Albert Hesse

New prospects in shallow depth electrical surveying for archaeological and pedological applications

Three different improvements in the galvanic method of shallow‐depth electrical prospecting need to be made. (1) A better definition of the electrode array(s) is needed in order to reduce the “apparent anisotropy” effect and increase the depth of investigation; the square array is one solution. (2) A resistivity meter that can make measurements very rapidly needs to be built. The rapid decrease of the induced electric field for small electrode distances makes such measurements possible. We propose a resistivity meter with an 8 ms measurement time. (3) The electrode‐ground contact problem needs to be solved by using a resistivity meter that can endure high contact resistances. As an alternative solution, we also propose a new type of electrode: a liquid jet one. These improvements could make the resistivity method very attractive and competitive, and open large future developments for the method.

Archaeological Prospecting using Electric and Electrostatic Mobile Arrays

The latest generation of mobile electric and electrostatic arrays allows the measurement of the apparent resistivity over large areas with a high spatial sampling and for several depths of investigation. This paper presents three experiments undertaken over three archaeological sites of three different historical periods (Iron Age, Roman, medieval) and three different subsoil covers (meadow, ploughed field, asphalt). The archaeological structures (ditches, enclosures or walls) are described with a good accuracy. They are integrated in their environmental and geological context. Copyright

A magnetic and electrical study of archaeological structures at Loma Alta, Michoacan, Mexico

This paper describes the results of high spatial resolution magnetic and resistivity surveys of the Loma Alta site in Michoacan, Mexico. This site is the largest of a series of man-made earthen islands built up within an ancient freshwater basin. Occupied during three main phases from 100 BC to AD 850, the site now shows no surface detail of the underlying structural complexity. Test pits and trenches excavated during several field seasons revealed a fraction of the large ceremonial complex and provided isolated archaeological data difficult to interpret. Geophysical prospection aimed to investigate the so far unknown settlement pattern and detect architectural remains. Magnetic prospecting of the stone architecture turned out to be excellent due to the high contrast between the volcanic rock and the sedimentary fill. A fluxgate gradiometer survey of the entire mound surface defined a large number of small aligned positive and negative magnetic anomalies. Electrical surveys complemented and verified the magnetic results. A series of verification excavations exposed structural elements predicted by the prospecting and aided a further interpretation of the data. The major results of the study are discussed, as they provide a clear image of the orthogonal layout of the highly structured ceremonial site.

Count Robert du Mesnil du Buisson (1895–1986), a french precursor in geophysical survey for archaeology

Geophysical surveys for archaeology are generally considered to have started in 1946 or 1947 with electrical measurements. This assumption neglects several predictions (1934) and experiments (1947) made at very early dates by a French archaeologist (R. du Mesnil du Buisson) who stated several clever and precursory conclusions on different methods. These are still almost unknown probably because they were not published in English until now. The paper gives an account of some interesting aspects of the subject and of historical details about the early times of our discipline. Unsuccessful attempts to establish possible links between R. du Mesnil du Buisson and the most prominent French geophysicists of that time reveals the archaeologist as a particularly independent and perspicacious precursor in this field. Copyright

Recent Developments In Shallow Electrical And Electrostatic Prospecting Using Towed Arrays

The application for ten years of mobile electrical and electrostatic quadripoles allowed a considerable increase in the size of the surveyed areas, together with keeping a high spatial resolution and a reduction of the total cost of a survey . Two new developments of towed arrays are illustrared here: i) a pole-pole array pulled by the operator himself constitutes a light solution for mapping large surfaces at a given unique depth of investigation (Wroxeter), ii) a multipole multidepth system allows a 3D investigation of the ground resistivity (Garchy).