The active growth of a fault-and-thrust belt in frontal zones of Himalaya is a prominent topographical feature, extending 2500 km from Assam to Pakistan. In this paper, kinematical analysis of frontal anticlines and spatial mapping of active faults based on geomorphological features such as drainage pattern development, fault scarps and uplifted Quaternary alluvial fans are presented. We analyse the geomorphic and hydrographic expressions of the Chandigarh and the Janauri active anticlines in the NW India Siwaliks. To investigate the morphological scenario during the folding process, we used spatial imagery, geomorphometric parameters extracted from digital elevation models and fieldwork. Folding between the Beas and Sutlej Rivers gives clear geomorphological evidence of recent fold growth, presumably driven by movements of blind thrust faults. Structural style within the Janauri and Chandigarh anticlines is highly variable (fault-propagation folds, pop-up structures and transfer faults). The approach presented here involves analysis of topography and drainage incision of selected landforms to detect growth of active anticlines and transfer faults. Landforms that indicate active folding above a southwest-dipping frontal thrust and a northeastdipping back-thrust are described. Along-strike differences in ridge morphology are measured to describe the interaction of river channel patterns with folds and thrust faults and to define history of anticline growth. The evolution of the apparently continuous Janauri ridge has occurred by the coalescence of independent segments growing towards each other. By contrast, systematic drainage basin asymmetry shows that the Chandigarh anticline ridge has propagated laterally from NW to SE. D

In this paper two geomorphologic maps (landform level and landscape level) are presented covering the French Guianan rainforest (84,000 km 2 ) using full-resolution Shuttle Radar Topography Mission (SRTM) data. The entire country was segmented into 224,000 landform units on the basis of an original object-oriented approach using a modified counting box algorithm. A Principal Components Analysis (PCA) followed by k-means clustering (Ward's method) identified 12 different landform types corresponding to theoretical elementary landforms. The landscape map was generated by analyzing the spatial distribution of the different landform types. The different maps and models were compared with topographic field data collected on 92 transects totaling 260 km in length. The object-focused approach is a very efficient method that preserves geomorphologic consistency and discriminates between landforms using simple descriptors that are easily understood by non-geomorphologists. Despite major noise in the data, the landform map proved to be reliable and provided a strong spatial structure for the definition of landscape units. We recommend using the landform map at scales 1: 100,000-1: 250,000. Landscape map, used on a 1:1,000,000-1:2,000,000 scale, enabled us to draw bio-geographical limits in this region and provides exhaustive relief information that usefully supplements the geological map.

International audienceThe purpose of this study is to propose a methodological essay for defining evolutionary trajectories of channel planforms and to examine the channel change in the middle Garonne River (southwest France) over a 130-year period. The study focuses on a reach of ~90 km situated downstream from the city of Toulouse. A set of four historical maps (1868, 1940s, 1970s, and 2000s) is used to build a geomorphometric diachronic database. Data processing through mixed multiple factor analysis (MFAmix) and hierarchical cluster analysis (HCA) allows distinction between four homogeneous zones within the study reach, depending on their evolutionary trajectories. Channel behavior in the upstream and median zones evolved as of the beginning of the study period (narrowing of the fluvial area, colonization by vegetation, and removal of alluvial bars), likely owing to punctual anthropogenic actions. The downstream zone is characterized by stabilization of the channel and alluvial bar removal over the second half of the twentieth century, coinciding with the campaign undertaken by French local authorities between 1960 and 1984 to protect river banks. The role of ACCEPTED MANUSCRIPT climate transition between the Little Ice Age (LIA) and the onset of the Global Warming period (GW) is also discussed. Results generally are consistent with the chronology established for most European rivers

Reçu le 25 mai 2003 ; accepté après révision le 28 octobre 2003 Résumé L'expression morphologique de la faille de la Têt ressemble à celle d'une faille active. Son fonctionnement, attesté pour le Pliocène, reste cependant débattu pour le Pléistocène. Un schéma d'évolution de l'escarpement de faille est proposé. Il se base sur les relations entre morphologie de l'escarpement et remplissage sédimentaire des bassins. Il souligne l'importance des phénomènes d'exhumation par incision du réseau hydrographique au cours du Pléistocène. Ainsi, les mouvements tectoniques pléistocènes apparaissent faibles et leur impact sur les caractéristiques du drainage limité. Le schéma proposé conduit également à minorer le rejet au cours du Pliocène, celui-ci étant réévalué entre 150 et 300 m. Une grande partie des mouvements tectoniques responsables du relief actuel sont donc antérieurs.

This work focuses on the impact of Maya agriculture on soil degradation. In site and out site studies in the area of the city of La Joyanca (NW Petén) show that "Maya clays" do not constitute a homogeneous unit, but represent a complex sedimentary record. A high resolution analysis leads us to document changes in rates and practices evolving in time in relation with major socio-political and economic changes. It is possible to highlight extensive agricultural practices between Early Pre-classical to Late Pre-classical times. Intensification occurs in relation with reduction of the fallow duration during Pre-classic to Classic periods. The consequences of these changes on soil erosion are discussed. However, it does not seem that the agronomic potential of the soils was significantly degraded before the end of the Classic period.

a b s t r a c tPalaeogeographic changes of the North Black Sea area during Early to Middle Holocene (i.e. 12e4 ka BP) is of crucial interest in the understanding of the spread of the Neolithic to central and western Europe. It is also a good method to develop a framework for Pre-and Proto-historic societal adaptation to environmental changes. This paper describes Black Sea coastal geomorphological changes associated with sea level rise, delta progradation and delta lobe shifts modifying the living conditions and habitability in the Danube delta during Neolithic to Chalcolithic time. An archaeological and palaeoenvironmental chronological framework allows comparison between environmental and social data. The rhythms of these changes are discussed in the light of spatial changes in settlements. The Neolithic to Chalcolithic transition (i.e. Hamangia, Boian and Gumelnit¸a) shows rapid adaptation to geographical conditions. The Early Neolithic gap in the Dobroudja is potentially the result of a taphonomic bias related to coastal position change in a context of a rapid flooding event.

Article history: Available online xxx a b s t r a c t This paper discusses the evolution of the Tech river lower plain, (western Mediterranean) from the Late Middle Ages, using geomorphological, archaeological and historical data. Geoarchaeological data was obtained from coring and trenching near a buried village and chapel. Radiocarbon and archaeological dating are used to reconstitute sedimentation rates and major flood event chronology. Additional data about channel avulsion are provided by historical data. Increases in sedimentation rate, flooding plain enlargement and repeated avulsion are identified between the last 13th to 15th century AD. This attests to a shift from low water-level regime (LWR) to flood dominated regime (FDR). Climatic or anthropogenic causes of this change are discussed on the basis of regional synthesis. On the western Mediterranean scale, 1250/1350 AD seems to be a wetter phase, associated with the progressive onset of the Early Little Ice Age phase from 1330 to 1450 AD.

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