Days of Terroir - Geology in a Glass 

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.

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 white wines from a "terroirist" winemaker in Alsace: "When he speaks of a granitic soil, the wine in your glass tastes of it."

Grapes – true berries

Grape growing regions are broadly distributed in the temperate zones around the globe.  Vinifera grapes can be characterized as requiring Mediterranean climates and are adapted to a wide variety of soil conditions, from high pH and slightly saline, to acidic and clayey. Deep, well-drained, light textured soils are best for wine grapes. Highly-fertile soils are unsuited to high-quality wine production, since the vigor and yield of the vines must be controlled and managed.

With an annual production exceeding 12 billion pounds worth an estimated $3 billion, grapes are the highest-value fruit crop in the United States. Today, United States grape and wine production is dominated by California; however, production is increasing is many other states.

Texas Viniculture

Some of the oldest wine growing areas in the United States are found in Texas. In the 1650s, Franciscan missionaries planted vines in West Texas near El Paso. Some vineyards in Texas pre-date the vineyards planted in California by more than one hundred years.

Texas is America's fifth largest grape and wine-producing state according to a 2007 study by industry analysts in conjunction with the Texas Wine and Grape Growers Association. Texas has more than 220 family-owned vineyards with 3,100 acres producing more than 2.4 million gallons of wine each year.

The University of Texas System is the largest wine producer in the state with over 1,000 acres planted near Fort Stockton. First established as an experimental vineyard in 1987, the university leases the land to a group of Bordeaux wine makers who produce under two labels - Sainte Genevieve and Escondido Valley.

Texas is roughly divided into three main wine growing regions spanning a diverse range of geology and microclimates that allows many different types of grapevines to grow. The North-Central Region spans the northern third of the state from the New Mexico border across the Texas Panhandle and towards Dallas. This includes the Texas High Plains which has the highest concentration of grape growers in the state. The eastern third of the state makes up the South-Eastern Region which encompasses the area around Austin, San Antonio, and Houston. The high humidity at the northern end of this area makes it difficult to grow vinifera grapes, while vines of the native muscadine family flourish. At the far south end of this region, along the Mexico–United States border is the state's oldest winery, Val Verde, which has been in operation for over a century. The Trans-Pecos Region encompasses the central-western third of the state where about 40 percent of the state's grapes are grown in some of the highest altitude vineyards. More than two thirds of the wine produced in Texas comes from this area.

The Texas High Plains have become a major wine grape production region and have been officially recognized as an American Viticultural Area since 1993. The distinctive characteristics of the High Plains are derived from its unique terroir - a semi-arid climate with hot summers and mild winters, high elevation, sedimentary and eolian geology, and suitable soils found nowhere else in the state.

Texas High Plains vineyards are planted primarily on three similar reddish calcareous soil series (tiera roja) widely distributed in the region. These are very deep, well drained, moderately permeable soils derived from sandy (Patricia and Brownfield series) or loamy (Amarillo series) eolian sediments from the Pleistocene-age Blackwater Draw Formation. These soils are well-suited for grape production with a low to moderate fertility and good drainage, yet adequate water-holding capacity.

Climatic conditions are also conducive to high-quality grape production; relatively low annual precipitation and low relative humidity provide an environment that inhibits most fungal diseases of grapes. Although the region is considered a hot climate for grape production, temperatures become favorably moderate at night during the fruit ripening period owing to the high elevation (more than 3,500 feet above mean sea level) and the low relative humidity. High solar radiation contributes to vine fruitfulness and good color development in red wine grapes.

The most notable wineries on the Texas High Plains are Llano Estacado, Caprock, and Pheasant Ridge. Pheasant Ridge, ten miles north of Lubbock, has been owned and operated for more than 15 years by geologist and former HGS member Bill Gipson. Gipson graduated with a degree in geology from the University of Texas in 1949, worked as a petroleum geologist for Pennzoil starting in the 1960s, and later was president of POGO Resources in the early 1990s. While working for Pennzoil and traveling frequently to California, he developed a great interest in wine and an appreciation for terroir. Seeking to become involved in viniculture in Texas, Gipson’s knowledge of geology and terroir led him the High Plains where the permeable calcareous loamy soils and the microclimate are similar to the classic wine-making regions in France. He purchased a share of the existing 50-acre Pheasant Ridge Winery in the 1980s and became the owner in 1993. Despite the threat of hail storms and late freezes, Pheasant Ridge now produces about 6000 cases annually and the winery’s cabernet sauvignon and chardonnay have won in national competitions.

