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Geology and architecture in Delos – GAD

Geology and architecture in Delos

From the 3rd millennium BC to the 6th century AD, hundreds of public and private buildings were erected in Delos combining local materials with those imported from the surrounding islands or from mainland Greece. The GAD project aims to study all steps of the use of stone in the architecture of Delos, from quarrying to building.

Kinds, origins and uses of the stones in the ancient constructions of Delos

Delos is an exceptional site for studying how a city combined in its architectural equipment its geological resources and imported stones; how techniques were transmitted on the construction sites financed by foreign cities or kings; and how geologists and specialists in ancient architecture have interacted for more than two centuries. Our project concerns all at once geology, history of ancient and modern science and technology, history of construction and economic history. The goals of our project are as follows:<br />1. To write the long and complex history of the relationship between geology and ancient architecture on the island of Delos by producing a collection of the texts of travellers who have been interested in the formation of Delos and its geology. Special research will be carried out on the work of the Morée Scientific Expedition and the work of L. Cayeux, who published the first geological map of Delos in 1911.<br />2. To characterize the major stone families used in Delos and determine their origins. Some like the granite and the gneiss used in the building outcrop in the island and thus could be purely local, but they are also found in the neighboring islands of Rinia and Mykonos, even others of the Cyclades. It is thus necessary to better characterize them, to specify the minerals which they contain, to get a more accurate map of where they are coming from.<br />3. To make assessment of the different criteria that the builders and sponsors took into account in defining strategies for exploiting local resources and importing the stones which was not available on the island.<br />4. To reconstruct all the various stages of the stonework, from the quarry to the finished work.

Methods for identifying rocks when they are not in their geological context can only be based on two aspects: the highlighting of their chemistry and their physical characteristics. On the one hand, the physical properties of rocks such as texture, granulometry, density or porosity are analysed, and on the other hand, their chemistry via their mineralogical composition. These classic, destructive analyses require samples to be taken. The heritage constraints on the island of Delos are such that it is difficult to envisage sampling the stones of the buildings in order to submit them to more precise analyses, but by their very nature destructive. In this project, we will therefore favour the use of portable instruments allowing non-destructive in situ measurements without sampling. As for the physical properties of rocks, we will use buzzer-type seismic sensors, porosimeters and portable microscopes to visualize the textures and internal structures of the rocks while quantifying the grain size. For chemistry we will use portable X-ray fluorescence (XRF).

Our first works evidence massive imports of gneiss, marbles and, to a lesser extent, poros, from the archaic period, both for constructions commissioned by the Delians and those built by foreigners, not only for public buildings but also for private ones. These new data largely change the image of the stone economy in Delos, where it was accepted that the Delos built mainly with local materials and foreigners with rocks extracted from their territory.
The identification of granite quarries on the island allows us to know a way of exploiting this stone that is quite different from those well documented for marbles and poros in the ancient Greek world.

Based on the study of the Delos case, our ambition is to propose a model of analysis protocol, petrographic identification techniques and heritage enhancement for other complexes associating quarries and ancient constructions made with materials extracted from them.

Moretti J.-Ch. et al., « Délos : géologie et architecture » chronique des travaux réalisés en 2019 », Bulletin de correspondance hellénique, forthcoming.

Vettor T. et al., « A non-invasive investigation for quarry provenance of Delos archaeological marbles », Journal of Archaeological Science, forthcoming.

Moretti I., « La pierre dans les grands sanctuaires de la Grèce antique, Délos et Delphes. Une enquête policière pour en comprendre les origines », Pour la science, 2020, forthcoming.

The island of Delos, which played a major role in the history of the ancient world and has been systematically excavated since 1873, has become the largest archaeological site in Greece. In 1990, it was labeled UNESCO World Heritage Site. From the 3rdmillennium BC to the 4rd century BC, hundreds of building, both public and private, were built, combining local and imported materials. Some came from the surrounding islands, others from mainland Greece. The aim of the GAD project is to study the different stages of the use of stone in the Delos monuments, from its quarry to its final use. The example of Delos is offering an especially rich documentation and will allow us to analyze the relationship between architecture and geology in the Greek world. From a historiographic point of view, we will also study the historical link between geology and the study of the ancient architecture. The Delian case was also chosen for its exceptional study conditions: Delos is the only Greek city whose territory has been entirely abandoned, allowing therefore a study of all the ancient quarries . It is also one of the few sites where construction accounts were found, engraved between the middle of the 5th and the 2nd century BC. Moreover, in Delos during the archaic, classical and hellenistic periods, many large buildings were erected by foreigners with stones imported from the largest Greek quarries. Its geology interested many western travelers and academics since the 15th century, including the members of the Morée scientific expedition (1829) and L. Cayeux (1906 and 1908) who all sampled the rocks in Delos. From this case study, we have the ambition to propose a model of analysis protocol, petrographic identification techniques and heritage enhancement for other ensembles associating quarries and ancient constructions.
The project, which obtained a favorable notification from the High Council of Archaeology in Greece and from the Cycladic Ephoria is led by J.-C. Moretti, DR1 at CNRS (Institut de recherche sur l’architecture antique, USR 3155) and director of the archaeological mission of Delos. Researchers and engineers from 5 institutional partners are involved in this project: (1) archeologists and architects from IRAA; (2) geologists and petrologists from the Museum national d’histoire Naturelle (IMPMC-UMR79, project leader V. Sautter); (3) structural and regional geologists from Institut des sciences de la terre (UMR 7193, Sorbonne University, CNRS, project leader: L. Jolivet, PR); (4) historians of science and technology from Centre Alexandre-Koyré (CNRS, EPHE, MNHN, UMR 8560, project leader: D. Juhé-Beaulaton, DR2) and (5) a topographer and a computer scientist from the French School of Athens (project leader : L Fadin). Three other Greek and French researchers from no-partners institutions will help us. The budget will mainly be used for the grant of a Phd student, several temporary positions, the purchase of an X-ray fluorescence instrument and the expenses of field works and seminars.
During these 4 years, our progress will be presented on a site “Hypotheses”, as well as on the website of the partners and on the web-SIG of Delos. We will also put online a multilingual illustrated lexicon of stone in ancient architecture and publish a book about stones in the architecture of Delos as well as a guide for the visitors of the archeological site on the same matter. An exhibition on the history of research on the geology of the Cyclades will be held in Paris and at the Archaeological Museum of Delos, highlighting the collections and samples of the Expédition scientifique de Morée preserved at the MNHN.

Project coordinator

Monsieur Jean-Charles Moretti (Institut de recherche sur l'architecture antique)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.


IRAA Institut de recherche sur l'architecture antique
IMPMC Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie
CAK Centre Alexandre Koyre
ISTEP Institut des sciences de la Terre Paris
EFA Ecole française d'Athènes
Société archéologique / Société archéologique
Ephorie des Cyclades / Ephorie des Cyclades

Help of the ANR 318,956 euros
Beginning and duration of the scientific project: October 2018 - 48 Months

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