Lesson 1 of 0
In Progress

Geologic history of the Pacific Northwest and the Missoula Floods

What made the Pacific Northwest great for wine?

To understand the wines of Washington and Oregon, we have to start with the formation of the geology of the regions. Throughout most of Washington and Willamette Valley in Oregon, we’re talking about just a handful of soil types for wine, making it easy to understand (unlike Napa Valley, which contains a full half of the known soil types of the world!).

We can break it into four simple groups.

Marine Sediment
Millenia ago, this whole region was under the ocean. As marine life died, it settled to the bottom of the sea and combined with the soils. Over time, as the earth’s plates pushed upward, this marine sediment layer became part of our story.

Volcanic Soils
Next up, the earth’s plates pushed together and the Pacific plate started to go under the continental plate. This caused upheaval (much like having a perfectly made bed, putting two hands on the blanket, and pushing forward), resulting in volcanoes being formed. As the volcanoes became larger and eventually blew, volcanic soils were developed along with a release of volcanic dust that blew all over the place.

Loess Soils
Pronounced “luhss,” these soils are wind-blown volcanic dust that settled throughout Washington and most of Oregon. It’s a great soil for vines, and positively ideal for winter wheat. Some areas have little to no loess, some areas have ten feet or more of loess soils.

The Missoula Floods
Now we get to the most recent ice age, and the biggest natural cataclysmic event the Pacific Northwest has ever seen. As the ice sheets melted and retreated into present day Canada, they formed Glacial Lake Missoula, which contained an extraordinary amount of water, held back only by an ice dam in present day northern Idaho.

When the dam broke, the lake drained. All at once.

Just imagine the force behind the flood. That wave was 400 feet high, racing at 60 miles per hour, destroying everything in its path.

And then the glaciers returned to do it all over again. Every 55 years, for a millennia, this cycle repeated itself.

What resulted from the Missoula Floods is the landscape and geology we know today. At elevation, above the flood line, the loess and volcanic soils dominate. At lower elevation, you have flood deposits (which are great for flowers, fruit, trees, and veggies, but not ideal for wine grape vines due to the high nutrition content … vines grow like weeds in the silt).

You can see the number of times the flood came through, via the layers of deposit it left behind.

Wine Folly: Gigantic Floods Made Washington Wine Country

I-Winereview: Mega-Floods and the Vineyards of Washington State

The top academic in the field of Washington State wines, soils, and geology is Dr. Kevin Pogue of Whitman College. Dr. Pogue has been featured in the New York Times as “Dr. Terroir” and his lectures are incredible.