent blurr the sonar. More serious however is the fact that the constant motion will constantly affect the picture that it shows. Monitoring of changes in the breach-profile thus becomes an extremely tiring job as it necessitates constant watching of the screen [7 x 24 hours a week]. Even when one of the dredgers was equipped with an obstacle avoidance sonar all sites were detected by the destructive cutter-head itself. For one thing this meant considerable damage to the remains, for another it meant that smaller and less resistent items went unnoticed. The scale of objects that were detected was thus larger than originally envisaged.



1. Wrecksite SL 1 1 .I Circumstances of discovery

1.1.1 The first hit 1.1.2 Preliminary assessment 1.1.3 Adjustment of the order of sand extraction 1.1.4 On-site inspection


1.3 Analyses 1.3.1 Dendrochronological analysis 1.3.2 Caulking and luting materials

1.4 Evaluation 1.4.1 The site 1.4.2 The ship

2. Wrecksite SL 2 2.1 Circumstances of discovery 2.2 Description of the recovered remains 2.3 Analyses 2.4 Evaluative considerations

3. Wrecksite SL 3 3.1 Circumstances of discovery 3.2 Description of the recovered remains 3.3 Analyses 3.4 Conclusions

4. Wrecksite SL 4 4.1 Circumstances of discovery

4.1.1 The first hit 4.1.2 On-site inspection 4.1.3 Considerations and decisions 4.1.4 Clearance 4.1.5 Renewed considerations


4.3 Analyses 4.3.1 Wood species 4.3.2 Dendrochronological analysis 4.3.3 Caulking and luting materials 4.3.4 Copper alloys 4.3.5 Coal

4.4 Evaluation 4.4.1 Introduction 4.4.2 The site 4.4.3 The ship and its construction 4.4.4 Developments in ship construction 4.4.5 Historical setting of ship and ship type 4.4.6 The cargo 4.4.7 Date of shipwreck

4.5 Conclusion

5. Wrecksi te SL 5 5.1 Circumstances of discovery 5.2 Description of the recovered remains 5.3 Analyses 5.4 Discussion

6. Wrecksi te SL 6

7. Miscellaneous f inds

[Fig. 131 Map showing the outline of the Slufter and the distribution of finds againstthe background of the 1985 depth contours.

Dieptekaart uit 1985met daarop de begrenzing van de Slufter en de verspreiding van de vindplaatsen.


1.1 CIRCUMSTANCES O F DISCOVERY

1.1.1 The first hit Shortly after midnight, in the early

hours of May 4 1986 the pump and cutter of the cutter-suction-dredger Hector got blocked for the first time by wood that turned out to be wreckage. Its position was x 60.228 and y 438.23 1 [Dutch National Grid coordinates] [fig. 131. The obstruction was as solid as to repeatedly block the cutter again. After more than five and a half hours of delay the Hector. had to be moved back. At the dump-site quite a few items were observed, such as pulley- blocks, pieces of rope and lengths of chain. Part of those items [i.e. only the chain] were collected later on. Others are said to have disappeared into private collections. The incident occurred on one of the very first days of on-site work. The Hector was dredging in an easterly direction. From the Gat vat2 de Hawk it was on its way to the area in the North where sand-extraction would begin. The itinerary chosen would make the most of the shelter that the shoals in the area could give. Waterdepth had been near zero and Hector directly broke in to a depth of 17 m. It was at that depth that the cutter hit wreckage. The dredger got stuck and had to back off for clearing. The ensuing delay had caused the channel to fill in so it had to be cleared once more. All through the day loose pieces of timber kept blocking the pump. It was, however, only the next night that the original spot of hitting was reached once more. Instead of its original depth of 17 m the dredger was lifted to a depth of 14 m and could pass the sensitive area without further delay. As soon as the cutter was thought to be clear it was lowered to 20 m. In the early morning it hit again. Planking rose to the surface and drifted away. A windlass came up floating and was lifted onto a barge. A collection of small stuff was collected from the cutter and the pump. For convenience' sake this first site was called SL 1.

