Shades of Schistosity

Shale

As a truly committed student of wine, you probably know that shale is a type of soft, foliated sedimentary rock composed (at least in part) of clay minerals and (sometimes) volcanic ash. Shale has visible stratification and a tendency to break or split along “layers” (known as “planes of weakness” or “rock cleavage” in geo-speak). This tendency to split along planes is known as fissility (which is just such a fun word).

You might also know that shale is well-represented in the vineyards of the world, including the Finger Lakes AVA (in New York State) and the Santa Cruz Mountains AVA (in California). Other wine areas known for shale-influenced soils include the western side of Paso Robles, the Mayacamas Mountains (between Napa and Sonoma), Heiligenstein (Alsace), and Austria’s Wachau region.

Shale is fascinating on its own but there’s more to the story, as shale can be transformed into slate, schist, or gneiss. These three types of rock are produced via varying degrees of metamorphism—changes resulting from heat, pressure, and deformation—and they all have different appearances and characteristics. Some of these differences are discussed below:

Slate

Slate: Slate, formed from shale, is a finely grained rock that may be formed under relatively low temperature and pressure conditions (low-grade metamorphism). Slate tends to be one solid color in addition to being very hard and brittle; when broken, it will form flat, smooth surfaces. Germany has several vineyards areas celebrated for their slate soils; these include the Mosel and the Rheingau—both of which also have significant outcroppings of shale (now we know why). Other wine areas rich in slate include the Clare Valley, the Cebreros VCIG (in Castilla y León), and Chile’s Aconcagua Valley.

Schist: Schist is formed (from slate or mudstone) under moderate levels of heat and pressure (metamorphic forces). Schist is identifiable by its visible “grains” (in layered formation), dull luster, and schistosity—the layer-like foliation that is found in certain coarse-grained metamorphic rocks. Despite the fact that it reminds me of a wine-geeky, made-up word (like matchsticky or porch-pounder), schistosity is a real thing.

Schist

Several vineyard regions are regarded as rich in both slate and schist; these include Priorat (Spain) and the Douro Valley (of Portugal). Parts of Tuscany are known for galestro—a soil rich in both clay and schist. Other areas known to be rich in schist include Corbières, Côte-Rôtie, Kastelberg (Alsace), the Valais (Switzerland), Ribeira Sacra, and Savennières. These areas are often described as having schistous soils—although schistous is definitely a made-up/wine geek word and does not appear in the geological lexicon (Maltman: Vineyards, Rocks, and Soils, p. 103). Schistes, however, is a real word (in French)—there is even a wine association to prove it: L’Association des Terroirs de Schistes.

Gneiss

Gneiss: Given the right combination of intense heat, pressure, and (perhaps) chemical activity, schist can transform into gneiss. Gneiss has visible “bands” of various colors composed of various minerals (gneissose banding). Having been formed under intense metamorphic pressures, gneiss is much heavier and harder than slate and schist and does not typically break along its foliation planes.

Vineyard regions known for gneiss include the Pays Nantais, Margaret River, Wachau, Kamptal, and the Middleburg AVA in Virginia (USA).

  • If you’d like to learn more about dirt, rocks, and soils, join me on May 2 (10:00 am) or May 6 (7:00 pm) for SWE’s Webinar, the Dish on Dirt. It’s free, and open-to-the-public. All of the other info is in the link.

References/for more information:

  • Feiring, Alice (2017). The Dirty Guide to Wine. New York: The Countryman Press.
  • Franzmeier, Donald, William McFee, John Graveel, and Helmut Kohnke (2016). Soil Science Simplified, 5th edition. Long Grove, Illinois: Waveland Press.
  • Maltman, Alex (2018). Vineyards, Rocks, & Soils: The Wine Lover’s Guide to Geology. New York, New York: Oxford University Press.
  • Robinson, Jancis and Julia Harding: The Oxford Companion to Wine, 4th Edition. Oxford, 2015: The Oxford University Press.
  • White, Robert (2009). Understanding Vineyard Soils. Oxford University Press.
  • http://www.terroirsdeschistes.com/
  • https://geology.com/rocks

The Bubbly Professor is “Miss Jane” Nickles of Austin, Texas… missjane@prodigy.net

 

 

Aspect: East, West, (and Romeo’s)

What light through yonder window breaks? It is the east, and Juliet is the sun.

