25 Maritime and Intertidal Archaeology

Sian E. Rees


Cadw: Welsh Historic Monuments

National Assembly for Wales, Cathays Park

Cardiff CF1

email: Sian.Rees@Wales.GSI.Gov.UK




The importance of the maritime and intertidal archaeology of Wales is emphasised and the existing methods of protection described. Management of maritime archaeology has particular problems and historically has suffered from lack of resources in terms of suitably qualified practitioners and appropriate financial support. Suggestions are made for further study and proposals made for strengthening current weaknesses in the management of the maritime heritage.



The seas around the Welsh coastline contain an immeasurable wealth of archaeological and historical artefacts. This includes not only the remains of sunken or beached vessels, their cargo and armaments, but also features associated with the management of the coastline, such as harbour installations; the exploitation of the intertidal zone, such as fish weirs; and submerged landscapes, formerly dry land, usually dating from early prehistoric periods. Maritime archaeology represents the same essential stuff of the historic environment as does the terrestrial, yielding information with a different but complementary slant about our past. Given that our nation was formed by its island status, and our settlement patterns, transport and supply, technology, communications and politics, attitudes and eccentricities were fashioned by our sea borders, our maritime archaeology must have an importance equal to terrestrial archaeology.



The management of the maritime resource presents challenges and problems of a particular nature. Every aspect of the management of the terrestrial historic environment, including survey and discovery, study and excavation, and protection of sites and features, is rendered more complex when attempted within maritime and intertidal zones. Protection of maritime archaeology is governed by separate legislation, complex, difficult to enforce and with different legislation governing salvage operations and human rights sometimes in conflict with one another. The environment is often hostile to conservation; protection of a ship structure protruding above the level of the sea bed is well nigh impossible in the long term. Where the nature of the sea bed is more sympathetic to survival of artefacts, this is usually at the expense of ease of discovery, survey or excavation. Long term survival of a wreck is more probable if the structure is buried in mud or silts and covered with weed growth, in which case, of course, it is impossible to find by conventional search methods. Maritime survey and excavation are subject to their own practical and logistical difficulties. Resources for protection and study of marine archaeology are difficult to come by, historically not being seen as part of the governmental brief. Coastal and intertidal archaeology is similarly dynamic, its environment difficult to predict and control and presenting particular problems of preservation in situ. There have never been restrictions on government’s ability to allocate resources to the intertidal zone, but survey, preservation and excavation tend to be expensive due to the nature of the environment and its archaeology.

In 1992 responsibility for management of the maritime historic environment passed to the appropriate body of government in each country responsible for terrestrial archaeology. Thus the Department of Culture, Media and Sport in England, Historic Scotland, the Department of the Environment in Northern Ireland and Cadw became the bodies responsible for implementation of the relevant legislation appertaining to the underwater heritage as they are for the terrestrial and intertidal zone. Recently Historic Scotland produced a Policy Statement for Maritime Archaeology (HS 1999) while English Heritage has produced an initial policy statement (EH 2002) anticipating the transfer of responsibilities for maritime archaeology from DCMS in 2002. Maritime archaeology in Wales could undoubtedly benefit from research agenda, but only if it is given sufficient weight within the study as a separate subject area with very separate problems. This preliminary paper attempts to define some of these differences.


Quantification of the Resource

There can be no doubt as to the wealth of historical and archaeological material sitting on the sea bed or within the intertidal zone awaiting discovery, let alone evaluation. Figure 26.6, the wreck chart for 1876-77 (Dean et al. 1992, Fig. 7) illustrates the extraordinary extent of marine casualty within a single year. When this is compared with the distribution map of the 53 designated wrecks off the British coast (Fig.26.6) the potential quantity of the evidence sitting unprotected on our shores can be appreciated. Many of the huge number of obstacles mapped as hazards to shipping by the Hydrographic Office are likely to be wrecks, either known as such or as unidentified mounds. The difficulty of identifying a feature on the sea bed as a named, historically documented wreck is well known, and is, indeed, half the fun when you start to work on one. But this uncertainty does not help when we are trying to quantify the extent of the resource. The Maritime Database in the National Monument Record (English Heritage) numbers 20,718 historic losses, 6277 known wreck sites and 7359 sea bed obstructions and isolated historic artefacts; while that in the Royal Commission on Ancient and Historical Monuments in Wales numbers only about 200. Some of these will be repeated records- a lump on the sea bed and a documented wreck which may ultimately prove to be the same thing. But a far greater problem is that of undercounting, as maritime archaeological surveying is in its infancy and we have barely begun to undertake comprehensive surveys of the sea bed or the intertidal zone. English Heritage suggests that the Maritime Database in England probably only holds records of 20% of eighteenth and nineteenth century losses, while the under representation of earlier vessels is bound to be worse still. The small numbers of sites included in the embryonic Maritime Database in Wales is in no way a reflection or a representation of the extent of the resource.