1.1.2 Preliminary assessment After the aforementioned channel had

been dug the cutter-suction-dredger Hector went on dredging in the northern part of the Slufter. The area where the wreck was hit upon was not to be in exploitation for quite some time. In keeping with the plan of action the spot was dragged with a grapnel from a small boat. Later on, on May 24, a bottom search was organised. Volunteer divers that regularly assist the underwater archaeological unit of the Ministry of Culture were mobilised for the purpose. The water was quite clear that day, amounting to about 2 to 3 metres under water visibility on the bottom, and systematic visual inspection of an area covering approximately 3,500 mZ could be carried out. Most of the channel had, however, filled in. Remaining depth was only 8 to 9 m and no wreckage protruded from the even bottom of loose sand. In short all information on the site one could go by was that at a depth of more than 14 m a wreck had been hit at spots as far apart as 40 m [according to guesses by the dredging personnel and the construction inspectors]. The fragments that had been lifted made it quite clear that the wreck was that of a post- medieval vessel of considerable size. All fragments that could readily be identified pointed to the upper deck structure in the bows. It was assumed to be highly probable that most of the vessel remained.

1.1.3 Adjustment of the order of sand extraction As mentioned before the area around

wrecksite SL 1 was not to be dredged for some time. The possibility that the discovered wreck was a complete or near complete ship and fell into category 6 of the plan of action was to be considered seriously. The wood was in very sound condition and the wreck might cause a serious obstruction for the dredgers. To assess both the extent to which this would be the case and its cultural importance it was thought that the planned diver inspection should anyhow take place. First however one would have to get rid of the tremendous


overburden of loose spill sand. To accommodate for this the order of sand extraction was adjusted. The cutter-suction- dredger Triton was to dredge in the vicinity from mid-summer onwards. In the original planning of the work it was to furrow forwards and back again so as to cover the whole area systematically. This method however was changed. TI-iton was instructed first to dredge a trench around wrecksite SL 1 so as to create overdepth were the overburden could temporarily be dumped [fig. 141.

1 . I .4 On-site inspection To remove the overburden itself, a

more gentle instrument than the cutter- suction-dredger was chosen. A so-called prop-wash deflector, mounted on the diving vessel Ursus 11, was used [fig. 15, 161. This vessel belongs to the Ecuador. diving team from the isle of Terschelling. Both the ship and the team have repeatedly assisted in archaeological work. Inspection was carried out on 19,20,21 and 22 September 1986. The wreckage proved to occur at a depth of approximately 18 m. As the Triton had not dredged beyond 17 m it was impossible to wash the overburden into a surrounding trench. The wreckage could not be cleared of overburden over areas measuring more than 4 m in diameter. To be able to correctly direct the prop-wash and to get a clear picture of the extent of wreckage the site was systematically probed with a 6 m water probe that was lowered from the surface. It consisted of a length of 1" steel piping fitted with a coupling and fed through a flexible hose. It sank into the sediments by its own weight and any obstruction could be readily noticed by the man handling the hose from the surface. The wreckage proved to have lost its structural integrity. During a total of 18 inspection dives in successive prop-wash-pits it was established that all wreckage consisted of deck-structure. It also became evident that the structure faced downwards, i.e. that the wreck had been lying upside down. It rested on a tough clay layer that was covered by an erosion layer containing loose objects. It was decided to lift loose pieces. They were cleared with an air lift [fig. 171. Apart from structural remains parts of the ship's rigging and inventory were brought up. Diving in the pits was seriously hampered by a layer of liquified silt that had formed over the deepest parts of the Slufter, due to three dredgers continuously running. In fact the density of the murky water gradually


[Fig. 141 Dredging-plan around wreck-site SL 1. Snedeplan rand SL 1.

[Fig. 151 Diving vessel Ursus 11. Onderzoeksvaartuig Ursus I1 van het Duikream Ecuador [foto IPL].

[Fig. 161 Schematic representation of a prop- wash-deflector. Werking van een prop-wash.

[Fig. 171 Schematic representation of an airlift. Werking van een airlift.

[Fig. 181 Examples of iron fastenings from SL 1. From top to bottom: iron bolt SL1 A89 [diameter 21 mml iron bolt SLl A6911 [diameter 21 mm] large iron spike SLl A6912 [13 x 13 mm]. Bij de bouw van het schip zijn ijleren pennen, nagels en spijkers gebruikt. Depennenhebbeneendoorsnedevan 21 mm. De hier afgebeelde spijker is 13 mm vierkant.


increased towards the bottom. Divers had problems to weigh themselves down. Working with the airlift brought some temporary relief. Individual dives were not extended beyond 30 min.

1.2 DESCRIPTION O F T H E RECOVERED REMAINS

1.2.1 The ship Some of the timbers recovered could

be reassembled to form what is probably part of the starboard fore deck area. Although various figures show these elements assembled they are first described . individually.