Many people will recognize these famous lines  from Shakespeare’s Romeo and Juliet (Act 2, Scene 2) . However, it would take a true-and-total wine geek to understand how hearing that line—one of the most romantic ever written—inspired me to write a blog post about east-west aspect and its effect on a vineyard (and yet it did). Something about Romeo invoking the sun rising in the east reminded me of the concept of eastern aspect—as it was used in a recent discussion of the vineyards of the Côte d’Or—and here we are.

.

Wine students are well-aware that in the Northern Hemisphere, south-facing slopes (hillsides with southern aspect) receive the benefit of more direct sunlight (solar radiation/insolation) than other areas (those that are flat or facing north). These directions are flip-flopped in the Southern Hemisphere, where hillsides with a northern aspect have the sunshine advantage. The CliffsNotes version of north-south aspect is that if a hill faces the equator, it receives the bonus insolation.

Lesser known to wine students (but very important to realtors, as I learned) are the effects of eastern and western aspects, as discussed below:

Eastern aspect: These vineyards receive sunshine in the morning, when the sun’s rays are at their gentlest, and the ambient temperature is comparatively cool. This morning glow helps to dry out the vineyards from dew and overnight rain, helping to prevent fungi, mildew, and some disease. Eastern aspect can “kick-start” photosynthesis in the morning and can also help prevent vines from over-heating in the hot afternoons. Vineyards with eastern aspect tend to have lower maximum daytime temperatures, cooler overall ambient temperatures, and may experience delayed budbreak as compared to other spots.

Western aspect: Vineyards on west-facing slopes receive a good deal of sunlight during the afternoon—typically the warmest time of the day. Vineyards with western aspect may warm earlier in the spring and be among the first vines to undergo budbreak. Western aspect can be especially beneficial in areas near the coast and other places that are susceptible to wind and marginal weather. Western aspect can be a boon to late-ripening and heat-seeking grapes that require a lot of warmth and energy in order to fully ripen. However, It can be a challenge in areas prone to humidity, as the drying-out of dew-, fog-, or rain-related moisture will occur later in the day (as compared to east-facing vines).

Does that make sense to you, Romeo?

References/for more information:

The Bubbly Professor is “Miss Jane” Nickles of Austin, Texas… missjane@prodigy.net

 

Everybody in the (Pyrazine) Pool!

.

Most wine students have heard of pyrazine—methoxypyrazine to be exact—as the chemical partially responsible for the “freshly cut green grass” aroma found in Sauvignon Blanc, as well as a range of other herbaceous aromas—from green bell pepper to gooseberries to asparagus—sometimes noted in various wines including Cabernet Sauvignon, Cabernet Franc, and Carmenère.

Pyrazines are legendary. The narrative—which has been repeated countless times—goes something like this: “The scent of pyrazine is so strong; it can be detected at concentrations equal to five drops in an Olympic-sized swimming pool.”

I’ve heard this so many times, I decided to check it out. After all, so many oft-repeated facts about wine turn out to be just oft-repeated myths, as I am sure you know!

For starters, according to Jancis Robinson, et al in The Oxford Companion to Wine (third edition), the sensory threshold for the strongest form of methoxyprazine is 215 ng/L in white wine. The ng refers to nanograms, which equate to one billionth of a gram.

.

As it turns out, after a bit of rudimentary calculations,* the sensory threshold for pyrazines is not exactly five drops in an Olympic sized swimming pool, it is closer to 11 drops—still a legendary amount.

Which leads us back to where we started: this stuff is sturdy.

In reality, what we refer to as pyrazines in wine are technically nitrogen-containing (organic) aroma compounds produced as a secondary by-product of amino acid metabolism. There are three main types, as applies to wine: Isobutyl-methoxypyrazine (IBMP), Secbutyl-methoxypyrazine (SBMP), and Isopropyl- methoxypyrazine (IPMP). IPMP appears to be the most abundant of the three, and is most-often implicated in the “asparagus” range of aromas. IBMP—which accounts for the 215 ng/L threshold— appears to be the strongest and is often detected as green bell pepper or gooseberry aromas.

