Geomorphology: The Mechanics and Chemistry of Landscapes, R. S. Anderson et S. P. Anderson

La géomorphologie dispose de plusieurs bons manuels consacrés aux processus qui façonnent les paysages. Celui du couple Anderson s’en distingue par son exceptionnel volume et, surtout, par une ampleur de vue inusitée qui en fait l’ouvrage de référence de « l’honnête homme » concerné par la science du relief. Il s’inscrit dans la droite ligne de l’école de géomorphologie anglo-saxonne, qui fait une large part à la quantification et à la modélisation des processus ainsi qu’à l’action des écoule..

Tectonique (4e Edition), J. Mercier, P. Vergely, Y. Missenanrd

La quatrième édition de ce manuel aussi classique qu’indispensable s’adresse, comme les précédentes, aux étudiants de licence 3, master, CAPES et Agrégation de Sciences de la Terre et, plus généralement, à tous ceux que concerne la connaissance du bâti de notre planète et des déformations de son écorce. Les auteurs justifient cette réédition et les mises à jour qu’elle comporte par l’évolution rapide de la disci­pline au cours des trois dernières décennies, notamment grâce à l’apport de la mé..

Aléas et risques naturels dans l’intérieur semi-aride du Nordeste brésilien : la crue-éclair du Rio Grangeiro (Crato, Ceará) du 28 janvier 2011

La crue du Rio Grangeiro qui s’est produite à Crato (Ceará) le 28 janvier 2011, est un exemple des événements brutaux qui menacent de plus en plus les biens, les infrastructures et les personnes dans le Nordeste brésilien. Malgré la répétition récente d’inondations catastrophiques, ici et dans d’autres régions du Brésil, la problématique des risques naturels n’apparaît guère dans l’aménagement et la planification urbaine. Bien plus fréquentes que les grands mouvements de masse récemment reconnus dans le rebord de la Chapada do Araripe, les crues et, en particulier, les crues-éclair, restent pourtant mal étudiées, en dépit des nombreuses déclarations faites après chaque inondation. L’objectif est donc de contribuer à combler cette lacune, à partir d’une étude de cas portant sur l’événement cité. Après une présentation du secteur étudié et des méthodes utilisées, l’article décrit cette crue violente, ses causes et ses conséquences, puis analyse les facteurs naturels et anthropiques en cause, en particulier les effets d’une canalisation inadaptée du torrent. Il aboutit à une réflexion sur le caractère de moins en moins exceptionnel de tels événements dans le contexte d’une urbanisation mal contrôlée qui modifie la formation et les modalités des écoulements, tout en aggravant les menaces sur les biens et les personnes. Notre réflexion porte aussi sur le rôle que peut jouer la connaissance géographique par rapport à la prise en compte de la question des risques naturels dans le processus d’urbanisation à l’intérieur du Nordeste brésilien.The catastrophic flood of the Grangeiro River, which seriously damaged the city of Crato (Ceará) on January 28th 2011, is a good example of the sudden events, which threaten properties, infrastructures and lives in Northeast Brazil. In spite of the repeated occurrence of such catastrophes here as well as in other regions of Brazil, the problematics of natural hazards and risks does not really appear in management and urban planning. Being more frequent than the large-scale mass movements recently discovered in the rim of the Chapada do Araripe, the floods, particularly flash floods, remain poorly studied and treated, in spite of the numerous announces repeated after each flood. Therefore our aim is to collect information on these events, through a case study bearing on the cited event. After a presentation of the study area and of the methodology, the article describes this violent flood, its conditions of occurrence and its consequences, and analyzes the natural and anthropogenic triggering factors, among them an inadequate canalization of the torrent. It demonstrates the less and less exceptional character of such events in the context of a poorly controlled urbanization, which modifies the formation and conditions of water runoff, and worsens the threats on properties and lives. We also show how important is the geographical knowledge for taking into account the natural hazard and risk problematics in the urbanization process of the Brazilian « Nordeste »

Suscetibilidade à Ocorrência de Movimentos de Massa no Maciço de Baturité - Ceará, Brasil

Os estudos de movimentos de massa são muito importantes na compreensão da evolução geomorfológica e na identificação de áreas de risco morfodinâmico. O maciço de Baturité se apresenta como a maior serra úmida do Ceará. Sua altitude média gira em torno de 800m, podendo atingir 1.000m. Do ponto de vista geomorfológico, constata-se uma grande variedade de feições tais como relevos dissecados nas vertentes, colinas intercaladas com planícies alveolares no platô e superfícies de erosão e de deposição nos setores circunvizinhos mais baixos. A distribuição e características dos movimentos de massa variam de acordo com as propriedades de cada área. Foram identificadosmovimentos de massa somente nas áreas com declives mais significativos, que se encontram basicamente nas vertentes e no platô. De maneira geral, constatou-se a ocorrência de deslizamentos rotacionais e translacionais associados com fluxos de lama e quedas de blocos. Tendo em vista a necessidade de elaborar mapeamentos voltados para a identificação de áreas de suscetibilidade morfodinâmica, foram estabelecidos critérios metodológicos envolvendo os agentes desencadeadores através de técnicas de álgebra de mapas. Foram identificadas áreas com alta suscetibilidade, nas vertentes ocidental, meridional e parte da oriental, áreas com suscetibilidade média nos demais setores elevados do maciço, e baixa suscetibilidade nas áreas circunvizinhas. Studies of mass movements are very important for understanding the geomorphologic evolution and identifying morphodynamic risk areas. The Baturite massif presents itself as the most significant wet hill of Ceará. Its average altitude is around 800m, and may have ridges above 1,000 m. From the geomorphologic point of view, there is a wide variety of features such as reliefs dissected on the hillsides, interspersed rolling hills with the deposition plains and surfaces of erosion and deposition in the lower surrounding areas. The distribution and characteristics of mass movements vary according to the properties of each area. Mass movements have been identified only in the areas with the most significant slopes, which are essentially found in uphills and in the plateau. In general, it was observed the occurrence of rotational and translational landslides associated with mud flows and falls. Considering the need to develop mappings aimed at identifying areas of morphodynamic susceptibility, methodological criteria involving the triggering agents using techniques of maps algebra were established. As a result, we identified areas with high susceptibility, in the western and southern hillsides and part of the eastern areas, with average susceptibility in other sectors of the uphill and low susceptibility in the surrounding areas

