Editor’s Column
June 2009
Days of Terroir:
Geology in a Glass
Michael F. Forlenza, P.G.
HGS Editor
Wine is the most civilized thing in the world.
Ernest Hemingway
The cabernet sauvignon shimmers garnet-red in the glass. The grapes for this wine were grown on vines rooted in the calcareous loamy soils formed on the Quarternary alluvium on the Texas High Plains. The taste of ripe red and black fruit is lush and distinct with hints of licorice and tobacco and a bite of tannins. But there are other tastes in the glass as well, something else. Is that something else a taste of the earth, maybe a taste of geology?
In the oldest wine-grape-growing regions in Europe, oenophiles speak of something called terroir, pronounced "teh-RWAHR." The term has its roots in the Latin word terratorium, from terra meaning land or earth. The same root used for the words terrain and territory. The French often use the phrase goût de terroir (taste of the soil) to refer to the earthy flavor of some wines.
In 1831, Dr. Denis Morelot, a wealthy landowner in Burgundy, observed in his Statistique de la Vigne Dans le Département de la Côte-d’Or that nearly all of the producers in the area made wine essentially the same way, so the reason that some tasted better than others must be due to the terroir — specifically, the substrata underneath the topsoil of a vineyard. Wine, Dr. Morelot claimed, derived its flavor from the site’s geology: in essence, from rocks.
When viniculture experts use the term terroir, it not only includes reference to the type of soil (chalky, claylike, gravelly, sandy), but also to other geographic factors that might influence the quality of the finished wine like altitude, position relative to the sun, angle of incline, water drainage, prevailing wind direction, and climate. The concept of terroir embodies a sense of place and a connection to the land and to the geology. In the United States, wine producers use the term microclimate to encompass the same considerations.
In Bordeaux and Burgundy, the top wine growing regions of France, premium wines from the well-respected domains (estate vineyards) sell for hundreds or even thousands of dollars per bottle, while nearby vineyards, often less than a mile away, produce wine categorized as vin ordinare that sells for less than five dollars per bottle. Decades of research by French geologists and other scientists, such as American James Wilson, author of the classic 1998 book Terroir: The Role of Geology, Climate, and Culture in the Making of French Wines, has shown that vineyard boundaries, in many cases dating back centuries, mirror underlying faults, facies changes, and other variations in geological properties.
Wine enthusiasts will say the characteristic minerality of wines produced in the Chablis region in France comes from the limestone beds underlying the vineyards. Eric Asimov, wine critic for the New York Times, describes wines from Chablis as having a taste and aroma of "crushed rocks" and "fossilized oyster shells" in a May 5, 2009 article.
Wines grown in the Champagne province owe their desirable characteristics to the Cretaceous chalk underlying northeastern France writes the Pulitzer Prize-winning author John McPhee in his article Season of the Chalk in the March 2, 2007 issue of The New Yorker magazine. The Cretaceous period gets its name for the French word for chalky. McPhee notes that the Cretaceous is the only geologic period named for a rock (with the debatable exception of the Carboniferous). The deep fertile chalk soils of Champagne are a natural moisture regulator for the chardonnay and pinot noir vineyards which are the source of the grapes used in the méthode champagnoise. The chalky soil absorbs an amount of water equal to up to 40 percent of its volume yet remains sufficiently well drained for good vine health. The soft chalk has also allowed vintners to excavate hundreds of miles of tunnels where more than a billion bottles of champagne are cellared.
Coarse glacial deposits and outwash gravels are the setting for some of the finest wine-producing areas of the world found in California, Oregon, Washington, New York, New Zealand, and France. In France, sediments from periods of glaciation in the Pyrenees Mountains and the Massif Central overloaded the Garonne and Dordogne rivers producing a series of gravel terraces where the best vineyards (so-called First Growth) occupy the same type of gravel. The well-known estates Chateau Lafite Rothschild, Haut-Brion, and Latour are located on a particular stratigraphic unit identified as the Günz gravel.
The Rise of the "Terroirists"
The general topic of terroir is of growing international interest among viticulturists and wine lovers as shown by the numerous recent publications and symposia. Earth scientists are no less smitten with the concept devoting sections of academic conferences to the topic such as at the 2003 Geological Society of America meeting in Seattle, the 2004 Geological Association of Canada meeting in Ontario, and the 2004 meeting of the International Geological Congress in Florence, Italy.
The allure of terroir has been lovingly embraced of wine writers, distributors, marketers, and sommeliers. Some of the language related to this new-found passion has become quite poetic: "Wines express their source with exquisite definition," asserts Matt Kramer in his 1989 book Making Sense of Wine. "They allow us to eavesdrop on the murmurings of the earth." Of a California vineyard’s highly regarded chardonnays, he writes, there is "a powerful flavor of the soil: the limestone speaks." In his monthly newsletter, Kermit Lynch, one of the most respected importers of French wine, returns repeatedly to the stony flavors in various