Contenu du sommaire : Relief, sol, eau, hommes. 75e anniversaire : florilèges géographiques

Abstract. - The chalky Normandy, especially the Pays de Caux, has some geomorphological characteristics : thick superficial formations (red clay with flints, loess) and poreous chalks. So this region is rich. However there are now many problems : pollution of the watertable, soil erosion). These problems are explained by the influence of the man (intensive agriculture, underground quarries) but also by the fragility of the natural conditions (fissuration of the chalk layers, karst development, erosional susceptibility of the loess).

Abstract. - Catastrophes due to run-off, erosion, and flooding process are frequent in the Pays de Caux, Seine-Maritime. They grow in the heart of little watersheds such as Grainville-la-Teinturière's. The analysis of this catastrophe gives a good example of these phenomenons' spatial running. The upstream watershed parts threaten the communities located downstream. The conjunction of an evolution of rural landscapes, entailing a run-off increase, along with the rural urbanization of the old villages, which is not always easy to contain, provokes chain reactions. In order to lead to a well thought-out management, it is necessary to have a systemic approach, analyzing all the spatial interactions so as to delimit the problems that are surging at the interface between agricultural zones and communities. This methodology requires a central geomorphologic analysis.

Abstract. - Drinking water theme, a central part of water management, is essentially considered to be technical, outside the hydrosystem. But, the drought of early 90's revealed insufficiences and malfunctions, for a long time forgotten, and showed that it is impossible to deal without the weight of nature. Environment and regional geography impose many constraints on drinking water management, from production to supply organization.

Abstract. - In spite of a cool and moist climate, Normandy has some animals and plants which have Mediterranean affinities. Thus populations of Green Lizards (Lacerta viridis) have been noticed on escarpments of «Suisse Normande». This paradoxical presence is explained by local factors (topography, soil, vegetation) which make up for regional climatic conditions and which offer an unexpected bio-geographic refuge to this thermoxerophilous reptile.

Abstract. - Since the last ten years, and due to climate changes, dryness in Basse-Normandie has been such that the shape of an yearly unbalanced estimation of the cost of the water resources. As the result of exposure to the outside environment, the soil is directly affected, and is dried out, causing dramatic damage to the agriculture. From an experimental study done at a large scale, this article shows that the exposing conditions of the slopes during the drought lead a different dryness of the cultivated lands.

Abstract. - Diverse slope deposits mainly derived from a hilltop Early Pleistocene fluviatile sheet and Late Pleistocene loess were established anterior to the Gallo-Roman settlement at Touffréville (Calvados). The relationship between certain deposits and anthropogenic ditches suggests later reworkings contemporary with or posterior to the Gallo-Roman occupation, doubtlessly associated with deforestation phenomena.

Abstract. - The interdisciplinary research carried out in the Authion valley supplies information about its Holocen history. In spite of a partial isolation, the lateral depression is closely linked to the river Loire, which determines its dynamic evolution, supplies it with complementary soils but exposes it to flood risk. The morphology of his area evolves from these correlations between human activity and alluvial environment.

The numerous fields situated near the paleoshores of North Cotentin certify an attraction for the coastal border during the temperate and boreal episodes of the Middle and Upper Pleistocene. With the presence of many natural sheds the coast gave opportunities to collect raw material on the coastal line. In the Cotentin, the flints seem to be mainly used. This coastal situation have enabled men to diversify the food habits founded on several ecosystems.

Abstract. - The eastern slopes of the mountainous volcano la Fournaise (la Reunion island, Indian ocean) directly face the trade winds. In 1996, Barcelo asserted an annual rainfall of 12 meters. This study confirms the first hypothesis established in 1986 by Robert. Trade winds (more than typhoons) play the first role in these heavy rains. But the results have only been obtained over three years (from 1993 to 1995) so they need confirmation in the future.