The Dirt on Oregon Wine
Millions of years of geology made the soil that makes the wine.
by Bill Hatcher, Rex Hill Vineyards
Push a cloth from the corner of a table to its center. It gathers in little folds running roughly parallel to each other. This is in essence the geology at the core of Oregon's wine country. For millions upon millions of years, the Juan de Fuca plate has nudged the continental tablecloth to pleat chains of running ridges from northwest to southeast.
Pinot Noir refinement
Just as the geological upheaval of an ancient sea that formed the Alps toppled the neapolitan of soils signature to Burgundy's Côte d'Or, these bunched, sun-dappled ridges of the Willamette Valley are at just the orientation and elevation to consistently produce Pinot Noir of refinement and charm.
Although Oregon is not graced with Burgundy's minute variations of soil where, all else being equal, 50 meters' difference will produce entirely different wines, there are nonetheless distinctions that trace wines to their provenance.
Northern Willamette Valley soils
Two broad classes of soils mark the northern Willamette Valley, one volcanic, the other sedimentary. The volcanic soils are the detritus of the great Columbia River lava flows that blanketed modern-day Portland to a depth of 1,000 feet before ebbing in estuaries that reached as far south as Salem. These are the indigenous soils of the Red Hills and Eola Hills, home to Oregon's earliest wineries. The wines from these vineyards tend to the red fruits that are the hallmark of the Willamette Valley - cherries, raspberries, strawberries - and of Burgundy and cassis.
The sedimentary soils - Willakenzie, Laurelwood, Carlton, notable among others - are yesterday's arrivals in geological time. Some 15,000 years ago, vast Ice Age floods, known as the Missoula Floods for their source, swept untold amounts of rock, gravel, sand and silt across Idaho and into Oregon, deepening the Columbia Gorge before depositing hundreds of feet of material onto the pre-existing lava flows that underlay the Willamette Valley.
These flows filled the valleys and lower slopes, leaving the hilltops covered in the volcanic basalt described above. The vineyards on these soils are relatively newer, comprising Ribbon Ridge, Chehalem Mountain, and the districts north of the towns of Carlton and Yamhill. The sedimentary series soils have less water retention capacity than the volcanic and thus tend to produce more angular, structured wines with black fruit characteristics.
Seasonal Weather also a factor
Naturally, the growing season itself accentuates or mitigates the inherent nature of the soil. A cool, damp year softens the sedimentary-based wines while a dry summer renders intense expression from the most demure volcanic vineyards. But it is in the great years that the two soil complexions merge in a union of blue fruits, firm structure, and wines of uniformly great breeding.
Two broad classes of soils mark the northern Willamette Valley: one volcanic, the other sedimentary.
Volcanic soils produce wines that tend to the red fruits that are the hallmark of the Willamette Valley. Sedimentary series soils have less water retention capacity than volcanic and thus tend to produce more angular, structured wines with black fruit characteristics.