“It’s Willamette, Damnit!”: Diving in to the Deep End of Willamette Valley Pinot Noir
The Willamette Valley AVA (American Viticulture Area) is famous for complex and nuanced Pinot Noir. The Pinot Noir grape is known for its expression of “sense of place” – meaning the wines reflect the land and the conditions in which it is grown more than most varietals. In this 2-part blog series, I’ll explore the geological history of the Willamette Valley and how the combination of soils and microclimates contribute to the many expressions of Pinot Noir from this highly-acclaimed young wine region.
Part 1: Let’s Get Geological
The gently-rolling hills, lush valleys, and tranquil river meandering through Oregon’s Willamette Valley belie the violent and tumultuous history that has made this corner of Northwestern Oregon perfect for producing world-class Pinot Noir. The story begins around 200 million years ago, when the supercontinent of Pangea was surrounded by the single great ocean, Panthalassa.
For hundreds of millions of years, much of the west coast was at the bottom of the ocean. As the Pangea landmass broke apart, the Juan de Fuca tectonic plate began to slowly subduct under the North American plate, gradually lifting the edge of the North American plate out of the depths. The tremendous force of the colliding plates buckled the land, giving rise to the inland Cascade Mountains and to the Coastal Range. Between these two ranges, the Willamette Valley was slowly pushed out of the ocean and the ancient marine sedimentary soils that had been formed by decaying sea life are newly exposed to air and sun.
The movement of the tectonic plates is also responsible for the existence of the “Ring of Fire” – the horseshoe-shaped zone encompassing nearly all of the Pacific Basin that is responsible for 90% of the world’s earthquakes and more than 75% of the world’s volcanoes. One of the largest volcanic events in the history of Earth occurred in the Cascade Range around 15 million years ago, when rivers of lava flowed from many fissures and covered the ancient marine sedimentary bedrock with layers of volcanic basalt.
Continued seismic activity from the many eruptions and plate subduction thrust even more ridges and hillsides up from the valley floor, twisting and contorting the earth to expose the many strata of sediments like an off-kilter layer cake. A few of these uplifts that dot the valley have been designated as sub-AVAs as they each have a unique combination of soils and microclimates that yield noticeable flavor profile differences (more on this in the next blog!)
The next major geological influence occurred during the Ice Age that began around 2.5 million years ago. Glaciers slowly eroded the rock and as the glaciers receded the powdery loess was carried to the valley by rivers and then blown onto the hillsides by gale-force winds, particularly in the Northern area of the Willamette Valley.
The final valley-defining geologic event known as the Missoula Floods was actually a series of floods that occurred over 40 times between 18,000 and 15,000 years ago. A massive ice dam (2,000 feet high and 30 miles across) blocked the flow of the Clark Fork River in what is now Montana, creating a massive glacial lake dubbed Lake Missoula. Every 30 to 60 years, the ice dam would breach and a wall of water over 400 feet high would rush down the Columbia River Gorge towards the ocean. This devastating recurrence would annihilate everything in its path. It widened and deepened the gorge, carried and deposited mammoth boulders and nutrient-rich soil along the way, and ended its westward journey in the Willamette Valley, where it formed a 400-foot deep lake, Lake Allison, leaving just the tops of the hills above water.
These events shaped the land and the complex mixture of ancient marine sediments, volcanic basalts, windblown loess, and the highly fertile topsoil of the valley floor contribute to the myriad of expressions that the Willamette Valley can produce. In the next blog, we’ll look at how these differing soil types influence the aromas, flavors, and style of Pinot Noir.
by @pdxwineseeker (Instagram)