Article By: Bill Nesto, MW
"I really don't want a Cabernet Sauvignon, Merlot or Chardonnay," I told the waitperson in a restaurant and pointed to a wine on the list. "Please bring me this one listed under Gravel over Clay." This is the fantasy of a diehard wine terroirist: to have wines identified by soil type rather than by grapevine variety. Grapevine varieties have legs. Merlot can grow in Chile, France, the USA, and anywhere else temperate enough. Climates too can move. Global warming. The most stable, but most difficult-to-understand, identifying factor of a wine is the soil where it originated.
So it was with great interest that I signed up for a seminar entitled, "Where Schist Rules". Schist is a soil type. Eric Solomon of European Cellars had collected some producers he imports. They had one thing in common, vineyards with high concentrations of schist.
So what is schist? I sought the help of the American Heritage Dictionary: "Any of various medium - to coarse-grained metamorphic rocks composed of laminated, often flaky, parallel layers of chiefly micaceous minerals." Following the thread, I looked up the entry for "Metamorphic", which referred me to "Metamorphism: Geology: Any alteration in composition, texture or structure of rock masses, caused by great heat or pressure."
But the meaning of two more 's' words, slate and shale, which are commonly linked to schist, still confused me. Authors Tom Stevenson of The New Sotheby's Wine Encyclopedia (DK Publishing, 2OO1) and Robert E. White of Soils for Fine Wines (Oxford University Press, 2OO3) helped clear my confusion. They explained that shale, slate and schist have similar chemical composition and have the same laminated, parallel layers. The key differences are the degrees of hardness and friability. This depends on the amount of heat and pressure the rock was subjected to during its formation - the more heat and pressure, the harder and less friable. Of the three, shale is the softest and most friable. One can break it between the fingers. Erosive action can easily release its moderate fertility to the soil. Shale that is over time exposed to more heat and to more pressure becomes slate. Slate is harder and less easily broken up into layered sheets. Because it erodes less easily, soils composed of slate have poorer fertility. Usually very dark in color, slate readily absorbs ambient heat and solar energy, a factor which can moderate the ambient temperature of the vine microclimate. What is called schist has been exposed to even more heat and pressure. It is the hardest of the three, the least subject to erosion, and hence the most reluctant to make available its nutrients to the vine.
Languages and cultures often complicate the picture (or refine it, depending on how you look at). It can challenge us with local terms and definitions. Just as there are many more words for snow in Eskimo than in the English language, so too do people living in schistous areas have words for subtle variations that go beyond the refinements of geology. Paul Strang in his book "Languedoc Roussillon" (2OO2. Mitchell Beazley) notes in his section on Faugeres, an AOC with pure schistous soil, that "Schist takes three forms in this region: large slates which they call "dalles", on which hardly anything grows and the vine can yield only tiny quantities of fruit; another less mean kind sometimes called "gresaux" because of its more sandstony texture; and the friable, very brittle, fragile type which you can break in your fingers, and which produces the frites." Dalles, gresaux and frites seem to be the local Faugeres equivalents of schist, slate and shale.
Schistous soils are particularly fine for vines when their layers are arranged perpendicular rather than parallel to the horizon. This happens frequently in the Douro and in Banyuls. Water can then easily seep between the layers. Such schistous-laced soils erode more quickly, particularly if there are winter freezes. Roots can use these channels to dig down into the schist in search of water and nutrients. Their activity results in additional erosion. The eroding rock provides a limitless, constant and measured source of nutrients, both basic and trace.
The confusion in the literature between the meanings of schist, slate, shale, and various local terms makes it difficult to associate exact soil types with locations. Nonetheless, I have mined my library in order to present the following schist-vineyard pairings.
Alsace North of Andlau is the vineyard called Kastelberg, which is Grand Cru for Riesling. The locals call the schist the "Steige".
Loire Valley There are two basic types of schist, St. Georges and Brioverian. On the left bank of the Layon and occasionally on the right bank (at Quarts de Chaume, for example), Chenin Blanc grows in Brioverian sandstone schist which is green or ochre in color.
