By Joseph V Micallef
This is the first portion of a three-part series exploring the wines of southern Oregon. Subsequent columns will explore the wines and wineries of the Umpqua and Rogue Valley regions.
Over the last several decades Oregon has emerged as a major wine producer. The Willamette Valley, in particular, has gained worldwide fame for its pinot noir. The valley has certainly become the center of Oregon’s wine universe, accounting for around 71 percent of the grapes grown in the state.
Along the way it’s been forgotten that southern Oregon was the birthplace of Oregon’s wine industry. Grapes were first planted in the region in the mid-19th century. In the mid-1850s, Peter Britt, arguably Oregon’s first commercial wine producer planted a vineyard, Valley View, still in operation, next to his house overlooking Jacksonville in what is now the Applegate Valley AVA in the Rogue Valley. He produced his first wine in 1858.
Britt may also have been the first to plant pinot noir in Oregon. During his lifetime, he is believed to have planted some 200 different varieties of grapes in his vineyards. One wine that he produced carried the designation Burgundy. It’s not clear, however, if that wine was made from pinot noir.
The first documented planting of pinot noir in the state occurred in southern Oregon. In 1964, Richard Sommers planted pinot noir at his HillCrest vineyard in the Umpqua Valley. That was a year before David Lett and Charles Coury planted pinot noir in the Willamette Valley. The first Oregon Wine Growers Association was organized in southern Oregon and its founding members were all vineyard owners in the Umpqua Valley.
Today, southern Oregon has been largely eclipsed by the vinicultural fame of the Willamette Valley. All too often the region is dismissed as being too warm to grow quality pinot noir, the one variety most closely associated with the state, and relegated to the role of being a supplier of bulk grapes to winemakers in northern Oregon and California. There are many other grape varieties grown there, however, from tempranillo to viognier, some with the potential of producing world class wines, but these are little known outside the area.
That’s unfortunate because southern Oregon is a world class vinicultural region, presenting a complex geology and a terrain and mesoclimates, which lends itself to the production of a broad array of quality grapes from both cool and warm climates. Only now is its true vinicultural potential being discovered and appreciated.
The geology of southwest Oregon is very different from that of the northwest corner of the state. The entire west coast of North America, from Alaska through California, was created by the amalgamation of a series of what geologists call accreted terranes or continental arcs. Numbering about nine in total, these slivers of continental crust were joined with North America as a result of tectonic forces pushing various continental plates against the North American plate. When this process started, about 200 million years ago, the west coast of North America corresponded to Idaho’s current western boundary.
As tectonic forces pushed these continental arcs into North America, they often also pushed up portions of the oceanic crust. Volcanic activity also often accompanied this process, resulting in volcanic eruptions or volcanic intrusions into the uplifting oceanic bedrock. The result was a complex geological layer cake consisting of alternating strata of continental and oceanic crust and marine sediments interspersed with the residue of volcanic eruptions and magma intrusions.
In the Willamette Valley, however, this bedrock geology was overlain by a series of repeated, massive, flood basalt eruptions, often termed fissure eruptions, which ejected some 42,000 cubic miles of lava across southern Washington and northern Oregon. That’s enough lava to bury the entire United States under 40 feet.
These deposits were further shaped by a series of gigantic floods that marked the end of the last ice age. These floods, potentially numbering several hundred over a period of roughly 3,000 years, between 15,000 and 18,000 years ago, were created when ice dams holding back Great Lakes sized bodies of water repeatedly burst, unleashing a wall of water amounting to several hundred cubic miles across eastern Washington and the drainage of the Columbia River. These massive floods created the scab lands of eastern Washington and the Columbia gorge, and were responsible for depositing hundreds of feet of rich sediments in the Willamette Valley.
The fertile soils that resulted made the Willamette Valley one of the most productive agricultural regions on earth. Such regions, however, often do not lend themselves to quality wine production. Instead, those higher elevation areas, whose nutrient poor soils remained above the flood waters unleashed by the various ice age floods and which were not subject to the deposition of sediments, would centuries later become the Willamette Valley AVAs.
Southern Oregon was spared the impact of those flood basalt eruptions, as well as the later ice age floods. Unlike the Willamette Valley, the bedrock geology was not buried under hundreds of feet of sediments. The result is a complex mosaic of some 50 different soils, many tens of millions of years old, spread across a heavily faulted landscape. It’s not uncommon in southern Oregon to walk a vineyard and see a fault line dividing it with two very different soil types on either side of the fault.
Moreover, the intersection of three mountain ranges, the Coast Range, the Klamath Mountains and the Cascades, creates an undulating landscape across the Umpqua and Rogue AVAs, which presents a variety of aspects and elevations. Each 100 feet of elevation typically affects average temperatures by one to two degrees F. A north facing slope at a higher altitude can easily be five to ten degrees F cooler than a lower elevation, south facing slope.
The river valleys funnel cool breezes from the Pacific Ocean, 50 miles away, further extenuating those differences. The peaks surrounding the intermountain valleys often act like natural calderas, trapping heat and creating warm zones on the valley bottom. The result is that cool clime varietals, like riesling or pinot noir, can often be found in close proximity, sometimes literally kitty corner, to warm climate varietals like grenache, tempranillo, cabernet sauvignon or viognier.
The result is that over a length of roughly 150 miles, the southern Oregon AVA can host a range of grapes, which in Europe would span from Alsace to central Italy and from Ribera del Duero to the Rhine, making the southern Oregon AVA one of the most unique vinicultural zones in the world.
