Underwater archaeology is
archaeology
Archaeology or archeology is the scientific study of human activity through the recovery and analysis of material culture. The archaeological record consists of artifacts, architecture, biofacts or ecofacts, sites, and cultural landscap ...
practiced underwater.
As with all other branches of archaeology, it evolved from its roots in pre-history and in the
classical era
Classical antiquity (also the classical era, classical period or classical age) is the period of cultural history between the 8th century BC and the 5th century AD centred on the Mediterranean Sea, comprising the interlocking civilizations of ...
to include sites from the historical and industrial eras. Its acceptance has been a relatively late development due to the difficulties of accessing and working underwater sites, and because the application of archaeology to underwater sites initially emerged from the skills and tools developed by shipwreck salvagers.
As a result, underwater archaeology initially struggled to establish itself as actual archaeological research.
This changed when universities began teaching the subject and a theoretical and practical base for the sub-discipline was firmly established in the late 1980’s. Underwater archaeology now has a number of branches including,
maritime archaeology
Maritime archaeology (also known as marine archaeology) is a discipline within archaeology as a whole that specifically studies human interaction with the sea, lakes and rivers through the study of associated physical remains, be they vessels, s ...
: the scientifically based study of past
human
Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...
life, behaviours and cultures and their activities in, on, around and (lately) under the sea, estuaries and rivers. This is most often effected using the physical remains found in, around or under
salt
Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quantitie ...
or
fresh water
Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...
or buried beneath water-logged
sediment
Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand an ...
.
In recent years, the study of submerged WWII sites and of submerged aircraft in the form of underwater
aviation archaeology
Aviation archaeology is a recognized sub-discipline within archaeology and underwater archaeology as a whole. It is an activity practiced by both enthusiasts and academics in pursuit of finding, documenting, recovering, and preserving sites import ...
have also emerged as bona fide activity.
Though often mistaken as such, underwater archaeology is not restricted to the study of
shipwrecks. Changes in
sea level
Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardised g ...
because of local
seismic
Seismology (; from Ancient Greek σεισμός (''seismós'') meaning "earthquake" and -λογία (''-logía'') meaning "study of") is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other ...
events such as the earthquakes that devastated
Port Royal and
Alexandria
Alexandria ( or ; ar, ٱلْإِسْكَنْدَرِيَّةُ ; grc-gre, Αλεξάνδρεια, Alexándria) is the second largest city in Egypt, and the largest city on the Mediterranean coast. Founded in by Alexander the Great, Alexandria ...
or more widespread
climatic
Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorological ...
changes on a
continent
A continent is any of several large landmasses. Generally identified by convention rather than any strict criteria, up to seven geographical regions are commonly regarded as continents. Ordered from largest in area to smallest, these seven ...
al scale mean that some sites of human occupation that were once on dry land are now submerged.
At the end of the last ice age, the
North Sea
The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian S ...
was a great plain, and
anthropologica
''Anthropologica'' is a biannual peer-reviewed academic journal and the official publication of the Canadian Anthropology Association, published by University of Victoria Libraries. It was established in 1955 and the editor-in-chief is Alexandrin ...
l material, as well as the remains of animals such as
mammoths
A mammoth is any species of the extinct elephantid genus ''Mammuthus'', one of the many genera that make up the order of trunked mammals called proboscideans. The various species of mammoth were commonly equipped with long, curved tusks and, i ...
, are sometimes recovered by trawlers. Also, because human societies have always made use of water, sometimes the remains of structures that these societies built underwater still exist (such as the foundations of
crannogs
A crannog (; ga, crannóg ; gd, crannag ) is typically a partially or entirely artificial island, usually built in lakes and estuarine waters of Scotland, Wales, and Ireland. Unlike the prehistoric pile dwellings around the Alps, which were b ...
,
bridges and
harbours
A harbor (American English), harbour (British English; see spelling differences), or haven is a sheltered body of water where ships, boats, and barges can be docked. The term ''harbor'' is often used interchangeably with ''port'', which is a ...