Fastenings The fastenings consist of treenails, iron bolts, iron spikes and iron nails. The treenails were mostly of softwood but some were oak. The diameters were between 25 - 31 mm although one piece of what is probably a wale was fastened with treenails 32 - 34 mm in diameter. They are roughly finished some being relatively rounded in section but others being more octagonal. Some are left plain but others were tightened. In many instances this was done by cuts that were caulked. More common still was the use of a deutel [central square wedge]. The former examples were cut several times across the head, presumably with a chisel. The pattern and depth of the cuts varied. Two or three of the cuts were rammed with caulking material [perhaps moss]. Also, in some cases a thin hardwood pin about 30 mm long and 4 lnln thick at the head was driven into the treenail. In one case the pin was driven into the centre of the cross-cuts but in another it was driven off-centre and clear of the cuts altogether. The mean diameter of the iron bolts is 21 mm. The iron is square in section but chamfered along the edge. The bolts had a definite head i.e. not merely widened through being driven. They were clenched over a washer. The spikes and nails were square shanked, ranging in size from the smaller nails of 4 mrn square up to the larger spikes of 15 mm square. The latter are also chamfered along their edges like the bolts. They all have similar facetted heads and flat, slightly rounded chisel shaped ends [fig. 181.

Frames SLl T75. A futtock 190 x 18 x 11.5 cm trapezoidal in cross section. Towards the foot it gradually tapers and curves slightly in two directions. In view of this shape it is probably

from the bow or stern if not a cant frame as such [fig. 191. At what is presumably its head it js pierced by two iron bolts. The hull planks were fastened by treenails 30 mm in diameter that were cut flush on the inboard surface. There are also several nail holes on both inboard and outboard surfaces. SLl T106. Futtockof 147 x 18.5 x 11 cm tapering at one end to 10 x 16 cm. At the head it is cut with a rebate. In this case a treenail projects from the inboard surface which is wedged with a deutel. There are also nail holes but less than in T75. There is one iron bolt at the foot. SLI T107. Futtock of 143 x 13 x 11 cm. Its curvature corresponds with that of T75. At the head it ends in a flat butt. Just below this is an iron bolt. The plank fastening treenails are also cut flush on the inboard surface as in T75 except for one. Where this treenail projects, iron stain and concretion indicate the grain of a ceiling plank [stringer?]. SLl T108. Futtock 122 x 18 x 12 cm. Heavily damaged, with the head being cut where a fork in the timber occurred. There are no treenails in this timber, only bolts and nails. SL1 T109. Short section of a futtock 18 x 13 cm in section. The treenails fastened both inboard and outboard planking. All of these timbers are oak and three have a certain amount of sapwood remaining. None are complete, all showing shipworm attack at the feet due to their inverted position on the sea bed.

Outer hull planking SLl T45. A plank, maximum width-of 21.5 cm and 4 - 4.5 cm in thickness which is curved and shaped in a manner that indicates a position next to the stem or stern post [fig. 201. Apart from the shape, on its inboard surface are the marks of the timbers to which it was fastened that ran horizontally across the stem or stern post. On the outer surface at the edge of the pointed end there is a mark where suggesting it fitted into a rabbet or was secured with a batten. There is also a rebate which may be a repair. There are two nail holes that could have fastened a patch. On both sides of this plank there are also former nail holes that have been plugged with wooden pegs. Other fragments of what are presumably hull planks also show these plugged nail holes on both faces. The average thickness of the planking in the straight body of the hull was around 6 cm in thickness. Lead tingle or repair patch 24 x 7 cm with small nail holes, that might have been used as a temporary patch on either hull or deck planking.

ARCHAEOLOGY OF T H E SLUFTER

[Fig. 191 Funock SLl T75. De zitter SL 1 T75. Het inhout is vermoedelijk uit het voorschip afkomstig. Erzijn twee ijzeren pennen doorgeslagen. De huid is bevestigd geweest met houten pennen die aan de binnenzijde van het inhout vlak zijn afgesneden.

[Fig. 201 Outer hull plank SLl T45. Huidplank SL1 T45. Deze plank die op een van de stevens aangesloten moet hebben, vertoont een aantal bijzondere kenmerken. Aan de buitenzijde is duidelijk te zien waar de plank in de stevensponning sloot. Aan de binnenzijde zijn de afdrukken zichtbaar van de horizontale banden, inhouten die dwars over de steven bevestigd waren. Aan weerszijden zijn spijkergaarjes re ontwaren die met houten pennetjes zijn afgedicht. Dat is oak bij de overige huidplanken het geval.

[Fig. 211 Treenail which has been cut, caulked and pinned. De kop van houten treknagels is ingesneden en gebreeuwd. Bovendien is er een houten pennetje ingeslagen [for0 IPLI.

