The relationship between wine and the vineyard earth has long been held as very special, especially in Europe. Tradition has it that back in the Middle Ages the Burgundian monks tasted the soils in order to gauge which ones would give the best tasting wine, and over the centuries this kind of thinking was to become entrenched. And why not? The vines were manifestly taking up water from the soil, and, presumably, with it everything else that they needed to grow and make grapes. The belief that the vineyard soil was central to wine flavour was simply self-evident. It seemed wine was made of the soil.
However, eventually there was the discovery of photosynthesis – that in fact vines are chiefly manufactured, as it were, from sunshine, air and water – but this didn’t really dent the popularity of the soil idea. Scientifically, we now know that while the vineyard geology – the rocks and soils in which the grapevines are rooted – supplies some of the vine’s (modest) nutritional needs, its main role is to do with providing the right amounts of water. In some circumstances there may be other effects, such as the thermal behaviour of the soil surface and the influence of alkalinity on microbiology, and certain grape cultivars do seem to prefer particular conditions. But scientifically it seems the primary influence of the geology on the vine, and hence indirectly on wine flavour, is in providing good drainage while at the same time possessing ways of conserving water for times of need. In fact these water matters are so important that in practice today they are routinely and precisely engineered with artificial drains and irrigation (just as the other factors are manipulated), which would seem to rather undermine the pre-eminence of the natural geology.
Nevertheless, despite this, the proposition that the vineyard geology shapes the eventual wine has nowadays risen to unprecedented heights. All over the world, remote-sensing technologies are being used to pinpoint variations in geological properties; vineyards are being peppered with soil pits. Of course, it all chimes with the current yearning for more “natural” foods and knowledge of provenance: through bestowing a “sense of place”, a wine said to depend on its vineyard geology offers immeasurable marketing possibilities. After all, the geology is one of the few things in wine-making that cannot easily be replicated elsewhere. Thus growers all over the world enthusiastically claim that their particular vineyard geology is wholly unique, and consequently their wines so very special.
It is now almost de rigeur to at least mention the geology in vineyard descriptions. Back-labels on wine bottles pronounce such things as: “the chateau is on sandy limestone from the Cretaceous period”; “the wine speaks of the vineyard’s granitic soil”; “the vines grow on argilo-calcareous soils with sea-shell fossils”; and (most impressively) “our vineyard has Triassic and Jurassic sediments on undulating Proterozoic granulite and migmatite with numerous dolerite dykes”. Some wine writers believe that the geology can actually be tasted in the wine: “you can taste the volcanic ash of nearby Vesuvius”; “wine allows me to taste soil and bedrock”; “a “graphite or schisty-ness flavor which I identify as coming from the soil of the Priorat”; “in Brouilly, there are veins of blue granite nuanced in the wines”.
And now, arcing over all this like a newly discovered comet in the night sky, we have the concept of minerality. This idea of tasting minerals in the wine glass is brand new. Suddenly, tasting notes not only declare wines to be ‘full of minerals’, ‘mineral laden’, ‘brimming with minerals’ and the like but even particular geological minerals are specified – as in a quartz, gypsum, or graphite minerality, or certain rocks -as in a chalky, slaty or granite minerality.
So, although the scientific basis has not changed, today in the world of wine there is a new level of interest in things geological. Now wine lovers need to know their tuff from their tufa, and their slate from their schist; writings about Burgundy’s Côte d’Or enthuse about colluvium and argilo-calcaire; numerous wines are named after varieties of rock – greywacke, orthogneiss, amphibolite, and mylonite among them. In view of all this, I imagine that those Burgundian monks would be highly pleased with their legacy!