) when traces on dry land have been lost. As a result, underwater
archaeological
Archaeology or archeology is the scientific study of human activity through the recovery and analysis of material culture. The archaeological record consists of artifacts, architecture, biofacts or ecofacts, sites, and cultural landscap ...
sites cover a vast range including: submerged indigenous sites and places where people once lived or visited that have been subsequently covered by water due to rising
sea level
Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardised g ...
s; wells,
cenote
A cenote ( or ; ) is a natural pit cave, pit, or sinkhole, resulting from the collapse of limestone bedrock that exposes groundwater. The regional term is specifically associated with the Yucatán Peninsula of Mexico, where cenotes were commonly ...
s, wrecks (
shipwrecks
A shipwreck is the wreckage of a ship that is located either beached on land or sunken to the bottom of a body of water. Shipwrecking may be intentional or unintentional. Angela Croome reported in January 1999 that there were approximately ...
;
aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines ...
); the remains of structures created in water (such as
crannogs
A crannog (; ga, crannóg ; gd, crannag ) is typically a partially or entirely artificial island, usually built in lakes and estuarine waters of Scotland, Wales, and Ireland. Unlike the prehistoric pile dwellings around the Alps, which were b ...
,
bridge
A bridge is a structure built to span a physical obstacle (such as a body of water, valley, road, or rail) without blocking the way underneath. It is constructed for the purpose of providing passage over the obstacle, which is usually somethi ...
s or
harbours
A harbor (American English), harbour (British English; see spelling differences), or haven is a sheltered body of water where ships, boats, and barges can be docked. The term ''harbor'' is often used interchangeably with ''port'', which is a ...
); other port-related structures;
refuse
Waste (or wastes) are unwanted or unusable materials. Waste is any substance discarded after primary use, or is worthless, defective and of no use. A by-product, by contrast is a joint product of relatively minor economic value. A waste prod ...
or
debris
Debris (, ) is rubble, wreckage, ruins, litter and discarded garbage/refuse/trash, scattered remains of something destroyed, or, as in geology, large rock fragments left by a melting glacier, etc. Depending on context, ''debris'' can refer to ...
sites where people disposed of their
waste
Waste (or wastes) are unwanted or unusable materials. Waste is any substance discarded after primary use, or is worthless, defective and of no use. A by-product, by contrast is a joint product of relatively minor economic value. A waste prod ...
, garbage and other items, such as ships, aircraft, munitions and machinery, by
dumping into the water.
Underwater archaeology is often complementary to archaeological research on terrestrial sites because the two are often linked by many and various elements including geographic, social, political, economic and other considerations. As a result, a study of an archaeological landscape can involve a multidisciplinary approach requiring the inclusion of many specialists from a variety of disciplines including prehistory,
historical archaeology
Historical archaeology is a form of archaeology dealing with places, things, and issues from the past or present when written records and oral traditions can inform and contextualize cultural material. These records can both complement and conflict ...
,
maritime archaeology
Maritime archaeology (also known as marine archaeology) is a discipline within archaeology as a whole that specifically studies human interaction with the sea, lakes and rivers through the study of associated physical remains, be they vessels, s ...
, and anthropology. There are many examples. One is the wreck of the VOC ship ''
Zuytdorp
''Zuytdorp'', also ''Zuiddorp'' (meaning "South Village", after Zuiddorpe, an extant village in the south of Zeeland in the Netherlands, near the Belgian border) was an 18th-century trading ship of the Dutch East India Company (Vereenigde Oost ...
'' lost in 1711 on the coast of Western Australia, where there remains considerable speculation that some of the crew survived and, after establishing themselves on shore, intermixed with indigenous tribes from the area. The archaeological signature at this site also now extends into the interaction between indigenous people and the European
pastoralists
Pastoralism is a form of animal husbandry where domesticated animals (known as "livestock") are released onto large vegetated outdoor lands (pastures) for grazing, historically by nomadic people who moved around with their herds. The animal s ...
who entered the area in the mid-19th century.
Research potential
There are many reasons why underwater archaeology can make a significant contribution to our knowledge of the past. In the shipwreck field alone, individual
shipwrecks can be of significant historical importance either because of the magnitude of loss of life (such as the
''Titanic'') or circumstances of loss (''
Housatonic'' was the first vessel in history sunk by an enemy submarine).
Shipwrecks such as ''
Mary Rose
The ''Mary Rose'' (launched 1511) is a carrack-type warship of the English Tudor navy of King Henry VIII. She served for 33 years in several wars against France, Scotland, and Brittany. After being substantially rebuilt in 1536, she saw her ...