Northern Cotes du Rhone In the vicinity of Ampuis, there is schist containing both muscovite (white mica) and biotite (black mica). At Cote Brune, the schist weathers to dark brown and hence the slope is called Cote Brune (in English, "brown hillside"). The Cote Blonde ("white hillside") is a weathered grayish schist and gneiss mix. Gneiss is a common metamorphic rock which has dark (micas, amphiboles) and light (quartz, feldspar) colorations much like the marbling of a sirloin steak.
The Diois The schistous sites here are the preferred soil for Muscat.
Beaujolais At Morgon, the ochre red colour of the crumbly rock topsoil is made up mainly of pyritic schist rich in iron oxide and manganese. This schist in combination with other compounds weathers to a smoky-gray soil called "roches pourries" ("rotted rocks"). The gamay wines Morgon are reputed to have a strong cherry smell that comes from this soil. In Julienas, there are schists of sedimentary volcanic origin. In Cotes de Brouilly, there is also some schist.
Languedoc-Roussillon At the Banyuls AOC, lightly metamorphosed, vertically positioned, brown Cambrian schists make up what is reputed to be the finest terroir for Grenache. At Maury AOC, there is black schist. There are schistous sites at Cabrieres in the Coteaux-du-Languedoc AOC, in the St. Chinian AOC, in the Corbieres AOC, at Cabardes to the north of Carcassone and west of the Montagne Noire, at La-Tour-de-France in the Cotes-du-Roussillon-Villages, and near the city of Tuchan in the Fitou AOC. The topsoil in the Faugeres AOC is pure Visean schist. Carignan is also a vine variety reputed to excel in schist.
Provence In the Cotes de Provence AOC, patches of light-colored, micaceous crystalline schist and of dark, slate-like schist containing crystals of quartz appear in some vineyards between the cities of Frejus an d Antibes.
Douro Across the demarcated Douro region, the Douro River cuts out a valley through schist and granite. The confines of the Port producing area outline the area where schist is predominant. The official point scale of the classification system for Douro vineyards identifies schist as the most valued terroir. Within this area, granite dominated soils are usually relegated to table wines or not allowed for Port or wine production at all. The system accords the least value to alluvial soils.
New York State Glacial deposits of shale, slate and schist characterize the Hudson River Valley.
Devon slate is considered ideal for Riesling. It is found on slopes in the Upper Ahr Valley, Mittelrhein, Middle Mosel, Saar, Ruwer, Lower Nahe valley, Rhine, and Pfalz.
In Priorat, gray to black micaceous slate lies over a base of reddish micaceous slate (called "llicorella" ). Garnacha is considered the perfect match for the schist of Priorat.
Throughout Tuscany, in spots, generally at elevations over 2OO meters, there is a brownish red clay-based shale that is locally called "galestro". This soil is considered ideal for Sangiovese.
Swartland and Glenrosa soil types are shale-derived. Red shale characterizes the soil of Klein Karoo.
My research uncovered that schist rarely is noted in connection with New World vineyard sites and that certain vine varieties are noted to excel on schist: Chenin Blanc in the Angers area, Grenache (Garnacha) in the Roussillon and the Priorat areas, Carignan in the Languedoc-Roussillon area, Muscat in the Languedoc-Roussillon and in the Diois areas, Riesling in Alsace and Germany, and Sangiovese in Tuscany. I have experience tasting galestro Sangiovese wines versus those made on more clayey and sandy soils. They have the most perfume and the most elegance and are the most long-lived. Patches of galestro soil pop up in many important appellations such as Chianti, Chianti Classico, Montalcino, and Scansano. One important Sangiovese appellation where galestro is noticeably absent is Montepulciano.
I tasted the wines, made on schistous soil, at the "Where Schist Rules" seminar. The participating producers, though they noted the beneficial ways that schist affects vines and their crop, did not go so far as to ascribe particular flavors to particular schist types.
ON the following page are my tasting notes of the wines presented. I scored the wines for quality using a O to 2O point scoring system. Customarily I score most wines between 1O and 15 points, with 1O being a clean but simple wine, 15, an excellent wine for its type
CALVET-THUNEVIN Located near the village of Maury.
