Acoustic response from lithics knapped by humans has been demonstrated to facilitate effective detection of submerged Stone Age sites exposed on the seafloor or embedded within its sediments. This phenomenon has recently enabled the non-invasive detection of several hitherto unknown submerged Stone Age sites, as well as the registration of acoustic responses from already known localities. Investigation of the acoustic-response characteristics of knapped lithics, which appear not to be replicated in naturally cracked lithic pieces (geofacts), is presently on-going through laboratory experiments and finite element (FE) modelling of high-resolution 3D-scanned pieces. Experimental work is also being undertaken, employing chirp sub-bottom systems (reflection seismic) on known sites in marine areas and inland water bodies. Fieldwork has already yielded positive results in this initial stage of development of an optimised Human-Altered Lithic Detection (HALD) method for mapping submerged Stone Age sites. This paper reviews the maritime archaeological perspectives of this promising approach, which potentially facilitates new and improved practice, summarizes existing data, and reports on the present state of development. Its focus is not reflection seismics as such, but a useful resonance phenomenon induced by the use of high-resolution reflection seismic systems.

This chapter presents a non-destructive survey technique under development: acoustic detection and mapping of submerged Stone Age sites. While it has been experimentally established that reasonable amounts of man-knapped flint pieces can be excited by and respond to specific acoustic signal through meters of sea floor sediment, it is not yet known how small assemblages of knapped flint pieces one can obtain a response from and how deep in the sea floor this will be possible. It also remains to check experimentally if other knapped materials than flint (obsidian, quartzite, basalt, etc.) respond in a similar way given that some of their basic characteristics potentially differ from those registered for flint. This technique will facilitate a much more effective and cheap detection and mapping of submerged Stone Age sites with knapped lithics compared to the techniques available at present. Especially the deep sites down to the approximately 120 m deep coastlines of the glaciations, which are very difficult to localize today, represent an important research potential. In general, the highly productive coast lines must be assumed to have played an important economic role of human society from the Palaeolithic onwards, which means that we miss an important part of the picture of the human cultural development. In spite of the promising perspective of methodological improvement, one must be aware of the limitations of the acoustic method. It will not be able to map Stone Age sites lacking knapped lithics. This chapter presents and discusses the method's basic technological principles and the experimental results obtained so far, elucidating its potential.

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