Mapping Submerged Archaeological Sites using Stereo‐Vision Photogrammetry

Creating photo‐mosaics and plans of submerged archaeological sites quickly, cost‐effectively and, most importantly, to a high level of geometric accuracy remains a huge challenge in underwater archaeology. This paper describes a system that takes geo‐referenced stereo imagery from a diver‐propelled platform and combines it with mapping techniques widely used in the field of robotic science to create high‐resolution 2D photo‐mosaics and detailed 3D textured models of submerged archaeological features. The system was field tested on the submerged Bronze Age town of Pavlopetri off the coast of Laconia, Greece, in 2010. This paper outlines the equipment used, data collection in the field, image processing and visualization methodology.     

Backscatter responses and resolution considerations in archaeological side-scan sonar surveys: a control experiment

The backscatter responses of submerged archaeological material remain poorly understood. To address this, a control experiment was conducted in Belfast Lough during July and August 2001. A selection of material and targets was arranged on the seabed in varying orientations, in an attempt to replicate the situation found on a range of archaeological sites where material is exposed on the seafloor. Repeat side-scan sonar surveys of the control array were conducted at variable ranges and fish heights to examine the backscatter responses and resolution of three commercially available side-scan sonar systems. Results indicate that the electro-acoustic specification of the pulse length and the beam angle of the acoustic sources govern the theoretical resolution of side-scan data. Backscatter data from the control experiment indicate both organic (wood and leather) and inorganic (metals, ceramics, glass and varying aggregate and ballast grades) natural and man-made materials can be imaged using side-scan sonar and a wide variety of archaeological material types and concentrations may be differentiated by their backscatter responses.     

Complications and Effectiveness of In Situ Preservation Methods for Underwater Cultural Heritage Sites

Abstract

Underwater Cultural Heritage (UCH) as an outstanding division of the cultural heritage of humanity appears to be crucial and complicated when more general issues regarding preservation and conservation are raised. The essence of in situ preservation should be equally discussable for any kind of archaeological remains; on land or underwater.

There is a long history of different methods and concepts of intervention in a variety of sub-aquatic archaeological sites; from shipwrecks to submerged settlements. This paper will present an introduction to different techniques and theories of preservation and conservation of underwater cultural and archaeological sites since this kind of heritage has scientifically been explored and studied. A range of different preservation methodologies, from total or partial transference inland, to preservation underwater, will be compared; the advantages and disadvantages of each option will be highlighted. Different examples of international best practices will be illustrated. Different types of in situ conservation/protection will be explained and categorized. Furthermore, there will be a focus on the UNESCO Convention of 2001 on Conservation and Preservation of UCH, where the in situ conservation option has been recommended.

Moreover, the technical issue for preservation of UCH sites, either in situ or after displacement, will be explained. The implication of relocation for different sorts of sites and materials will be argued; for example, cases where some sites, such as shipwrecks, would more easily be displaced compared with submerged settlements, villages, or ports.

Finally, by stressing that the state of ‘being underwater’ makes many sites qualified to be regarded as UCH, the in situ preservation approach will prevail that this state is maintained.     

Airborne laser bathymetry – detecting and recording submerged archaeological sites from the air

A new generation of airborne bathymetric laser scanners utilises short green laser pulses for high resolution hydrographic surveying in very shallow waters. The paper investigates its use for the documentation of submerged archaeological structures, introducing the concept of airborne laser bathymetry and focussing on a number of challenges this novel technology still has to face. Using this method, an archaeological pilot study on the northern Adriatic coast of Croatia has revealed sunken structures of a Roman villa. The results demonstrate the potential of this novel technique to map submerged archaeological structures over large areas in high detail in 3D, for the first time providing the possibility for systematic, large-scale archaeological investigation of this environment. The resulting maps will provide unique means for underwater heritage management.     