The idea of geology imparting its essence to wine, that one can taste the earth in a glass, is appealing, a welcome link to nature and a place in a delocalized world. "The trouble is, it’s not true," write Harold McGee and Daniel Patterson in a May 2007 New York Times article titled Talk Dirt to Me. The authors contend that the skills of the winemakers and the biological interactions of yeast and the grape during fermentation are responsible for the range of tastes and textures, even minerality, that are found in wines.

"Plants don’t really interact with rocks," explains Mark Matthews, a plant physiologist at the University of California, Davis who studies vines. "They interact with the soil, which is a mixture of broken-down rock and organic matter. And plant roots are selective. They don’t absorb whatever’s there in the soil and send it to the fruit. If they did, fruits would taste like dirt." He continues, "Any minerals from the solid rock that vine roots do absorb — sodium, potassium, calcium, magnesium, iron, a handful of others — have to be dissolved first in the soil moisture. Most of them are essential nutrients, and they mainly affect how well the plant as a whole grows."

The fermentation process metabolizes grape sugars into alcohol coincidentally producing dozens of aromatic chemicals that make wine more than just alcoholic grape juice. McGee and Patterson write, "It’s because of the yeasts that we can catch whiffs of tropical fruits, grilled meats, toasted bread, and other things that have never been anywhere near the grapes or the wine. The list of evocative fermentation products includes an organic sulfur molecule that can give some wines a ‘flinty’ aroma. And there are minor yeasts that create molecules called volatile phenols, whose earthy, smoky flavors have nothing to do with the soil but are suggestive of it."

So, if vines absorb only select elements from rock that are dissolved in soil moisture, if grape and wine components are not a reflection of the rocks’ minerals, and if earthy aromas in wine come from microbes and not from the earth, do soil minerals have any real role in wine flavor?

Maybe. Hildegarde Heymann, a sensory scientist at the University of California, Davis, is skeptical about the usefulness of the terms "terroir" and "minerality." "People who talk about minerality are describing something they perceive that’s hard to grab on to," she says. "We do know that mineral ions can affect wine flavor by affecting acidity, chemical reaction rates and the volatility of aromas. And we’re just now looking at whether they can affect the body of wine, its ‘mouth feel.’ They might." It is possible, then, that soil minerals may affect wine flavor indirectly, by reacting with other grape and yeast substances that produce flavor and tactile sensations, or by altering the production of flavor compounds as the grape matures on the vine.

Beer of various varieties has been consumed for thousands of years dating back to at least the third millennium BC. Beer is alcohol fermented from grain, and most beer today is fermented from barley that is partially germinated, or malted. Hops, a type of flower, is added to give a bitter, fruity taste to the beer.

But it is the water used to make beer that provides the direct connection to geology, writes Chang. Beer is more than 90 percent water, and because almost all brewers use water from wells, not from surface water sources, the mineral content of the product is strongly affected by the underlying geology. Thus, local geology has had a strong influence on the style of the traditional beers brewed in different regions.

Early commercial brewers in the 1800s encountered the problem that beer spoiled quickly and did not travel well. However, beers from the 30 or so breweries in the small town of Burton-on-Trent in England were the exception. Decades later it was demonstrated that groundwater from the sandstone formations underlying Burton-on-Trent were ideal for making the traditional regional style of beer called pale ale or English bitter. Some of these beers traveled so well they were carried to far-off British colonies as India pale ale. The groundwater was rich in minerals like gypsum and sulfates and was slightly acidic in the pH in the range of 5 to 5.5 that is necessary for the proper extraction of malts. The sulfates in the groundwater acted as a preservative.