[Fig. 231 Inverted hanging knees SLl T95 and SL l T96. Twee verticale knieen waarvan het lijf onderdeks was aangebracht en het korte gedeelte een Iuikhoofd gesteund heeftlfoto IPLI.


SLl T104. A thick timber that is probably part of a wale 23.5 cm wide by 9.5 cm in thickness. It had been fastened with treenails and still has some of the caulking material on its edges. The treenails have been tightened by being cut, caulked and pinned in the manner described above [fig. 211.

Ceiling Four fragments of thick planking which in the absence of caulking would seem to be from inboard. One is damaged but of the other three, two are 23 cm and the other is 38.5 cm in width. Their thickness ranges between 9 and 11.5 cm so they are probably stringers. They are fastened with iron bolts, nails and treenails. A rebate in one of them suggests it might be a beam shelf. Below the rebate is what appears to be a treenail hole that was started then abandoned. In the same piece a treenail hole passing through the plank has been plugged with an off-cut of a treenail.

Knees SLI T78. A hanging knee 165 cm in height but incomplete due to teredo attack at the foot [similar to the frame timbers]. The horizontal arm has been damaged and is incomplete. It is well finished but the grain direction of the timber from which it was cut was not ideal. It also included areas of sapwood. It is rebated to fit against and partly beneath a deck beam and was fastened to the hull and the beam with iron bolts. Four in the lower arm and a bolt and two large spikes in the upper arm. The uppermost bolt projects 29 cm beyond the back of the knee. The next two project 25 and 23.5 cm respectively. This indicates the top bolt passed through the main wale. The lower arm is rebated to a depth of 3.5 cm, presumably to fit over stringers and the shelf [fig. 221. At the end of the bolts passing through the lower arm there is concretion that bears the cast impression of the hull planking. SLl T21. Hanging knee which is much more of a grown timber although of much rougher finish [fig. 221. Height is 116 cm. The arm is 74 cm in length. The lower arm is rebated also to fit over stringers. Two bolts and two spikes fastened the lower arm. The upper arm is not rebated but merely flattened to fit against the deck beam. It was fastened to it with two bolts, three heavy iron spikes and three smaller nails. In the outer face there is a shallow hole [15 mm] presumably where a treenail hole was augered through the futtock for a hull plank. SLl T98. Fragment of a hanging knee, also a suitably grown timber like T21 but the upper

arm is very thin. The head was rebated to fit around the beam but the arm itself being so thin was merely flattened against the beam in a similar manner to T21 [fig. 221. It is fastened in a similar manner to the other hanging knees. SL1 T93. The upper fragment of a knee with a deep rebate probably also for a beam. It also has a shallow rebate cut out of the crown and on one side has indications that there were planks set vertically against it. Although it is also presumably a hanging knee [the fastenings are the same in principle as the others] it would seem either the beam was deeper or the knee was set higher relative to it. The slight indication of adjacent planking suggests it might have been positioned at the junction of the hold and cabin areas [fig. 221. SL1 T48. Upper fragment of a hanging knee similar in shape and finish to T75. SLl T95 and T96. Two elbow shaped knees with their surfaces flattened. They were positioned horizontally with the short arm vertical to support a hatch structure [figs. 22, 231. They were fastened with large iron spikes and in one case with an additional bolt. The angle of the knees reflects the camber of the deck and the slight inward lean of the hatch structure. The lower arm ran between the hatch and the side, the heel of the knee butting against the side. SLl T97. Knee from grown timber which is either a lodging knee or, in view of the shallow depth of its long arm, a standing knee. It was fastened with three bolts and spikes [fig. 221.

Waterway, beam shelf, deck beams and deck planks SLI T63. Two loose pieces of timber that are likely to be part of the waterway [fig. 241. They are 8.5 - 9 cm in thickness and the piece which is preserved for its full width is 30 cm. The sectional shape is a parallelogram. Bolts passed through them horizontally and fastened through the full thickness of the hull. Sloped dove-tail rebates were cut into the inboard edge to retain the half beams but their ends were also nailed in place. In line with the rear of these rebates the waterway is slightly bevellecl downwards. Along the bevel is a mark and a line of nail holes indicating the edge of a plank. This suggests that in this part of the ship there was a gutter between the outermost deck plank and the bulwark. In one of the pieces similar to T63 there are holes [6 x 6 mm] in the side opposite the rebates. These are probably the holes from large spikes fastening through the futtocks


[Fig. 221 Knees from SL 1. Knieen. Oe verticale knieen SL 1 T78, SL 1 T21 en SL 1 T98 zijn aan de onderzijde door paalworm aangevreten. Aan de bovenzijde is er een sponning ingekapt waar zij op de dekbalken aansluiten. SL 1 T97 is mogelijk een horizontale knie. Zie voor SL 1 T96 fig. 23.