Clos del Rey, Cotes du Roussillon-Villages, 2OO3 Medium-light garnet-ruby with ruby-purple rim; strong rusty water nose, cola, aromatic; tart, very tannic, some bitterness. 12
Calvet-Thunevin, Clos del Rey, Vins de Pays 2OO2 (6O% Carignan, Grenache 4O%) Medium-light red-brown with ruby rim; spicy, rusty water, licorice, rosemary; tart, dry, dusty tannins, softer and more fleshy than the 2OO3; spicy finish. 13
Calvet-Thunevin, "Cuvee Hugo", Cotes du Roussillon-Villages, 2OO3 (45% Grenache, Syrah 1O%, Carignan 45%) Medium garnet with ruby rim; prune (overripe), chocolate, rusty water; tart, woody; lead pencil finish. 12
Calvet-Thunevin, "Cuvee Hugo" Cotes du Roussillon-Villages, 2OO2 (45% Grenache, Syrah 1O%, Carignan 45%) Medium-light garnet with red rim; strong rusty water nose, very aromatic; richer and softer than the 2OO3, riper tannins; sandalwood, tobacco finish. 13
Mas Doix "Doix", Priorat (Poboleda), 2OO3 (45% Grenache, Syrah 1O%, Carignan 45%) Light-medium garnet with purple rim; elegant, rusty water, licorice, lacks fruit; thick, tart, with nice tannic texture. 12.5
Mas Doix, "Doix", Priorat ( Poboleda), 2OO1 (Grenache 55%, Carignan 45%) Medium-light garnet with ruby rim; strong licorice, sandalwood, and marmalade bouquet; substantial and thick in the mouth. 13.5
Mas Doix, "Salanques", Priorat (Poboleda), 2OO3 (Grenache 6O%, Carignan 2O%, Cabernet, Merlot, Syrah 2O%) Light-medium garnet-red with ruby rim; less aromatic than the other Mas Doix wines, gamey, strawberry preserves; round but quite tart, mute on the palate, too. 11.5
Mas Doix, "Salanques", Priorat (Poboleda), 2OO1 (Grenache 6O%, Carignan 2O%, Cabernet, Merlot, Syrah 2O%) Medium-light garnet with ruby rim; rusty water, rosemary; substantial and full on the palate with dry, fine sandpaper tannins, dusty tannins. 14
Clos Erasmus, Priorat (Gratallops), 2OO3 (Grenache 85%, Cabernet Sauvignon 8%, Syrah 7%) Light-medium garnet with purple-ruby rim; marmalade, licorice; high alcohol, drying tannins, thin: oak in the finish, sandalwood. 12
Clos Erasmus, Priorat (Gratallops), 2OO1 (Grenache 78%, Cabernet Sauvignon 17%, Syrah 5%) Medium-light garnet with ruby rim; licorice, fresher fruit than in the 2OO3, elegant nose; soft, rich, very tannic, elegant. 14
Niepoort, "Vertente", Douro, 2OO1 (Touriga Nacional 4O%, Tinta Roriz, Touriga Franca, 15 others 6O%) Medium-light garnet with garnet rim; walnuts, licorice, Port nose; new oak noted in the mouth, very tannic. 12
Niepoort, "Batuta", Douro, 2OO1 (Field blend of Tinta Roriz 3O%, Tinta Amarela 2O%, Touriga Franca 2O%, others 2O%) Medium-light garnet with garnet-purple; elegant nose, aromatic, difficult to analyze; delicate, round, moderate weight, fine tannins, balanced. 14
Niepoort, "Batuta", Douro, 2OO3 (Field blend of Tinta Roriz 3O%, Tinta Amarela 2O%, Touriga Franca 2O%, others 2O%) Medium-light garnet-ruby with ruby rim; Concord grape jelly nose; tart in the mouth, clumsy, lacks definition. 12
Niepoort, "Charme", Douro, 2OO2 (Tinta Roriz 3O%, Touriga Franca 3O%, 15 others 4O%) Light-medium red with red rim; elegant, red Burgundy-like nose, earthy; full, soft, moderate tannins, Pinot Noir-like palate, very tart. 14
Note Those who would like to know more about the world's terroirs should consult "Great Wine Terroirs" by Jacques Fanet. 2OO4. University of California Press. $4O retail.