Tag Archives: Yakima Folds

Contemplation in Geology

“The Yakima Folds”
As Seen From Selah Ridge

A few days ago, we were walking along the new path of our irrigation pipeline when I stopped and gazed down through the Selah Valley into Yakima. What I saw was an excellent near ground-level perspective of the Yakima Folds. It made me stop and contemplate how the Yakima Folds were created and how they affected the way our local communities evolved.

The Yakima Folds were created 15.6 million years ago when opposing tectonic plate movement compressed the landscape, causing fold-like ridges to be created. The above image was taken from the base of Selah Ridge, north of Selah, looking down the throat of the gaps created by the Yakima River. The first set of ridges is the Yakima Ridge which separates Selah from Yakima. The second set of ridges are the Ahtamum/Rattleshake Hills Ridge which separate the city of Yakima from the lower Yakima Valley. The ridges in the far background are the Horse Heaven Hills.

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Looking Up

Selah Ridge

Looking up between the rows of trees, I can catch glimpses of the Selah Ridge.  The sagebrush covered hill sides are what the land is like without irrigation.  The strip of basalt rock is from the great Columbia Basin lava flows which occurred 14-6 million years ago.  It was pushed up as part of the Yakima folds development.

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A Perspective of Time

Argillite Boulder – Rattlesnake Mountain, Washington

This image depicts an interesting perspective of time.  The rock in the foreground was deposited here on Rattlesnake Mountain around 15,000 years ago.  The Rattlesnake Mountain and the Horse Heaven Hills in the background were created as part of the Yakima Fold formation about 1.5 million years ago.  The bedrock of this area is basalt from basalt flows through eastern Washington from 6-15 million years ago. The argillite boulder in the foreground is metamorphic rock from western Montana formed 1.5 billion years ago.

So here I was, sitting on a rock created before life on earth existed, brought here by a humongous flood around 15 thousand years ago, deposited on mountains uplifted 1.5 million years ago, created by a series of gigantic lava flows about 2 miles thick 6-15 million years ago.  And I think I am old at 67 years. As many of my Whizzy friends would say, “It’s a thinker.”

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