A great number of vineyards are perched on the side of river valleys, in well-drained gravel deposits. Vine do better in poor, well-drained soils which make them plunge their roots deeper to find water and goodness. The great wines of Bordeaux come from gravel soils (Graves means gravel) which particularly suit the Cabernet Sauvignon. Much depends, however, on the other kinds of soil with which the gravel is combined. If it is over clay, the wine will have less acidity than if it is over limestone.
The granite vineyards of the southern Rhone, home of Chateauneuf-du-Pape and Tavel rose, are littered with huge “pudding stones”, making the cultivation of anything seem virtually impossible. Once vines are established, however, the stones act as reflectors, bouncing the heat from the sun back on to the grapes. The end result is that they produce big, high-in-alcohol reds and France’s most famous dry rose. In the Beaujolais, granite suits the Gamay; its chemical properties reduce the wine’s natural acidity.
Chalk, too, makes for very good drainage and forces the vines to work hard for a living.
Not all vine varieties like predominantly alkaline soil. Those that do best on chalky hillsides produce white wines of unique character such as the Chardonnay, which forms part of the inimitable blend for Champagne. The keynote of wines made from grapes grown on chalky – limestone – soil is their acidity, a characteristic that links Champagne, Chablis and Sancerre.
The richer minerals found in slatey soils suit some vines admirably. The alluvial deposits on the banks beside the Rhine and Mosel rivers in Germany are responsible for the delicate fragrance of the gently fruity local wines, produced on the precipitous, barren-looking slopes. The locals say: “Where the plough may go, no great wines grow.” The main advantage of slate in regions like the Mosel is its heat retention, which compensates for the low temperatures in which the grapes have to ripen. Slate is also credited with the quality of Rieslings from the far warmer region of Clare in South Australia.