Our understanding of the coastal resource in Wales has been considerably enhanced by the recent Coastal Surveys undertaken with Cadw funding by the four Archaeological Trusts in Wales (DAT, CPAT, GAT, GGAT 1994-98). This involved fieldwalking the entire length of the coastline entering sites on the Sites and Monuments Records and recommending some for statutory protection. While, by the very nature of some of the Welsh intertidal zone, this survey can never be regarded as complete, we may regard it as having identified much of the important resource. Survey in all areas, especially on eroding landscapes such as the Severn Levels, needs to be continuous if we are to avoid losses from natural erosion, flood defences, water treatment or the infrastructure required by maritime development.


Records for Maritime Archaeology

The SMRs of the four Archaeological Trusts have long gathered material from the intertidal zone and include buried landscapes and forests, harbour installations and coastal industries, individual artefacts and hulks. These are often fairly well known though their importance is frequently undervalued, such as the Louisa (Fig.26.4) the hulk on the Taff Estuary, which only attracted serious study when she was threatened by the Cardiff Bay barrage. Other areas of the intertidal zone are impossibly difficult to record. Elusive, dynamic but often spectacular sites on the Severn Levels, such as the thirteenth century Magor Pill boat (Nayling 1998), the Romano-Celtic Barland’s Farm boat (Nayling et al 1994) and prehistoric settlement sites at Goldcliff (Bell et al 2001) testify to this. The Trusts’ SMRs hold records of designated wrecks and other important ship sites, but are not geared up to hold a national maritime database nor to gather material of that nature.


The Maritime Database in Wales was set up as part of the NMR in RCAHMW in 1992, following the recommendations of the Joint Nautical Archaeology Committee’s report ‘Heritage at Sea’ (JNAC 1989) and the subsequent Government White Paper ‘This Common Inheritance’ (1990). This database now forms the central national database recording the historic maritime environment in Wales. During initial work, data from the National Hydrographic Office, the Trusts’ SMRs and public and private record collections was gathered. The curator does not do active field work himself to supplement this but will enhance the record by taking information compiled by others. Work undertaken by amateur divers and information from the Receiver of Wreck is important in this respect. Especially useful is data from the sidescan sonar and visual survey searches undertaken as part of environmental statements for licence applicants such as the oil, gas, water companies for dredging, pipe laying or other developments such as off-shore wind farms. Maritime surveys are undertaken by other bodies such as Countryside Council for Wales for ecological research and in support of designation or the establishment of marine nature reserves, the Hydrographic Office to map shipping obstacles, by sport divers and diving schools and, of course, by salvage companies.


An effective Maritime and Intertidal database is an essential tool in study and protection and it is vital that the Welsh record, still somewhat embryonic, is given further resources specifically to fulfil its role within the management of the historic environment. We should, at the very least, ensure that the results of survey work undertaken by others, institutions, developers or amateurs, are fed into the Welsh Maritime Database. Consideration could be given to funding further survey work or historical research to enhance the database in a more proactive way.


Development Control

The Maritime Database and the SMRs assist in protection of the marine heritage by informing those involved with the planning of marine developments and the license granting bodies so that damage to known important sites may be avoided. Though the planning legislation is not operative below low water mark, Environmental Statements are now required from potential developers before licences are awarded. These may give results of remote sensing and side scan sonar surveys of sea bed features which can help inform us of hitherto undiscovered sites. Thus far the situation is similar to that of land archaeology. But the difficulties of survey in marine environments are pronounced and there must be a fair failure rate of detection. When approval has been granted, marine development is often on a vast scale with concomitant health and safety issues; the equivalent of the land ‘watching brief’ is virtually non-existent. A colleague who was given permission to watch commercialdredging operations soon realised that any remains would have been mashed into matchstick sized pieces by the time he was able to see them, though the use of smaller, carefully operated equipment can achieve useful results (Adams et al 1990). Equally worrying is the scale of error in positioning pipelines or other sub marine objects, where being out by tens of metres is not uncommon.


Development Control in the intertidal and coastal zones follows similar procedures as on land and depends upon the Trusts’ SMRs, survey and evaluations required by environmental statements for planning permission or government regulations. The recent coastal studies undertaken by the four regional Trusts for Cadw are of considerable assistance in the protection of the coastal and intertidal resource.


