Geoarchaeology – EN

Geoarchaeology - Ombrone south of Campagnatico (GR)
The Ombrone river south of Campagnatico (GR), here the water course has shifted 200 meters in 200 years.

Geoarchaeology is archaeology
with the application of concepts and methods of earth sciences

Geoarchaeology shares with archaeology the field of research and part of the aims.

The application of the techniques and methods of geological sciences to archaeological research is justified by the consistency of earth shaping processes and their resulting stratigraphies. And it is necessary since it has been realized that the association of items within the deposits at the excavation is not merely the result of contemporaneous or episodic human activity, but often a consequence of the influences of numerous natural formation processes acting through time.

Useful techniques and methods are available within the wide range of earth sciences applied to archaeology, among which particularly: physical geography (the study of earth surface dynamics), sedimentology (the study of sedimentation processes and sediments), geophysics (offering the techniques for non destructive prospection) and soil science (the study of soils and the transformation processes of the earth surface).

A short outline of how and when geoarchaeology may be involved in the study and management of the historical-cultural heritage.

  • Archaeological prospections

Geophysics offers a wide range of non destructive prospection techniques, among which georadar, geoelectrics, geomagnetics and thermic infrared measures. Also in the case of trench prospection, the methods of geoarchaeology allow a more efficient layout planning and therefore a more favourable cost/benefit rate for the operation.

  • Archaeological survey

A large part is of the archaeological heritage still remains buried just below the earth surface, essentially within the soil (study object of pedology or soil science). The application of the methods of geoarchaeology, particularly those of soil science, allows a correcter prevision, identification and interpretation of the archaeological survey data, especially in the case of pre-protohistorical material.

  • The archaeological excavation

The excavation site is generally composed of naturally or culturally formed layers containing archaelogical items. The sedimentary processes are in may cases similar to those in natural sedimentary basins, since the laws of sedimentation, determined by the gravitational and hydraulical forces, are equally valid both in natural and anthropical environments. The involvement of geoarchaeology implies the optimization of the excavation project.

  • Interpretation of the data

The reconstruction of the original environmental conditions requires a profound knowledge of the dynamics of earth surface processes. A correct interpretation of the paleo-environment is necessary not only from the scientific viewpoint, but also for education and divulgation scopes.

  • Management of the cultural heritage

The idea is spreading of an archaeological research all-in, from prospections and survey, to excavation and management. At the Italian national level the possibilities of such an approach are still largely unexplored. Also in this case, the application of geoarchaeological techniques may be cost and time saving.

Major rivers tend to lateral shifting in the course of history, but the intensity of this process may differ in the various stretches. The meandering middle Ombrone river in Tuscany has a particularly mobile stretch between Campagnatico and Istia. Here during the great flood of 1966 the Voltina meander was cut off naturally.
The use of aerial photographs and the Catasto Leopoldino of 1823-1825 for the Roman Peasants Project shows clearly the intensity of the lateral shifting in this area, which largely hampers the reconstruction of possible historical fords or ferries.
In less mobile stretches of the Ombrone, as between Sasso and Paganico, where the river is confined between steep slopes, such a reconstruction is more reliable.
The straight and steeply incised river stretch between Paganico and Campagnatico is strictly related to local tectonics.

Geoarchaeology - Ombrone bridge near Sasso (GR)
A downstream view from the modern bridge over the Ombrone near Sasso (GR), with relicts of older bridges in the foreground and the location of the early XIXth century ferry in the background.
Geoarchaeology - WP_Cinigiano_fords_Leopoldino_detail
Detail of the ferry (“Barca”) over the Ombrone near Sasso (GR) as indicated on the Catasto Leopoldino of the early XIXth century; the modern bridge is located 400 m to the NW.

I can form a pretty rapid idea of a country as soon as I know by examination which way even the least brook runs, and can determine the river to whose basin it belongs. By this means, even in those districts which it is impossible to take a survey of, one can, in thought, form a connection between lines of mountains and valleys.

Goethe’s Italian Journey, 1786.

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Earth Sciences for Archaeology