About Erratic Rock State Natural Site
This 90-ton rock, known as a glacial erratic, was transported over 500 miles by an iceberg during Ice Age floods 12,000 to 17,000 years ago, carried by the Columbia River into the Willamette Valley. When the ice melted, the rock was left behind, making it the largest glacial erratic discovered in the valley.
The rock is composed of a type of stone not native to Oregon, originating instead from the Northern Rocky Mountains. Its presence offers a tangible reminder of the massive glacial floods that once filled the valley, and visitors can view the surrounding landscape and envision the immense volumes of water that shaped the region.