Friday, August 13, 2010
WALLA WALLA -- The Walla Walla Valley is renowned for its wine, but what about the area makes it particularly suitable for viticulture? According to geologist Kevin Pogue, the answer to that question lies buried just beneath our feet.
In a tour sponsored by Walla Faces Winery over the weekend, Pogue, chairman of the geology department at Whitman College, led a group of wine critics and members of the wine industry through millions of years of geological history.
Although Walla Walla's wine industry has burgeoned within the past decade, according to Pogue the ground for Walla Walla winemaking was literally laid 15 million years ago. That's when massive lava flows in Southeastern Washington, Northeastern Washington and Western Idaho created what Pogue described as "one of the largest basalt deposits on Earth."
That dense, heavy basalt bedrock weighed down the Earth's crust, pushing the Columbia River Basin and Snake River Valley to lower altitudes than the surrounding landscape. Walla Walla's low altitude is essential: Warm temperatures and long growing seasons are usually associated with elevations below 2,000 feet, although Pogue said his research suggests that wine can thrive at up to 3,000 feet in the area.
The next chapter of Walla Walla's wine story coincides with what Pogue called, "One of the greatest stories in geology" -- the Missoula floods, which occurred between 15,000-12,000 BCE.
The floods left sand and mineral deposits in Walla Walla, after the narrowness of the Wallula Gap forced the floods -- which contained 10 times more water than the combined flow of all the world's rivers -- to flow back into the Yakima, Snake River, and Walla Walla valleys creating a massive lake. At its deepest, the lake that was periodically created by Missoula flood waters would have taken about five days to drain, and submerged elevations as high as 1,200 feet in the Walla Walla Valley.
"What happens when a massive amount of water -- turbulent crazy water -- hits a constriction (and pools for five days)? All the sediment that's suspended is going to drop out." Pogue said.
The soils that dropped out of suspension Missoula flood waters, are the single most important "geological influence" of Walla Walla viticulture, Pogue wrote in a chapter of a book published in 2009. "The vast majority of Columbia Basin vineyards are planted in soils derived directly or indirectly from flood-deposited silt and sand. These well-drained soils facilitate irrigation and encourage the vines to root deeply." Pogue wrote.
While geological events created the foundation for Walla Walla viticulture, other factors like latitude and climate play an essential role in wine production. During the tour, Pogue explained that our latitude of 46 degrees north puts us right between renowned viticulture centers like Bordeaux and Burgundy. Additionally, while Walla Walla's arid climate might seem to contrast sharply with French countryside, according to Pogue the evolutionary ancestor of the modern grapevine originally grew in the arid Caucasus Mountains.
Although the right soils, climate, topography and other factors coalesce in the Walla Walla Valley to create excellent locations for viticulture, the diverse geology, geomorphology and climate patterns in the valley means that our vineyards are far from homogeneous.
Pogue uses the term "physical terroirs" to describe four different areas in the Walla Walla AVA that produce "distinct sensory characteristics" because of their physical locations.
The four Walla Walla physical terroirs include higher elevation vineyards (in the Palouse-like hills and Blue Mountain foothills) situated on the East ; lower elevation vineyards on the West side of the Valley with a thinner layer of loess that covers Missoula flood sand and mineral deposits; vineyards sown over the rocky remains of dry creek beds (creeks have moved across the surface of the valley over the course of millennia); and recent, experimental sites in the canyons and escarpments of the Blue Mountains, where viticulturists in have started mixing the thin top layer of loess with basalt by carving into the basalt bedrock.
Scientific studies indicate that mineral and chemical content of soil probably does not directly influence wine aroma and taste--in other words, you're not likely to pick out gentle murmurs of manganese in your wine's bouquet. The composition of soil, however, does indirectly affect wine quality by altering the "textural, hydrologic and thermal properties of vineyard soils," Pogue wrote. Since the composition of soil affects wine quality, wines grown in different soil compositions will have unique sensory qualities particular to their geological settings.
To test for evidence of the effect of physical terroir, Pogue has taken blind barrel tastings, finding what he called significant differences not only between vineyards with distinct terroir, but within vineyards of the same terroir as well. In a blind test, Pogue claims he can identify which one of Christophe Baron's (Cayuse) vineyards his barrel sample of wine came from.
Using barrel samples to taste for terroir is essential, since the wine that comes out of a finished bottle could be dramatically altered by the wine making process. "The wine making can completely overwhelm and mask any of the effects that the physical terroir is going to have," Pogue said.
After touring five different wineries that exemplified the different Walla Walla terroirs, Walla Faces (loess), Leonetti's aptly named Loess Vineyard, Pepper Bridge (Missoula Deposits), Cayuse (gravel stream bed) and Seven Hills (Louse/Basalt mix), visitors were invited to test/treat their palettes to different Walla Walla terroirs.
Richland wine blogger Dan McCool (idrinkyourwine.com) was anxious to see how much physical terroir had to do with the actual flavor of wine. After the tour, McCool and other guests imbibed two wines identical in vintage, grape and winemaker but came from two different terroirs (one from Leonetti's Loess Vineyard, the other from Forgotten Hills, a basalt cobblestone vineyard with silt and loam in the soil.
"Wow, way different ... I'm actually liking the Forgotten Hills better, it has more body and a much bigger nose," McCool said after the taste test. In the tasting rooms, others agreed that the two wines boasted distinct flavors and aromas. Of course, McCool cautioned the flavor of these barrel samples could change a great deal by the time the winemaker bottled them.
Although this tour was intended to publicize Walla Walla's viticulture to industry insiders, Lois Jasmer with Walla Faces said Walla Faces will hold similar tours for the public soon -- either this fall or spring. Jasmer said that the three-hour tour and subsequent wine tasting will cost around $50.
"Most of the wine tours around town are, more or less, people going from vineyard to vineyard tasting as many wines as they can; we wanted to do something a little bit different," Jasmer said.
For more information about the Walla Faces Geological tours contact Lois Jasmer firstname.lastname@example.org.
Omar Ihmoda can be reached at email@example.com.
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