Laurent Chalumeau

Stone uses in Reims Cathedral: provenance, physical properties and restoration phases

Abstract Reims Cathedral is a major monument in the NE of France originally built with local Lutetian limestone. The recent closure of the last quarries has made restoration using the same stone more complicated. The restoration stones used currently are Lutetian limestones from the centre of the Paris Basin (Saint-Pierre-Aigle and Saint-Maximin stones). Mapping of the Cathedrals façades confirmed the data from ancient manuscripts: Courville stone was the original building stone, but several other local stones from various quarries and beds were also used. As a follow-up to this mapping, Lutetian limestones from five disused quarries were sampled for petrophysical characterization tests: thin section analyses, porosimetry, capillary and drying kinetics. The petrophysical properties of the limestones showed differences between the two main local stone types (Ditrupa limestone and miliolids limestone) and also between the quarries. This study addresses the difficulty of selecting new stone for restoration. Should ancient quarries be re-opened? If so, which ones?

GIS-based variability of building materials towards the Île-de-France cuesta (Paris Basin, France): inventory, distribution, uses and relationship with the environment

Abstract The Pays rémois in the eastern Paris Basin is an administrative area of 1394 km2; in the surroundings of Reims (France). Two main geological substrata are separated by the Île-de-France cuesta: the Tertiary substratum in the western part is composed of various types of geomaterials (clay, sandstone, limestone, burrstone), whereas the substratum in the eastern part is composed only of Cretaceous Chalk. A field survey in each commune of the Pays rémois identified 26 building materials documented in a Geographic Information System database (GIS-database) that includes information about them (lithology, petrographical and petrophysical data, weathering) and the corresponding buildings (e.g. town, georeferenced data, building type, position on the façade). The spatial analysis of the building materials’ distribution (Standard Deviational Ellipse) with GIS identifies their uses and the criteria established for the selection of the materials: availability, efficiency, workability and durability. Some lithologies were preferred for particular buildings or selected for their efficiency in specific positions. The study also defines the relation between the stones’ origin (local and non-local stones) and their application. This database is useful to establish stone replacement strategies in the Pays rémois.

Les plans directeurs de la Grande Guerre - Une nécessaire innovation cartographique

Le theme de la Grande Guerre a fait l’objet de nombreuses publications dans le cadre du centenaire dans lesquelles l’approche est generalement historique ou sociale mais pas spatiale. Pourtant, l’archeologie de la Grande Guerre, les recherches genealogiques, les travaux des associations et le devoir de memoire utilisent de nombreux extraits de cartes militaires de la zone de front ou de plans directeurs. L’objectif de cette contribution est double. D’une part, elle replace les plans directeurs dans le contexte des cartes francaises existantes avant la Grande Guerre, demontrant ainsi la necessite d’innover du fait de l’adoption de la guerre de position par les differents belligerants, marquee par plusieurs rideaux defensifs de tranchees. Et d’autre part, elle propose de presenter les clefs de lecture des plans directeurs (systeme de coordonnees, construction, echelles, projection, legende).

Impact of lateral variations of geologic facies on water resources in homogeneous basins: example of tertiary plateaus in the Paris Basin

Spatial disparity of run-off conditions during low-water period in homogeneous watersheds depends on the degree of incision of valleys, but may also be influenced by a structural partitioning or some lateral variations in the aquifer lithology. For small basins (area <300 km2), often hydrometrically unsupervised, campaigns of serial flow measurements, gauging, conductivity and temperature are achieved. The Ardre basin, localised in the Tertiary formations of the Paris Basin is used as a workshop basin. Results validated by hydrological and physico-chemical profiles show increased hydrological yields in the basin which correspond to the increase in the thickness of aquifers and their porosity. These lateral variations of facies and of aquifer thicknesses are related to Eocene sedimentary conditions (Lutetian) for homogeneous basins, which explain the spatial disparity of water resources.