Tunkalilla Vineyard

Eola-Amity Hills


Geology and Soil

Tunkalilla Vineyard is a concave slope in the belly of the south-facing escarpment of the southern end of the Eola Hills.

The Eola Hills run north south, parallel to the sedimentary coastal range to the West and the mighty volcano dotted Cascades to the east including Mt. Adams, Mt. St. Helen, Mt Hood, Mt. Jefferson and the Three Sisters most of which are visible from Tunkalilla Vineyard on a clear day.

Mount Hood from the top of Tunkalilla Vineyard (piror to Xmas tree removal)

At the southern foot of this terminal slope of the Eola Hills is the Van Duzer Corridor, which cuts westward through the coastal range allowing cool humid air to creep into the Willamette Valley from the cold Pacific to the west.

Tunkalilla Vineyard is perched above the eastern inland opening of the Van Duzer Corridor.

The Eola Hills (Eola is derived from the Greek for wind) are uplifted folds in volcanic basalt that flowed down the Columbia Valley from the Cascades to the east between 15 and 6 million years ago. 

The soil of Tunkalilla Vineyard is derived from this Miocene volcanic basalt, full of basalt rubble and boulders and very red and deep with minimal profile differentiation and is classified as the highly prized Jory soil of Oregon.

The soil and boulders of Tunkalilla Vineyard

The Jory soil is the state soil of Oregon and “are very deep, well-drained soils that formed in the colluvium derived from basic igneous rock.” They grade from dark reddish brown silty clay loam at the surface, to dark reddish brown clay, to red clay down at 4 to 6 feet deep.  

Tunkalilla Vineyard is at 600 feet ASL and is too high to have been inundated by the ice age Missoula Floods (400 feet) that have left a trail of sedimentary erratics (foreign geologies) across the Oregon landscape derived from Canada, Montana and all places between there and the Pacific where the mighty Columbia River enters the Pacific. The Columbia River and its spectacular Gorge were redefined by the more than 20 successive Missoula Floods over the last ice age 15,000 to 13,000 years ago. The Missoula floods are an interesting story but they are irrelevant to Tunkalilla Vineyard, which was high and dry, 200 feet above them when they happened.