Statutory Protection

The Welsh coast certainly has its share of maritime archaeology, be it in the form of wreck or sites connected with coastal management and former settlement. The importance and the condition of sites is as variable as on land and, accordingly, we have to be selective in choosing those which merit statutory protection. Such protection may be granted in two ways. The specific legislation for sub tidal archaeology is the Protection of Wrecks Act, 1973. This empowers the National Assembly for Wales to designate historic wreck sites which prevents any unlicensed interference from human activity, including non intrusive diving, incidental fishing and potting, as well as intrusive excavation, dredging, sea bed disturbance from developments and pipe laying. A license may be granted for some activities, and, historically, the Secretary of State and successor bodies have sought guidance from the Advisory Committee on Historic Wreck Sites before designation or granting licenses. There are currently four types of licence - excavation, surface recovery, survey, and visitor/monitoring. Excavation and survey licences have, in the past, been granted for work on the designated wrecks of the Royal Yacht Mary (Fig 26.1) and the Bronze Bell wreck off Barmouth (Fig 26.3). However the act is undoubtedly seen as fairly drastic legislation, controlling, as it does, non-intrusive survey or even diver access. Consequently selection criteria for designation are severe and the numbers of designated sites few. It allows for no government expenditure on proactive site management and is almost entirely restrictive; it is also notoriously difficult to police. Financial support for underwater projects, at least in England, is now permitted under the National Heritage Act 2002, while the 1979 Act (see below) may allow funding of similar projects in all territorial waters.


Less draconian, though less specific, is protection by scheduling under the 1979 Ancient Monuments and Archaeological Areas Act which prevents interference but allows visiting and non intrusive surface survey. Historic Scotland has recently used this legislation to protect the Scapa Flow fleet vessels, long used by sports divers for recreation, survey and training. It has also been used in Wales to protect the wreck of the Louisa, on the Taff near Cardiff, which, since impoundment for Cardiff Bay, is now classified as an inland waterway, outside the territorial waters within which the Protection of Wrecks Act may be used.


Scheduling is also the most appropriate mechanism for protection of sites within the intertidal zone, and a number of hulks, fish weirs, and prehistoric landscapes are protected in this way. The Severn Levels are also afforded some wider protection by inclusion in the non statutory Register of Historic Landscapes of Special Interest in Wales. We can also share in the protective legislation given by other bodies, such as CCW whose SSSIs, SACs and Marine Nature Reserves effectively serve to give protect the wider historic environment. Cardigan Bay, the Dee Estuary and various other parts of the Welsh coastline are included within these. There are only six designations of historic wrecks in Welsh waters, and there are three scheduled hulks on the shore or within inland waterways. Clearly this is a minuscule proportion of known wrecks, but there are now non-statutory criteria for the selection of wrecks for designation and the numbers are gradually increasing. There is no doubt that we need to increase this number to achieve a defensible sample representative of our maritime past. The tables given in Fenwick and  Gale (1999) show this is far from the situation at the moment. There are, however, enormous difficulties in achieving such a representative sample:

1. There is little archaeological survey being actively pursued.

2. The archaeological community is dependent upon divers discovering wreck sites informing the appropriate body of their discoveries.

3. There is great difficulty in identifying and dating wreck sites.

4. Older wrecks, which inevitably are of particular interest, will not survive above sea bed level and are difficult to discover; if they have cargo or armaments, these may often be visible on the sea bed but may merely reflect disposal or accidental loss at sea.


Outreach, awareness, training and the role of the amateur

Marine archaeology in Britain has traditionally been the preserve of the amateur. Any study of history of wreck discovery leading to designation, historic research on wrecks, and maritime survey and excavation will show that it is overwhelmingly the amateur diver with an archaeological or historical interest who has undertaken the work. Some is undertaken with considerable expertise and as the numbers of sports divers continue to increase there will continue to be a willing source of man power, equipment and expertise which should be seen as an asset.


It must be accepted, however, that some of the work by amateurs has not always been of the highest quality and there remains, perhaps, amateurs’ suspicion of the professional taking over project work and restricting their involvement. It is vital to retain the goodwill and interest of the sports divers and to work with them in raising standards in marine archaeological projects. Cadw funds the Nautical Archaeology Society to run training courses, and the Society also tries to engage sports divers by the promotion of schemes such as ‘Diving with a Purpose’ that include ‘Adopt a Wreck’ and the reporting and survey of newly discovered wrecks. The provisions of the Merchant Shipping Act by which anyone who raises an artefact from the sea bed must inform the Receiver of Wreck appear to be working well, especially since the reorganisation of the Receiver’s work into one single post. The energetic administration of the recent Wreck Amnesty, by which previous defaulters were able to report past recovery within a specific period in 2001 without danger of prosecution, has been a triumph and has done much to raise awareness and a sense of responsibility within the diving world.


