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It's the Soil, Silly!
by Cole Danehower

In one of the most felicitous phrases in wine writing, the great Hugh Johnson once called vineyard soil “the unseen dankness where the vineroots suck.” It is in this deep and dark place where many people believe wine is really made.

Here in the Pacific Northwest, some of the most cataclysmic geologic forces ever to scar the face of the earth have created unique terraforms that profoundly influence the character of our wines and helps distinguish them from wines grown on other geologic foundations. Understanding the nature of our soils and their relationship to our wines can only help us better appreciate the special qualities of Pacific Northwest wines.

The Theory of Terroir

It is common these days to hear a lot of loose talk about “the terroir of Oregon” or the “terroir of Washington,” (and even the terroir of this vineyard or that site) but little is ever written to define what is meant by terroir.

“Terroir is an overused word,” says Patty Green of Patricia Green Cellars in Newberg, Oregon, “but to me it describes what different soil types deliver into the wine—for me soils play a huge part in the flavor of a wine.”

The idea that it is the character of the soil that is most responsible for the character of the wine is, like most great concepts in winemaking, primarily the invention of the French. But here in America, we have tended to radically simplify their complex and nuanced concept of terroir, and allowed it to become a shorthand term meaning generally “the impact of the land and soils on the vine and wine.”

And since the Pacific Northwest has landforms and soils that are distinct from other regions (California, for instance), it would seem to follow by the theory of terroir that the wines we produce would be distinctive as well.

After all, it only stands to reason: grapevines depend upon the soil for their nourishment, and it is because of that nutriment that they can fulfill their reproductive imperative, the ripening of fruit. The compositional qualities of different soils—their varying mineral and nutritional contents—must surely influence the way the vine grows, and consequently the characters of the fruit that vine can ripen.

And so, it would seem, it does!

The Willamette Valley Soils

Perhaps the place in the Northwest that most clearly shows how soils can impact wine character is Oregon’s Willamette Valley. Here the cataclysmic forces of earth’s geology (see sidebar) have resulted in two predominant soil types upon which Pinot noir is planted: volcanic and sedimentary.

At the mid- and higher elevations of the hills and bluffs that rise from the floor of the valley, volcanic soils—typically a distinctive red color—are generally found that contain decayed basalt, clay, and occasional interloping rocks and boulders delivered here by the Missoula Floods (an ancient series of massive floods that periodically swept through what is today the Columbia River basin). The most commonly recognized volcanic soil type is Jory, which tends to be between 4- and 6-ft. deep, overlaying a basaltic bedrock base. This is the predominant soil type from the prime Pinot producing areas of the Dundee and Eola Hills.


Artist's Idea of the Glacial Lake Missoula, by Byron Pickering

Sedimentary soils (some of which are marine in origin, and some which were deposited by the Missoula Floods) are found at lower hill elevations in the north Willamette Valley, along the foothills of the Coast Range, and in hills around Eugene, in the south Willamette Valley. These soils consist of yellow-brown-red silty-clay and loam, usually overlaying sandstone bedrock by 3- to 5-ft. This is the soil type often generically referred to as WillaKenzie (though a recent reclassification of sedimentary soils has changed the technical nomenclature). Pinot noir is planted on the sedimentary soils surrounding the Dundee Hills, the Chehalem Hills, Ribbon Ridge, Coast Range foothills, and other locations.

Over the years, winegrowers have come to see that the broad character of Pinot noir is different depending upon which if these two soil types it was grown in. Taking a broad view, Pinot from the volcanic soils tends to show big cherry and brambly red berry flavors along with accents of flowers and spices. Winemakers have noticed as well that these wines are often very consistent in their character, from the time they are picked, through fermentation and ageing, and even in the bottle.

Sedimentary soil Pinot noir, on the other hand, tends to display a darker fruit aspect, with more blackberry and plum nuances, as well as additional notes of earth, pepper, and minerals. Also, these wines tend to evolve more as they age, displaying subtly different aspects as they evolve.

Patty Green, for one, attributes these different styles to the different soils.

“After our first vintage,” working with sedimentary soil vineyards, she says, “we clearly had a feel that there was something different going on with the wines from the marine sediment soils as opposed to the volcanic soils we had in the cellar previously. It was really exciting to see how these wines each had their own character, and how the taste of the soil was delivered in each of the wines.”


The Columbia Valley Soils

Washington’s Columbia Valley appellation (encompassing the Yakima Valley, Red Mountain, and Walla Walla AVAs) was perhaps even more dramatically impacted by the Missoula Floods then the Willamette Valley was. However, the Columbia Basin experienced much more volcanic activity, and the topography and soil composition is thus quite different than in Oregon.

The bedrock of most of the Columbia Valley consists of massive basalt flows—in fact, the largest lava flows on earth—that were deposited by massive volcanic eruptions. Over the eons, the force of the Missoula Floods eroded huge channels and cataracts in the landform and deposited layers of sediments across the Columbia Plateau. As geologic time progressed, wind and other forces eroded rocks on the high points of the plateau, and helped re-arrange and re-deposit sediments across the area.

Today, much of the region is covered by a thick layer of loess (fine grained calcerous silt) that provides the topsoil for much of the region’s best vineyards. But the actual composition of the loess varies considerably, and accounts for distinctive wine qualities, even in nearly contiguous vineyards.

