The acoustic imaging, reconstruction and characterization of buried archaeological material
Maritime archaeologists are increasingly required to investigate important sites in a nondestructive manner. Therefore, this thesis aimed to adapt and apply sub-bottom acoustic techniques to shallowly buried shipwrecks and submerged palaeo-landsurfaces. The imaging of archaeological sites requires a geophysical source with high resolving power. A model was developed to determine the vertical resolution of the Chirp sub-bottom profiler, the source used throughout this thesis. The horizontal resolution, on the other hand, was determined by modelling the directivity pattern of an array of Chirp transducers. The results were then used to choose a suitable Chirp sweep to image shallowly buried objects. Three sites were selected to test the ability of the system to image, reconstruct and characterize archaeological material. The first site comprised of a shipwreck buried within muddy riverine sediments: the Grace Dieu (1418). The survey utilized both a 2D- and 3D-Chirp system. In both cases, the source was pushed over the site by divers. Close survey line spacing, accurate navigation and decimeter-scale resolution data enabled the construction of a pseudo- and full 3D-image of the site. In the second site, the Yarmouth
Plets, Ruth Mieke Karen
CC Archaeology
The acoustic imaging, reconstruction and characterization of buried archaeological material. Maritime archaeologists are increasingly required to investigate important sites in a nondestructive manner. Therefore, this thesis aimed to adapt and apply sub-bottom acoustic techniques to shallowly buried shipwrecks and submerged palaeo-landsurfaces. The imaging of archaeological sites requires a geophysical source with high resolving power. A model was developed to determine the vertical resolution of the Chirp sub-bottom profiler, the source used throughout this thesis. The horizontal resolution, on the other hand, was determined by modelling the directivity pattern of an array of Chirp transducers. The results were then used to choose a suitable Chirp sweep to image shallowly buried objects. Three sites were selected to test the ability of the system to image, reconstruct and characterize archaeological material. The first site comprised of a shipwreck buried within muddy riverine sediments: the Grace Dieu (1418). The survey utilized both a 2D- and 3D-Chirp system. In both cases, the source was pushed over the site by divers. Close survey line spacing, accurate navigation and decimeter-scale resolution data enabled the construction of a pseudo- and full 3D-image of the site. In the second site, the Yarmouth
acoustic reconstruction characterization bury archaeological_material maritime archaeologist increasingly required investigate important site manner therefore_aim adapt apply sub bottom acoustic technique bury shipwreck submerge palaeo image archaeological_site require geophysical source high resolve power model_develop determine vertical resolution sub bottom source_use throughout_thesis horizontal resolution hand determine model pattern array use choose suitable sweep image bury object three_site select test ability system image reconstruct characterize archaeological_material first site comprise shipwreck bury within riverine sediment grace survey utilized system case source push site diver close survey line spacing accurate navigation scale resolution data enable construction pseudo full image site second site