Relevos vulcânicos na região metropolitana de Fortaleza, o exemplo do Monte Caruru.

Relevos vulcânicos na região metropolitana deFortaleza, o exemplo do Monte Caruru

The large Thaumasia graben on Mars: Is it a rift?

We investigate the morphology and topography of one of the largest fault-bounded tectonic structures on Mars, a complex, approximately N-S trending system of troughs and scarps at the western border of the Thaumasia plateau in the Claritas region (hereinafter referred to as “Thaumasia graben,” or TG). It is located between 15°S and 38°S latitude and at ∼255°E longitude. No detailed investigation of its morphotectonic setting has been performed yet. The region is a complexly fractured area with a number of different fault sets, including simple and complex graben. The TG extends over more than 1000 km along its trend, averaging 100 km in width and 1.6 km in depth. Crustal extension is accommodated by the formation of a system of asymmetric graben, or halfgraben. On the basis of fault orientation and trough depth, the TG can be subdivided in a north-south direction into three segments. Except for the northernmost segment, the predominant master fault system is located along the eastern flank of the TG, highlighting the overall asymmetric architecture. Fault length segments vary from 50 to 90 km with observable displacements of 1.3–2.2 km. Crustal extension, inferred from gridded MOLA topography across scarp offsets, varies along trend between 0.5 km and ∼4 km, assuming a fault dip of 60°. This is relatively moderate extension if compared to terrestrial continental rifts, but consistent with extension measured across the Tempe Rift on Mars. We find that the Thaumasia graben displays some characteristics which are common to terrestrial continental rifts, whereas other properties are distinctively not rift-like

A new methodological contribution for the geodiversity assessment: applicability to Ceará State (Brazil)

The concept of geodiversity aggregates the abiotic elements of nature and promotes the geoconservation. The main objective of this work is to contribute to the upgrade of the method for the assessment and quantification of geodiversity proposed by Pereira et al. (2013). The method is based on the superposition of a regular grid of 12 × 12 km on different maps (lithology, geomorphology, soil, paleonthology, mineral and geological energy resources) at scales of 1:250,000 to 1:600,000. In addition to other up- grades, the water resources are regarded here as a new com- ponent to consider when quantifying geodiversity. The sum of these maps generated the quantitative Map of Geodiversity Indices and the Map of Geodiversity Assessment, ranging from very low to very high geodiversity. The analysis of the geodiversity map of the State of Ceará (Brazil) shows the applicability and advantage of this method, highlighting two regions with higher levels of geodiversity (Northwest and South) and another region with the lowest levels (Sertões Cearenses). The results also allowed the characterization of the State of Ceará concerning the individual components of the geodiversity, especially the water resources. Geodiversity indices and maps are comprehensive and user-friendly data in the territorial planning, considering the geodiversity either as a whole, or each of its components, especially the more sensi- tive such as fossil conservation, and water, mineral, and non- renewable energy resources management.The authors express their gratitude to the Brazilian research fostering institution "Coordenação de Aperfeiçoamento de Pessoal de Nível Superior" (CAPES) for awarding the Ciência Sem Fronteiras (CsF) PhD scholarship that enabled this work. This work was partially co-funded by the European Union through the European Regional Development Fund, based on COMPETE 2020 (Programa Operacional da Competitividade e Internacionalização), project ICT (UID/GEO/04683/ 2013) with reference POCI-01-0145-FEDER-007690 and national funds provided by Fundação para a Ciência e Tecnologia

Conservation of geosites as a tool to protect geoheritage: the inventory of Ceará Central Domain, Borborema Province - NE/Brazil

The Ceará Central Domain, in the northern Borborema Province/NE Brazil, encompasses important geological records (geosites) which allow understanding a relevant period of the Earth’s evolution, mainly associated to Neoproterozoic Brazilian/Pan-African Cycle and West Gondwana amalgamation, besides Neoarchean to Ordovician records. The presented geoheritage inventory aims to characterise the geosites with scienti c relevance of Ceará Central Domain. By applying a method for large areas, the nal selection resulted in eight geological frameworks represented by 52 geosites documented in a single database. This is the rst step for a geoconservation strategy based on systematic inventories, statutory protection, geoethical behaviour and awareness about scienti c, educational and/or cultural relevance of geosites.We specially thank all experts that helped us with this inventory: Afonso Almeida, Carlos E.G. de Araújo, César Veríssimo, Christiano Magini, Clóvis Vaz Parente, Felipe G. Costa, Irani C. Mattos, Neivaldo de Castro, Otaciel de Melo, Sebástian G. Chiozza, Ticiano Santos and Stefano Zincone. We are also thankful to Kátia Mansur, Ricardo Fraga Pereira and anonymous reviewers for their valuable contributions. PM is grateful to Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) for PhD mobility scholarship PDSE Program/Process n 88881.132168/2016-01info:eu-repo/semantics/publishedVersio