Shipwreck
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 three million shipwrecks worldwide[1] (an estimate rapidly endorsed by UNESCO[2][3] and other organizations[4]).
Historic wrecks are attractive to maritime archaeologists because they preserve historical information: for example, studying the wreck of Mary Rose revealed information about seafaring, warfare, and life in the 16th century. Military wrecks, caused by a skirmish at sea, are studied to find details about the historic event; they reveal much about the battle that occurred. Discoveries of treasure ships, often from the period of European colonisation, which sank in remote locations leaving few living witnesses, such as Batavia, do occur as well. Some contemporary wrecks, such as the oil tanker Prestige or Erika, are of interest primarily because of their potential harm to the environment. Other contemporary wrecks are scuttled in order to spur reef growth, such as Adolphus Busch and Ocean Freeze. Many contemporary and historic wrecks, such as Thistlegorm, are of interest to recreational divers that dive to shipwrecks because they are interesting to explore, provide large habitats for many types of marine life, and have an interesting history.
Well known shipwrecks include the catastrophic Titanic, Britannic, Lusitania, Estonia, Empress of Ireland, Andrea Doria, or Costa Concordia. There are also thousands of wrecks that were not lost at sea but have been abandoned or sunk. These abandoned, or derelict ships are typically smaller craft, such as fishing vessels. They may pose a hazard to navigation[5] and may be removed by port authorities.[6]
Poor design, improperly stowed cargo, navigation and other human errors leading to collisions (with another ship, the shoreline, an iceberg, etc.), bad weather, fire, and other causes can lead to accidental sinking. Intentional reasons for sinking a ship include: intending to form an artificial reef; destruction due to warfare, piracy, mutiny or sabotage; using the vessel for target practice; or removing a menace to navigation. A ship can be also used as breakwater structure.
The above - especially the stratification (silt/sand sediments piled up on the shipwrecks) and the damages caused by marine creatures - is better described as "stratification and contamination" of shipwrecks. The stratification not only creates another challenge for marine archaeology, but also a challenge to determine its primary state, i.e. the state that it was in when it sank.
Stratification includes several different types of sand and silt, as well as tumulus and encrustations. These "sediments" are tightly linked to the type of currents, depth, and the type of water (salinity, pH, etc.), which implies any chemical reactions that would affect potential cargo (such as wine, olive oil, spices, etc.).
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