'' can also be important for archaeology because they can form a kind of accidental
time capsule
A time capsule is a historic cache of goods or information, usually intended as a deliberate method of communication with future people, and to help future archaeologists, anthropologists, or historians. The preservation of holy relics dates ba ...
, preserving an assemblage of human
artifacts at the moment in time when the ship was lost.
Sometimes it is not the wrecking of the ship that is important, but the fact that we have access to the remains of it, especially where the vessel was of major importance and significance in the history of science and engineering (or warfare), due to being the first of its type of vessel. The development of submarines, for example, can be traced via underwater archaeological research, via the ''
Hunley
Hunley is a surname. Notable people with the surname include:
People
*Con Hunley (born 1945), American country music singer
*Gary Hunley (born 1948), American child actor
*Helen Hunley (born 1920), Canadian politician
*Horace Lawson Hunley (1823-1 ...
'', which was the first submarine to sink an enemy ship (''Hunley'' also had unique construction details not found in previous vessels and was one of the few historic warships ever raised intact);
the ''
Resurgam
''Resurgam'' (Latin: ''"I shall rise again"'') is the name given to an early Victorian submarine and its prototype, designed and built in Britain by Reverend George Garrett. She was intended as a weapon to penetrate the chain netting placed ...
'' ''II'', the first powered submarine;
and ''
Holland 5'', which provides insight into the development of submarines in the British Navy.
UNESCO Convention
All traces of human existence underwater which are one hundred years old or more are protected by the
. This convention aims at preventing the destruction or loss of historic and cultural information and looting. It helps states parties to protect their underwater cultural heritage with an international legal framework.
On the basis of the recommendations defined in the above-mentioned UNESCO Convention various European projects have been funded such as the CoMAS project
for in situ conservation planning of underwater archaeological artefacts.
Challenges
Underwater sites are inevitably difficult to access, and more hazardous, compared with working on dry land. In order to access the site directly,
diving equipment
Diving equipment is equipment used by underwater divers to make diving activities possible, easier, safer and/or more comfortable. This may be equipment primarily intended for this purpose, or equipment intended for other purposes which is found ...
and
diving skills are necessary. The depths that can be
accessed by divers, and the length of time available at depths, are limited. For deep sites beyond the reach of divers,
submarines
A submarine (or sub) is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term is also sometimes used historically or colloquially to refer to remotely o ...
or
remote sensing
Remote sensing is the acquisition of information about an object or phenomenon without making physical contact with the object, in contrast to in situ or on-site observation. The term is applied especially to acquiring information about Earth ...
equipment are needed.
For a marine site, while some form of working platform (typically a
boat
A boat is a watercraft of a large range of types and sizes, but generally smaller than a ship, which is distinguished by its larger size, shape, cargo or passenger capacity, or its ability to carry boats.
Small boats are typically found on inl ...
or
ship
A ship is a large watercraft that travels the world's oceans and other sufficiently deep waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research, and fishing. Ships are generally distinguished ...
) is often needed, shore-based activities are common. Notwithstanding, underwater archaeology is a field plagued by
logistics
Logistics is generally the detailed organization and implementation of a complex operation. In a general business sense, logistics manages the flow of goods between the point of origin and the point of consumption to meet the requirements of ...
problems. A working platform for underwater archeology needs to be equipped to provide for the delivery of air for example, recompression and medical facilities, or specialist remote sensing equipment, analysis of archaeological results, support for activities being undertaken in the water, storage of supplies, facilities for conservation for any items recovered from the water, as well as accommodation for workers. Equipment used for archaeological investigation, including
water dredge A water eductor or water dredge is an eductor-jet pump-based tool used by underwater archaeology, underwater archaeologists to remove sediments from an underwater archaeological site. airlift (dredging device), Airlifts may be used for the same pur ...
and
airlifts create additional
hazard
A hazard is a potential source of harm
Harm is a moral and legal concept.
Bernard Gert construes harm as any of the following:
* pain
* death
* disability
* mortality
* loss of abil ity or freedom
* loss of pleasure.
Joel Feinberg giv ...
s and logistics issues. Moreover, marine sites may be subject to strong
tidal
Tidal is the adjectival form of tide.
