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More on terroir: a geologist speaks

Those of you who have been scanning the news columns might have seen that the concept of terroir made the big time recently. Some of the leading news sources picked up on a press release generated by an article in the scientific journal Geology Today by Professor Alex Maltman from the University of Wales at Aberystwyth, entitled ‘Wine, beer and whisky: the role of geology’ (Geology Today 19:22–29). It’s not a research piece, as such, but instead a well written review the role of geology in influencing the flavour of each of these three types of drink.

Of course, the newspapers pulled a rather simplistic message out this piece, running with the theme that geology proves the notion of terroir is nonsense. But this isn’t a fair reflection of the article’s content. Dr Maltman contacted me because he’d seen my Harpers piece on terroir, which came out the same week, and kindly sent me a reprint of his piece so I could see for myself.

It begins by looking at the role of geology in wine production, and the idea that flavours of the soil can be transmitted by vine roots to the grapes. ‘It’s a seductive mental jump to suppose that somehow flavours are being communicated between bedrock and wine’, says Maltman. ‘Unfortunately, no one knows how this can actually happen’. He then enters into a detailed discussion of how geology might have more plausible effects on vine growth and, indirectly, wine flavour. In fact, he’s clearly sympathetic to the idea that geology is important for vine growth, and illustrates this with diagrams of the geology of vineyards in Chablis, Corton (Burgundy) and Sonoma County. Maltman also discusses why these effects of geology are often dismissed by new world wine producers.

He cites four main reasons. First, because of the suddenness with which new world wine regions have ascended to fame, which means that they haven’t had time to test the ideas. Second, because new world winemaking has typically focused on the winery rather than the vineyard. Third, because many new world wineries are large and grow a wide range of different varieties, thus blurring any geological influences. Fourthly, he looks at the geology itself. ‘It has to be said that discussions in the popular literature are replete with geological misunderstandings and mistakes that can hardly help in clarifying things’, says Maltman. He then explains that many new world vineyards are planted on flat valley floors rather than hillsides. ‘Such areas are underlain by thick, mixed alluvial deposits with complex soils, and hence minimal influence from the bedrock substrate.’

These ideas fit in with the notion that terroir ‘speaks with a quiet voice’. The effects of the soils and microclimate of a vineyard are subtle ones, and are easily missed or lost where people aren’t looking for them or are working in an interventionist style. If you are growing just one or two grape varieties across your property, then you are more likely to be in a position to spot the site-specific effects than if you are growing several. Interestingly, the increasing adoption of precision viticulture technologies – where growers use spectral information gained from satellite imaging of their properties to identify areas of homogeneous growing conditions – could provide a short-cut to help locate areas that are geologically and climatically uniform within each vineyard area. These areas can then be planted and managed in such a way as to optimise their natural characteristics. It’s also likely that for some vineyards planted on fertile, deep soils, there will never be much of a terroir effect.

Back to Maltman’s article. He then goes on to investigate the effects of geology on brewing and whisky. It surprised me to find out that geology has far more of a direct influence on beer than it does on wine. Maltman explains that this is because the chemical properties of the water used for brewing are crucial, and depend on the ground where the water was extracted. Burton-on-Trent, for example, has ideal brewing water because it has a naturally balanced blend of beneficial ions perfect for brewing pale ales. Other famous brewing locales such as Pilsen and Budvar have suitable ground water. Dublin is perhaps the most famous case: everyone goes on about how Guinness tastes better when it’s made from Liffey water. Well, the water used in Dublin Guinness is crucial, but it’s actually taken from the Grand Canal, fed by limestone inputs. This hard water necessitates the use of dark roasted malts, which thus dictate the style of the beer.

What about whisky? Here Maltman argues that the water used has very little influence on the taste of the whisky, whatever the advertising campaigns might suggest. The reasons are several, and space doesn’t permit me to detail them here. And any water that is added after distillation is carefully deionised, so there is no influence at this late stage. The most likely influence of geology, argues Maltman, is on the tap water that you may be adding to your whisky.

For those wishing to see a copy of this article, I suggest contacting Professor Maltman directly:

Professor Alex Maltman
Institute of Geography and Earth Sciences, University of Wales, Aberystwyth SY23 3DB, Wales, UK
Phone 44 01970 622655 Fax 44 01970 622659
email ajm@aber.ac.uk

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