Site Management

Cadw, with DCMS, Historic Scotland and Northern Ireland Department of Environment ensures that each designated wreck is subject to periodic inspection by professional underwater archaeologists to assess condition and stability. The government’s contractor for inspection of designated wrecks is currently the Archaeological Diving Unit based at St Andrew’s, which inspects each designated wreck every three years, assesses wrecks proposed for designation, and gives advice on management issues. In addition, Cadw remains indebted to amateur diving archaeologists who hold monitoring licences for most of the designated wrecks and who write supplementary reports on condition of wrecks, suggest wrecks for designation and undertake survey on wrecks where a survey licence is held.


Management of designated wreck sites is in its infancy. We attempt to control human interference, but even this is difficult. Managing the wrecks from the hostile environment in which they lie, subjected to storm and current damage, marine life burrowing and infestation, disintegration of wood and corrosion of metal is scarcely attempted. Studies have been undertaken on site stabilisation but little has been actively pursued, apart from cathodic protection to slow down the rate of corrosion, which is one method of management adopted for the 1886 submarine Resurgam (Fig. 25.2). Lifting and conserving artefacts and ship structures has generally been the preferred method of protection. This is probably the correct way for the extraordinarily important wrecks, such as the Mary Rose or the Magor Pill boat, but costs of retrieval, immediate and long term conservation are phenomenal, and this is no answer for the less spectacular vessel. Stabilisation of sites on, rather than under, the sea bed should be attempted on important wrecks which do not merit recovery, if only to help us understand the mechanisms by which this can take place. But in other cases, survey and excavation to remove artefacts may be the only answer, to retrieve information before the wreck inevitably collapses to achieve its own stability under the sea bed.



Research agenda


a. Role of the Agenda

The technical difficulties of post-designation management are probably beyond the remit of research agenda, which should, perhaps, more usefully look at the:


1.      Inadequacy of the database for the protection of sites from development; and, in some cases, as a source for selection for designation

2.      Lack of professional archaeological survey of subtidal archaeology and also, probably, of the intertidal zone

3.      Lack of curation of and response to results of the survey by developers, sports’ divers, CCW, etc

4.      Lack of curation and conservation of artefacts from excavation of wrecks and material declared to Receiver of Wreck

5.      Inadequacy of some reporting on excavations on wrecks

6.      Lack of professional archaeologists to undertake work in the subtidal waters of Wales


Research agenda should consider methods of combating such weaknesses by examining methods of:


1. Identifying areas of the coastline and types of deposits of high potential in the marine historic environment

2. Identifying threats to the conservation of intertidal and maritime sites such as erosion, development, dredging and mineral exploitation and identifying appropriate response mechanisms

3. Encouraging primary fieldwork, both amateur and professional, especially in potentially rewarding areas, and as a fast response after storm damage

4. Continuing and extending training for such fieldwork among amateurs and among staff in appropriate organisations with responsibilities for coastline and marine management

5. Raising awareness of the National Maritime Database

6. Encouraging partnership within appropriate large scale projects, either research based or development projects

7. Selecting for scheduling or designation sites of national importance within the intertidal and maritime zones; encouraging appropriate local authorities and conservation bodies to designate other non-statutory zones of importance


b. Identification of candidates for future study

I. Early sites

Given the highly unrepresentative nature of our known surviving subtidal archaeology, it is unnecessary to point out the importance of study and protection of any wreck dating before 1800. The numbers of surviving wrecks datable to before 1800 are extremely small and it is clearly important that, where past excavations have been undertaken on such wrecks, the results are fully published and artefacts properly curated and conserved. The find spots of sixteenth- and seventeenth- century cannon deserve to be better documented and surveyed and, if they signify an adjacent in situ wreck, should be considered for designation. Similarly, the findspots of any artefacts of historic importance declared to the RoW deserve to be visited and surveyed and a mechanism for enabling this to happen should be initiated.


II. Technological advancement in later sites

The numbers of wrecks known from the earlier nineteenth century are much higher once the adoption of iron hulls became commoner and the technological innovation of the cladding of hulls and incorporation of iron knees and other structural members has recently received study (Stammers 2000). Indeed two of the most recently protected wrecks, that of the Diamond in Cardigan Bay and the Louisa on the Taff at Cardiff (now scheduled) fall into that category. A case could be made for promoting survey and study of such vessels which would include examination of hulks within the intertidal zone. Survey in this dynamic environment needs to be repeated as storm damage and tidal erosion push back the borders of the shore.


