I met Scott Burns at the
Pacific Northwest Section NAGT conference last June.
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| Scott Burns at 2011 PNW NAGT Field Conference in Malheur Count, Oregon |
Over some bottles of wine at the conference, it was suggested that I try and have some geology lectures at my community college. Since our berg is located at the edge of two separate viticulture regions, I invited Scott to come out and talk about Terroir, the relationship between geology/geography and wine. It turns out that this year Scott is on sabbatical having been selected as the
AEG Richard Jahns lecturer, he is travelling around the world giving talks on Terroir, Missoula Floods, Landslides, and or the Cascadia Subduction zone.
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| Washington Viticulture Areas |
I do not know much about wine, and I am far from a wine connoisseur (the subtle flavors and bouquets elude me), but the talk answered a couple of questions I had (and some I didn't even know I had). One thing which has vexed me is that when we moved to our current house, I planted a grape vine. In three years, I haven't gotten even a blossom, much less a grape so I have been watering and fertilizing it to try and get it healthy enough to produce grapes. It turns I have it all wrong. not only do vines typically take three years to mature, in order to get them to bear fruit, you have to stress them by withholding nutrients and/or water.
The other misconception I had had was that the reason Eastern Washington and Eastern Oregon were prime wine growing regions was because of the volcanic soils. While it is true that many of the Oregon wines are from volcanic soils, that is mostly in the cooler/rainier western part of the state where the lace of soil nutrients can be the stress that promotes fruit growth. Here in the eastern part, it is more likely to be water (or the lack thereof) that stresses the vine into producing grapes, thus most of the vineyards in this area are in richer silty soils deposited by the Missoula Floods.
Most of the main channel flooding occurred north and west of here, but the natural constriction of the Columbia River Gorge caused water to backflow up the John Day and Umatilla drainages (Lake Condon). A similar lake (Lake Lewis) was formed by flood waters backing up the Walla Walla drainage due to the restriction at Wallula Gap.
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| Missoula Flood transient Lakes created by topographic constrictions |
The emplacement of these flood deposit silts answered my final question, which was that despite similar climates, grapes were being grown in the Walla Walla Valley and in the Hermiston Area, but not further up the Umatilla River in the Pendleton or Mission areas. The simple answer is that the soils aren't there because the deposits were constrained to the narrow river valleys. I suspect that if I spend some time along the Umatilla River Valley, I should be able to correlate where the Umatilla river valley constricts near Echo to the deposition of Missoula Flood soils.
In all it was a good talk, it gave me more things to think about regarding the geology of the area, and learning more about terroir is a good reason to stop in some of the local wineries.