For instance, two of the most famous Washington vineyards are separated by only about 500 yards, yet each produces wines of distinctly different characters. Ciel du Cheval vineyard sits on top of an ancient gravel bed, with a thin layer of weathered topsoil. The red wines grown here are well-known for their elegance, complexity, and softness. Nearly next door, Klipsun Vineyard’s soils are much deeper, sandier, and with more loam. Their red wines are famous for displaying bigness, power, and concentration.

Connoisseurs of Washington’s Cabernet sauvignon and Merlots will undoubtedly have compared their relative qualities with the great wines of the same varietals from California. If terroir has any reality, the differences in overall character (winemaking expertise aside) can be chalked up to the differences in soil compositions. Washington’s relatively arid, calcerous, and sandy soils are said by many to impart mineral notes, depth, and softness that are different from wines made in California’s more fertile soils.

In the end it may not be quite fair to say that the great wines of the pacific Northwest taste like dirt, but it is certainly the dirt of the Northwest that makes great wines!

 

From the USDA:

The Jory series soil consists of very deep, well-drained soils that formed in colluvium derived from basic igneous rock. These soils are in the foothills surrounding the Willamette Valley. They have been mapped on more than 300,000 acres in western Oregon. They are named after Jory Hill, Marion County, Oregon.

Jory soils generally support forest vegetation, dominantly Douglas fir and Oregon white oak. They are very productive forest soils. Many areas have been cleared and are used for agricultural crops. The Jory soils and the climate of the Willamette Valley provide an ideal setting for the production of many crops, including Christmas trees, various berries, filberts (hazelnuts), sweet corn, wheat, and many varieties of grass seed.

The soils are suitable for the grapes used in the expanding wine industry. Growing urbanization of the Willamette Valley is resulting in a great deal of pressure for development in areas of the Jory soils.


Reprinted with permission USDA

 

 




 






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Terroir - A French concept that is difficult to translate, but which is frequently used in wine discussions. The full term, gôut de terroir, generally means the total characteristics of a vineyard location that combine to create a unique “taste of place.” The idea is that each grape growing site has its own particular set of circumstances—elevation, aspect, topography, soil composition, wine, rail, sunlight hours, etc.—that combine to create a unique character that can be tasted in the wines grown from that spot. Further, terroir is neither good nor bad, but is indigenous to the spot where the grapes were grown—it is just as possible to have a terroir that is unpleasant as it is to have one that is good.

The idea, then, is for the grower to find terroirs that produce appealing wines. Unfortunately, most people feel that terroir doesn’t truly show itself in a vineyard until the vines reach a certain age, or until the roots of the vines grow deep enough to be in contact with the bedrock. Though a controversial concept in American winegrowing, ity has proven particularly appealing in the northwest.

 

The most commonly recognized volcanic soil type is Jory, which tends to be between 4- and 6-ft. deep, overlaying a basaltic bedrock base. This is the predominant soil type from the prime Pinot producing areas of the Dundee and Eola Hills.

 

What About Climate?

Skeptics of terroir point out that the effects of climate—sunlight, rainfall, temperature, wind—have at least as much, if not more, to do with the ultimate quality of grape growing as does the soil in which the vine is planted.

They have a point!

It would be difficult indeed to declare that there is an “ideal soil” for the growing of winegrapes—there is almost no soil type, given proper drainage, where vinifera can’t be grown. Yet it is quite easy to define an “ideal climate” for different winegrape varietals, Indeed, vinifera grapes simply can’t be ripened (or even grown at all) under many common climate conditions.

So climate most definitely does play a pivotal role in determining the quality of wine. Just look at how Pinot noir grown in Oregon’s cool climate regions consistently delivers a different character wine from Pinot noir grown in California’s warmer climate areas.

But the importance of climate does not invalidate the importance of soil in determining the character of wine. The fact is, the full meaning of terroir encompasses both the soil and the climate (as well as, truth be told, the culture and even psychology of the winegrower and winemaker).

It is a misunderstanding of the concept of terroir that leads people into the false dichotomy of “soil is more important” or “climate is more important.” Actually, they both are more important—and the best Northwest winegrowers constantly strive to understand and use the myriad ways the weather and dirt interact with the vine!

 

Titanic Tectonics
of the Northwest

The geology and topography of the Pacific Northwest are the result of some of the most titanic tectonic events ever detected. Nowhere else on earth have geologists found evidence of such gargantuan volcanoes and floods as is found in what is today the wine country of eastern Washington and northern Oregon.

For instance, the bedrock of the Columbia Valley consists of an estimated volcanic eruption volume of 3,000 cubic kilometers of what is today basalt rock. As a comparison, the eruption of Mt. St. Helens released approximately one cubic kilometer of material—and we think that was big! The erosions and uplifts of this material over the eons has resulted in some of the largest swaths of sedimentary soils on the continent.

The Missoula Floods were equally enormous. Geologists estimate that the ancient ice dam that held back the glacial Lake Missoula (formed during the last Ice Age along the Clark Fork River in northern Idaho)) was about 1,968 feet deep. When that dam broke (as it repeatedly did over time), it sent approximately 2,500 cubic kilometers of water across the Columbia Plateau and down into the Willamette Valley. The water raced at a speed and volume that equaled 10 times the combined flows of all the world’;s rivers today—that’s a heck of a lot of water! It has been estimated that the depth of the flood in the Willamette Valley may have been as high as 400-ft.

For more about the Missoula Floods and the formation of the Columbia Gorge, see our article:

Catyclysm, Light & Passion, How Washington Came to Produce Some of the World's Greatest Wines
by Tim Seury