Geophysical Methods for Wreck‐Site Monitoring: the Rapid Archaeological Site Surveying and Evaluation (RASSE) programme

Rapid advances in geophysical techniques over the past decade have provided the maritime archaeological community with significant opportunities for re‐defining the procedures for wreck‐site mapping, evaluation and monitoring. The techniques which offer most potential for high‐resolution survey are acoustic‐based and include sidescan sonar, swath‐bathymetry sonar and multibeam sonar. These techniques were tested on an artificial test‐site in Plymouth Sound and over the wreck of the Stirling Castle. Results demonstrate that the techniques can provide the maritime archaeologist with the opportunity to rapidly and cost‐effectively map and monitor small, centimetric changes on sites, with the potential for long‐term monitoring and management. © 2009 The Authors     

Reburial and Analyses of Archaeological Remains in the Marine Environment — Investigations into the Effects on Metals

Abstract

The treatment and long-term storage of recovered cultural material from underwater heritage sites is becoming less cost effective, and reburial of archaeological sites and the associated artefacts in the marine environment is becoming increasingly common practice in managing the submerged cultural resource. Following recent large-scale underwater archaeological excavations in Marstrand harbour, Sweden, the majority of recovered finds were reburied in defined trenches in the harbour sediment. Subsequently, the Studio of the Western Sweden Conservators in conjunction with the Bohus County Museum initiated a fifty-year research project to evaluate reburial as an appropriate method of preserving waterlogged archaeological artefacts in the long term. The research project, entitled ‘Reburial and Analyses of Archaeological Remains’, was launched in 2002 and consists of six sub-projects. The main aims of these sub-projects are to analyse the extent of deterioration of the most common material types found on underwater archaeological sites, assess the stability of packing and marking materials used in archaeological documentation, and monitor the reburial environment.

The aim of the metals sub-project is to investigate the short- to long-term corrosion behaviour of metals buried in the marine environment by examining the deterioration of reburied and exposed modern metal coupons and eventually compare these results to the analysis of actual shipwreck artefacts. The environmental monitoring sub-project is designed to complement the other sub-projects by assessing the physico-chemical changes occurring in the reburial environment over time and the effect on the deterioration of the different reburied material types. In comparing the results obtained over the past seven years from both the metals and monitoring sub-projects, it should be possible to more accurately evaluate the effectiveness of reburial as a long-term in situ preservation strategy for metallic archaeological remains.     

Project SAMPHIRE: Crowd Sourcing Maritime Archaeology data off Scotland's West Coast

Perhaps the greatest barrier to effective management of underwater cultural heritage is the lack of data on the nature and location of offshore archaeological resources. This is a problem shared with terrestrial archaeology, but is particularly acute due to the limitations of survey techniques in the underwater environment. In Scotland <15% of known ship losses from the last 200 years have been located and the record is far less comprehensive for earlier periods, verging on a near total data gap. Most known archaeological sites in Scottish waters have been discovered through large-scale sonar survey of relatively low resolution and a considerable bias has been introduced in the archaeological record; this has favored the discovery and documentation of larger and more recent, often upstanding, metal shipwrecks. This article presents the methods and results from a three-year project designed to reduce this bias by demonstrating large-scale prospecting for maritime archaeology through a community-based crowd-sourcing approach. Project SAMPHIRE (the Scottish Atlantic Maritime Past: Heritage, Investigation, Research and Education Project) was geographically focused on the west coast of the Scottish mainland and was undertaken between 2013 and 2015, resulting in a large number of new archaeological discoveries, including shipwrecks, aircraft, and other material of a much more varied nature than what is typically found through large-scale hydrographic surveys.     

Submerged Mesolithic Landscape Investigation,Eleven Ballyboes,Republic of Ireland

This paper reports on the first systematic attempt to conduct archaeological survey and excavation for submerged prehistory on the island of Ireland. Fieldwork was conducted in two small bays where Early Mesolithic flint artefacts washed ashore hinted at the presence of a submerged assemblage. Methods employed include non‐intrusive survey, hand coring and excavation. Together, these allowed identification of the artefact source, albeit reworked, in one bay and an early Holocene peat in the other. Though the subtidal assemblage is reworked and relatively small, it is significant in an Irish context and more widely illustrates the potential preservation of prehistoric sites and palaeo‐landscapes in high‐energy settings.     

