HR: 0800h
AN: NS51C-08    [Abstracts]
TI: Geophysical Investigations Over the Archaeological site of Rirha (Morocco)
AU: * SENECHAL, G
EM: guy.senechal@univ-pau.fr
AF: MIGP UMR 5212, Avenue du Doyen Poplawski - Université de Pau et des Pays de l'Adour, PAU, 64000, France, Metropolitan
AU: ROUSSET, D
EM: dominique.rousset@univ-pau.fr
AF: MIGP UMR 5212, Avenue du Doyen Poplawski - Université de Pau et des Pays de l'Adour, PAU, 64000, France, Metropolitan
AU: CALLEGARIN, L
EM: laurent.callegarin @wanadoo.fr
AF: Groupe de Recherche Archaélogique JE2245, Avenue du Doyen Poplawski - Université de Pau et des Pays de l'Adour, PAU, 64000, France, Metropolitan
AU: KBIRI ALAOUI, M
AF: Institut Nationale des Sciences de l'archélogie et du patrimoine, av. J Kennedy, Rabat, Morocco
AB: The roman site of Rirha has been evidenced in the 1920's and loosely studied until nowadays. Archeaological evidences show a pre-roman to medieval occupation of the site. Excavations have revealed thermae and other buildings while their context, rural villa or urban domus was still unknown. A new survey began in 2004, focusing on the pre-roman occupation of the site, as well as the characterization of the roman occupation. The zone of interest, a hill in a river loop, is about 11hectares. A comprehensive geophysical survey was out of reach, so geophysical tests have been carried on with two goals. The first one was to identify the suitable methods adapted to this, the second one was to use these preliminary results to distinguish between rural or urban settings for the roman site. The first survey has been conducted in April 2005, using conductivitymeter (Geonics EM38) in order to get informations about the spatial organization of the site. The selected zone was located in an unsurveyed part of the site. Resistivity maps show orthogonal structures, far from the known roman remains. This result supports the hypothesis of the site being a roman town and not a large farm or a villa. The second survey has been carried on in February 2006 and involved GPR and DC tomography, in very wet conditions. DC survey aimed at constraining the geological context of the site and at finding the remains of a large wall described by early authors. GPR experiment was primarily a test of the tool there and has been conducted on the previously studied area to get some depth information. The geological context has been studied by carrying on a 2D vertical section, 330 m long and 25 meters deep. showing a substratum of river deposit (sand, gravel, pebbles with possible clay layers) located at 8 to 10 m deep. Above this formation, we observe a very conductive layer interpreted as a clay formation (3 to 6 m thick) and finally, just below the surface, a laterally heterogeneous formation with rocks and adobe masonry. 2D DC sections succesfully located the remains of the surrounding wall of the site supporting even more the town hypothesis. GPR 3D results (250 MHz) are in agreement with conductivity maps but are of poor quality due to the very low resistivity of the soil.
DE: 0925 Magnetic and electrical methods (5109)
SC: Near-Surface Geophysics [NS]
MN: 2007 Joint Assembly