Erratic Rock State Natural Site, Geological state park in Willamette Valley, Oregon, United States.
Erratic Rock State Natural Site is a geological park in Willamette Valley, Oregon, featuring a massive 40-ton rock sitting on a 250-foot hill surrounded by vineyards and farmland. From the top, visitors can see across to the Oregon Coast Range and the surrounding agricultural landscape.
The Missoula Floods began in western Montana 15,000 to 20,000 years ago and repeatedly inundated the Willamette Valley. The 40-short-ton argillite boulder was carried from Canada encased in an iceberg and dropped here as the ice melted. The Duerst and Ramsby families sold the land to the state in 1956, when it was named Erratic Rock Wayside; a new historical marker was dedicated in June 2005.
The rock's name reflects how people understand this unusual formation in the landscape as a glacial erratic, a boulder found far from its source. Its presence among vineyards and farms makes it a point of local interest and curiosity for both visitors and residents of the region.
The rock is reached via a paved trail about 0.2 miles long starting from the parking area on SW Oldsville Road near Oregon Route 18. Access is straightforward and the walk takes only a few minutes for most visitors.
The rock is estimated to be around 600 million years old and originated from an ancient sea floor, making it one of the oldest objects at this site. It remains the largest erratic of its kind in Willamette Valley, demonstrating the tremendous power of glacial forces to move such massive material across such distances.
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