Evidence in the Private Sphere: Assessing the Practicality of Amnesties to Record Lost Information

Archaeological sites on land and underwater have long suffered from human impact in the form of looting, souvenir hunting or treasure hunting. Some countries have declared archaeological amnesties to either acquire lost or stolen artefacts or to document collections and information held in private hands. Very little information has been published to date on archaeological amnesties around the world. For maritime-related or submerged sites, there have been three amnesties declared around the world: in Australia, in the United Kingdom and in Bermuda. Whilst there are obvious benefits to having amnesties, they can also prove costly if little thought has been given for the short- and long-term consequences. How much information is derived from these private collections is dependent upon how much information the collector is able or willing to provide and how much effort is made to document information before they are permanently lost.     

Marine geophysical investigation of the inshore coastal waters of Northern Ireland

Northern Ireland has been subject to significant maritime influences throughout its 9000-year known human history. In 1997 the University of Ulster in partnership with the Environment and Heritage Service (DOE, NI) embarked on a programme of seabed mapping in an attempt to record the submerged and buried archaeological resource using a suite of geophysical equipment including a side-scan sonar, a Chirp sub-bottom profiler and a proton precession magnetometer. The geophysical research programme has successfully imaged 80 19th- and 20th-century wrecks, and 20 targets of further archaeological potential. These data will aid the production of wreck-prediction indices for the coastline of Northern Ireland based on site formation processes and site stability. This information will make valuable additions to both Sites and Monuments Records and to the shipwreck database currently under consideration at the University of Ulster.     

Commercial developments and their impact on maritime heritage: the Northern Ireland experience

This paper refers to the body of international, national and regional legislation that exists to protect submerged cultural heritage sites. It advocates the use of the consultation process available through current legislation to protect submerged sites through preservation or through record by archaeological mitigation. It reviews the main types of commercial seabed developments and opens discussion on the appropriate archaeological response.     

Maritime Cultural Resource Investigation, Management, and Mitigation in Coastal Ghana

Four field seasons of maritime archaeological research in coastal Ghana offer insights into submerged cultural heritage, but also highlight serious concerns for its preservation and protection. A discussion of cultural heritage legislation and its ineffective implementation, as well as imminent and potential threats to submerged cultural heritage frames the argument for the mitigation and protection of submerged sites in coastal Ghana. Work on the Benya Lagoon vessel and the Elmina Wreck site is presented here as both documentation and mitigation in terms of the context of threats to submerged heritage in coastal Ghana, and preventative mitigation is proposed for its protection.     

An Overview of Maritime Archaeological Research of the Colonial Period in the French Antilles

This article provides a summary of the various maritime archaeology projects undertaken in the French Antilles (Guadeloupe and Martinique) since the 1980s that date to the 17th–19th century Colonial period. These projects are presented in the context of the principal maritime archaeological research questions. The results are analysed thematically touching on different aspects of archaeological research in littoral and underwater zones: coastal plantations, ports, and micro‐islets. Research carried out on wreck‐sites is presented with respect to their maritime use (commercial, naval, and cabotage). The nature and distribution of such sites provides information both on maritime routes and traffic, trade, conflicts, and environmental risks specific to the Antilles in the Colonial period.     

Local Resources,Global Heritage: An Introduction to the 2001 UNESCO Convention on the Protection of the Underwater Cultural Heritage

On January 2, 2009, the 2001 UNESCO Convention on the Protection of the Underwater Cultural Heritage entered into force, setting an international precedent for the protection and preservation of underwater archaeological resources and providing guidelines for site management and responsible investigation. Historically, submerged cultural resources, particularly shipwrecks, have been exploited primarily for their potential monetary value. Over the last 50 years archaeologists have challenged this perception, demonstrating the cultural and scientific value of submerged cultural resources.     

