PHD DEFENSE: NINON BLOND

Holocene sediment dynamics and agricultural terraces in the Eastern Tigray Mountains (Ethiopia) – Evolutions, trajectories and functioning of a palimpsest landscape over the past 8,500 years. 

Tuesday December 10, at 2pm – Benveniste Amphitheatre (Ground Floor), Maison de l’Orient et de la Méditerranée (7 rue Raulin, 69007 Lyon).

• François Bart, Honorary Professor, University of Bordeaux, Examiner
• Yann Callot, Professor Emeritus, University of Lyon 2, Supervisor
• Nathalie Carcaud, Professor, Agrocampus Ouest, Rapporteur
• Pierre Dérioz, Senior Lecturer HDR, University of Avignon, Rapporteur
• Iwona Gajda, Research Officer, CNRS, Examiner
• Nicolas Jacob-Rousseau, Senior Lecturer, University of Lyon 2, Co-Supervisor
• Michel Rasse, Professeur, Professor, University of Lyon 2, Examiner

Abstract: The northern Tigray (Ethiopia) is characterized by vast plateaus with steeply sloping valleys on their edges. They are now filled with sediment and densely cultivated using terraces. Aksumite archaeological remains have been discovered at Wakarida site. Are the current terraces the result of the centuries-old transmission of a “fossil” landscape? Do the fillings result from a controlled sedimentation undertaken for a long time by the Aksumites and their descendants? To answer these questions, a systemic methodology was applied. The study of sedimentary accumulations in the valleys revealed the main filling phases and the various factors (biophysical or anthropogenic) controlling detritism. From the 7th millennium BCE onwards, the wet conditions of the African Humid Period dominated and low-energy flows deposited fine sediments. Conditions deteriorated from the 4th millennium BCE onwards and the influence of societies is clearer from the 1st millennium BCE. Fillings do not result from controlled sedimentation. Archives show the persistence of techniques over a long period of time, with the exception of terraces. They do not appear before the 1960s in the Tigray. According to archives and interviews, they were erected from the 1990s onwards around Wakarida, in connection with agrarian reforms and socio-political events. The current structures, of recent construction, are therefore based on old fillings that continue to evolve. Thus, hydroagricultural landscapes of the Wakarida region are not fossils but palimpsests.

NB.: Due to the work on the campus, access to the amphitheatre is via the inner courtyard: entrance through the black gate, then to the right