Jean-Michel Carozza

Landform and landscape mapping, French Guiana (South America)

In this paper two geomorphologic maps (landform level and landscape level) are presented covering the French Guianan rainforest (84,000 km2) 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 (Wards 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.

Landscape change and archaeological settlements in the lower Danube valley and delta from early Neolithic to Chalcolithic time: A review

Palaeogeographic 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 Preand 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 Gumelniţa) 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. 2010 Elsevier Ltd and INQUA. All rights reserved.

Landuse and soil degradation in the southern Maya lowlands, from Pre-Classic to Post-Classic times: The case of La Joyanca (Petén, Guatemala)

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.

New geomorphic criteria on lateral propagation of blind thrust-related fold growth accommodating oblique convergence

The aim of this contribution is to show the styles of growing anticlines and the ways in which they accommodate oblique convergence through proximal foreland basins and intramontane basins. The four natural examples of individual fault-related-folds are: the Chandigarh anticline in the Siwalik foothills of Himalaya (NW India), the Pakuashan anticline in the western foothills of Central Range (Taiwan), the J. Bou Dhar-Tamdafelt fold belt (Morocco) and the Marand anticline in the North-Tabriz Fault-Zone (NW Iran). The evolution of these geomorphic criteria and drainage patterns shows evidence of lateral propagation of folds accommodating oblique convergence. This paper focuses on the geomorphic indicators that could be used to provide information on the timing of fault-related folding and direction of lateral propagation. Several tectonic scenarios has been analysed and an attempt has been made to delineate the sequential evolution of anticlines accommodating oblique convergence.

The Holocene fluvial history of the Tremithos river (south central Cyprus) and its linkage to archaeological records

Abstract This study aims to reconstruct the Holocene fluvial history of the Tremithos river, south central Cyprus and examine linkages to regional and local archaeological records. Three stratigraphic profiles (Sp1, Sp2 and Sp3) located in the lower valley have been investigated using sedimentology and magnetic parameters. The 14C dating of 10 samples reveals mid-Holocene ages for Sp1 and Sp2, while the upper most part of Sp3 can be attributed to the early to mid-Holocene. Two main phases of vertical accretion have been recognised: the first, recorded in the lower most part of Sp3, could not be dated but might relate to the late Glacial period. It is not associated with any archaeological artefacts. The second, recorded in all profiles, dating from ca. 5000 to ca. cal 2800 BC, spans the Late Neolithic Sotira (cal 4800/4000 BC) and Late Chalcolithic (cal 2900–2500 BC) cultures. The sediments of Sp1 and Sp2 are up to 8–10 m thick and mainly composed of fine material. However, an intercalated phase of coarse sediment has been identified at the beginning of the third millennium BC, indicating a sudden change in river dynamics, potentially associated with the 5.2 ka rapid climate change regional event. Typical mid-Chalcolithic (ca. cal 3300–3050 BC) ceramics found in a palaeosol in Sp2 indicate for the first time human occupation of the Tremithos river terraces. Two other palaeosols have also been recognised in Sp3 and radiocarbon dated to ca. cal 5600–4100 BC and ca. cal 2900–2600 BC, respectively. These results make it possible to propose a palaeogeographic reconstruction of the Holocene evolution in the Tremithos valley and to make a preliminary assessment of the relative roles of tectonics, climate and anthropogenic forcing.

The Vosgian-Alsatian Side of the Rhine Graben: A Unique, Tectonically Controlled and Manmade Landscape

Large-scale Alsatian landscapes are dominated by structural organisation inherited from the Cenozoic rifting of the Upper Rhine Graben (URG). This results in a subdivision into three main units, from west to east: the Vosges Mountains, the Vosges foothills and the Ill-Rhine plain. In each of these three units, the weight of structural control, i.e. tectonic or lithological, remains strong. Transition from the northern Vosges to the southern Vosges appears dominated by differential uplift and transition between crystalline rocks to Triassic sedimentary cover. In the Vosges foothills, tectonics factors are lesser than lithological one. Despite a common hilly shape, frequent lithological changes give rise to a mosaic of ‘terroirs’ of complementary interest, but chiefly dedicated to vineyard. The Ill-Rhine plain is organised along a downstream gradient under regional tectonic control. There, despite its young age and strong anthropogenic impact, the stigmata of tectonic remains marked in the landscape. These strong structural constraints and their consequences have been exploited through historical times as one of the most recognisable cultural landscape of France.

Réponse des bassin-versants du Roussillon entre le XIIe et le XIXe siècle : un impact du Petit Age Glaciaire ?

Au cours du deuxieme millenaire, les hydrosystemes de la plaine du Roussillon ont ete transformes de maniere radicale par les interventions humaines d’une part et les evolutions sous controle climatique d’autre part (Bascule entre OM/ PAG). Les travaux de geoarcheologie menes depuis le debut des annees 2000 ont egalement montre l’importance des modifications de la topographie de la plaine par des depots sedimentaires et que la configuration de son reseau hydrographique actuel avait ete profondement remaniee au cours du deuxieme millenaire. La relation entre forcages anthropiques et climatiques de l’evolution de la plaine est discutee a la lumiere des donnees recentes.

Conjectures et réfutations [Réponse à la note de Monsieur le Professeur Calvet]

Carozza Jean-Michel, Delcaillau Bernard. Conjectures et refutations [Reponse a la note de Monsieur le Professeur Calvet]. In: Geomorphologie : relief, processus, environnement, Octobre-decembre, vol. 6, n°4. pp. 272-274.

L'enregistrement géomorphologique de la tectonique quaternaire par les nappes alluviales: l'exemple du bassin de la Têt (Roussillon, France)

Abstract In a low sismo-tectonic activity zone, the geometry of a Quaternary alluvial body can be used as a neotectonic tracer tool. Geometry characteristics of individualized terrace levels are extracted from a Digital Elevation Model by superposing elevation and geological data. The longitudinal profile of each terrace is compared to the best fitting exponential theoretical profile, deduced from hydrodynamic parameters. This analysis, applied to the Tet river terraces (Mediterranean southern France) shows the splitting of a sedimentary body, corresponding to hydrodynamic break interpreted as morphostructural segmentation of the Roussillon basin.