Walla Walla, Wash. -- Washington state claims for itself, “the perfect climate for wine,” but Whitman College instructor Dr. Kevin Pogue will travel to Italy later this week to highlight Columbia Valley terroir’s contribution to growing conditions, too.

Pogue presents a paper about the influence of basalt on the terroir of the Columbia Valley AVA at the VIII International Terroir Congress in Soave, Italy, on June 14-18. His paper focuses on the effects this distinctive igneous rock (predominant in the Columbia Basin) has on vines, specifically with respect to soil temperature, cluster temperature, vine chemistry and other attributes.

Basalt is relatively rare in vineyards of the world, Pogue notes in the paper; viticultural areas with basalt soils include the Canary Islands, the slopes of Mount Etna in Sicily, south-central France, northern Italy and Oregon’s Willamette Valley. The palisades above Napa Valley on Mt. St. Helena are columnar basalt.

Typically, basalt occurs where volcanic activity was or is common. In the case of the Columbia Valley and the Pacific Northwest, basalt  erupted more than 5 million years ago and today is covered by loess deposited during the glacial inundations known as the Missoula floods, between 13,000 and 15,000 years ago.

Pogue’s paper concludes that the chemical and thermal properties of basalt in the soils of the Columbia Valley have a significant influence on the AVA’s terroir.

“Vineyards within the Columbia Valley AVA covered by fractured basalt bedrock or basalt-rich alluvium have higher average ground surface and subsurface temperatures than their grass-covered counterparts,” the paper’s conclusion notes. “The extra heat is derived from infrared radiation from the sun-warmed dark-colored basalt, not from conduction from heated air.”

The paper also notes that vineyards planted on basalt bedrock should show an elevated iron content, due to the availability of iron here versus in the loess. “I hope to get our area in the spotlight a little bit while I’m over there,” Pogue told Wines & Vines.

This year’s conference currently has 147 registrants from 21 countries, but Pogue said it hasn’t typically attracted a lot of attention in the U.S. Just three U.S. researchers attended the previous congress in Switzerland. This year, Dr. Greg Jones from Southern Oregon University is on its scientific committee. Norm McKibben of SeVein Vineyards in the Walla Walla AVA, which lies entirely within the Columbia Valley, says Pogue’s research provides a better understanding of local growing conditions. “We do get a flavor change,” says McKibben, who opened his vineyards to Pogue for research.

But he adds that the influence of basalt is just one of several factors at play in his properties, which include the SeVein properties south of Walla Walla towards the Oregon line, and Les Collines, which sits at a higher elevation in the foothills of the Blue Mountains east of the city.

“You really have to taste it quite a bit in different regions to tell whether you’re getting the results of older vines giving a little better flavor or the basalt, or the vineyard manager changing his approach a little bit,” he says. “There’s no question in my mind that the basalt does help, but I can’t say that all of a sudden I can get this flavor of lead pencil in there.”

The fruit off the vineyards pleases winemakers, however, as it offers extra depth to the wines. This is true of Les Collines, which sits just three feet above the basalt rock, whereas the gentle terrain at SeVein sits about 12 feet above the basalt.

McKibben expects Pogue’s presentation to generate some interest in Washington state, where many wineries are showing a growing appreciation for regional differences. The number of AVAs in the state is increasing (two were approved last year alone), and seminars at industry meetings regularly showcase differences from wines made with grapes from different vineyards.

“Anything that draws attention (to our wines) so that people will try them is going to help us,” McKibben says.

The Columbia Valley AVA includes 6,670 acres of vines, primarily at elevations below 400 meters (1,300 feet).