Sancerre and Soave: It never occurred to me that they had much in common, other than their sibilant sound. One’s from the Loire, the other from Italy. Sancerre is pure sauvignon blanc, and Soave is garganega, sometimes with a splash of trebbiano. Where’s the overlap?

Two recent tastings suggested that they do share a common thread. In a word, it’s soil. Or more precisely, rock.

Both Sancerre and Soave reside on outcroppings of a very specific kind of rock. Not the same rock, mind you. They’re diametrically opposed: Sancerre sits atop marine fossils (white soil), whereas Soave’s turf is volcanic (black soil). Water and fire—quite different cradles. But the results are similar insofar as the best Sancerre and the best Soaves draw their personality and flavor profiles from their respective rock.

That jumped out at last week’s Loire tasting, organized by the WINE MEDIA GUILD. We tasted 20 wines—all 100 percent sauvignon blanc—from six regions: Touraine, Reilly, Quincy, Menetou-Salon, Sancerre, and Pouilly Fume. There were many fine wines, but when I look back over my notes, the majority of those marked with stars and loving descriptors (see below) are Sancerre.

Okay, I’ve always loved Sancerre. Compared to sauvigonon blancs from around the world, it has the most finesse and poise. It’s not an over-the-top head-banger the way New World sauvignon blanc can be. But even within this Loire group, the wines from Sancerre tended to stand out for their beautiful minerality, depth of flavor, and long finish.

Now I understand why. It’s that KIMMERIDGIAN limestone, made from fossilized seashells. Like a Loch Ness serpent, the Kimmeridgian ridge starts in the Dorset town of Kimmeridge, where it was first identified, dives underground, then rears its head near the white cliffs of Dover. It then plunges under the English Channel to reemerge in France, where it snakes through the most esteemed vineyards of Champagne, the Loire Valley, and the grand cru of Chablis. In some places, like Menetou-Salon, there’s a layer of scree covering this chalky base. In others, like Pouilly Fume, discrete veins of it run through the soil. But in Sancerre, Kimmeridgian rules, interlaced with stretches of silex (Latin for flint) and caillottes (pebbly clay-limestone).

This Kimmeridgian kinship helps explain a post-phylloxera phenomenon in Paris. Before that louse ravaged the vineyards of Burgundy in the late 1800s, Chablis had been the drink of choice at Parisian bistros, according to our speaker, John Gilman, author of the e-newsletter View From the Cellar. Sancerre rose to prominence when Chablis fell into short supply and bistros started serving Sancerre instead. Coming from virtually identical soils and sharing a racy acidity and enticing minerality, the switch was easy. Gilman also noted that Sancerre’s success in bistros encouraged winemakers to adopt a style of vinification meant for early consumption. That style still dominates, though, due to its high acidity, Sancerre could be made to age, just like Chablis.

Meanwhile in Italy, a different, fire-breathing serpent runs down the spine of the peninsula: volcanoes. Italy has more volcanic area than anywhere in Europe, and some volcanoes are still active: Mount Etna has had 50 eruptions in the past few months, and winemakers routinely have to wash the ‘black rain’ laden with soot off their grapes.

Volcanic soil also rules in SOAVE, the largest production region in Italy specializing in white wine. The best Soave comes from the hilly Classico zone. Here one finds basalt, tufa, and pumice of volcanic origin, sometimes with outcroppings of limestone. This black soil is rich in magnesium and iron. It’s also characterized by macro-porosity, which means that the rocks can store water—up to 100% of their weight—then release it slowly, even during years of drought. That porosity also allows the roots to breathe and interact with gaseous substances contained within the rock’s pores.

Over the years, I’ve found that the best Soaves have two ingredients: old-vine garganega and vinification as single-vineyard cru. When those cru sit over basalt and limestone, magic happens. (Think PIEROPAN’s Soave La Rocca, MONTE TONDO’s eponymous cru, or LE ALBARE’s Vigna Vecia.)