Holocene paleoshorelines,water levels and submerged prehistoric site potential of Rice Lake (Ontario,Canada)

Rice Lake, located in the eastern Great Lakes of North America, has a high density of prehistoric (11–0.5 ka BP) terrestrial archaeological sites. It has been speculated that a large number of sites are submerged on the lakebed, as lake levels have risen >9 m since the arrival of Early Paleoindian peoples (∼11 ka BP). In order to better understand the submerged landscape and its archaeological potential, a detailed bathymetric survey and sediment-coring program was conducted across a 30-km² area of northeastern Rice Lake. Changes in Holocene water levels and shoreline positions were reconstructed by integrating core data with a digital elevation and bathymetric model (DEBM) that accounted for differential isostatic uplift and basin sedimentation. The DEBM was used to generate a series of maps showing changes in the lake paleobathmetry and paleogeography and areas of prehistoric archaeological potential.     

Do Ships Shape the Shore? An Analysis of the Credibility of Ship Archaeological Evidence for Landing Site Morphology in the Baltic Sea

In the context of the development of different kinds of watercraft during prehistory an interdependent line of development for landing sites and harbours is often suggested, and used to argue that it is almost impossible archaeologically to locate small and early landing sites. Although the constructional properties of prehistoric watercraft suggest that landing‐structures were not absolutely necessary, there is nevertheless archaeological evidence of landing‐facilities from the Stone Age, as well as landing‐facilities for smaller boats to consider. This article will discuss to what extent ship archaeological evidence could be seen in a corresponding development to landing sites in its respective periods. © 2012 The Author     

Studying the Cannons of Punta Santa Anna,Spain: In Situ Conservation,Promoting Public Access,and Monitoring Iron Corrosion

The 2001 UNESCO convention for the Protection of Underwater Cultural Heritage (UCH) encourages and supports projects that would make accessible to the general public underwater cultural sites. Since 2010 the Catalonian Federation of the World Underwater Federation (FECDAS), have been developing outreach activities with the objective of promoting the protection of the UCH among recreational scuba divers. The purpose of this paper is to introduce one such project, the Punta Santa Anna in Blanes, Spain. This project has three objectives: the promotion of UCH to the general public, the in situ protection of this underwater archaeological site, and a case study on iron corrosion processes. FECDAS/CMAS will create an underwater archaeological park where recreational scuba divers will be able to visit some purposely selected archaeological iron cannons. To expose UCH to the general public will potentially affect the integrity of these artefacts. This risks potential damage and so, with the objective of minimizing potential threats, a series of protective measures and a systematic monitoring programme have been planned. The programme is designed to study the relationship between the underwater environment and the artefacts. The aim is to acquire a better understanding of the corrosion processes of iron objects present in marine underwater sites.     

Initial Archaeological Survey of the ex-USS <Emphasis Type="Italic">Independence</Emphasis> (CVL-22)

The Boeing Company, collaborating with NOAA to address innovative ways to make ocean observations, provided their autonomous underwater vehicle, Echo Ranger, to conduct the first deep-water archaeological survey of the scuttled aircraft carrier USS Independence in the waters of Monterey Bay National Marine Sanctuary in March 2015. While a preliminary effort, and not comprehensive, the survey confirmed that a sonar feature (previously not proven to be an archaeological feature) charted at the location was Independence, and provided details on the condition of the wreck. At the same time, new information from declassified government reports provided more detail on Independence’s use as a naval test craft for radiological decontamination as well as its use as a repository for radioactive materials at the time of its scuttling in 1951. The wreck is historically significant, but also of archaeological significance as an artifact of the early years of the atomic age and of the Cold War. This article summarizes Independence’s contexts, its nuclear history, and the results of the survey of the wreck site.     

Mapping Submerged Landscapes Using Multibeam Bathymetric Data: a case study from the north coast of Ireland

This paper outlines work currently being undertaken to reconstruct submerged archaeological landscapes off the north coast of Ireland. This research uses the recently‐completed Joint Irish Bathymetric Survey (JIBS), which has provided full‐coverage high‐resolution multibeam bathymetric data for the sea‐bed off the north coast. This data has been examined for evidence of past sea‐level change and been used to produce palaeo‐geographic reconstructions of the past landscape, which in turn have facilitated the identification of ten areas of high archaeological potential. The results presented here will form the basis of a future programme of archaeological survey and prospection. © 2010 The Authors