Message #1153

[Deanna Witmer]

Site Survey
The type of survey 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[15] by divers using depth gauges and tape measurements. Research[16] 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 Vehicles (ROVs) enable observation and intervention with control by personnel located at the surface[17]. 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[18].

Remote sensing or Marine Geophysics[19] 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, especially side-scan sonar or multi-beam sonar[20] may be used to image an underwater site. Magnetometry[21] can be used to locate metal remains such as metal shipwrecks, anchors and cannons. Sub-bottom profiling[22][23] utilizes sonar to detect structures buried beneath sediment.