Italians are so convinced of the specialness of volcanic soil that they created an association in 2009 called the VULCANIA PROJECT. Named after Vulcan, the Roman god of fire, this promotional entity wants to send a message: that volcanic wines should be a subcategory within the world of white wines. Joining hands in this effort are the wine zones of Soave, Campi Flegrei (west of Naples), Ischia (an island offshore from Naples), and Mount Etna, with Vesuvius poised to join in 2012.

These volcanic wines express “the best antidote to globalization: exalting those characteristics that cannon be reproduced anywhere else,” proclaims the Vulcania group. And they’re right. Volcanoes aren’t portable like French oak, nor (hopefully) are they repeatable like the chemistry that enologists apply in some cellars. Terroir is unique.

Back at the Loire tasting, the differences between the 20 wines were mostly due to terroir and vintage, according to reps from LOIRE VALLEY WINES. The winemaking practices were fairly consistent. Most Loire winemakers ferment and age their sauvignon blanc in stainless steel, eschew malolatic fermentation, and give extended contact with fine lees. The following were my favorites of the lot:

DOMAINE DE LA CHAISE 2010 (Gabrilla Importers) $12 – This Touraine sauvignon blanc actually received an applause at the end of our luncheon. At $12, the price/quality ratio couldn’t be beat. Made by the sixth-generation Davault family from vines on tuffeau soil (marine sedimentary rock), this wine was clean and bright, with white grapefruit dominating the palate.

HENRY PELLE, MOROGUES 2009 (Michael Skurnik Wines) $20 – This luscious wine put Menetou-Salon on my radar. Made by Henry Pelle, considered a pioneer of the region, it showed wonderful concentration of fruit—white grapefruit, but somewhat rounded with yellow apple—plus great minerality and nice acidity.

DOMAINE LAPORTE, LE ROCHOY 2009 (Fruit of the Vines, Inc.) $23 – This Sancerrecru is planted on flint rocks (cailloux), which explains its flinty notes. But it’s the gooseberry that dominates. Not the longest finish, but a powerful blast of fruit on the attack and mid-palate. (I tried it later with Brussels spouts, which are said to go with no wine, and it was a perfect match. Voila!)

FOURNIER PERE ET FILS WINES (Martin Scott Wines)

The back room at Felidia’s had five wines from Fournier, a winery owned by three brothers—agronomist, enologist, and chef. The label began in 1950 with an estate in Sancerre, but subsequently expanded with the acquisition of other properties in eastern Loire and beyond. All were killer wines, but my favorites were:

MENETOU-SALON, LA CHARNIVOLLE 2008, $23 – Lots of character, this one. Bursting with citrus, plus a nutty undertone. Crisp and food-friendly. (I made sure to grab a bottle for our lunch table.)

SANCERRE BELLES VIGNES 2009, $26 – Probably my favorite of the entire tasting. Great nose, great concentration, a benchmark Sancerre, with grapefruit, gooseberry, and minerality galore. Made from 15–20 year old vines planted in limestone, clay, and flint. I preferred it even to their two cru, as it seemed to be a purer expression of sauvignon blanc.

SANCERRE CUVEE SILEX 2008, $40 – Still, this cru was dynamite, full of stoney minerality (remember, silex = flint) and concentrated fruit. This seemed to have some residual sugar, though that richness could derive from the 30-year-old vines and/or the long lees contact with batonnage.

And finally…

FRANCOIS COTAT, CULS DE BEAUJEU 2009, (Michael Skurnik), $50 – This wine—not my favorite—definitely stood out from the pack. It prompted a friendly debate at my lunch table, mostly over its 15% alcohol, which gave a sweet sensation that didn’t quite complement the grape, in my opinion. But as Gilman explained, Francois Cotat is one of the last two traditionalists in Sancerre. He ferments in ancient oak casks, which are encrusted with 100 years of tartaric crystals, then ages in casks or iron (!) vats. He harvests late, collecting grapes with higher sugar levels (thus the 15%). This is a winemaker who looks to Chablis and Champagne as his model, rather than Parisian bistros, with age-worthy Sancerre his goal.

I hope to give this wine another try in 10 years. But meanwhile, I have a short list of wonderful Loire whites that I’ll seek out next summer.