Inquiring Winemaker


Geo-Scientists Dig Into Terroir

January 2010
by Tim Patterson

  • After decades in which the notion of terroir was mostly embraced by wine writers and others in romantic, personal-experience terms, scientists are now furthering our understanding of it.
  • A recent session at the annual meeting of the Geological Society of America showcased growing interest among geologists in how place affects wine.
  • Earth and environmental scientists have organized interest groups and scheduled panels, reflecting increasing interest in terroir beyond departments of enology and viticulture.

The modern form of the notion of terroir—the idea that the place grapes are grown can imprint a distinctive signature on the wines produced—has been around for a century or more. Wine writers often have led the advocacy, waxing rhapsodic over this or that bottle, claiming on the basis of their superior palates to be able to taste the place. Wine educators have trained generations of students to differentiate, in almost ritual terms, the wines of the Côte Brune and the Côte Blonde in the Rhône Valley’s Côte Rôtie, and to cherish the variations between the upper, middle and lower rows in the great vineyards of the Mosel.

With more modesty, working winegrowers have learned the ways of their vineyard sources, finding that year after year, one block produced wines with spicy notes and another wines with backbone. And with no shame at all, the wine sales force and the marketing departments have claimed all manner of things, hoping that asserting a place’s specialness, real or imagined, could bring an extra couple bucks per bottle.

But for most of terroir’s history, the relationship with science has been uneasy. As a result, the explanation of why a particular place does what it does has been murky at best. Many hard-science types have dismissed the idea as pure metaphysics, and many terroir zealots have been quick to say they really don’t give a fig what the scientists think.

Those days are over. For some time in Europe, and increasingly now in the U.S., the action has shifted to the scientists and away from the romantics. In both the Old Wine World and the New, across several academic disciplines, the folks with the lab coats and the GPS gizmos and the mass spectrometers and the controlled micro-vinifications are the ones pushing forward our understanding of wine terroir—not dismissing it, but rendering it much more objective.

This new dynamic may make some old school terroirists squirm—but from here, it’s a breath of fresh air.

Geological Society in Portland
The new scientific momentum was on display in mid-October at the annual meetings of the Geological Society of America in Portland, Ore. In strictly scientific terms, my expertise in geology is limited to knowing (sometimes) the difference between a rock and a hard place. But with press credentials, I was lucky enough to sit in on the terroir session, along with John Buechsenstein, a veteran winemaker and wine educator with whom I am working on a terroir project. The dozen brief presentations showed a good cross-section of how earth and environmental scientists are grappling with these questions from various angles and with varying degrees of sophistication. What all the presenters had in common was the search for, and respect for, hard data and systematic explanations, not just personal opinion.

The highlight of the session undoubtedly was the talk about the mysterious phenomenon of “minerality” given by Alex Maltman, a geologist at the Institute of Geography and Earth Sciences at the University of Wales. Maltman made a splash in international wine debate circles with a March 2008 article in the Journal of Wine Research, which offered a devastating critique of the notion that vineyard geology is somehow directly transmitted into the glass. His Portland remarks were a condensed version of that demolition job.

Maltman argued persuasively that both plant physiology and winemaking operations lead to a complete “decoupling” of the chemical composition of vineyards and their wines; that inorganic ions show up in wine at levels well below human thresholds; that these ions in any case are tasteless, and that wines that do show perceptible levels of inorganic ions are usually thought of as contaminated and quickly discarded.

In sum, he concluded, “Whatever ‘minerality’ in wine is, it is not the taste of vineyard minerals.” Maltman, of course, is not alone in this critique. He’s just more systematic than most minerality skeptics. Repeated demonstrations of the physical impossibility of tasting vineyard minerals in wine haven’t stopped wine writers from using the term with numbing abandon, but at least in serious discussions of terroir, a little science has cleaned out this part of the conceptual clutter.

Maltman is not only a rock hound, he’s a wine hound who clearly believes there are connections between the places grapes are grown and the character of the wines that result. The point of ruling out simple-minded, pre-scientific notions of minerality is to make room for more complex and indirect explanations, and Maltman’s hard-edged talks and papers are sprinkled with what might be called loopholes for further research—“Maybe there could be some relationship between X and Y; it’s just that no one has demonstrated it yet,” and so on.

