Underwater archaeology is the study of past human life, behaviors and cultures using the physical remains found in salt or fresh water or buried beneath water-logged sediment. It is most often considered as a branch of maritime archaeology. One of the key areas of maritime archaeology is the exploration and preservation of shipwrecks.
Researchers investigating the archaeology of shipwrecks need to understand the processes by which a wreck site is formed so that they can allow for the distortions in the archaeological material caused by the filtering and scrambling of material remains that occurs during and after the wrecking process.
When a ship is wrecked, it suffers many changes of state until the remains eventually reach equilibrium with their environment. Initially, the wrecking process changes it from the human organized form of a working vessel to an unstable state of structure and artefacts underwater.
Natural forces act upon it during the wrecking process and continue to act until equilibrium is reached. Heavy items sink rapidly, lighter items may drift before sinking, while buoyant items may float away completely. This causes a filtering and scrambling of the material remains.
The sudden arrival of a structure on the seabed will change the currents, often resulting in new scour and deposition patterns in the seabed. Once underwater, chemical processes and the action of biological organisms will contribute to the disintegration. At any point in these processes, humans may have intervened, for example by salvaging items of value.
Prior to being wrecked, the ship would have operated as an organized machine, and its crew, equipment, passengers and cargo need to be considered as a system. The material remains should provide clues to the functions of sea-worthiness, navigation and propulsion as well as to ship board life.
Finally the ship as a means of transport can be considered as an element in a geographically dispersed social, political and economic system. Warships impose political will by force; cargo vessels exist in a system of commerce; while passenger carrying vessels give clues to social classes and structure.
Social status may also exist within the ship, for example, between segregated officers and seamen.
Some links of interest:
@ Advisory Council on Underwater Archaeology
@ French Archaeology - Ministry of Culture
@ Generality on Underwater Archaeology
@ Ships Exploration Discovery Research
@ SubArch - Discussions concerning Underwater Archaeology
@ New Archaeological Uses of Autonomous Underwater Vehicles
@ A few Questions and Answers about Underwater Archaeology