Tidal may also refer to:
* ''Tidal'' (album), a 1996 album by Fiona Apple
* Tidal (king), a king involved in the Battle of the Vale of Siddim
* TidalCycles, a live coding environment for music
* Tidal (servic ...
flows or poor weather which mean that the site is only accessible for a limited amount of time. Some marine creatures also pose a threat to diver safety.
Underwater sites are often dynamic, that is they are subject to movement by
currents
Currents, Current or The Current may refer to:
Science and technology
* Current (fluid), the flow of a liquid or a gas
** Air current, a flow of air
** Ocean current, a current in the ocean
*** Rip current, a kind of water current
** Current (stre ...
,
surf,
storm
A storm is any disturbed state of the natural environment or the atmosphere
An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmos ...
damage or tidal flows. Structures may be unexpectedly uncovered, or buried beneath
sediment
Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand an ...
s. Over time, exposed structures will be eroded, broken up and scattered. The dynamic nature of the environment may make
in-situ conservation
''In-situ'' conservation is the on-site conservation or the conservation of genetic resources in natural populations of plant or animal species, such as forest genetic resources in natural populations of Teagan species. This process protects th ...
infeasible, especially as exposed organics, such as the wood of a shipwreck, are likely to be consumed by marine organisms such as
piddocks. In addition, underwater sites can be chemically active, with the result that iron can be leached from metal structures to form
concretions
A concretion is a hard, compact mass of matter formed by the precipitation of mineral cement within the spaces between particles, and is found in sedimentary rock or soil. Concretions are often ovoid or spherical in shape, although irregular ...
. The original metal will then be left in a fragile state.
Artifacts recovered from underwater sites need special care.
Visibility
The visibility is the measure of the distance at which an object or light can be clearly discerned. In meteorology it depends on the transparency of the surrounding air and as such, it is unchanging no matter the ambient light level or time of ...
may be poor, because of sediments or
algae
Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...
in the water and lack of light penetration.
This means that survey techniques that work well on land (such as triangulation), generally can not be used effectively under water.
In addition it can be difficult to allow access to the results of the archaeological research as underwater sites do not provide good
outreach
Outreach is the activity of providing services to any population that might not otherwise have access to those services. A key component of outreach is that the group providing it is not stationary, but mobile; in other words, it involves meetin ...
possibilities or access for the general public. Work has been done to bridge this difficulty through the use of the
World Wide Web
The World Wide Web (WWW), commonly known as the Web, is an information system enabling documents and other web resources to be accessed over the Internet.
Documents and downloadable media are made available to the network through web se ...
for
webcasting
A webcast is a media presentation distributed over the Internet using streaming media technology to distribute a single content source to many simultaneous listeners/viewers. A webcast may either be distributed live or on demand. Essentially, web ...
projects, or dedicated virtual reality systems that allow users to perform a virtual diving into an interactive 3D reconstruction of the underwater archaeological site. An example is the excavation of the ''
Queen Anne's Revenge
''Queen Anne's Revenge'' was an early-18th-century ship, most famously used as a flagship by Edward Teach, better known by his nickname Blackbeard. Although the date and place of the ship's construction are uncertain, it was originally believed ...
'' and the ''QAR DiveLive'' program,
a live interactive virtual field trip to the wrecksite.
Techniques
Although specialised techniques and tools have been developed to address the challenges of working under water, the archaeological goals and process are essentially the same as in any other context. Investigating an underwater site however, is likely to take longer and be more costly than an equivalent terrestrial one.
An important aspect of project design is likely to be managing the
logistics
Logistics is generally the detailed organization and implementation of a complex operation. In a general business sense, logistics manages the flow of goods between the point of origin and the point of consumption to meet the requirements of ...
of operating from a boat and of managing
diving operations. The depth of water over the site, and whether access is constrained by tides, currents and adverse weather conditions will create substantial constraints on the techniques that can feasibly be used and the amount of investigation that can be carried out for a given cost or in a set timescale. Many of the most carefully investigated sites, including the ''Mary Rose'' have relied substantially on avocational archaeologists working over a considerable period of time.
As with archaeology on land, some techniques are essentially manual, using simple equipment (generally relying on the efforts of one or more scuba divers), while others use advanced technology and more complex logistics (for example requiring a large support vessel, with equipment handling cranes, underwater communication and computer visualisation).
