Washington Wines and the Ice Age Floods

Fine Wines from the Ice Age Floods
Washington wines are famous for bold fruit, zesty acidity and balanced tannins, but why? It was the ancient Ice Age Floods that created a region that’s good at growing grapes. These floods were big, really big. The floods that carved out the Columbia Valley were over 10 times taller (400 ft tall) and raged across the land at 60 mph. Fortunately, this happened 20,000 years ago, so there weren’t many Washington residents — save for a few wooly mammoths.

How did flooding create a wine region?
The land in eastern Washington closest to the ancient Lake Missoula is sparse and this area is called the ‘Scablands’. During the cataclysmic floods occurring at the end of the last ice age, the torrents rushed down the Clark Fork and the Columbia River to collect in eddies and valleys and drop sediment. If you can imagine, they dropped everything from large boulders and trees to microscopic silt. The silt, referred to as ‘Warden silt loam’, is what collected in the many river valleys of Washington.

(Articles condensed from Wine Folly - Gigantic Floods Made Washington Wine Country)

So, what is it about this flood that makes wine so good?
The deposits are deep, relatively low nutrient and well drained. For vineyards this is perfect terroir; it means the vines grow very deep root structures to collect nutrients and water. The more the vine is integrated with the soil, the more it creates consistently good grapes. Just so you know, there is a strange correlation to the highest rated wines coming from mature vineyards with deep deposits of this special flood soil.

Concentrated Fruit Flavors
The younger soil keeps the wines tasting fresh and fruity but, in order to have the concentration, there needs to be a lot of sun. Eastern Washington is a high desert area that gets 300 days of sun!

Heightened Acidity
The acidity in Washington wines is typically higher than California wines. This is what gives Washington wines a tart mouth-watering taste and it also means they have age-worthiness. In order to produce grapes with higher acidity in a sunny area, the nights need to be cool. Cold nights reset the vineyards and make it possible so that as grapes ripen, they don’t lose precious acidity.

Medium Tannins
Great wines have tannin, but not too much. Wine growing and grape selection (e.g. Merlot) has a lot to do with how much tannin a wine has, however a region’s environmental traits affect how the tannin tastes. Thick skins and ripe seeds are important factors to a smooth and ‘sweet’ tasting tannin.