Brewers in the town of Pilsen, Czech Republic draw groundwater from underlying aquifers composed of fractured metamorphic rocks. This groundwater water has a very low mineral content and moderate acidity producing the light, clean taste of the traditional regional lager-style beer known as Pilsner.

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It has been a tumultuous year for Houston and the Houston Geological Society. It was a year that saw wild swings in energy prices, a powerful hurricane, an economic collapse, and a historic and often rancorous presidential election.

When the HGS’s administrative year kicked off in July 2008, the price of a barrel of oil was riding high, surging to a record price of more than $147. There seemed to be no stopping the upward trend. Record oil company profits and boom times were here again. Raise your hand if you thought we would see $200 per barrel oil by the end of 2008. I see a few hands, but the rest of you who did not raise your hand are just in denial. See the Editor’s column in the September 2008 HGS Bulletin for some perspective on the price of energy from the distant historical viewpoint of nearly a year ago.

Since those bygone giddy days of last summer, the price of oil fell to less than $35 per barrel by the end of 2008. It turns out that the spike in the price of oil in 2008 really was due to speculation after all. By May 2009, the price of oil had recovered somewhat to around $54 per barrel. Forecasts for future prices are now more moderate, but likely more realistic.

There have been other oil booms, notably during the period between 1982 and 1985 when workers from around the United States surged into a burgeoning Houston. These heady times are inevitably followed by a downturn. The mid-1980s downturn lasted many years. In retrospect, the year 2008 may be notable for having one of the briefest oil boom-bust cycles.

As summer slid towards autumn, the Gulf of Mexico turned violent, unleashing Hurricane Ike. On September 13, 2008, Hurricane Ike roared across the Texas coastline and raked Houston and neighboring municipalities. While life returned to normal for most Houstonians shortly after power was restored, coastal communities were devastated and may take many years or decades to recover, if ever. See the Editor’s column in the December 2008 HGS Bulletin for a discussion of the merits of the Galveston seawall.

The autumn and winter tumble in the price of oil coincided with the slide in the stock market and the disintegration of the global economy. The real estate market in many parts of the country crumbled leading to record foreclosures and toxic debt. We are now facing the worst economic situation at any time since the great depression. The federal government has had to provide tens of billions of dollars in TARP and stimulus funds to prop up profligate banks and financial institutions.

A full economic recovery may be years away, but there are hopeful signs that the crisis is ebbing. Houston has fared better through this economic whirlwind than many parts of the country. Because Houston real estate prices did not rocket they way they did in Florida, Arizona, and California from 2001 to 2007, the fall here has been less severe.

At the end of 2008 and the beginning of 2009, America participated in the ideals of founding fathers by electing a president and witnessing the peaceful transition of our government to a new administration, a new administration with a stated goal of restoring "science to its rightful place." Science and politics have not always been companionable. See the Editor’s column in the November 2008 HGS Bulletin about this sometimes contentious relationship.

With this issue of the HGS Bulletin, my term as Editor draws to a close. Hopefully, you found some worthwhile reading in these pages. It has been a great experience and I have learned a lot. I have had the pleasure of meeting many dynamic people who donate their time to make the HGS a great organization. I encourage all members to get involved with some part of the society even if you just come out to the technical meetings.

My thanks go to the fine HGS editorial board of Charles Revilla, James Ragsdale, and editor-elect Gordon Shields. Their insightful and timely editorial reviews and comments kept me on the right path often through some tough sledding. Good luck to Mr. Shields as he dons the editor’s mantle for 2009 - 2010.

Thanks also to Lisa Kruger for her patience and skill each month assembling the Bulletin and producing a great looking publication. Prime Source Office Solutions did a fine job as the Bulletin printer and mailer. Gratefully acknowledgement also goes to Lily Hargrave in the HGS office who managed the flow of advertisements from diverse sources and the financial aspects of the Bulletin.

Thank you to our advertisers for your support throughout the year and to the authors who contributed the items presented in the Bulletin.

Be well, do good work, and stay in touch.

 

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Michael F Forlenza
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