A high-frequency, narrow-beam sub bottom profiler for archaeological applications

Shipwrecks in deep water are often found by their surface expressions, such as exposed ceramic containers. Fully investigating or excavating those sites, however, requires understanding what is buried beneath, including organic materials and the remains of ship structure. This paper lays out the archaeological and technical justification for a high-frequency, narrow-beam sub-bottom profiler. It describes an ultrasonic (150 kHz) device built to image local areas of the seafloor beneath the mud. The final section presents a data set collected with the instrument operating on the ROV JASON over an 8/sup th/-century B.C. shipwreck found off the coast of Israel. Precise sub-bottom imagery can aid in characterizing a site before excavation, and enables a three-dimensional computer model of a buried structure to be built with acoustic techniques, without ever disturbing a wreck.