Читать книгу The River Rhone Cycle Route. From the Alps to the Mediterranean онлайн

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Natural environment

Physical geography

The course of the Rhone has been greatly influenced by geological events approximately 30 million years ago, when the Alps were pushed up by the collision of the African and European tectonic plates. As well as forming the Alps, this caused rippling of the landmass to the north, creating a ridge that forms the limestone mountains of the Jura and pushing up the older hard rocks of the Massif Central. Subsequent glaciation during a series of ice ages resulted in the Rhone cutting a series of deep U-shaped valleys through the high Alps (Stages 1–4). At the base of the glaciers a large lake formed (Lake Geneva, Stages 5–6). The outflow from this lake cut a winding gorge between the Jura mountains and Savoy Alps (Stages 7–10). At Lyon where the river reached the hard rock of the Massif Central it was forced south through the wide and straight sillon Rhôdanien (Rhone furrow) all the way to the Mediterranean (Stages 11–18). As this valley was subject to frequent flooding the river developed a winding course through a marshy environment. For most of its length the river cuts down through soft limestone and carries large quantities of sediment. Some of this sediment is deposited in Lake Geneva, which is slowly filling up though it will take many thousands of years to fill completely. The rest is carried down to the flat lands of the Mediterranean littoral (Stages 19–20), where the slow flowing Rhone has deposited considerable quantities of sediment to form the Camargue delta.