.

Pyrazines are, for the most part, created in the vineyard. They are initially produced during the early stage of fruit set as a defense/survival mechanism for the baby grapes (a mouthful of raw herb flavor is perhaps none too delectable to baby goats and wild boars). The level of pyrazines in the grapes can run amuck in cases of excess water or overly-dense canopies—particularly if the baby grapes spend too much time in the shade.

I happen to love herbaceous character in my wines, so as far as I am concerned, bring on the pyrazines! However, most wine lovers prefer their wines to be balanced, as opposed to the green-meanie style of wine that I adore.

Luckily, Mother Nature has her own ways of controlling pyrazines. For one, the level of pyrazine in grape berries typically drops as grapes approach ripeness. For another, increased sun exposure will sort of “burn them off.” On the other hand, cloudy days, cool climates, dense canopies, over-watering, and less-than-ripe grapes are a pyrazine’s best friend.

.

Everybody in the (pyrazine) pool!

.*If we do the math—which in this case is admittedly non-scientific and making use of generalizations such as standardized water volume vs. weight—it might go as such:

  • For starters, there are 2,500,000 liters (2.5 mega-liters [2.5 million liters]) of water in an Olympic size swimming pool.
  • If we multiply 215 nanograms times 2.5 million, we see that 215 X 2,500,000 = 537,500,000 nanograms, or 0.537 grams.
  • If one teaspoon of water equals 4.93 grams, then 0.537 grams = 0.11 of a teaspoon.
  • If we use a typical culinary calculation of 98 drops in a teaspoon, 0.11 of a teaspoon = 10.78 drops.
  • Conclusion: It’s not exactly five drops in an Olympic sized swimming pool, but at just shy of 11 drops, it is still a legendary amount.

References/for more information:

The Bubbly Professor is “Miss Jane” Nickles of Austin, Texas… missjane@prodigy.net

Dolomite and the Dolomites

.

Dolomite (which sounds to my ear like “dynamite”) is a loaded word with several meanings. The term may be used to refer to a mineral, a rock, a mountain range, a UNESCO World Heritage Site, or a region (loosely defined as an area stretching across the northern reaches of Trentino/Alto Adige, Veneto, Friuli (perhaps), and a small part of Austria as well).

Starting with the most basic use of the term—the mineral—dolomite is largely composed of calcium carbonate and magnesium. Dolomite (the mineral) is often found in long-buried sedimentary stones and bedrock. These stones are often known as dolostone or simply dolomite.

Sharp students of wine and/or geology may have recognized the previous mention of calcium carbonate and considered that dolomite (the stone) might be similar to limestone. This is true: dolomite and limestone are very similar, and form in the same manner—that is, via sedimentation in warm, calcium carbonate-rich, shallow waters. The main difference between the formation of limestone and dolomite is that dolomite contains more magnesium. Dolomite is sometimes even formed from limestone, as limestone is modified by magnesium-rich limewater. The resulting rock may be termed dolomite or dolomitc limestone.

.

Dolomite (the stone) is famously found in several specific portions of the Italian Alps, and one such range—made up of 18 peaks reaching high above the surrounding valleys—is known as the Dolomites.

The Dolomites (the mountains) stretch across 350,000 acres (140,000 ha) and form a series of sheer walls, steep valleys, pinnacles, steeples, and cliffs. Fifteen of the Dolomite Mountain peaks are more than 10,000 feet (3,300 m) high and some of the sheer rock cliffs tower as much as 4,425 feet (1,500 m) higher than the surrounding countryside. The sheer rocks reflect the sunlight and glimmer in a range of pink, gold, and coral hues—contrasted by the forests and meadows below. This stunning natural beauty is part of the reason the area was declared a UNESCO World Heritage Site in 2009.

The Vigneti delle Dolomit IGT: Wine enthusiasts may remember seeing the term “dolomite” on a wine label hailing from Trentino, Alto Adige, or the northern reaches of Veneto (sometimes a portion of Friuli is included in the loop as well)—calling attention to the well-drained, alkaline, and mineral-rich soils of the area. There is even an geographical indication—Vigneti delle Dolomiti IGT (Indicazione Geografica Tipica)—named for the dolomites, covering the area and including parts of Trentino-Alto Adige and Veneto. As the German language is also widely spoken in this area, the Vignetti delle Dolomiti IGT is also known as the Weinberg Dolomiten.

