I can hear you ask… What is a sedimentary boulder or erratic rock? Let me give you a little history lesson.
As we look back in history and look to where Canada is now. Yes, I know it has nothing to do with Oregon right now. But, Canada was once covered by a prehistoric sea. Over millions of years with climates changes it caused the continent to shift. I know you wonder why this made a difference to Oregon.
Well, when the continent shifted it caused a great flood known to us as the Missoula Floods which washed down into Oregon. Bringing billions of tons of sediment and hundreds of chunks of glacier and trapped rocks.
Erratic Rock received its name because of its mineral composition. It is different from any of the other native bedrock in Oregon. The erratic rock a type of sedimentary rock is made up of compressed particles that had been deposited on the floor of that prehistoric Canadian sea.
I know you are still wondering why I am talking about an erratic rock. Well, during the Missoula Floods and all the sediment, chunks of glacier and rocks that was deposited here in Oregon there has been about 400 erratics found in the Willamette Valley of Oregon. A 15×6-foot erratics rock was found just outside of McMinnville, in Yamhill County. It is the largest erratic rock known to date here in Oregon. This rock traveled all the way from the center of Canada in the Missoula Floods to Oregon.
It sits in its own state park of 4.5 acres know as the Erratic Rock Natural Site, just off highway 18. I know it may not mean to much to many of you. But, I find it interesting that a rock that size traveled that far.
If you find your self traveling through Oregon take a moment and stop and see a rock that is millions of years old.
Have a great day in Oregon!