Archaeologia Islandica - 01.01.2011, Síða 15

ARCHAEOLOGICAL ASSESSMENT OF SELECTED SUBMERGED SITES IN VESTFIRÐIR
aware of the submerged heritage and that
artifacts removed from a submerged site
without proper archaeological procedure
robs the site of its historic and
environmental integrity, eventually
destroying its scientific, educational and
recreational value.
Methodology and approach
The project approached the problem of
locating unknown submerged sites in two
ways; a) historical research and b)
archaeological survey. The historical
research for shipwrecks was focused on
the period 1875 - 1890 to get an idea of
how many Icelandic and foreign boats
were lost per year in this period. Other
historic documents were only examined on
a limited scale and were primarily used to
locate important land based sites, i.e.
trading posts, whaling stations, etc.
(Annálar 1400-1800, 1922, íslenskir
annálar 1847)
The second stage of the research
focused on surveying the sites selected
ffom the historical research. A predefmed
area was marked out using global
positioning system and the area was
systematically surveyed with various
survey methods and in some cases
including geophysical methods such as
side scan-sonar and an underwater camera
(ROV). A number of dives were
subsequently carried out on some of the
sites, selected ffom the survey data, to gain
further information on the underwater
environment.
The side-scan sonar is mounted in a
tow-físh that is towed behind a boat and
uses a wide angle sonar pulse, emitted to
the sides and displays the intensity of the
sound scattered back to the tow-fish from
the sea floor and objects exposed on the
bottom. This system gives an undistorted
images of the sea-floor in real time and can
in some cases be interpreted in the field
(Bowens, A. 2009). The sonar operated at
a 455 khz and was set at a range of 40
meters and was towed behind a boat at an
average speed of 4 knots (2 m/sec) (fig. 3).
Figure 3. The side-scan sonar and towfish during operation in Steingrímsjjörður.
13