Position fixing
Knowing the location of an archaeological site is fundamental to being able to study it. In the open sea there are no landmarks, so
position fixing
Geopositioning, also known as geotracking, geolocalization, geolocating, geolocation, or geoposition fixing, is the process of determining or estimating the geographic position of an object.
Geopositioning yields a set of geographic coordinates ...
is generally achieved using
GPS
The Global Positioning System (GPS), originally Navstar GPS, is a Radionavigation-satellite service, satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of t ...
. Historically, sites within sight of the shore would have been located using
transects
A transect is a path along which one counts and records occurrences of the objects of study (e.g. plants).
There are several types of transect. Some are more effective than others.
It requires an observer to move along a fixed path and to count ...
. A site may also be located by visually
surveying
Surveying or land surveying is the technique, profession, art, and science of determining the terrestrial two-dimensional or three-dimensional positions of points and the distances and angles between them. A land surveying professional is ca ...
some form of marker (such as a
buoy
A buoy () is a floating device that can have many purposes. It can be anchored (stationary) or allowed to drift with ocean currents.
Types
Navigational buoys
* Race course marker buoys are used for buoy racing, the most prevalent form of yac ...
) from two known (mapped) points on land. The depth of water at a site can be determined from charts or by using the depth sounding
sonar
Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigation, navigate, measure distances (ranging), communicate with or detect o ...
equipment that is standard equipment on ships. Such
sonar
Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigation, navigate, measure distances (ranging), communicate with or detect o ...
can often be used to locate an upstanding structure, such as a shipwreck, once GPS has placed the research vessel in approximately the right location.
Site survey
The type of
survey
Survey may refer to:
Statistics and human research
* Statistical survey, a method for collecting quantitative information about items in a population
* Survey (human research), including opinion polls
Spatial measurement
* Surveying, the techniq ...
required depends on the information that is needed to resolve archaeological questions, but most sites will need at least some form of topographical survey and a site plan showing the locations of artifacts and other archaeological material, where samples were taken and where different types of archaeological investigation were carried out. Environmental assessment of archaeological sites will also require that environmental conditions (water chemistry, dynamic properties) as well as the natural organisms present on the site are recorded. For shipwrecks, particularly post-industrial age shipwrecks, pollution threats from wreck material may need to be investigated and recorded.
The simplest approach to survey is to carry out three-dimensional
surveying
Surveying or land surveying is the technique, profession, art, and science of determining the terrestrial two-dimensional or three-dimensional positions of points and the distances and angles between them. A land surveying professional is ca ...
by divers using
depth gauge
A depth gauge is an instrument for measuring depth below a reference surface. They include depth gauges for underwater diving and similar applications, and engineering instruments used to measure the depth of holes and indentations from a refer ...
s and
tape measure
A tape measure or measuring tape is a flexible ruler used to measure length or distance.
It consists of a ribbon of cloth, plastic, fibre glass, or metal strip with linear measurement markings. It is a common measuring tool. Its design all ...
ments.
Research shows that such measurements are typically less accurate than similar surveys on land.
Where it is not practical or safe for divers to physically visit a site,
Remotely Operated Vehicle
A remotely operated underwater vehicle (technically ROUV or just ROV) is a tethered underwater mobile device, commonly called ''underwater robot''.
Definition
This meaning is different from remote control vehicles operating on land or in the ai ...
s (ROVs) enable observation and intervention with control by personnel located at the surface.
The low technology approach of measuring using tape measures and depth gauges can be replaced with a more accurate and quicker high technology approach using acoustic positioning.
ROV technology was used during the ''Mardi Gras'' Shipwreck Project. The "Mardi Gras Shipwreck" sank some 200 years ago about 35 miles off the coast of
Louisiana
Louisiana , group=pronunciation (French: ''La Louisiane'') is a state in the Deep South and South Central regions of the United States. It is the 20th-smallest by area and the 25th most populous of the 50 U.S. states. Louisiana is borde ...
in the
Gulf of Mexico
The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...
in 4,000 feet (1220 meters) of water.
Remote sensing
Remote sensing is the acquisition of information about an object or phenomenon without making physical contact with the object, in contrast to in situ or on-site observation. The term is applied especially to acquiring information about Earth ...
or Marine Geophysics
is generally carried out using equipment towed from a vessel on the surface and therefore does not require any one, or any equipment to actually penetrate to the full depth of the site. Sensitive
sonar
Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigation, navigate, measure distances (ranging), communicate with or detect o ...
