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Underwater Excavation

Excavation is the process or the act of digging. This is mostly done in archaeology when something important and specific is being removed from the underground. The origin of the word excavation is a Latin word excavationem which means hollowing out. The word excavationem is made up of two parts ex which means out and cavare which means to hollow out. There are many methods of excavation; however, in this paper, only underwater excavation method is discussed. Understanding the definition of Underwater Excavation is only the surface. You will have to dive deeper to recognize underwater excavation more fully. Some concepts which help in understanding underwater excavation is Importance of Under Water Excavation Method, Challenges of Underwater Excavation, Underwater Excavation Site Survey.

Importance of Under Water Excavation Method

The main aim of carrying out underwater excavation is to carry out research, study, restore, preserve and examine the submerged archaeological wealth (Nautical & Bowens, 2009). This archaeological wealth includes all sorts of harbor works, edifice, fortifications, cities among others that due to geological changes sank into such as oceans and seas. During underwater excavation, an archaeologist can observe submerged wealth, such as warships, fishing vessels that sank with their luggage. The luggage of the submerged wrecked water-body vessels may contain an item of everyday use belonging to persons who were involved in the accident. The submerged wealth may include big jars containing salted fish, sarcophagi, architectural elements, wine amphorae and work of art transported from one place to another. For example, the great works of art that explain to a certain degree the forces that embellished foreign museum and Greek were the Getty Museum USA, the bronze of Race, the jockey, and the Poseidon from Cape Artemision.

Underwater excavation is a difficult task since the specialists and scientists will have to work in an extreme environment deep down in the sea. This is quite a dangerous task. Although the first law to protect underwater excavation or submarine activities was proposed in 1834, the bill was not adequately enforced. Even though underwater excavation is a dangerous task, the profession is highly paid, and people still go for the job. The lowest amount that a sunken excavator could be paid was thirty thousand dollars in a year.

Challenges of Underwater Excavation

There are many challenges related to underwater extraction. The first challenge is that the underwater site is inevitably cumbersome to navigate and access. The sites are more toxic as compared to working on dry land. To access underwater excavation sites, diving skills and diving vessels are required. The length of time that a diver can spend under the water is limited. Moreover, the depth that a diver can dive is also limited. This makes underwater excavation an expensive endeavor. In case of deep depths that a diver cannot jump, specialized equipment such as submarine vessels and remote sensing equipment are required. In underwater excavation, people mainly work from ships or boats. However, the work also requires offshore activities. Nevertheless, underwater excavation is an activity that is plagued by logistic problems. A working station for underwater excavation needs to be appropriately equipped for air delivery. The working platform needs to be provided with a variety of items: accommodation for workers, medical and repression facilities, support for activities being taken underwater, analysis of archaeological results, specialized remote sensing equipment, storage supplies and facilitates. Airlift and water dredge create additional logistic issues and hazards. Also, the marine site is often accompanied by strong tidal flow and poor weather which may make the site inaccessible for some time. Moreover, some marine animals pose health threats (Nautical & Bowens, 2009).

The underwater excavation sites are also dynamic, that is, they are subject to tidal flows, storm damage, surf and movement by the currents. The progressive state of underwater excavation may of the site infeasible. Marine piddocks may consume exposed organic matter such as wood from shipwreck. The marine structure may be unexpectedly buried by sediments or uncovered. The uncovered structures may be eroded making it difficult for the archaeologists to achieve their objectives. The underwater site is often chemically active, in that, an iron can be leached from the metal to form concretion, and the residue metal is a fragile structure that needs special care.

The visibility of underwater sites is reduced due to sediments, lack of light and presence of marine plants and small animals. That means that the survey methods used in the land are not applicable in an underwater site. Another important challenge to note is that the artifacts collected from the underwater site are not easily accessed by the general public.

Underwater Excavation Site Survey

The survey used to explore an underwater archaeological site depends on the information that is needed to address the question of interest. Most of the archaeological studies will require a site plan and an analysis that shows the exact location of the product and a topographical survey. The research also needs a thorough outline of areas where samples were taken and where archaeological study and investigations were carried out. Another critical aspect to note is the present environment which includes indicating the different environmental conditions such as dynamic chemistry, water chemistry as well as recording the natural organisms present at the excavation site. For shipwrecks, the pollution threat from shipwreck materials should be examined, analyzed and documented (Rupp & Barstad, 2013).

The easiest ways to survey underwater excavation site is to carry out a . This is carried out by using tape measurements and depth gauge. Many research shows that such are less accurate than a similar surveys conducted on earth. When it is not possible for deep sea divers to practically visit a particular location in the sea, Remotely Operated Vehicles (ROVs) are used to conduct investigations. A specialist located on the surface operates the ROVs. Besides, the profound knowledge of using depth gauge and measurement tapes can be replaced by acoustic positioning. For example, the ROVs was used to identify the location of Mardi Gras shipwreck which was four thousand feet in depth, thirty-five miles from the coast of Louisiana in the Gulf of Mexico and the wreck had sunk two hundred years ago (Bailey & Flemming, 2008).

On the other hand, marine Geophysics or marine sensing is carried out by an equipment on the land surface and therefore it does not require any person or any device to penetrate through the water to record the site of excavation. Sensitive sonars such as multibeam sonar or side-scan sonar are used to take images in the underwater excavation site. Magnetometers can be used to locate submerged metallic items such as cannon, anchors and shipwrecks. Archeologist can also use sub-bottom profiling techniques which utilize sonar to detect structures concealed beneath sediments.

Different techniques are available for divers to record research findings. The primary method involves scale drawing. Pencils are used to draw beneath the water on matt laminated paper, permatrace and plastic dive slates. Videography and photography are the primary methods used in recording. This is more convenient with the invention of an affordable yet HD water-resistant digital cameras. The challenge is that they are low visibility and distortion of images by refraction. However, this can be solved by picking a series of pictures from different points which can be combined into a photomosaic photo of the entire site. 3D photogrammetry has also become a conventional method to record images under the water. Underwater excavation is a broad subject that is further for fertile (Leshikar, Denton & Erreguerena, 2016). However, all the elements of underwater excavation are beyond the scope of a single college paper.

References

Bailey, G. N., & Flemming, N. C. (2008). Archaeology of the continental shelf: marine resources, submerged landscapes and underwater archaeology.Quaternary Science Reviews,27(23-24), 2153-2165.

Leshikar-Denton, M. E., & Erreguerena, P. L. (Eds.). (2016).Underwater and maritime archaeology in Latin America and the Caribbean (Vol. 56). Routledge.

Nautical, A. S., & Bowens, A. (2009).Underwater Archaeology: The NAS Guide to Principles and Practice: The NAS Guide to Principles and Practice. Hoboken, United Kingdom: Wiley-Blackwell.

Rupp, C. V., & Barstad, J. F. (Eds.). (2013).International handbook of underwater archaeology. Springer Science & Business Media.

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