.

Wines produced under the Vigneti delle Dolomit IGT are made in many styles—including still and sparkling wines of red, white, and rosé—as well as passito (dried grape) and dessert wines (also of red, white, and rosé). A long list of grape varieties are allowed, including international superstars Chardonnay, Sauvignon Blanc, Cabernet Sauvignon, Merlot, and Pinot Nero (Pinot Noir). However, some of the more interesting and indigenous grapes of the area are cultivated here as well. These include Marzemino, Nosiola, and Teroldego, as described below:

  • Marzemino: Marzemino is a red grape, native to northern Italy. It is known for producing light-to-medium bodied wines with crisp acidity, dark color, and flavors of sour cherry, violets, plums, and herbs. It is often used in red blends, and may be used to produce a dried-grape, passito-style sweet wine. However, its leading claim to fame is that it was beloved by Mozart, and mentioned in his opera Don Giovanni: “Versa il vino! Eccellente Marzimino!” (Pour the wine, the excellent Marzemino)!
  • Teroldego: A darkly-hued red grape native to Trentino, Teroldego produces medium-to-full bodied red wines with intense color, moderate tannins, crisp acidity, and a hint of bitterness. Studies show it is related to Syrah, which helps to explain the typical flavors of sour cherry, licorice, hints of tar, almond and herbs. Oak-aged versions can be spicy and redolent of pine. The Teroldego Rotaliano DOC, located in the northern section of the Trentino province, is approved for the production of 100% Teroldego-based red or rosato (rosé) wines.
  • Nosiola: Nosiola is a golden-skinned white grape variety native to Trentino used to produce crisp, clean, and easy-drinking table wines as well as sweet (late-harvest, botrytis-affected, or passito) sweet wines (including Vin Santo). Dry wines tends to be fruity, floral, and herbal in tone, while sweet wines tend to show a nutty hazelnut character. This makes sense, as the name of the grape—Nosiola—is based on an Italian term for hazelnut: nocciola.

The vineyards of Trentino/Alto Adige, northern Veneto and Friuli contain abundant fragments of dolomite as well as the weathered remnants of the Alps, carried down to the vineyards via gravity, water, and other forces. So, while a springtime trip to the Dolomites sounds delightful, and nice glass of Marzemino or vino bianco from Trentino might be a good substitute (for now).

A shout-out to science: The Dolomites are named in honor of Dieudonné Dolomieu, an 18th-century French geologist who made the first scientific study of the geology of the region.

References/for more information:

The Bubbly Professor is “Miss Jane” Nickles of Austin, Texas… missjane@prodigy.net

Rendzina Soil and the Wokewine Mountains: the Robe GI

The historic Cape Dombey Obelisk in Robe, South Australia

Robe—one of the six wine regions located in South Australia’s Limestone Coast Zone—is named for the small township of Robe, located on the shores of Guichen Bay.  Robe was named after the fourth Governor of South Australia, Major Frederick Robe, who chose the site as a port in 1845.

The area—with its unspoiled, rugged coastline and multiple lakes—has a long history of aquaculture, agriculture, and tourism. Robe bills itself as “Australia’s Favorite Seaside Town” and is listed as one of the “Top 50 small towns in Australia.” Fishing, boating, hiking, camping, and sea-side conservation areas are a big deal in Robe.

As might be expected, the area enjoys a degree of fame for its seafood—particularly the lobster—but viticulture is a fairly new arrival to the area.

Photo of the seaside town of Robe by Kym Farnik via Wikimedia Commons

The area’s first vineyards were planted as recently as 1989, with the first commercial vineyards planted by Penfolds in 1994. Other (mostly independent) wineries followed suit and today you can find several wineries—including Karatta Wines, Woodsoak Wines, and Governor Robe Wines—in the area.  The Robe wine region, which stretches along the coast from the town of Robe to the town of Beachport in the south, was officially recognized as a Geographical Indication in 2006.

