How different soils may support different varietals.

When we speak of terroir most of us think of it as a combination of all the physical elements that affect winegrowing: temperature, climate, exposure, rainfall, and the physical composition of the soil. That seems to be the New World view on the matter. The French, however, have quite a different view and, after all, the word terroir belongs to them.

Terroir In the Eyes of the French

To French viticulturists terroir is primarily about the soil, the other factors affecting winegrowing taking second place. Soils throughout the winegrowing world have been extensively studied and mapped. It's not enough, however, to isolate a particular soil—say a stony limestone with around 50% clay (called marl)—as a good general soil type for winegrowing. That soil, say the French, is particularly suited to Pinot Noir and Chardonnay. Indeed, the entire Burgundian Côte d'Or is underlain by this soil type. But as soon as you leave the Bourgogne appellation the soil type changes dramatically to Paleozoic granite. Here the Gamay Noir grape of Beaujolais makes its finest statement. And gone are the Pinot Noir and Chardonnay.

Pinot Noir in Oregon and California

But if Pinot Noir has a strong preference for marly soils, how do we explain the spectacular success of Oregon Pinot Noir which grows exclusively on volcanic clays? See our article on Oregon Pinot Noir. These red soils have yielded Pinot Noir wines that can rival the best of Burgundy.

In California the best Pinot Noir vineyards are planted on soils derived from marine sediments—in riparian environments (Russian River) and mountainside environments (Santa Rita Hills). The great Pinot Noirs of Oregon and California are not growing in limestone. But other varietals are...

Syrah and Grenache in France and California

As we travel south from Burgundy and then Beaujolais, we enter the Rhône valley, home of the world's greatest Syrah based wines. Here we find the best vineyards planted on Granitic soils (Côte Rotie, Hermitage). So Syrah prefers granite? Well, not in California. Many of California's finest Syrah based wines are from vineyards planted in a chalky limestone known as Linne Calado. The chalk is in the form of fist-sized rocks that absorb moisture in the rainy season and retain much of it well into the dry season. This soil type is prominent in the hillside vineyards west of Paso Robles.

Grenache seems to perform particularly well in limestone soils, both in France (southern Rhône) and California (Paso Robles). The owners of Ch. de Beaucastel, producer of superb Châteauneuf-du-Pape, operate a second winery in Paso Robles whose site was chosen because of the similarity in soils.

Australian Shiraz

So Syrah can't decide whether it prefers granitic or limestone soils? Ask an Aussie viticulturist and he'll be happy to explain that the greatest Aussie Shiraz (Syrah) grows on Precambrian and Cambrian sandstone in the Barossa and Eden Valleys! These include Penfold's Grange and Henshke's Hill of Grace.

Cabernet Sauvignon in France and California

Here's where the plot thickens. No one would dispute that many of the world's finest Cabernet Sauvignons are made in Bordeaux, where the vines grow on stony terraces laid down by successive incursions and retreats of the sea over the past 60 million years. These pebbly soils, called Quaternary Terraces, are so celebrated by Bordelais that one of their Premiere Cru wineries, Ch. Beaucaillou ("pretty stones") is named in their honor. The entire appellation of Graves is named for the gravelly soil that produces not only the finest Cabernets but also some of the world's best dessert wines (Sauternes).

In California, Cabernet Sauvignon reaches its pinnacle on entirely different soils. Few would contest that the New World's best Cabernets come from the marine sediments of Napa Valley, whose soils range from silty/sandy to stony. Many of the best examples of Napa Valley Cabernet are made from the fruit of hillside vineyards (Shafer, Stag's Leap) that have about as much in common with Bordeaux terraces as red has with blue. And excellent Cabernet Sauvignon also comes from the volcanic soils of the Columbia Valley.

A Scientific View of Soils

Increasingly, New World viticulturists are being influenced by the scientific community which points out not only the lack of compelling evidence that soil chemistry affects the flavor of grapes, but that it's likely that it's the physical composition of the soil that really matters. That is, a soil's ability to drain well, yet retain a suitable level of moisture as in the case of the Linne Calado soils of Paso Robles.

We know that plants suck up nutrients and water from the soil, plus possibly some mineral ions. But there's no known mechanism whereby a plant absorbs flavor components from a soil, whether sedimentary, granitic, or volcanic.

Many New World winegrowers dispute the notion, however, because their personal experience suggests otherwise. So maybe the French are on to something after all. They've had two hundred centuries to sort out which vines are best suited to each particular soil. Add to that the fact that most French appellation boundaries (which determine which varietals may be planted) were established long before the first geologic mapping occurred. It turns out that French geologists and soil scientists largely confirm the knowledge gained over two thousand years of trial and error.

See also our article on the role of Climate on Terroir.