[Fig. 241 Individual timbers from the deck and waterway assembly. SLl T80 is a deck beam. SL1 T99 is described as a stringer, SLl T63 as part of the waterway, SL1 T l l O might be the end of a wale. Onderdelen van de dekconstructie. Hoewel de onderdelen sterk beschadigd zijn was her mogelijk de onderlinge samenhang te reconstrueren. Zie hiervoor fig. 27,28 en 62. In de zwaluwstaartvormige inkepingen in SL 1 T63 hebben halve balken gerust. Ook de dekbalk SL 1 T80 is met een zwaluwstaen afgewerkt. Twee vulstukjes waren nodig om de dekplanken te ondersteunen. In het oppervlak van een aantal van deze onderdelen zijn merkwaardige gaten aangetroffen die soms ruw met houtzijn afgedicht Zie hiervoor fig. 25 en 26.


supplementing the bolts. SLl T74. A large curved piece of grown timber rebated for a main deck beam and two half beams. It is well finished but includes traces of sapwood. The main beam rebate is flared on both sides whereas the smaller half beam rebates are straight on one side. It was bulted and nailed through to the futtocks. Next to the beam it has been built up on one side with a thin filling piece, corresponding to the top surface of the beam, so that the deck plank would bed flush onto it. SLl T80. Damaged piece of deck beam fitting the rebate in T74. A good quality timber but it has had to be built up at the edge with two small fillets of wood to provide flush bedding for the planks [fig. 241. Nail holes in the top surface are from the nails that fastened the deck planks. There are also various tool marks. Where it has broken, there is the edge of a rebate, probably for a carling or hatch coaming for a companion way. There were apparently no knees reinforcing this beam, being only retained by the dove tailed rebate in the shelf. There are two holes in the beam, one probably for a deck fitting, the purpose of the other is doubtful as it apparently does not pass through the deck plank. Several nail holes in the side of the beam and a mark on the under side indicate partition planking. There are also several peculiar oval holes which deserve special attention. They are not in any way connected with construction itself and they might be associated with the transport of the baulk of timber prior to its conversion. In that case the holes could be left by the dogs, large staple-like spikes used to stabilise logs which have been bound together in rafts for transport downriver [fig. 2.51. These holes also occur on one of the other loose timbers, probably also part of a beam. Some of those holes have been plugged with soft wood and flat wedged in the manner of a treenail [fig. 261. SLl T77. A deck beam, virtually complete, which is 4.68 In in length [4.65 m true horizontal distance between ends]. At one end is a dove-tail where it was let into the shelf. The other end is damaged. On one side [probably the aft side] there are bolt holes where the upper arms of the hanging knees were fastened. The upper side bears the nail holes from the deck planks. There are four blind holes in the upper side, evidence for deck fittings of some kind. On the [aft] face 1.61 m from the side there is a rebate presumably for a carling. Presumably there was a corresponding rebate at the other end of

the beam but damage has removed all trace of it. On the fore side on both sides there was a small iron hook, which might be associated with internal partitioning, for which there is some evidence in the form of nails holes under the beam. On the same side as the hooks there is a small repair piece let into the edge of the beam. SLl T99 and SLl TI 13. SLI TI 13 is the outermost deck plank [margin plank] that was recovered. Associated with it was an oak timber that lay above: T99. Together the two timbers appear to function as a waterway [fig. 271. The interface between them was well waterproofed with a luting compound of oakum and tar. The lower plank is slightly thickened where the oak timber is located. The outer edge of the plank is roughly cut but generally follows the shape of the shelf piece below. Aft of T99 the plank is not preserved for its full width but luting on the upper surface indicates there was another timber overlying it in the same manner. Both the timbers were nailed and bolted to the beams. T99 is rounded in section with a raised lip on the outer top edge [fig. 241. SLl TI 14. A deck plank preserved for its whole length of 6.85 m. It was nailed to each deck beam in a regular pattern: four nails in the form of a square and one centrally placed similar to thefive on a gaming dice. This plank was positioned at the end of the vessel and its foremost end is bevelled accordingly. Its top surface is marked where it fitted under a waterway or such like. In the cabin area the plank was painted on the under side in a greylblue paint except where passing over the beams. It therefore accurately records the beam spacing in this par

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Dredgers-and-Archaeology-Shipfinds-from-the-Slufter