Impacts of Mayan land use on Laguna Tusp an watershed (Pet en, Guatemala) as seen through clay and ostracode analysis

International audienceMost of the cities built by the Mayas in the Pet en area, in the Central Yucat an Peninsula, were abandoned 1200 to 1000 years ago. The phenomenon is sometimes un-appropriately called " the collapse of the Maya civilization ". Its main causes are still debated, ranging from climatic according to the occurrence of severe or modest droughts, to societal in the form of environmental mismanagement of the environment. In both processes, it is inferred that stress triggered the formation in many Pet en lake sediments of erosional clay deposits, known as 'Maya clays'. This work presents a high resolution, multi-proxy study of 'Maya clays' in lacustrine sediments from Laguna Tusp an, near the archaeological site of La Joyanca. Micropaleontological (ostracodes), mineral-ogical (clay minerals) and geochemical (bulk elemental composition and stable isotopes in organic carbon) records reveal three different phases of soil erosion throughout the last 5300 years. The oldest phase from 5281 to 2998 cal yr BP (i.e. 3331 e 1048 BC) is characterized by successive natural and moderate soil erosion deposits which follow climatic variations recorded in the American tropical belt. The time interval between 2998 and 1281 cal yr BP (i.e. 1048 BC and AD 661) contains four distinct erosional layers which, according to clay mineralogy, are indicative of both increased erosion of the regolith and strong soil loss. The most recent, also the most massive, deposit of Maya clay ends around 1281 cal yr BP (AD 661), that is some 200 years before the so-called 'Maya collapse' in the Pet en area. Recent archeological fieldwork studies indicate that a population mobility took place into the city of La Joyanca from its hinterland by the early Late Classic Period (ca. AD 600), that is, at the end or just after this erosion episode, and well before the occurrence of the Terminal Classic-Postclassic (AD 800e1250) drastic climatic changes. Shifts in environmental management by the local society and timing of urbanization may explain environmental changes better than droughts per se

Développement professionnel des responsables de formation, analyse d’un dispositif de formation

This article describe and analyse a training program for training managers in entreprise developed since few years at the Namur University (Belgium) with the University of Sherbrooke (Canada). The program aimes the professionnel development, especially the development of identity and professionnel competencies of participants.L’article présente et analyse un dispositif de formation pour responsables de formation en entreprise développé depuis quelques années au DET (Université de Namur - Belgique) en collaboration avec l’université de Sherbrooke (Canada). Ce dispositif vise le développement professionnel et, plus spécifiquement, le développement de l’identité et des compétences professionnelles des participants. Du point de vue des concepteurs, nous décrivons et analysons le programme en mettant en évidence les intentions sous-jacentes aux stratégies choisies. L’analyse du dispositif nous permettra de mieux comprendre et de clarifier les liens entre les différentes stratégies pédagogiques et le processus de développement professionnel, défini comme le produit des apprentissages planifiés ou non, qui aboutit au développement des compétences professionnelles au bénéfice de l’individu et de l’organisation et à l’élargissement de son identité professionnelle en tant que professionnel de formation. Cette analyse est réalisée après deux ans de fonctionnement du programme.Charlier Evelyne, Dejean Karine. Développement professionnel des responsables de formation, analyse d’un dispositif de formation. In: Les dossiers des sciences de l'éducation, N°11, 2004. Les formateurs : dynamiques identitaires et engagements professionnels. pp. 119-127