This coast-side location makes for a cool climate and resultant long ripening season. However, the area’s commercial vineyards are planted on the eastern (inland) side of the Wokewine Mountains, which provide a bit of a barrier to the cool ocean breezes. The mountains also provide a small degree of altitude—many vineyards are planted at elevations of 164 feet (50 m) to as high as 495 feet (51 m)—as well as some areas of northern exposure ideal for red grapes (remember, we are in the Southern Hemisphere so northern exposure = more sun). The many large lakes located between the mountains and the coast also help moderate the climate somewhat.

Map of the Robe GI via: Phylloxera and Grape Industry Board of South Australia

The area has a wide range of soil types, which includes the famous terra rosa found throughout much of the Limestone Coast Zone. Many vineyards are planted on rendzina soils, a specific type of darkly-colored clay-and-humus-rich terra rosa found mainly in mountainous regions.

Today, there are a total of 1,705 acres (690 ha) of vines planted in the Robe G.I. Of these, 72% are planted to red grapes, led by Cabernet Sauvignon, Shiraz, Pinot Noir, and Merlot (in that order). Of the 28% planted to white grapes, Chardonnay makes up the great majority, followed by Sauvignon Blanc, Pinot Gris, and Semillon.

Many of the grapes grown in the Robe area are used, somewhat anonymously, for wines labeled under the Limestone Coast, South Australia, or South Eastern Australia Geographical Indications. However, those bottled under the Robe G.I. are worth seeking out. If you find yourself in South Australia sometime soon, you’ll want to make sure to treat yourself to some of that Guichen Bay lobster and a bottle of Robe Chardonnay.

This is the sixth and final installation in our six-part series on Australia’s Limestone Coast. Click here for the first article, on the Mount Benson GIclick here for the article on Mount Gambier, here for the article on Coonawarra, here for the article on Wrattonbully, and here for the article on Padthaway. 

References/for more information:

The Bubbly Professor is “Miss Jane” Nickles of Austin, Texas… missjane@prodigy.net

Good Water and the Riddoch Highway: the Padthaway GI

Photo of Henry’s Drive via: https://www.henrysdrive.com/media-and-trade

Padthaway is a wine region in South Australia, located just to the north of Wrattonbully and about 40 miles (64 km) inland from the coast. The area is flat, with the highest elevation reaching just 165 feet (50 m) high. Most of the area sits atop a shallow ridge located along the western slope of West Naracoorte Range—which runs parallel to the ocean. The climate has both maritime and Mediterranean influences, and there are a variety of soil types as well—including the famous terra rossa shared with Coonawarra and Wrattonbully, its neighbors-to-the-south.

Padthaway—as would be expected due to its flat terrain and slightly-inland setting—is the warmest of the six wine regions located in Australia’s Limestone Coast Zone. The first vineyards of the area were planted by Karl Seppelt in 1963, and soon thereafter many of Australia’s other big-name wine companies—including Wynn’s, Lindeman’s, Hardys, and Penfolds—soon followed suit. The area was officially declared the Padthaway Geographical Indication in 1999.

While many of the grapes grown in the Padthaway Region still make their way to large wineries in other regions, Padthaway now has about two dozen small producers making local wine. These include Henry’s Drive Vignerons and Padthaway Estate—both of which offer tastings at the cellar door.

Map of Padthaway via: Phylloxera and Grape Industry Board of South Australia

The name Padthaway—meaning “good water”—was bestowed upon the region by its original inhabitants, the Potawurutj Aboriginines.  The shape and size of the area is unique—long and narrow, stretching for over 38 miles (62 km) following the Riddoch Highway from the town of Naraccorte to just north of the town of Padthaway. By contrast, the region is a mere 5 miles (8 km) wide at its widest point. The Riddoch Highway is named after John Riddoch, a businessman who—in the 1890’s—planted the first vineyards in the area, in what is now known as Coonawarra.

The Padthaway GI currently has about 10,000 acres (4,050 ha) planted to vines. About 60% of the vines are red grapes, led by Shiraz and Cabernet Sauvignon with a bit of Merlot and Pinot Noir in the mix. Of the 40% planted to white grapes, the majority are Chardonnay—along with a smattering of Riesling, Pinot Gris, Semillon, and Sauvignon Blanc.

