Air prospection

Appeared as of the Years 1950, the air prospection largely developed since thanks in particular to the accessibility to the means of private flights of the general aviation.

It consists with Photographie R with low and average altitude of the zones cleared then to study and interpret the indices collected. For example in Archeology, one will fly over while seeking and by photographing all the visible traces and indices. One then speaks about air Archéologie. It is not a question of a total photographic cover, but of an intentional research.

It gave its more spectacular results in the plains of Western Europe and in the arid zones of the the Middle East.

Its principle is based on the observation in altitude of indices which remain invisible on the ground. Three kinds of modifications, due to the presence of structures or hidden Vestige S, are detectable on the Photographie S obtained under optimum conditions of season and lighting:

1. The modifications of levels, extremely weak sometimes, are underlined by a shaving lighting and particularly take a significance when they are seen of Avion, in arid zones.

2. Modifications of color of the ground, due to the traces of mortar reassembled of the ploughings, hearths or pits with humus. The darker traces of moisture indicate a more movable ditch or holes of posts in a ground more Calcaire. By a phenomenon of difference in conductibility of heat, these traces can beings underlined by a fugitive deposit of hoar frost in winter.

3. Modifications of growth, flowering and maturation of the cultures, more provided above the zones major and filled of humus (filled ditches), close-cropped above the vestiges of masonries. At the time of important the Dryness S as that of 1976 these indices are amplified and reveal, mainly by selective yellowing of cereals, a great number of unknown sites.

The pioneers who developed this technique are Antoine Poidebard in Syria, towards 1925, and O.G.S. Crawford with the the United Kingdom. Then in years 1960 appeared on a regional level Roger Agache in the North of France, Jacques Dassié in Poitou-Charentes, Bernard Edeine in the Manche, Rene Goguey in Burgundy, Daniel Jalmain in Île-de-France, Louis Monguilan in Provence. One will note the great influence of the professor Raymond Chevallier on the French researchers, thanks to his historical Séminaire of topography and photo-interpretation of the École of the high studies in social sciences of Paris. Others came more tardily, of which Maurice Marsac in the West of the Poitou and Henri Delétang in Touraine. The current number voluntary air prospectors can be estimated at several tens.

More recently, the novel methods of treatment computerized of the images or the catches of sights in Infra-red, made it possible to widen the field of application of air photography and to also prospect on the forest zones. Photographs then showing completely invisible indices with the human eye. Numeric photography largely facilitated the operations by the instantaneity of its results and its directly exploitable files.

The air force carries out thousands of air photographs daily, with its reconnaissance aircraft. Unfortunately, these military images are not accessible to the archeologists.

Internal bonds

External bonds

air Prospection by Roger Agache
air Prospection in the north of France
Technical of air archeology explained, illustrated and commented on by Jacques Dassié.

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