, especially
side-scan sonar
Side-scan sonar (also sometimes called side scan sonar, sidescan sonar, side imaging sonar, side-imaging sonar and bottom classification sonar) is a category of sonar system that is used to efficiently create an image of large areas of the sea ...
or multi-beam sonar
[Multibeam sonar evaluated by Wessex Archaeology](_blank)
as part of ALSF funded "Wrecks on the Seabed" project may be used to image an underwater site.
Magnetometry
A magnetometer is a device that measures magnetic field or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, o ...
[Magnetometry evaluated by Wessex Archaeology](_blank)
as part of ALSF funded "Wrecks on the Seabed" project can be used to locate metal remains such as metal
shipwrecks
A shipwreck is the wreckage of a ship that is located either beached on land or sunken to the bottom of a body of water. Shipwrecking may be intentional or unintentional. Angela Croome reported in January 1999 that there were approximately ...
,
anchors and
cannon
A cannon is a large- caliber gun classified as a type of artillery, which usually launches a projectile using explosive chemical propellant. Gunpowder ("black powder") was the primary propellant before the invention of smokeless powder ...
. Sub-bottom profiling
[Sub-bottom profiling sonar evaluated by Wessex Archaeology](_blank)
as part of ALSF funded "Wrecks on the Seabed" project[Sub-bottom profile investigation of the ''Grace Dieu'' from The University of Southampton](_blank)
/ref> utilizes sonar to detect structures buried beneath sediment.
Recording
A variety of techniques are available to divers to record findings underwater. Scale drawing
Plans are a set of technical drawing, drawings or two-dimensional diagrams used to describe a Location (geography), place or Object (philosophy), object, or to communicate building or Manufacturing, fabrication instructions. Usually plans are d ...
is the basic tool of archaeology and can be undertaken underwater. Pencils will write underwater on permatrace, plastic dive slates, or matt laminated
Lamination is the technique/process of manufacturing a material in multiple layers, so that the composite material achieves improved strength, stability, sound insulation, appearance, or other properties from the use of the differing materia ...
paper.
Photography
Photography is the art, application, and practice of creating durable images by recording light, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film. It is employed ...
and videography
Videography is the process of capturing moving images on electronic media (e.g., videotape, direct to disk recording, or solid state storage) and even streaming media. The term includes methods of video production and post-production. It used ...
are the mainstays of recording, which has become much more convenient with the advent of reasonably priced digital still and HD video cameras. Cameras
A camera is an optical instrument that can capture an image. Most cameras can capture 2D images, with some more advanced models being able to capture 3D images. At a basic level, most cameras consist of sealed boxes (the camera body), with a ...
, including video cameras
A video camera is an optical instrument that captures videos (as opposed to a movie camera, which records images on film). Video cameras were initially developed for the television industry but have since become widely used for a variety of other ...
can be provided with special underwater housings that enable them to be used for underwater videography
Underwater videography is the branch of electronic underwater photography concerned with capturing underwater moving images as a recreational diving, scientific, commercial, documentary, or filmmaking activity.
History
In 1909, Albert Samama ...
. Low visibility underwater and distortion of image due to refraction mean that perspective photographs can be difficult to obtain. However, it is possible to take a series of photographs at adjacent points and then combined into a single photomontage or photomosaic image of the whole site. 3D photogrammetry
Photogrammetry is the science and technology of obtaining reliable information about physical objects and the environment through the process of recording, measuring and interpreting photographic images and patterns of electromagnetic radiant ima ...
has also become a very popular way to image underwater cultural materials and shipwreck sites.
Excavation
Where intrusive underwater excavation is appropriate, silts and sediments can be removed from an area of investigation using a water dredge A water eductor or water dredge is an eductor-jet pump-based tool used by underwater archaeology, underwater archaeologists to remove sediments from an underwater archaeological site. airlift (dredging device), Airlifts may be used for the same pur ...
or airlift
An airlift is the organized delivery of supplies or personnel primarily via military transport aircraft.
Airlifting consists of two distinct types: strategic and tactical. Typically, strategic airlifting involves moving material long distanc ...
. When used correctly, these devices have an additional benefit in tending to improve the visibility in the immediate vicinity of the investigation. It is also important to note that for very deep sea excavation submarines are sometimes used to view sites. Underwater photography can also be conducted from these submarines which assists the recording process.
