Agriculture Reference
In-Depth Information
Figure 1.5
Grapevines growing on steep slopes along the shore of Lake Geneva in the central
part (Lavaux) of the Vaud region, Switzerland.
and on the upper slopes of the Rhine River in the Rheingau region, Germany, a
premier region for Riesling wines. The soils on such slopes are very shallow and
well drained unless they contain glacial till or in some cases loess (windblown
material).
Transport of weathered materials by water or ice is a most important means
of distributing parent material for subsequent soil formation. At times during the
Pleistocene epoch (see box 1.2), much of the present-day wine regions of Europe was
covered by glacial ice that moved weathered rock materials—fragments and finely
ground “rock flour”—over the landscape. Relatively young soils (<10,000 years
of age) have formed on these deposits of glacial till but are usually not well suited
to vineyards because of poor drainage. During the interglacial (warm) periods of
the Pleistocene, however, glaciers retreated and, as they melted, large amounts of
melt water containing a heterogeneous mix of rock material swept down rivers and
formed glacifluvial deposits. Some of the best vineyard regions have developed on
the better drained soils formed on such deposits, as in the Médoc region and south-
ern Rhone Valley in France and the Bio-Bio, Maule, and Rapel Valleys in Chile
(figure 1.6).
Over most of the land surface, erosion of weathered material by water has
produced areas of alluvial deposits in the form of extensive plains and river
