The winefield of Alsace is located in the area where the ancient mountains of the Vosges-Forêt Noire descend and fall away. This tectonic event, which created the plain of Alsace some 50 million years ago, passed through two stages : a first slow phase, and a second more violent and rapid one.
The result was two lines of fractures running North to South. These are the fault-line of the Vosges region, running along the foothills of the mountains, and the fault-line of the Rhine between the plain and the hills. The two lines define three well-known geographical zones, namely the mountainous area of the Vosges, the hills of the lower Vosges, and the plain of the Rhine.
The western boundary of the winefield itself is defined by the Vosges chain of mountains, and the eastern boundary is the plain of Alsace. Between the western edge (the Vosges) and the eastern edge (the plain of Alsace) one can distinguish four discrete areas :
- the ridge of the Vosges mountain chain, soaring to an altitud of around 450 m.
- the hills of the lower Vosges, composed of numerous different geological materials which create the region's "mosaic of soils".
- the plain of the Rhine, with its fertile alluvial cones formed as the rivers of the Vosges run off the hills,
- the embankments of loess, a clay-silt deposit, which have formed mainly where the plain meets the hills.
The outstanding feature of the winefield is an extreme diversity of soils types within limited geographical zones.
It is offered protection from the effects of an oceanic climate by several geographical forces : the Vosges mountains, the semi-continental nature of the Alsace plain, and the foehn (a warm dry wind which rises from the Mediterranean and blows down the Northern slopes of the Alps). The result is one of the lowest rainfall averages in France. The summers are hot and stormy, with many hours of direct sunshine. Moreover, storms are often the only source of water at this time of year. The winters are usually cold, but it is a cold mitigated by the fact that the whole of the winefield faces a south-easterly direction.