Page 42 - Manual for Activities directed at the Underwater Cultural Heritage

 © E.Trainito. Site assessment of a wreck from the 3th century AD discovered in the Baia Salinedda, Sardinia, Italy.
Heritage should not be disturbed in the absence of good reasons. Unavoidably, any research directed at a site has an impact. Rules 3,
4, 5 and 6 specify the general principles in view of qualifying impact and regulating activities accordingly. It is the relative impact of activities that should be limited. A site should thus not be disturbed beyond what is strictly necessary to attain the objectives of a project. Non-destructive techniques are to be preferred to intrusive methods, whenever intrusion can be avoided.
on preliminary work, the most relevant present-day techniques, such as sonar and swath-bathymetry, are discussed in a sidebar on the process of inventory. These techniques are used to visualise the bottom surface of a body of water.
In relation to underwater cultural heritage, such survey methods, as well as magnetometers were at first solely applied to find, retrace and position individual sites. The integration of data generated by geophysical techniques, with accurate positioning data generated by global or local positioning systems (such as GPS), allowed for the application of these tools to precisely map large or smaller areas at great resolution. That in itself is of great help both in research and management. Developments continue, however, and the integration of various techniques of surface mapping and sub-bottom imaging means that non-destructive techniques can now provide an understanding of thus far unknown and invisible structures. Certainly there is no end to development. In many fields, probing by means of sound, light, magnetism and radiation find application, leading to the development of ever more sensitive devices, and using ever more different ranges of the various physical spectra. Equally important, software to process, filter and distil two- and three- dimensional scale images from data is being developed for a wide range of applications. The development of techniques that may be useful in archaeology is thus
- All research and management depends on data.
- Data gathering by non-destructive techniques is
essential.
- In all activities non-destructive techniques come
first.
- Non-destructive techniques are to be preferred
to intrusive methods, whenever intrusion can be avoided.
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General Principles