Fully submerged shipwreck sites act as open systems, with the exchange of material (sediment, water, organic and inorganic objects) and energy (wave, tidal, storm) across system boundaries (Quinn, 2006). Formation processes at wreck sites are driven by some combination of chemical, biological and physical processes, with physical processes dominant in initial phases (Quinn, 2006). Depositional and erosional patterns that form in response to hydrodynamic forcing are often difficult to quantify at sites due to the spatial and temporal scales at which these processes occur.
To date, the CMA strategy for mapping submerged wreck sites has concentrated on the integration of single-beam bathymetric, side-scan, magnetometer and sub-bottom data to identify sites of archaeological potential (Bull et al., 1998; Quinn et al., 2000; 2002a,b, 2007; Quinn, 2006). These data have been interpreted in the context of a series of control experiments, designed to mimic the geophysical signatures of submerged archaeological material (Quinn et al., 1998 a,b; 2005). This experimental approach was developed to inform interpretation of geophysical data acquired over potential archaeological sites. However, to date, the limited availability (and relatively low-resolution) of data off the north coast has hindered this approach. The provision of the JIBS data presents a unique opportunity to study wreck site formation processes at a resolution and scale previously unobtainable.
GIS map of study area showing colour-coded JIBS data, MSMR entries, shipwrecks known to sports divers and database of anomalies detected from the JIBS data.
Comparison between bathymetric data acquired over the S.S. Lochgarry site, gridded to 6m, 4m and 1m.
(A) 1m resolution bathymetric and (B) backscatter data acquired over the HMS Drake wreck site. Note the importance of the backscatter data in providing a clearer image of the wreck remains as well as giving information on sediment types (dark areas = gravel; light areas = sand). (C) Result of manual segmentation using QTC-multiview – note the area around the wrecks is picked out as a separate class.