Columbia River Basalts overlaying the Dale Tuff
The Dale tuff is a rhyolitic volcanic ash deposit outside of Dale, OR, which was formed by eruptions from the Tower Mountain caldera to the northeast (approx. 28 mya).
It was then later that eruptions of the Columbia River basalts flowed overtop of the Dale tuff (approx. 16 mya), creating the scene below.
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