The Southern Oregon AVA
The southern Oregon AVA covers some 2.2 million acres, of which only about 8,000 acres are in vineyards. It consists of five separate AVAs, separated by four major rivers and includes portions of three mountain ranges.
Moving from north to south, those AVAs are: the Elkton, Red Hill, Umpqua Valley, Rogue Valley and Applegate Valley. The Elkton and Red Hill AVAs are enclosed within the Umpqua Valley AVA, while the Applegate Valley AVA is largely enclosed within the Rogue Valley AVA.
The principal grape varietal grown in the southern Oregon AVA is pinot noir. It amounts to 44 percent of the total vineyard acreage. Most of these grapes are sold in bulk to wine producers in the Willamette Valley and northern California. That’s unfortunate, because southern Oregon pinot noir, when properly cropped on the right sites, can have a very distinctive aroma and flavor profile.
The warm climate ensures both physiological and sugar ripeness, while the pronounced diurnal temperature variation ensures the retention of acidity. The result, on cool sites, when cropped at levels of around three tons per acre, can be lush, fruit forward wines with a backbone of well-integrated tannins and medium acidity.
Pinot gris amounts to 10 percent of the vineyard acreage, meaning that more than half of all of the vineyard acreage is devoted to pinot varietals. Syrah amounts to nine percent, cabernet sauvignon to seven percent and merlot to four percent of plantings. These warm climate varietals can thrive on the right site, producing cabernet’s reminiscent of Sonoma, while the syrah’s have a decidedly northern Rhone-like quality to them.
Chardonnay amounts to seven percent of total plantings. Tempranillo is generally considered a warm climate grape, but it has the advantage of early ripening. Its name is derived from the word temprano, Spanish for early. It accounts for three percent of total plantings, as does riesling, another cool climate varietal. There are approximately 70 other varietals that account for the remaining 16 percent of vineyard plantings.
The climate in the southern Oregon AVA varies from maritime to Mediterranean, with cool, damp winters and warm, dry summers. Site selection, however, can have a big impact and can offer a range of cooler and hotter mesoclimates.
Cooler portions of the Umpqua AVA, at higher elevations, are rated at about 1700 Growing Degree Days (GDD), roughly equivalent to cool climate regions like Champagne or Tasmania.
The southern portion of the Umpqua AVA is rated at around 2300 GDD, roughly equivalent to the Willamette Valley, Burgundy, Alsace or Ribera del Duero. Conversely, the warmer regions of the Rogue Valley AVA can rate as high as 3000 GDD, roughly equivalent to Bordeaux, Piedmont or Portugal’s Douro Valley.
Significantly, the southern Oregon AVA also has one of the most pronounced diurnal temperature swings of any wine producing region in the world, on average about 30 degrees F during the growing season and especially during the critical ripening period.
The region has more than 50 different vineyard soils. These soils fall into three main categories: volcanic, marine sedimentary bedrock and river sediments. The volcanic soils are different and far older than the volcanic soils in the north Willamette Valley. These soils are associated with two very different, albeit related, geologic processes. The volcanic soils in the north Rogue Valley are derived from the volcanic eruptions that created the Cascade Range to the east, which date from 10 million to about 50 million years ago.
To the west, there are volcanic soils associated with the amalgamation of the Siletz terrane, the last terrane to get absorbed into the west coast of North American. These volcanic soils were the result of underwater volcanoes and magma intrusions associated with the uplift of the oceanic sea floor as the Juan de Fuca tectonic plate collided with and was subducted under the North American plate.
These Jory soils make up a large portion of the Red Hill AVA in Douglas County and are similar to the Jory soils found in the Dundee Hills of the Willamette Valley. Additionally, there are pockets of volcanic soils, associated with local eruptions, scattered throughout the southern Oregon AVA, especially on its western side.
These volcanic soils are 35 to 45 million years old, making them roughly three times as old as the volcanic soils of the north Willamette Valley. They are more weathered, which means they have higher clay content, an advantage in southern Oregon as it allows for more water retention, and have even less nutrients.
Although they are all basaltic in origin, the volcanic soils in southern Oregon are associated with the subduction of the Juan de Fuca plate, rather than the hot spot induced flood basalt eruptions, and have a different geochemical profile.
The marine sedimentary soils are part of the oceanic crust, and its related sediments, which were forced up and accreted to North America as the tectonic plates collided. These are similar to the marine sedimentary soils found in the north Willamette Valley. These soils have a higher clay content than the sedimentary soils in the Willamette Valley and a darker red hue. They also tend to have more nutrients than volcanic soils.
The last major category of soils are stream terraces and alluvial fans that were laid down by ancient rivers beginning some two million years ago. These terraces consist of soils that have been eroded from higher elevations and mark the ancient courses of rivers. They are comprised of a mix of silt, sand and gravel. The combination of the three components being determined by the speed of the water carrying them.
The complex geology of Southern Oregon, its various soil types and wide-ranging topography permit the region to grow a broad range of grape varietals. Additionally, the extended hang time and the pronounced diurnal variation ensures both physiological ripeness and the retention of acidity. That’s the reason why southern Oregon can produce full bodied, aromatically complex, fruit forward wines with the acidity and tannic backbone that gives them the structure for prolonged aging.
Next, we will look at the wines of the Umpqua Valley.
Read the full article and subsequent articles here.