Paleogeography and anthropogenic activity in the southern Vosges (France).

Abstract

Article in French.

 Original tittle: Paleogeographie et action anthropique dans les Vosges meridionales (France)

The situation and peculiarities of the Ballon d'Alsace West-East highlands, the morphostructure are first called to mind. The crests are flat and smooth because they are remnants of the exhumed posthercynian planation surface, well preserved westward, more or less reshaped during Miocene. But the old surface has been lifted up along a system of faults South-Southwest to East-Northeast and over the „Seuil de Bourgogne, during plio-pleistocene epoch. These landforms, the rise of altitude together with the plio-quaternary climatic changes explain the importance of glaciation in the Southern Vosges. The snow of firns and ice caps covered the fiat highlands, above 800 or 900 m, valley glaciers carne down as far as the outlet in the lowlands. The problems of snowlines, glaciers types and network, cirques, glacial deposits and chronology are discussed.

The main present day landforms arc remnants of the last glaciation and of the tardiglacial erosional processes. Since Holocene and especially since Subboreal forest has covered the slopes from top to bottom of the valleys, but the cover of sand and rock debris, moraines or periglacial deposits has been very often washed down on the steep slopes of the valleys. The present day typical fir and beech forest has been reclaimed for pasture on the highlands (Hautes Chaumes), pasture and cultivation at the bottom of the valleys, the wood has been worked for mining and metallurgy, and deforestation has been extensive from the XVIth to the first part of XXth century. The stream discharge is very high but historical erosion has been low up to present time when recreation and urbanisation brought changes in the land use of the highlands and valleys, and heavy machines are used.