The GSA panelists also included Jonathan Swinchatt, co-author of The Winemaker’s Dance, a well-received 2004 study of the geological underpinnings of the Napa Valley. One of the central threads of that work was an emphasis on the role of bedrock, not simply the soils on the surface, in shaping the makeup of vineyard sites and their wines. These days, Swinchatt seems to have backed off a bit from the implicit geo-determinism of that book; in his presentation, for example, he twice quoted Alex Maltman on the disjuncture between vineyard chemistry and what’s in the glass.

But he went on to insist, quite plausibly, that there are many ways in which a relationship can and does exist—through such thin gs as drainage, water accessibility, soil temperature, substrate microbiology and trace element chemistry. Calling the connections “elusive” and “devilishly complex,” he nonetheless portrayed them as exciting areas for further research.

Several other presentations centered on unraveling the geology of specific vineyards and regions: an examination of the Yakima Fold Belt structures in the Columbia Valley, the influence of fragipans and pisolites on one particular vineyard in Washington County, Ore., and so on. Often these more focused investigations seemed to want to draw tidy, direct lines between a rock and a wine place, without getting very far into how that might be occurring. Such investigations can be quite helpful to winemakers in understanding their vineyards, even if they don’t illuminate the more generalized mechanisms of terroir.

And of course there was a tasting afterwards, mainly demonstrating how much fun tastings are, and helping perhaps to explain why so many geologists are venturing into this area. Much better than a rock tasting, even for fans of minerality.

Does climate change make terroir a moving target?

Taking the podium twice during the annual meeting of the Geological Society of America, Greg Jones of Southern Oregon University wasn’t talking about rocks at all, but climate, climate change and the suitability of various shifting climate zones for different grape varieties.

The downside of the projections by Jones and other wine-and-climate researchers—that some traditional terroirs are threatened by global climate change—is matched by an upside—that terrific new ones, as yet undiscovered, are in the offing. In a presentation focused on Oregon’s Rogue Valley, Jones presented an innovative approach to mapping an entire winegrowing region, overlaying climate and geological data and thus pointing toward promising places to plant various vines. Advances in technology have clearly moved us past the simple counting of degree-days.

Jones’ talk on the Rogue was an excellent illustration of a point Jamie Goode makes in The Science of Wine about Old World and New World approaches to terroir. Old World terroir-seekers, he says, strive to make wines that reveal the typicité of a particular place; the New World search for terroir is geared more toward finding good sites for quality grapes.


Disciplines in motion

Denyse Lemaire, a geographer at Rowan University in New Jersey, readily agreed that many of the researchers looking into wine and terroir are also wine enthusiasts eager to apply their passions to their field. Her understanding of how the two things fit in with her role as the organizer of a series of panels on wine regions, climate and terroir at the March 2009 meetings of the American Association of Geographers in Las Vegas. She also is organizing the 2010 panels, which are nearly full.

Two other things were obvious from the beginning of my call to Dr. Lemaire. First, she is very French, and second, for that reason she has little patience with the idea that the scientific study of terroir is something new. “Perhaps in the New World that has not been the case,” she said, “but in France and Italy and Germany, it goes back a very long time.” And from digging through all the footnotes and citations in recent scientific terroir literature, I can attest that she’s right—there’s plenty of important work, some of it still not translated, going back well into the 1980s at least.

Scott Burns, a geologist at Portland State University and organizer of the GSA session, says panels on wine topics have been a feature of the annual meetings for about a decade, after some years in which geologists interested in the topic had to find outlets in Canadian journals. Burns himself has been at it since a 1976 paper on how science can be tasty, and concurred that “almost all of us are wine fans, too.

It’s not just the viticulture and enology crowd working on terroir any more. And that’s a great thing.

Tim Patterson
writes about wine and makes his own in Berkeley, Calif. Years of experience as a journalist, combined with a contrarian streak, make him interested in getting to the bottom of wine stories, casting a critical eye on conventional wisdom in the process. Contact him through

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