Spectral Induced Polarisation – a Geophysical Method for Archaeological Prospection in Peatlands

Abstract

AbstractAbstractCompared to conventional electrical conductivity surveys the spectral induced polarisation (SIP) method measures the frequency dependence of conductivity amplitude and the phase shift between injected current and the resulting voltage signal. The phase shift is related to polarisation effects of materials. Laboratory investigations of peat, wood and soil samples show a considerable variation in the spectra of conductivity amplitude and phase shift.From the results of laboratory investigations it could be concluded that characteristic features of the phase spectra can be used to detect wooden relics of trackways or pile dwellings in the wetland's subsurface.Field surveys in the Federsee bog in southern Germany and the Campemoor bog in northern Germany prove that the method of spectral induced polarisation can be considered as a prospecting tool for archaeological surveying in wetlands. A shallow trackway in the Campemoor bog could be clearly verified by higher phase values measured at a frequency of 3Hz. The weak phase signal of a somewhat deeper plankway in the Federsee bog became only visible after data processing.Keywords: GEOPHYSICSSPECTRAL INDUCED POLARISATION (SIP)ELECTRICAL CONDUCTIVITYTRACKWAYSFEDERSEE BOGCAMPEMOOR BOG