The Role of Vineyard Geology in Wine Typicity

Vineyard geology—bedrock and overlying soils—is widely supposed to help explain the typicity of wine from a particular area, though there has been little analysis of how this might come about. Such an evaluation is attempted here. Geology does underpin some of the physical parameters that affect vine performance, but in an indirect way and the factors are commonly manipulated artificially. A direct geochemical influence on wine flavour is widely inferred but remains undemonstrated. The popular model of nutrients being taken up by the vine and persisting to be tasted in the finished wine is untenable. The amounts that reach the fermenting must are minuscule, bear little relation to the substrate composition, and can be further complicated by contamination and fining. In the final wine these inorganic nutrients normally exist in concentrations far below human recognition thresholds and are ‘swamped’ by the organic secondary metabolites that do dominate wine flavour. Hence, any geochemical influence, like that of the physical factors, has to be highly complex and indirect. The notion of being able to taste the vineyard geology in the wine—a goÛt de terroir—is a romantic notion which makes good journalistic copy and is manifestly a powerful marketing tactic, but it is wholly anecdotal and in any literal way is scientifically impossible. Thus critical evaluation leads to the conclusion that the role of geology tends to be exaggerated.