We seem to be publishing a series of posts on Australia’s Limestone Coast. Click here to read the first installment (Mount Benson) and here to read the second (Mount Gambier). Soon to come: Coonawarra, Wrattonbully, and Robe.

References/for more information:

The Bubbly Professor is “Miss Jane” Nickles of Austin, Texas… missjane@prodigy.net

The Newer Volcanics and Leg of Mutton Lake: the Mount Gambier GI

Blue Lake at Mount Gambier, South Australia

In terms of wine regulations, Mount Gambier is the youngest of the six regions that make up Australia’s Limestone Coast wine zone. The first vineyards here were planted in the 1980’s, with the area being officially declared the Mount Gambier Geographical Indication in 2010. Most of Mount Gambier’s vines were planted between 2001 and 2010.

The Mount Gambier GI is located in the southeast corner of the state of South Australia, bordering the state of Victoria to the west, the Coonawarra Region to the north, and the ocean to the south. The area surrounds the town of Mount Gambier as well as Mount Gambier itself.

Mount Gambier (the mountain), considered a young and not-quite-dormant volcano, rises to a height of 620 feet (190 m). The top of Mount Gambier is crowned with a landmark known as the Centenary Tower, built to commemorate the 100th anniversary of the Mountain’s sighting by European explorers and it’s naming in honor of Lord James Gambier, the admiral of the fleet. The mountain is also known as Ereng Balam—the name given to the mountain by the original Aboriginal inhabitants of the area—meaning “home of the eagle hawk.”

The Newer Volcanics: Mount Gambier is part of the Newer Volcanics—a chain of small volcanoes and mantle plumes formed by the East Australia Hotspot that stretches across Southeastern Australia. These volcanoes are the source of the young volcanic soils that are found in the area—in addition to the limestone formed many millennia ago. Click here to see a surprising map of Australia’s Newer Volcanics. 

Photo of Leg of Mutton Lake circa 1880, via the State Library of South Australia #B 21766/6 (Public Domain)

Leg of Mutton Lake: The area on and surrounding Mount Gambier (the mountain) contains four maars—volcanic craters with low rims—that have filled with rain water to become the four lakes of the area: Blue Lake, Leg of Mutton Lake, Valley Lake, and Browns Lake. Two of these, Browns Lake and Leg of Mutton Lake, have become dry in recent years due to the lowering of the water table. The irresistibly-named Leg of Mutton Lake is, as one would hope, so-called due to its shape. Both of the surviving lakes—Blue Lake and Valley Lake—are surrounded by pine trees and hiking trails despite being located just outside of the town center.

Blue Lake, as its name would imply, turns a vibrant cobalt-blue color (from its more typical steely-grey) every December through May. The precise cause of the changing color is not quite agreed-upon, but most scientists believe it to be the result of the warming of the surface layers of the lake, which allows tiny crystallites of calcium carbonate (a by-product of the region’s limestone bedrock) to form. This phenomenon results in a scattering of the blue wavelengths of sunlight, creating the bright blue hue. Blue Lake is about 240 feet (73 m) deep, making the bottom of the lake itself about 98 feet (30 m) below the level of the town’s main street (Commercial Street).

Map of the Limestone Coast Zone via: Phylloxera and Grape Industry Board of South Australia

The Wines of the Mount Gambier GI: There are currently 470 acres (190 ha) of vines planted in the Mount Gambier GI. Of these, 66% are white grapes including Sauvignon Blanc, Chardonnay, and Pinot Gris (in that order) along with smatterings of Viognier, Riesling, and Semillon. Of the 34% of the vines that are planted to red grapes, the great majority are Pinot Noir, along with smaller amounts of Cabernet Sauvignon and Merlot.

Wineries operating out of the Mount Gambier GI include Benarra Vineyards, Blue Water Wines, Caroline Hills, Herbert Vineyards and Nangwarry Station. Few if any of these wines are exported to the United States, so you’ll want to seek them out on your next trip to South Australia. Mount Gambier is located mid-way between Adelaide and Melbourne and just a day’s drive (280 miles/450 km) away from each.

References/for more information:

The Bubbly Professor is “Miss Jane” Nickles of Austin, Texas… missjane@prodigy.net