The importance of soil and geology in tasting terroir; a case history from the Willamette valley, Oregon

Wines differ from each other based on seven different factors: the type of grape; the bedrock geology and resulting soils; the climate; the soil hydrology; physiography of the site; the winemaker and the vineyard management techniques. The first five of these factors make up what the French call terroir, “the taste of the place”. All around the world the geology and soils make up an important component of the terroir of the wine. In the Willamette Valley of Oregon in the United States, the terroir is strongly influenced by the bedrock geology and soils. The three dominant groups are the volcanic soils, the Jory Series, that are developed on the Columbia River Basalts and the Willakenzie Series of soils developed on uplifted marine sedimentary rocks in the foothills of the Oregon Coast Range. The third group is developed on Laurelwood Soils in weathered loess with pisolites in it on weathered Columbia River Basalt. The wines developed out of grapes from the three different soils are very different. They are so different that the Willamette Valley AVA has been subdivided into six new AVA’s based on the differences in terroir, primarily the soils and geology.