III Maritime Archaeology: the Welsh Dimension

The maritime history of Wales has to be seen as part and parcel of that of Britain as a whole; there is little point in our working on vessels where better preserved examples survive off English or Scottish shores. Wrecks in Welsh waters may be important and demand our care but may only accidentally lie within Welsh waters; the Resurgam, for instance, was built at Birkenhead but just happened to sink off Rhyl. However the most important contribution we can make to maritime history could arguably be to concentrate on the study of vessels which were peculiar to our shores or shipping lines. The sixteenth-century slate carrying vessel, Pwll Fanog, the medieval Bristol Channel cargo vessel at Magwr Pill, or the cross- Atlantic cargo and passenger vessels like the Diamond are characteristic of functions relevant to Wales. Our resources might be best concentrated on those vessels where a Welsh dimension is especially distinct and certainly these humbler vessels must be viewed as having an importance of their own.  


IV. Surveys on vulnerable areas of high potential

Because of the inevitably disparate nature of our resource, it might be sensible to concentrate on area rather than period based studies. The Severn Levels are an obvious candidate for on-going survey and excavation. Similarly, where there are known coastal early prehistoric landscape such as areas on the southwest shoreline of Pembrokeshire, survey should extend below the low tide mark, when opportunities arise. Less obvious candidates are, perhaps, off shore sand banks known as a danger to shipping where large numbers of vessels have foundered. The potential richness of the maritime archaeology on these shallows, both in terms of wreck and for early dry land sites, makes survey work especially valuable. Some of these sand banks, especially those in the sheltered Bristol Channel, are attractive as sand deposits for dredging and thus are vulnerable to modern exploitation. Natural shipping hazards with rocky gullies, such as at the Smalls, off Pembrokeshire would also reward intensive survey. The north coast of Wales is now attracting the development of off-shore wind farms, and therefore survey work in this area as part of Environmental Statements will doubtless enrich our understanding of the maritime resource in that area. We should be willing to analyse information revealed in such surveys to prioritise sites for further study and appropriate protection.





Adams, J, van Holk, AFL, and Maarleveld, Th J 1990 Dredgers and Archaeology; Shipfinds from the Slufter, Archeologie onder water, 2e onderzoeksrapport, Ministerie van Welzijn, Volksgezondheid en Cultuur

Bell, MG, Caseldine, AE and Neumann, H 2000 Prehistoric Intertidal Archaeology in the Welsh Severn Estuary, CBA Research Report 120: York

Dean, M, Ferrari, B, Oxley, I, Redknap, M and Watson, K 1992 Archaeology Underwater: The NAS Guide to Principles and Practice, Nautical Archaeology Society and Archetype Publications

English Heritage 2002  Taking to the Water, English Heritage’s Initial Policy for The Management of Maritime Archaeology in England. (held at English Heritage)

Fenwick, V and Gale, A 1999 Historic Shipwrecks Discovered, Protected and Investigated, Tempus: Stroud

JNAC 1989 Heritage at Sea: Proposals for the better protection of archaeological sites underwater, Joint National Archaeology Committee, National Maritime Museum: Greenwich, London[ISBN 0-948065-07-9]

Nayling, N, Maynard, D and McGrail, S 1994 ‘Barland’s Farm, Magor, Gwent: A Romano-Celtic boat’, Antiquity 68, 596-603

Nayling, N 1998 The Magor Pill Medieval Wreck, CBA Research Reports 108: York

Government White Paper 1990 This Common Inheritance, English Heritage: London

Stammers, MK 2001 ‘Iron Knees in Wooden Vessels – an attempt at a typology’, International Journal of Nautical Archaeology 301, 115-21



CPAT 1997 Coastal Erosion Survey, Clwyd-Powys Archaeological Trust Report 194 (held at Trust, RCAHMW and Cadw)

DAT 1996, 1997, 1998, 1998 Coastal Erosion Surveys, Dyfed Archaeological Reports (held at Trust, RCAHMW and Cadw)

GAT 1994, 1996, 1997 Coastal Erosion Surveys, Gwynedd Archaeological Trust Reports 79, 198, 251, 253, (held at Trust, RCAHMW and Cadw)

GGAT 1996, 1997, 1998 Coastal Erosion Surveys, GGAT Reports 96/015, 97/011, 98/010 (held at the Trust, RCAHMW and Cadw)

Historic Scotland 1999 Policy Statement for Maritime Archaeology, (held at Historic Scotland, Longmore House, Salisbury Place, Edinburgh, EH9 1SH)