“Steptoe Butte”
The Palouse, Washington
The Columbia River Lava flows make up most of the bedrock of the Palouse. Fifteen to eighteen million years ago fissures in southeastern Washington, northeastern Oregon, and southwestern Idaho spewed out great lava flows over the Columbia Basin. Steptoe Butte created by a metamorphic rock protrusion 400 million years ago rises 1000 feet above the lava flows.
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