Archaeological science
A variety of archaeological sciences are used in underwater archaeology. Dendrochronology
Dendrochronology (or tree-ring dating) is the scientific method of dating tree rings (also called growth rings) to the exact year they were formed. As well as dating them, this can give data for dendroclimatology, the study of climate and atmos ...
is an important technique especially for dating the timbers of wooden ships. It may also provide additional information, including the area where the timber was harvested (i.e. likely to be where the ship was built) and whether or not there are later repairs or reuse of salvaged materials. Because plant and animal material can be preserved underwater, archaeobotany
Paleoethnobotany (also spelled palaeoethnobotany), or archaeobotany, is the study of past human-plant interactions through the recovery and analysis of ancient plant remains. Both terms are synonymous, though paleoethnobotany (from the Greek words ...
and archaeozoology
Zooarchaeology (sometimes called archaeozoology), also known as faunal analysis, is a branch of archaeology that studies remains of animals from archaeological sites. Faunal remains are the items left behind when an animal dies. These include bon ...
have roles in underwater archaeology. For example, for submerged terrestrial sites or inland water, identification of pollen
Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametophyt ...
samples from sedimentary or silt layers can provide information on the plants growing on surrounding land and hence on the nature of the landscape. Information about metal artifacts can be obtained through X-ray
An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...
of concretions. Geology
Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ear ...
can provide insight into how the site evolved, including changes in sea-level, erosion
Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distin ...
by rivers and deposition by rivers or in the sea.
Artifact recovery and conservation
Artifacts recovered from underwater sites need stabilization to manage the process of removal of water and conservation. The artifact either needs to be dried carefully, or the water replaced with some inert medium (as in the case of The Mary Rose). Artifacts recovered from salt water
Saline water (more commonly known as salt water) is water that contains a high concentration of dissolved salts (mainly sodium chloride). On the United States Geological Survey (USGS) salinity scale, saline water is saltier than brackish water, ...
, particularly metals
A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typicall ...
and glass
Glass is a non-crystalline, often transparent, amorphous solid that has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics. Glass is most often formed by rapid cooling (quenching) of ...
need be stabilized following absorption of salt or leaching of metals. In-situ conservation
''In-situ'' conservation is the on-site conservation or the conservation of genetic resources in natural populations of plant or animal species, such as forest genetic resources in natural populations of Teagan species. This process protects th ...
of underwater structures is possible, but consideration needs to be given to the dynamic nature of the site. Changes to the site during intrusive investigation or removal of artifacts may result in scouring which exposes the site to further deterioration.
Interpretation and presentation of underwater archaeology
Diver trails also called wreck trails can be used to allow scuba-divers to visit and understand archaeological sites that are suitable for scuba-diving One excellent example is the Florida Public Archaeology Network
The Florida Public Archaeology Network, or FPAN, is a state supported organization of regional centers dedicated to public outreach and assisting Florida municipalities and the Florida Division of Historical Resources "to promote the stewardship ...
's (FPAN) "Florida Panhandle Shipwreck Trail." The Florida Panhandle Shipwreck Trail features 12 shipwrecks
A shipwreck is the wreckage of a ship that is located either beached on land or sunken to the bottom of a body of water. Shipwrecking may be intentional or unintentional. Angela Croome reported in January 1999 that there were approximately ...
including artificial reefs
An artificial reef is a human-created underwater structure, typically built to promote marine life in areas with a generally featureless bottom, to control erosion, block ship passage, block the use of trawling nets, or improve surfing.
Many re ...
and a variety of sea life for diving, snorkeling and fishing offshore of Pensacola, Destin, Panama City and Port St. Joe, Florida
Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...
. Otherwise presentation will typically rely on publication (book or journal
A journal, from the Old French ''journal'' (meaning "daily"), may refer to:
*Bullet journal, a method of personal organization
*Diary, a record of what happened over the course of a day or other period
*Daybook, also known as a general journal, a ...
articles, web-sites and electronic media such as CD-ROM). Television programs, web videos and social media can also bring an understanding of underwater archaeology to a broad audience. The ''Mardi Gras'' Shipwreck Project integrated a one-hour HD documentary, short videos for public viewing and video updates during the expedition as part of the educational outreach. Webcasting is also another tool for educational outreach. For one week in 2000 and 2001, live underwater video of the ''Queen Anne's Revenge
''Queen Anne's Revenge'' was an early-18th-century ship, most famously used as a flagship by Edward Teach, better known by his nickname Blackbeard. Although the date and place of the ship's construction are uncertain, it was originally believed ...
'' Shipwreck Project was webcast
A webcast is a media presentation distributed over the Internet using streaming media technology to distribute a single content source to many simultaneous listeners/viewers. A webcast may either be distributed live or on demand. Essentially, web ...
to the Internet
The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a '' network of networks'' that consists of private, pub ...
as a part of the ''QAR DiveLive'' educational program that reached thousands of children around the world. Created and co-produced by Nautilus Productions
Nautilus Productions LLC is an American video production, stock footage, and photography company incorporated in Fayetteville, North Carolina in 1997. The principals are producer/director Rick Allen and photographer Cindy Burnham. Nautilus specia ...
and Marine Grafics, this project enabled students to talk to scientists and learn about methods and technologies utilized by the underwater archaeology team.
Environmental impact
History
Publications
Publication is an essential part of the archaeological process and is particularly crucial for underwater archaeology, where sites are generally not accessible and it is often the case that sites are not preserved in-situ.
The specialist journals on maritime archaeology
Maritime archaeology (also known as marine archaeology) is a discipline within archaeology as a whole that specifically studies human interaction with the sea, lakes and rivers through the study of associated physical remains, be they vessels, s ...
, which include the long established '''', ''The Bulletin of the Australasian Institute for Maritime Archaeology'' (AIMA) and the recently launched ''Journal of Maritime Archaeology'' publish articles about maritime archaeological research and underwater archaeology. However, research on underwater sites can also be published in mainstream archaeological journals, or thematic archaeological journals. Some institutions also make their unpublished reports, often called 'Grey Literature', accessible thereby allowing access to far more detail and a wider range of archaeological data than is otherwise the case with books and journals. An example is the works of the Department of Maritime Archaeology at the Western Australian Museum
The Western Australian Museum is a statutory authority within the Culture and the Arts Portfolio, established under the ''Museum Act 1969''.
The museum has six main sites. The state museum, now known as WA Museum Boola Bardip, officially re-ope ...
.
The public interest market is covered by a number of diving, shipwreck and underwater archaeology books, beginning with the works of Jacques Cousteau
Jacques-Yves Cousteau, (, also , ; 11 June 191025 June 1997) was a French naval officer, oceanographer, filmmaker and author. He co-invented the first successful Aqua-Lung, open-circuit SCUBA (self-contained underwater breathing apparatus). T ...
.
The techniques of underwater archaeology are also documented in published works, including a number of handbooks,[Archaeology Underwater, The NAS Guide to Principles and Practice; eds Martin dean, Ben Ferrari, Ian Oxley, Mark Redknap and Kit Watson. Published by Nautical Archaeology Society, Archetype Press, 1992 ] and Muckelroy's classic work on Maritime Archaeology.
See also
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* (Shipwrecks & Underwater Archaeology)
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* – Unidentified objects submerged in water
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References
External links
RPM Nautical Foundation
Institute of Maritime History
Institute of Nautical Archaeology
Lighthouse Archaeological Maritime Program (LAMP), St. Augustine, Florida
* ttp://www.cma.soton.ac.uk/ Centre for Maritime Archaeology University of Southampton
Centre for Maritime Archaeology, University of Ulster, Coleraine
by E. Lee Spence
East Carolina University Maritime Studies
National Park Service Submerged Resources Center
Mystery Mardi Gras Shipwreck Short
Florida Public Archaeology Network
Nordic Underwater Archaeology
Resources for maritime archaeologists
"Shipwrecks" in Stillwell, Richard, William L. MacDonald, Marian Holland McAllister, eds. ''Princeton Encyclopedia of Classical Sites'', 1976, Includes alphabetized list of known wreck sites from Classical Antiquity.
National Park Service Archeology Program
Submerged Landscapes Archaeological Network
University of Southern Denmark Maritime Archaeology Program
The "Mardi Gras" Shipwreck Project
Institut Européen d'Archéologie Sous-Marine
{{Authority control
Maritime archaeology
Methods in archaeology